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US-China Workshop for Early Career Chemical Scientists
——Supramolecular Chemistry
Tsinghua University, Beijing
October 26-31, 2009
US-China Workshop for Early Career Chemical Scientists ——Supramolecular Chemistry
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Table of Contents
Welcome Addresses………………………………………………………………………5
Prof. Dr. Jiannian Yao, Vice President, NSFC Prof. Dr. Chunli Bai, President, CCS Dr. Thomas H. Lane, President, ACS
Program…………………………………………………………………………………………..9
Abstract of Lectures (order of the program)
Xi Zhang (Tsinghua University)
Supramolecular Amphiphiles for Controlled Self-assembly and Disassembly………………………….15 Ronald K. Castellano (University of Florida)
Emerging Lessons from the Assembly of Donor-σ-Acceptor Molecules…………………………………17
Guangtao Li (Tsinghua University)
Functional Materials Based on Ordered Porous Structure………………………………………………..19
Linda S. Shimizu (University of South Carolina)
Porous Materials from Self-assembling Cyclic Ureas…………………………………………………..…21
Elsa C. Y. Yan (Yale University)
Probing Signal Transduction of G Protein-Coupled Receptors…………………………………………..23
Minghua Liu (Institute of Chemistry, CAS)
Design of L-Glutamic Acid Based Gelators and Their Corresponding Supramolecular Gels: Self-assembly and Functionalization…………………………………………………………………………25
José M. Rivera (University of Puerto Rico)
Adventures in Supramolecular Space: The Advent of Smart Self-assembled Supramolecules……………………………………………………..27
Table of Contents
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K. Travis Holman (Georgetown University)
Self-assembly and Electronic Modification of Container Molecules……………………………………29 Chuan-Feng Chen (Institute of Chemistry, CAS)
Novel Triptycene-Derived Hosts: Synthesis and Their Applications in Supramolecular Chemistry..31 Jovica D. Badjic (The Ohio State University)
Gated Molecular Encapsulation…………………………………………………………………………….33
Zhan-Ting Li (Shanghai Institute of Organic Chemistry, CAS)
Preorganized Aromatic Amide Oligomers: Toward the Development of a Novel Generation of Soft Frameworks……………………………………………………………………………………………………35
Adam R. Urbach (Trinity University)
Molecular Recognition and Sensing of Peptides by Self-assembled Receptors……………………….37
Feihe Huang (Zhejiang University)
Threaded Structures Based on Crown Ether Derivatives…………………………………………………39
Christopher W. Bielawski (The University of Texas)
N-Heterocyclic Carbenes: New Applications in Materials Chemistry……………………………….…41
Yuguo Ma (Peking University) Copper-Free Huisgen 1,3-Dipolar Cycloadditions in Crystals Mediated by Arene-Perfluoroarene Interaction………………………………………………………………………………………………………..43
Wei-Yin Sun (Nanjing University)
Metal Complexes with Multidentate Ligands: Structure Diversity and Anion Exchange Property….45 Amar H. Flood (Indiana University)
The Statics and Dynamics of Anion Supramolecular Chemistry: Artificial Anion-Binding Motifs and Mechanistic Studies of Motion…………………………………….47 Li-Zhu Wu (Technical Institute of Physics and Chemistry, CAS)
Highly Selective Photocyclodimerization of 2-Naphthalene Derivatives in Supramolecular Systems…………………………………………………………………………………………………………...49
Lei Zhu (Florida State University)
Fluorescent Heteroditopic Ligands for Zinc Ion……………………………………………………………51
Junqi Sun (Jilin University)
Rapid Fabrication of Layer-by-Layer Assembled Functional Films……………………………………..53
Table of Contents
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Karl J Wallace (The University of Southern Mississippi)
Squaraine Dyes: Their Use in Supramolecular Chemistry and Trace Element Detection…………….55
Shiyong Liu (University of Science and Technology of China)
Synthesis and Supramolecular Self-assembly of Responsive Polymers…………………………………57
Padma Gopalan (University of Wisconsin)
Directed Assembly of Block Copolymer Materials………………………………………………………...59
Yongfeng Zhou (Shanghai Jiao Tong University)
Supramolecular Self-assembly of Hyperbranched Polymers……………………………………………..61
List of Participants……………………………………………………………………….63
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Welcome Addresses
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Dear Colleagues: On behalf of National Natural Science Foundation of China (NSFC) I would like to extend my warmest welcome to all the participants of the China-US Workshop for Early Career Chemists on Supramolecular Chemistry 2009. Such series workshop is initiated by NSFC, National Science Foundation (NSF) of US and the American Chemical Society (ACS), financially supported by NSFC and NSF. The workshop will bring together outstanding young chemists of supramolecular chemistry from both countries. They will take this opportunity to present their new research work and discuss the frontier topics of supramolecular chemistry in different aspects. Inspired by biological systems, supramolecular chemistry aims at developing highly complex chemical systems from components interacting by non-covalent intermolecular forces, and over last two decades has grown into a major domain of modern teaching, research and technology with a broad multidisciplinary and interdisciplinary characteristic. In this field, USA is a strong nation, while the related research in China is also developing very fast in recent years. Scientific communication and international networking are crucial for the success of the global scientific development. The major goal of the present China-US workshop is just to build such a platform and to advance the scientific communication between chemists from both sides, especially young chemists, to establish lasting relationship and to promote international collaborations between the two countries. I sincerely congratulate the opening of China-US Workshop for Early Career Chemists on Supramolecular Chemistry, and wish every success of this workshop. Once again welcome to Beijing and enjoy your stay during the workshop.
Prof. Dr. Jiannian Yao Vice President of National Natural Science Foundation of China
Welcome Addresses
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Dear Colleagues: I am pleased to welcome all of you to come over Beijing for China-US Workshops for Early Career Chemical Scientists--- Supramolecular Chemistry, and ---New Materials and sincerely wish every success of the two workshops. This workshop series has been funded jointly by the Chinese National Natural Science Foundation (NSFC) and the US National Science Foundation (NSF). The first workshop took place in Shanghai in May of 2007 with the theme of Chemical Biology. The workshop is designed for young chemists from both countries, because you will be the main force of future chemistry. Chemistry research in China has gained rapid progress these past years. This progress benefits from the favorable policy of promoting Chinese science and technology toward making China an innovative country. With the help of the great increase of research funding by the Chinese government, we have provided better research facilities for chemists and attracted more chemists to devote to their research. Although Chinese chemists have accomplished significant progress in some fields of the chemistry, we are also clear that to enhance the quality of research, there are more things to be done than just to increase the number of papers. Therefore, I hope that Chinese scientists are eager to face the major challenge of chemistry and to do more creative work for advancing chemistry and promoting technology transfer. The US has been one of the leading countries in chemistry research and education. In addition, you have the tradition to combine chemical research and industry closely. I am happy to see that the communication and collaboration between the two countries are becoming more and more frequent and tight. Hopefully, young chemists from both countries are able to take the opportunity of these bilateral China-US workshops by exchanging your ideas and sharing your update research progress. More importantly, you may take the full time of round table discussion to find common interests and work together in the future, thus enhancing the existing collaboration. I promise you that I will try my best to push forward the communication and collaboration between US and China in the field of chemistry research. Let me thank the joint-organizing committee of Chinese Chemical Society, American Chemical Society, Tsinghua University, and Peking University for their time and effort in organizing such a nice communication platform. Last but not least, I want to thank NSFC and NSF for their financial support.
Prof. Chunli Bai President of Chinese Chemical Society Executive Vice President of Chinese Academy of Sciences
Welcome Addresses
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Dear Colleagues: On behalf of the American Chemical Society I extend my warmest welcome to the participants of the US-China Workshops for Early Career Chemical Scientists. This outstanding workshop series was developed to foster sustainable ties between researchers in the US and China, to tackle some of society’s greatest challenges through collaborative research. Funded jointly by the US National Science Foundation and the National Natural Science Foundation of China, the series emphasizes the priority placed by our countries on the cutting-edge work being done by leading early career chemical scientists; resolving some of our toughest challenges through chemistry-related breakthroughs. The first workshop in the series took place in 2007 in Shanghai, and was a great success in bringing together top researchers in the field of Chemical Biology. This week the second and third workshops in this series will take place in Beijing, which involve New Materials, with sub-themes of Energy, Bio/Med and Nano and Supramolecular Chemistry. These fields of Chemistry are of great interest and advancement at this time, and are critical to the resolution of myriad global challenges faced by the world today. I would like to thank our partners from the Chinese Chemical Society, Peking University and Tsinghua University for their excellent work in the organization of these workshops. Thanks to their efforts in designating time for both technical sessions as well as roundtable discussion, the workshops have great potential not only to foster academic exchange at the meeting itself but also to jump-start long-term collaborations that may be sustained throughout your careers. I hope that you enjoy the presentations and dynamic discussions during the workshops as well as the beautiful surroundings and historic sites of Beijing. Best wishes for your continued success.
Thomas H. Lane, Ph.D. President American Chemical Society
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US-China Workshop for Early Career Chemical Scientists
——SUPRAMOLECULAR CHEMISTRY Wenjin Hotel, Beijing, China
(Oct. 26-31, 2009)
October 26 (Monday)
Registration: 9:00-18:00, Wenjin Hotel
Reception: 18:00, Wenjin Hotel
October 27 (Tuesday)
Chair Xi Zhang
9:00-9:30 Opening Ceremony 9:30-10:00 Tea Break
Chair Minghua Liu 10:00-10:30 Xi Zhang (Tsinghua University)
Supramolecular Amphiphiles for Controlled Self-assembly and Disassembly
10:30-11:00 Ronald K. Castellano (University of Florida)
Emerging Lessons from the Assembly of Donor-σ-Acceptor Molecules
11:00-11:30 Guangtao Li (Tsinghua University)
Functional Materials Based on Ordered Porous Structure
11:30-12:00 Linda S. Shimizu (University of South Carolina)
Porous Materials from Self-assembling Cyclic Ureas
12:00-14:00 Lunch
Chair Christopher W. Bielawski 14:00-14:30 Elsa C. Y. Yan (Yale University)
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Probing Signal Transduction of G Protein-Coupled Receptors
14:30-15:00 Minghua Liu (Institute of Chemistry, CAS)
Design of L-Glutamic Acid Based Gelators and Their Corresponding Supramolecular Gels: Self-assembly and Functionalization
15:00-15:30 José M. Rivera (University of Puerto Rico)
Adventures in Supramolecular Space: The Advent of Smart Self-assembled Supramolecules
15:30-16:00 Tea Break
16:00-18:00 Round Table Discussion
18:00 Dinner
October 28 (Wednesday)
Chair Li-Zhu Wu
8:30-9:00 K. Travis Holman (Georgetown University)
Self-assembly and Electronic Modification of Container Molecules 9:00-9:30 Chuan-Feng Chen (Institute of Chemistry, CAS)
Novel Triptycene-Derived Hosts: Synthesis and Their Applications in Supramolecular Chemistry
9:30-10:00 Jovica D. Badjic (The Ohio State University)
Gated Molecular Encapsulation
10:00-10:30 Tea Break Chair Ronald K. Castellano 10:30-11:00 Zhan-Ting Li (Shanghai Institute of Organic Chemistry, CAS)
Preorganized Aromatic Amide Oligomers: Toward the Development of a Novel Generation of Soft Frameworks
11:00-11:30 Adam R. Urbach (Trinity University)
Molecular Recognition and Sensing of Peptides by Self-assembled Receptors
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11:30-12:00 Feihe Huang (Zhejiang University)
Threaded Structures Based on Crown Ether Derivatives
12:00-14:00 Lunch
Chair Zhan-Ting Li 14:00-14:30 Christopher W. Bielawski (The University of Texas)
N-Heterocyclic Carbenes: New Applications in Materials Chemistry
14:30-15:00 Yuguo Ma (Peking University)
Copper-Free Huisgen 1,3-Dipolar Cycloadditions in Crystals Mediated by Arene-Perfluoroarene Interaction
15:00-15:30 Tea Break
15:30-17:30 Round Table Discussion
17:30 Dinner
October 29 (Thursday)
Chair José M. Rivera
8:30-9:00 Wei-Yin Sun (Nanjing University)
Metal Complexes with Multidentate Ligands: Structure Diversity and Anion Exchange Property
9:00-9:30 Amar H. Flood (Indiana University)
The Statics and Dynamics of Anion Supramolecular Chemistry: Artificial Anion-Binding Motifs and Mechanistic Studies of Motion
9:30-10:00 Li-Zhu Wu (Technical Institute of Physics and Chemistry,
CAS)
Highly Selective Photocyclodimerization of 2-Naphthalene Derivatives in Supramolecular Systems
10:00-10:30 Tea Break Chair Shiyong Liu
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10:30-11:00 Lei Zhu (Florida State University)
Fluorescent Heteroditopic Ligands for Zinc Ion
11:00-11:30 Junqi Sun (Jilin University)
Rapid Fabrication of Layer-by-Layer Assembled Functional Films
11:30-12:00 Karl J. Wallace (The University of Southern Mississippi)
Squaraine Dyes: Their Use in Supramolecular Chemistry and Trace Element Detection
12:00-14:00 Lunch
Chair K. Travis Holman 14:00-14:30 Shiyong Liu (University of Science and Technology of China)
Synthesis and Supramolecular Self-assembly of Responsive Polymers
14:30-15:00 Padma Gopalan (University of Wisconsin)
Directed Assembly of Block Copolymer Materials
15:00-15:30 Yongfeng Zhou (Shanghai Jiao Tong University)
Supramolecular Self-assembly of Hyperbranched Polymers
15:30-16:00 Tea Break
16:00-18:00 Round Table Discussion
18:00 Dinner
October 30 (Friday) Sightseeing in Beijing
October 31 (Saturday) Departure
Abstracts of Lectures (order of the program)
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Supramolecular Amphiphiles for Controlled Self-assembly and Disassembly
Xi Zhang *, Yapei Wang, Chao Wang, Huaping Xu Department of Chemistry, Tsinghua University, Beijing, China, 100084
e-mail: [email protected]
Amphiphilicity is one of the molecular bases for self-assembly. By tuning the amphiphilicity of the
building blocks, controllable self-assembly and disassembly can be realized. As shown in Fig. 1, in general,
there are two methods, reversible or irreversible, that can be applied to adjust amphiphilicity of the building
blocks. The irreversible methods can convert amphiphilic building blocks to either hydrophilic or
hydrophobic by various chemical approaches, e.g. photochemistry. There are also reversible methods that
can be used to tune the amphiphilicty reversibly. In this respect, reversible stimuli-responsive chemistry
and supramolecular chemistry are involved. Conversion between hydrophilic and hydrophobic parameters
allows for reversible self-assembly and disassembly.
SupramolecularChemistry
Reversible
SupramolecularChemistry
Reversible Reversible
Photochemistry
Irreversible Reversible
Photochemistry
Irreversible
Photochemistry
Irreversible
AmphiphilicityAmphiphilicity
Fig. 1: Schematic illustration of the general methods for tuning the amphiphilicity of the building blocks.
This presentation will discuss how to employ supramolecular amphiphiles for controlled self-assembly and
disassembly. supramolecular amphiphiles refer to amphiphiles that are ‘synthesized’ by non-covalent
interactions. Among different non-covalent interactions, host-guest interaction has aroused particular
interest for its specificity and reversibility. In our work, an azobenzene-containing surfactant can form a
supramolecular amphiphile with α-CD driven by the host-guest interactions. Upon photo stimuli, the
host-guest interactions can be manipulated reversibly through the photoisomerizaiton of azobenzene.
Therefore, α-CD can move between the azobenzene head group and the alkyl chain to change the
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amphiphilicity of the supramolecular amphiphile, further tuning the aggregation behavior reversibly.
Apart from classical noncovalent interactions, we have also employed charge-transfer interaction between
electron donor and acceptor as a new driving force to tune the amphiphilicity of the supramolecular
amphiphile. For this purpose, we have designed and synthesized a surfactant (PYR) containing
electron-rich pyrene group. PYR can form a supramolecular amphiphile with a hydrophobic electron
acceptor (DNB) driven by charge transfer interactions. An interesting finding is that the introduction of
charge-transfer interaction into the supramolecular assembly results in a transformation from tubes-like to
vesicles. Therefore, supramolecular amphiphile could be a general concept for fabricating supramolecular
soft materials with tailor-made nanostructure and adaptive functions.
Keywords: Supramolecular amphiphiles, amphiphilicity, host-guest interactions, charge transfer interactions, self-assembly References [1] Y. P. Wang, H. P. Xu, X. Zhang, Tuning the amphiphilicity of building blocks: controlled self-assembly and
disassembly for functional supramolecular materials, Adv. Mater. 2009, 21, 2849.
[2] Y. P. Wang, N. Ma, Z. Q. Wang, X. Zhang, Photo-controlled reversible supramolecular assembly of an
azobenzene-containing surfactant with α-cyclodextrin, Angew. Chem. Int. Ed. 2007, 46, 2823.
[3] C. Wang, S. C. Yin, S. L. Chen, H. P. Xu, Z. Q. Wang, X. Zhang, Controlled self-assembly manipulated by charge
transfer interaction: from tubes to vesicles, Angew. Chem. Int. Ed. 2008, 47, 9049.
Brief Curriculum Vitae of the speaker Prof. Xi Zhang earned his Ph.D. (1992) in the field of polymer chemistry and physics under the joint-supervision of Prof. Jiacong Shen, Jilin University and Prof. Helmut Ringsdorf, University of Mainz, Germany. He worked at Key Lab of Supramolecular Structure and Materials, Jilin University as a lecturer and then full professor from 1992 to 2004. Since 2004, he is a full professor of the Department of Chemistry, Tsinghua University, Beijing. He is senior editor of Langmuir and has served as Editorial Board Members of several journals, including Chemical Communications. In 2007, he was selected as a member of Chinese
Academy of Sciences. His research interests are focused on supramolecular assembly, polymer thin films, and single-molecular force spectroscopy of polymers.
Emerging Lessons from the Assembly of Donor-σ-Acceptor Molecules
Y. Li,1 L. Yuan,1 M. B. Baker,1 A. J. Lampkins,1 B. G. Sumpter,2 V. Meunier,2 K. A. Abboud,1 and Ronald K. Castellano*,1
1 Department of Chemistry, P. O. Box 117200, University of Florida, Gainesville, FL 32611, USA; 2Computer Science and Mathematics Division and Center for Nanophase Materials
Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA e-mail: [email protected]
The development of organic molecules for electronic, optoelectronic, and materials applications has been
well-served by an appreciation of intermolecular interactions and the ability to tailor structure/organization
in solution and in the bulk. Over the past several years we have explored how seemingly weak
through-bond donor–acceptor interactions
within saturated molecules can strongly affect
their self-assembly, macromolecular behavior,
and emergent electronic structure. Among the
more recent “donor-σ-acceptor” molecules
explored are amide-functionalized 1-aza-adamantanetriones (AATs) 1 (Fig. 1a), many of which
self-assemble to form transparent gels in organic solution (Fig. 1b) and fibrous structures in the solid state
(Fig. 1c). While the assembly behavior observed is generally complex, it does respond predictably to
changes in molecular structure. That aromatic stacking interactions are important, for example, is shown
through the more robust solution-phase aggregation of naphthyl derivative 1b versus phenyl derivative 1a,
an experimental finding that agrees well with dimer binding energies predicted from gas phase (MBPT)
calculations (i.e., 2.4Edimer(1a) = Edimer(1b)). Our current efforts in this area are leveraged by synthetic
access to 1 in two steps from tribenzofuranone,
a recently introduced molecule whose
properties and potential applications will also
be discussed.
High-level theory further reveals the electronic structure that can accompany self-assembly of
donor-σ-acceptor molecules in the gas phase, and points to opportunities for such systems in
“supramolecular electronics”. In particular, periodic plane-wave pseudopotential calculations have been
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Salutes to Excellence Award (2007).
used to predict the properties of 1-D arrangements of 1a and 1b. A short intercore distance (4.9 Å)
defines the molecular stacking of 1b (Fig. 2a), wherein theory predicts orbital delocalization through both
the cores (LUMO) and the peripheral naphthyl groups (triply-degenerate HOMO). Along these lines, the
calculated band structure for (1b)6 (Fig. 2b) shows significant dispersion, a direct bandgap of ~ 1.5 eV, and
an indirect bandgap of 0.98 eV, all features typically discussed in the context of π-conjugated materials and
organic electronic devices.
Keywords: donor-acceptor interactions, N- and O-containing heterocycles, phloroglucinol, self-assembly, stereoelectronic effects, through-bond interactions References [1] Y. Li, A. J. Lampkins, M. B. Baker, B. G. Sumpter, J. Huang, K. A. Abboud, R. K. Castellano, Benzotrifuranone:
Synthesis, structure, and access to polycyclic heteroaromatics, Org. Lett. 2009, ASAP.
[2] A. J. Lampkins, Y. Li, A. Al Abbas, K. A. Abboud, I. Ghiviriga, R. K. Castellano, Assessable consequences of
through-bond donor–acceptor interactions in β-aminoketones, Chem. Eur. J. 2008, 14, 1452.
[3] B. G. Sumpter, V. Meunier, E. F. Valeev, A. J. Lampkins, H. Li, R. K. Castellano, A new class of supramolecular wires,
J. Phys. Chem. C 2007, 111, 18912.
Brief Curriculum Vitae of the speaker Ron Castellano obtained his B.S. degree in chemistry from Gettysburg College in 1995, and a Ph.D. from the Massachusetts Institute of Technology (2000) working with Julius Rebek, Jr. For the next two years he was an NSF postdoctoral fellow in the labs of Prof. François Diederich at the Swiss Federal Institute of Technology (ETH) in Zürich. Ron joined the faculty of the University of Florida (UF) in 2002 where he is currently an Associate Professor of Chemistry. His research interests include the design and synthesis of functional small-molecule and supramolecular architectures, the optical and
electronic properties of donor–acceptor systems, and stereoelectronic interactions in self-assembly. Since arriving at UF he has received a Research Corporation Research Innovation Award (2003), an NSF CAREER Award (2006), and an ACS
Functional Materials Based on Ordered Porous Structure
Guangtao Li *, Xiaobin Hu, Weixia Zhang, Wei Zhu Department of Chemistry, Tsinghua University, Beijing, China, 100084
e-mail: [email protected]
Ordered macro- or nanoporous structure is characterized with a series of features, including large specific
surface area, high mass transport, space confinement and unique optical properties. Such distinct features
make ordered porous structure ideal as versatile platform for designing and constructing chemical systems
or advanced functional materials. In our laboratory, based on the ordered porous structure, a general
strategy to construct such high-performance sensors was developed, which enable quickly, easily,
sensitively and directly to report recognition event by a change of absorption color without any transducers
and treatments for analytes (chiral drugs, viruses, amino acids and proteins). In addition, using porous
structure as nanoreactor, uniform carbon nanofibers with diameter below 1nm and pure single-layer
graphenes were efficiently fabricated.
Fig. 1: Schematic illustration of the fabrication of pure single-layer graphene.
Keywords: Ordered porous structure, Self-assembly, Photonic, Molecular imprinting, Nanocable, Chemical sensor, Molecule gating, Nanostructured carbon References [1] W. X. Zhang, J. C. Cui, C. A. Tao, Y. G. Wu, Z. P. Li, L. Ma, Y. Q. Wen, G. T. Li, Angew. Chem. Int. Ed. 2009, 48, 5773.
[2] W. X. Zhang, J. C. Cui, C. A. Tao, C. X. Lin, Y. G. Wu, G. T. Li, Langmuir 2009, 25, 8235.
[3] W. X. Zhang, J. C. Cui, C. X. Lin, Y. G. Wu, L Ma, Y. Q. Wen, G. T. Li, J. Mater. Chem. 2009, 19, 3962.
[4] X. B. Hu, J. Huang, W. X. Zhang, M. H. Li, C. A. Tao, G. T. Li, Adv. Mater. 2008, 20, 4074.
[5] X. B. Hu, G. T. Li, M. H. Li, J. Huang, Y. Li, Y. B. Gao, Y. H. Zhang, Adv. Funct. Mater. 2008, 18, 575.
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[6] Z. Wu, C. A. Tao, C. X. Lin, D. Z. Shen, G. T. Li, Chem. Eur. J. 2008, 14, 11385.
[7] Z. Wu, X. B. Hu, C. A. Tao, Y.Li, J. Liu, C. D. Yang, G. T. Li, J. Mater. Chem. 2008, 18, 5452.
[8] X. B. Hu, G. T. Li, J. Huang, D. Zhang, Y. Qiu, Adv. Mater. 2007, 19, 4327.
[9] X. B. Hu, Q. An, G. T. Li, S. Y. Tao, J. Liu, Angew. Chem. Int. Ed. 2006, 45, 8145.
[10] G. T. Li, S. Bhosale, T. Y. Wang, Y. Zhang, H. S. Zhu J. H. Fuhrhop, Angew. Chem. Int. Ed. 2003, 42, 3813.
Brief Curriculum Vitae of the speaker Dr. Guangtao Li was born in 1965, graduated from the Department of Chemical Engineering, Beijing Institute of Technology in 1986, received his Ph.D from the Institute of Organic Chemistry, Free University of Berlin, Germany in 1999 with Prof. G. Kossmehl. He then jointed the group of Prof. J.H. Fuhrhop at the same university as Postdoc and stayed until 2003. Now, he is a full Professor of the Department of Chemistry, Tsinghua University. His research interests are focused on the electrochemistry of conjugated polymers, dye chemistry, and the fabrication of functional
nanostructured materials and chemical systems using molecular self-assembly approach.
Porous Materials from Self-assembling Cyclic Ureas
Linda S. Shimizu Department of Chemistry and Biochemistry, University of South Carolina, SC, USA, 29208
e-mail: [email protected]
We are interested in developing homogeneous porous materials with functionalized cavities for use as confined
environments for reactions. Simple, rigid macrocyclic bis-ureas reliably self-assembled to form columnar
structures containing channels of predetermined dimensions. The self-assembly of these monomers is directed
by the formation of strong urea-urea hydrogen bond and by the stacking of the aromatic surfaces in the linkers.
This approach allows one to control the size, structure, and functionality of the channel by altering the structure
of a small molecule, a macrocyclic bis-urea. These porous crystals can reversibly absorb guest molecules,
much like zeolites. For example, crystals of 1 absorbed α,β-unsaturated ketones and facilitated their highly
stereoselective head-to-tail [2+2] photodimerizations in high conversion. While bis-urea 2 promoted the
photoisomerization of trans-β-methyl-styrene. We examined a series of bis-ureas varying the size, shape and
interior functional groups to probe the limits of this structural motif. Recently our group has synthesized
pyridine and bipyridine functionalized bis-urea macrocycles that are capable of binding metal cations.
Potentially, these monomers can be guided via three interactions (metal-ligand, hydrogen bonding and aryl
stacking) into highly ordered functional materials.
self-assembly
Guest Absorption
ProductExtraction
Porous Crystals
Guest-filled Crystals
DissolveAssembly
Reaction
Product-filled Crystals
1: X = O 2: X = C=O
3: X =
X
NH
O
X
NH
HN
HN
O
Fig. 1: Bis-urea macrocycles stack into columns and pack against each other to form crystals that display permanent porosity. These crystals reversibly absorb guests and can be used as confined environments for
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reactions. Keywords: Self-assembly, host-guest interactions, crystal engineering, nanoreactors, solid-state photochemistry References [1] J. Yang, M. B. Dewal, D. Sobransingh, Y. Xu, M. D. Smith, L. S. Shimizu, An examination of the structural features
that favor the columnar assembly of bis-urea macrocycles, J. Org. Chem. 2009, 74, 102.
[2] M. B. Dewal, Y. Xu, J. Yang, F. Mohammed, M. D. Smith, L. S. Shimizu, Manipulating the cavity of a porous material
changes the photoreactivity of included guests, Chem. Commun. 2008, 3909.
[3] J. Yang, M. B. Dewal, S. Profeta, Y. Li, M. D. Smith, L. S., Origins of selectivity for the [2+2] cycloadditions of
α,β-unsaturated ketones within a porous self-assembled organic framework, J. Am. Chem. Soc. 2008, 130, 612.
[4] M. B. Dewal, M. W. Lufaso, A. D. Hughes, S. A. Samuel, P. Pellechia, L. S. Shimizu, Absorption properties of a porous
organic crystalline apohost fromed by a self-assembled bis-urea macrocycle. Chem. Mater. 2006, 18, 4855
Brief Curriculum Vitae of the speaker Prof. Linda Shimizu earned her Ph.D. in 1997 in peptide synthesis and conformational analysis under the direction of Prof. Daniel S. Kemp at the Massachusetts Institute of Technology. She was an NIH post-doctoral Fellow with Prof. John Essigmann also at M. I. T. She relocated to the University of South Carolina for family reasons and worked part-time as a research assistant professor, adjunct instructor, and consultant and secured external funding through the National Science Foundation. In 2005, she was appointed as an Assistant Professor on the tenure-track at the
University of South Carolina. Her research interests are focused on functional self-assembled organic materials, photochemistry, and reactions in confined environments.
Probing Signal Transduction of G Protein-Coupled Receptors
Elsa C. Y. Yan *, Nivedita Mitra, Evgeny Serebryany, Harrison Xiao Bai Department of Chemistry, Yale University, New Haven, CT06511
e-mail: [email protected]
G protein-coupled receptors (GPCRs) belong to the largest gene family in the human genome and represent an
important class of drug targets in pharmaceutical industry. GPCRs bind to their native ligands and convey the
signals across the membranes by changing their conformations. Functioning as chemical detectors in cell
membranes, they constitute the most important and diverse signaling pathways for cell communication. We
focus on developing biophysical methods for probing conformational changes of GPCRs responsible for the
signal transduction process. We use a bioreactor to culture mammalian cells to express GPCRs in milligram
quantity and develop method to purify GPCRs using nanoscale lipid bilayer disc particles (NanoDiscs). We
apply unnatural amino acid mutagenesis to site-specifically incorporate spectroscopic probes into GPCRs.
Because purification of GPCRs in the quality and quantity that allows biophysical studies is one of the biggest
challenges in studying structure and activity of this important class of proteins, our approach could potentially
provide a breakthrough to obtain highly selective spectroscopic readout to investigate conformational changes
of GPCRs. The results will provide insight into molecular mechanism of transmembrane signal transduction
and development of cell-free molecular assays for screening drug candidates.
(a) (b)
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Fig. 1: (a) Nanodiscs are disc-shaped lipid bilayers in a diameter of 10-15 nm wrapped around by a helical
scaffold protein. They stabilize G protein-coupled receptors in lipid environments for biophysical studies. (b)
Unnatural amino acids are in vivo incorporated into recombinant proteins using a genetic approach.
Keywords: nanoscale lipid bilayer disc particles, NanoDiscs, G protein-coupled receptors, biophysical spectroscopy, unnatural amino acid mutagenesis References [1] S. Ye, C. Köhrer, T. Huber, M. Kazmi, E. C. Y. Yan, P. Sachdev, A. Bhagat, U. L. RajBhandary, T. P. Sakmar, Site-specific
Incorporation of Keto Amino Acids Into Functional G Protein-Coupled Receptors Using Unnatural Amino Acid
Mutagenesis J. Biol. Chem. 2008, 283, 1525
[2] T. H. Bayburt; Y. V. Grinkova; S. G. Sligar, Self-assembly of discoidal phoaspholipid bilayer nanoparticles with
membrane scaffold proteins Nano Lett. 2002, 2, 853
Brief Curriculum Vitae of the speaker Elsa Yan was born and grew up in Hong Kong. She graduated in the Chinese University of Hong Kong in 1995. Working with Kenneth Eisenthal on nonlinear optics and surface sciences, she obtained her Ph.D. at Columbia University in 2000. From 2000-2004, she was a postdoctoral fellow in Richard Mathies's lab at UC Berkeley and a visiting fellow in Thomas Sakmar's lab at the Rockfeller Univeresity. She combined Raman spectroscopy with techniques in molecular biology to understand the molecular mechanism of signal transduction in G protein coupled receptor rhodopsin. In 2004, she joined The
Rockefeller University, where she continued to develop methods in expression and purification of membrane proteins. In 2007, Elsa became an Assistant Professor of Chemistry at Yale University. She focuses on applying biophysical spectroscopy to investigate biomolecular interactions.
Design of L-Glutamic Acid Based Gelators and Their Corresponding
Supramolecular Gels: Self-assembly and Functionalization
Minghua Liu *, Pengfei Duan, Yuangang Li, Jian Jiang Institute of Chemistry, The Chinese Academy of Sciences, Beijing, China, 100091
e-mail: [email protected]
Recently, there is an increasing interest in the Low-molecular-weight organogelators (LMOGs), which form
supramolecular gels with various organic solvents. Upon gelation, the organogelators self-assembly into
various nanostructures such as fiber, tape, ribbons, platelets, tubular structure and so on, which formed
highly anisotropic 3-D network and immobilize the organic solvents. These nanostructures together with
the solvents formed soft materials, which could show various functionality. In addition, the
nanostructures formed through the gelation can be further used as the template to synthesize other nano
materials. This presentation showed our recent results on how to design gelator molecules and
functionalize the supramolecular gels. We have designed a series of L-glutamic acid based gelators,
including the bolaamphiphilic gelators, two-alkyl chain derivatives (LBG) and dendritic glutamic acid
derivatives and so on, as shown in Scheme 1. These gelator molecules could form various gels with water
or organic solvents and their functionality was investigated.
Fig. 1. The L-glutamic acid based gelators and AFM pictures of the organogels of LBG.
Bolaamphiphilic EDGA could gel a 1 : 1 mixture of alcohol–water and self-assembles into a helical
spherical-nanotube, the wall of which is composed of a monolayer. Double- and multi-wall silver
nanotubes were synthesized by using the uniform nanotubes as the template.
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LBG can gel nearly all kinds of common organic solvents. Furthermore, the gelators could also
form organogels with other functional compounds, which could not form the organogel individually, when
mixing with the compounds. For example, LBG could gel an achiral porphyrin derivative and transfer the
chirality to the formed porphyrin aggregates. We have also prepared chiral silver nanoparticles and chiral
silver nanoparticulated films using silver(I) ion-coordinated organogel as templates by in situ reduction.
The designed L-glutamate based dendrons contains aromatic cores, ranged from phenyl, naphthyl to
anthryl. They are good ambidextrous gelator, which could form organogels in hexane and simultaneously
formed the hydrogels in water.
Keywords: Supramolecular gels, chirality, lower molecular-weight organogel, hydrogel, self-assembly References [1] P. F. Duan, M. H. Liu, Design and Self-Assembly of L-Glutamate-Based Aromatic Dendrons as Ambidextrous
Gelators of Water and Organic Solvents. Langmuir 2009, 25, 8706.
[2] T. Y. Wang, Y. G. Li, M. H. Liu, Gelation and self-assembly of glutamate bolaamphiphiles with hybrid linkers:
effect of the aromatic ring and alkyl spacers, Soft Matter 2009, 5, 1066.
[3] Y. G. Li, M. H. Liu, Fabrication of chiral silver nanoparticles and chiral nanoparticulate film via organogel,
Chem. Commun. 2008, 5571
[4] Y. G. Li, T. Y. Wang, M. H. Liu, Gelating-induced supramolecular chirality of achiral porphyrins: chiroptical
switch between achiral molecules and chiral assemblies, Soft Matter 2007, 3, 1312
[5] P. Gao, C. L. Zhan. M. H. Liu, Controlled synthesis of double- and multiwall silver nanotubes with template
organogel from a bolaamphiphile, Langmuir 2006, 22, 775
[6] C. L. Zhan,.P. Gao, M. H. Liu, Self-assembled helical spherical-nanotubes from an L-glutamic acid based
bolaamphiphilic low molecular mass organogelator, Chem. Commun. 2005, 462.
Brief Curriculum Vitae of the speaker
Prof. Minghua Liu received his Ph.D. (1994) in the colloid and interface science in Saitama University with Prof. Kiyoshige Fukuda. He then joined the Institute of physical and chemical research (RIKEN) as a special postdoctoral researcher in RIKEN for three year. In 1998, he returned to Institute of photographic chemistry, Chinese Academy of Sciences (CAS). Since 1999, he is a full professor of the Institute of Chemistry, CAS. He is the advisory member of Langmuir and Soft Matter. His research interests are focused on supramolecular assemblies in relating with the supramolecular chirality, Langmuir-Blodgett films based on the new-type amphiphiles such as bolaamphiphile and Gemini amphiphiles, supramolecular gel-based soft materials.
Adventures in Supramolecular Space:
The Advent of Smart Self-Assembled Supramolecules
José M. Rivera Department of Chemistry, University of Puerto Rico, Río Piedras Campus,
San Juan, Puerto Rico 00931 e-mail: [email protected]
The bottom-up approach to the construction of supramolecular nanostructures requires the availability of
recognition motifs that are easy to synthesize and self-assemble with good selectivity and fidelity. The guanine
base (G) stands out as an excellent candidate for such purposes since it can form tetrameric structures that
self-assemble in the presence of a variety of cations to form higher ordered structures known as G-quadruplexes.
Our strategy for nanoconstruction relies on the use of recognition motifs made from 8-arylguanine derivatives
(8ArGs) that are relatively easy to make and offer robust and reliable self-recognition properties in both organic
and aqueous media. Our results indicate that the properties of the resulting supramolecular assemblies can be
modulated by parameters that are intrinsic (i.e. structural features) or extrinsic (environmental conditions such as
solvent, temperature, cation template, etc.) to the 8ArGs. The use of intrinsic parameters to drive the formation
enables the reliable construction of a desired assembly with relative independence from the environmental
conditions. Modulation of extrinsic parameters, on the other hand, enable the elaboration of responsive systems
that switch their state as a function of external stimuli. The usefulness of these 8ArGs will be highlighted by
their use in the development of smart supramolecular nanostructures like self-assembled dendrimers and
self-assembled ligands.
Keywords: supramolecular, self-assembly, G-quadruplexes, smart-materials References [1] Rivera-Sánchez, M.C.; Andújar-de-Sanctis, I.; García-Arriaga, M.; Gubala, V.; Hobley, G.; Rivera, J. M. Walking a
supramolecular tightrope: A Self-Assembled Dodecamer from an 8-Aryl-2’-deoxyguanosine Derivative J. Am. Chem.
Soc. 2009, 131, 10403–10405.
[2] Betancourt, J. E.; Martín-Hidalgo, M.; Gubala, V.; Rivera, J. M. Solvent-Induced High Fidelity Switching Between two
Discrete Supramolecules J. Am. Chem. Soc. 2009, 131, 3186–3188.
[3] García-Arriaga, M.; Hobley, G.; Rivera, J. M. Isostructural Self-Assembly of 2'-Deoxyguanosine Derivatives in
Aqueous and Organic Media J. Am. Chem. Soc. 2008, 130, 10492–10493.
[4] Betancourt, J. E.; Rivera, J. M. Hexadecameric Self-Assembled Dendrimers Built from 2'- Deoxyguanosine
Derivatives Org. Lett. 2008, 10, 2287-2290.
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s for biomedical applications.
Brief Curriculum Vitae of the speaker José M. Rivera obtained his B.S. in chemistry from the University of Puerto Rico at Río Piedras in 1995 and his Ph.D. from MIT in 2000 working under the guidance of Julius Rebek, Jr. After a postdoctoral experience in the group of Jeffery Kelly at The Scripps Research Institute in La Jolla, he moved back to the University of Puerto Rico at Río Piedras in 2002 where he is currently an Associate Professor. His research interests are focused on supramolecular science, in particular, on the use guanine derivatives to
elucidate fundamental self-assembly phenomena and to develop multifunctional nanostructure
Self-Assembly and Electronic Modification of Container Molecules
K. Travis Holman*, Robert M. Fairchild, Onome Ugono, Sayon A. Kumalah, Scott T. Mough Department of Chemistry, Georgetown University, Washington, DC, USA, 20057
e-mail: [email protected]
Container molecules are a family of hollow, spheroidal, typically rigid molecules that, as the name suggests,
possess the ability to encapsulate other chemical species. As such, they may selectively bind, store,
protect, transport, or organize molecular substrates for a variety of conceivable applications—e.g. catalysis,
separations, sensing, storage, etc. This presentation will highlight some contributions to supramolecular
container-molecule chemistry from the Holman research group at Georgetown University, from addressing
synthetic challenges via approaches of self-assembly, to their use in metal-organic/coordination polymer
chemistry, to their interior/exterior modification for the purposes of affecting the electronic structure of
their interiors.
= 0°θ
Keywords: container molecules, cryptophanes, cavitands, self-assembly, anion-pi interactions References [1] S. A. Kumalah, K. T. Holman, Polymorphism and Inclusion Properties of 3D Metal-Organometallic Frameworks of
an η-6-Metalated Terephthalate Ligand, Inorg. Chem. 2009, 48, 6860-6872
[2] R. M. Fairchild, K. T. Holman, [(η5-C5Me4CH2R)Ru(η6-arene)]+ and [(η5-C5Me4CH2R)Ru(CH3CN)3]+ Compounds
Possessing Pendant Arms, Organometallics 2008, 27, 1823-1833
[3] S. T. Mough, K. T. Holman, A soft coordination polymer derived from container molecule ligands, Chem. Commun.
2008, 1407-1409
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[4] O. Ugono, J. P. Moran, K. T. Holman, Chiral, closed-surface, metal-organic nanocapsules derived from cavitand
ligands, Chem. Commun. 2008, 1404-1406
[5] O. Ugono, K. T. Holman, An achiral form of the hexameric resorcin[4]arene capsule sustained by hydrogen bonding
with alcohols, Chem. Commun. 2006, 2144-2146
[6] R. M. Fairchild, K. T. Holman, Selective anion encapsulation by a metalated cryptophane with a π-acidic interior, J.
Am. Chem. Soc. 2005, 127, 16364-16365
Brief Curriculum Vitae of the speaker Associate Professor Travis Holman earned his Ph.D. (1998) in Chemistry from the University of Missouri-Columbia under the mentorship of Prof. Jerry L. Atwood. He was awarded a Natural Sciences and Engineering Research Council of Canada post-doctoral fellowship, which he exercised in the research group of Prof. Michael D. Ward in the Department of Chemical Engineering and Materials Science at the University of Minnesota. In 2001, Dr. Holman joined the faculty at Georgetown University, rising to the rank of Associate Professor in 2008. In 2004, he was awarded a U.S. National Science Foundation early CAREER
award. His interests lie at the intersection of supramolecular, solid-state, and organometallic chemistries. He has given 40 invited lectures and co-authored 46 publications in these areas.
Novel Triptycene-Derived Hosts: Synthesis and Their Applications in Supramolecular Chemistry
Chuan-Feng Chen*
Institute of Chemistry, Chinese Academy of Sciences, Beijing, China, 100190 e-mail: [email protected]
Triptycene and its derivatives are a class of interesting compounds with the 3D rigid frameworks. They
have been found unique electrochemical and photochemical properties, potential pharmaceutical properties,
and attractive applications in molecular machines and materials science.
Recently, we are interested in the development of new supramolecular systems with specific structures
and properties based on triptycene derived macrocyclic hosts. Consequently, a series of novel hosts based
on triptycene or pentiptycene building blocks have been designed and synthesized, and their applications in
molecular recognition and molecular assembly have been explored.1 In this report, the detail results will be
presented.
OO O
O
OOO
OOO O
OOOO
O
OOO O O O
OO
O
O O
ON
O2N NO2
N
NO2O2N
O
O O
ON
O2N NO2
N
NO2O2N
OO
OO
OO
O
O
O
OO
O
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O
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O
O OOO
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O
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O
O
OOO
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O
OOO
O
HN
HNN OO
NH NO O
NH HNNOO
NH
HNNH NO O
O O O OOOOO
O O O OOOOO
OR
RO ROOR
O O O OOOOO
O O O OOOOO
OR
RO
HN
HN NH
NHN
NC CN
N
CNNC
HN
HN NH
NHN
NC CN
N
CNNC
ROOR
O O O OOOOO
OR
RO
Molecular Recognition
Molecular Assembly
Keywords: Triptycene, host-guest chemistry, synthesis and structure, molecular recognition, molecular assembly References [1] C. F. Chen, T. Han, Y. Jiang, Advances on the synthesis and applications of triptycene and its derivatives, Chin. Sci.
Bull. 2007, 52, 1349
[2] J. M Zhao, Q. S. Zong, T. Han, C. F. Chen, Guest-dependent complexation of triptycene-based macrotricyclic host
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with paraquat derivatives and secondary ammonium salts: a chemically controlled complexation process, J. Org.
Chem. 2008, 73, 6800 [3] M. Xue and C. F. Chen, Triptycene-based tetralactam macrocycles: synthesis, structure and complexation with
squaraine, Chem. Commun. 2008, 6128
[4] J. Cao, Y. Jiang, J.-M. Zhao, C. F. Chen, A pentiptycene-based bis(crown ether) host: synthesis and its complexation
with cyclobis(paraquat-p-phenylene), Chem. Commun. 2009, 1987
[5] J. Cao, H. Y. Lu, X. J. You, Q. Y. Zheng, C. F. Chen, Complexation of a pentiptycene-based tweezer-like receptor
with paraquat derivatives: ion-controlled binding and release of the guests, Org. Lett. 2009, accepted
Brief Curriculum Vitae of the speaker
Prof. Chuan-Feng Chen completed his Ph.D. (1991-1994) at Nanjing University under the supervision of Professor You-Cheng Liu. From 1994 to 1996, he served as a postdoctoral fellow at Institute of Chemistry, CAS, and then became an Associate Professor at the same Institute. After he worked as a visiting scientist at University of New Mexico for three years (1998-2001), he came back to the Institute of Chemistry, and was promoted as a full Professor in 2001. In 2000, he was selected for Hundred Talents Program by CAS. In 2006, he was awarded National Science Fund
for Distinguished Young Scholars. His current research is focused on development of new supramolecular systems with specific structures and properties.
Gated Molecular Encapsulation
Jovica D Badjic Department of Chemistry, The Ohio State University, Columbus, OH 43228 USA
e-mail: [email protected]
The encapsulation of guest molecules by artificial hosts allows (a) the stabilization of reactive
intermediates, (b) the change in the rate of chemical reactions occuring inside the host, and (c) the
modulation of guest’s conformational dynamics. The incorporation of dynamic elements of design into
artificial hosts could be essential for increasing the efficiency of any encapsulation-based catalyst, yet there
is poor understanding of the relationship. In that vein, constrictive binding has been defined as a physical
barrier that a guest molecule needs to overcome to leave its host. Interestingly, high constrictive binding is
critical for stabilizing reactive intermediates and thus facilitating a chemical transformation but at the same
time could be detrimental for reaction’s turnover. The quandary can be addressed by developing new ways
for controlling the kinetic lability of the encapsulation complexes, e.g. the rate by which guest molecules
exit (enter) hosts. Accordingly, our research program focuses on examining working mechanisms of
basket-like receptors designed to
regulate the kinetic lability of
incarcerated guests via gating (see
Figure).1 The trafficking of guests, to
and from baskets, is mediated by a set
of revolving gates forming a net of
intramolecular hydrogen bonds.2 The
kinetic stability of guest molecules can be tuned by adjusting the conformational dynamics od baskets.3
Linear free energy relationships have, furthermore, been developed to reveal fundametal rules that guide
recognition kinetics in gated receptors.
The lecture will focus on presenting the utility of gated molecular baskets for understanding the
recognition phenomena and their relation to chemical reactivity in dynamic environments.
Keywords: Molecular Encapsulation, Molecular Dynamics, Recognition Kinetics, Constrictive Binding.
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References:
1. V. Maslak, Z. Yan, S. Xia, J. Gallucci, C. M. Hadad, J. D. Badjić Design, synthesis, and conformational dynamics of a gated molecular basket, J. Am. Chem. Soc. 2006, 128, 5887-5894. 2. B-Y. Wang, X. Bao, Z. Yan, V. Maslak, C. M. Hadad, J. D. Badjić A 3-fold Butterfly Valve in Command of the Encapsulation's Kinetic Stability. Molecular Baskets at Work. J. Am. Chem. Soc. 2008, 130, 15127-15133. 3. B-Y. Wang, S. Rieth, J. D. Badjić, Tuning the Rate of Molecular Translocation. J. Am. Chem. Soc. 2009, 131, 7250-7252.
Brief Curriculum Vitae of the Speaker Jovica D Badjic received his diploma in Chemistry (1994) from the University of Belgrade. He obtained Ph.D. in Organic Chemistry (2001) from Iowa State University (USA) and received Henry Gilman Fellowship and Research Excellence Award for graduate work. From 2001 to 2004 he was a postdoctoral research fellow in the group of J Fraser Stoddart at UCLA where he was awarded Chancellor's award for outstanding research accomplishments in postdoctoral work. He joined the faculty at the Ohio State University as an assistant professor in 2004.
Preorganized Aromatic Amide Oligomers: Toward the Development of a
Novel Generation of Soft Frameworks Zhan-Ting Li*
State Key Laboratory of Bioorganic and Natural Products Chemistry Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences
354 Fenglin Lu, Shanghai 200032, China
e-mail: [email protected]
Foldamers, linear molecules that are induced by noncovalent forces to adopt compact
conformations, have recently received considerable attention. Because of the strength and directionality
of the hydrogen bonding and the inherent rigidity and planarity of aromatic amide units, hydrogen
bonding-driven aromatic amide-based foldamers usually possess a high structural predictability, while
their synthesis are simply based on the well- established amide coupling reactions. Furthermore, by
changing the position of the hydrogen bonding sites, many different conformations or shapes can be
readily realized. Therefore, this family of foldamers are new versatile soft frameworks that are
potentially useful in many different areas, including molecular recognition, supramolecular self-
assembly, catalysis and organic synthesis.
N N
ORRO
O
HBuO
N
OR
ORO H
OBu
N
RO
RO
O
H OBu
N
N
2
O
O
N
ORRO
O
HO
N
OR
ORO H
O
N
N
NRO
RO
O
H ON
N
OROR
O
HO
N
OR
ORO H
O
N
N
NRO
RO
O
H ON
O
3
n-C4H9O
O
N
i-BuO
Bu-iO
N
O
OMe
O
N
i-BuO
Bu-iO
N
O
OC4H9-n
OC4H9-n
O
N
OBu-i
Oi-Bu
N
O
OMe
O
N
OBu-i
Oi-Bu
N
O
n-C4H9O
NNN
NNN1
H H H H
HHHH
RO
RO
N
O
N
ON
O
N
O
O O
NO N ON NO O
N
O O
N
RO
RO
OR
ORBu-n Hn-BuH
H
H
H
H
H
H
HHMe Me
R =
O
NH O
N(C8H17)2
4
RO
RO
N
O
N
ON
O
N
O
O O
NO ONN NO O
RO
RO
O
N
O
N
O
OR
H
H
H
H H
H
H
H
H5
R = C10H21
Our recent efforts have focused on the applications of this family of preorganized frameworks in
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directing the formation of complicated macrocyclic systems and the self-assembly of new assembled
architectures.1 We have demonstrated that in many cases, macrocyclic structures can be obtained in
high yields from rationally designed foldamer-derived precursors.2 By employing the dynamic covalent
chemistry, we can also quantitatively prepare many mono-, multi- and bilayered macrocyclic
architectures.3 Compounds 1-3 are the examples of the macrocyclic systems that are prepared by using
this approach. The rigid preorganized frameworks also have a great tendency of stacking in polar media.
Therefore, compounds 4 and 5 have been revealed to self-assemble into vesicles in methanol and
organogels in many organic solvents,4,5 respectively. The details will be discussed in the presentation.
Keywords: Foldamer, hydrogen bonding, self-assembly, macrocycle, vesicle, organogel
Acknowledgment. We are grateful to NSFC, MOST, STCSM and CAS for financial support of this work.
References
[1] Z.-T. Li, J. L. Hou, C. Li. Peptide Mimics by Linear Arylamides: A Structural and Functional Diversity Test.
Acc. Chem. Res. 2008, 41, 1343-1353.
[2] X.-N. Xu, L. Wang, J.-B. Lin, G.-T. Wang, X.-K. Jiang, Z.-T. Li. Hydrogen Bonding-Mediated Dynamic Covalent
Synthesis of Imine-Based Capsules and Formation of Pseudo[3]rotaxanes. Chem. Eur. J. 2009, 15, 5763-5774.
[3] Y.-Y. Zhu, Z.-T. Li. Synthesis of Macrocycles from Hydrogen Bonding- Mediated Preorganized Precursors by
“Click” Chemistry. Org. Biomol. Chem. 2009, 7, 3243–3250.
[4] W. Cai, G.-T. Wang, Y.-X. Xu, X.-K. Jiang, Z.-T. Li. Vesicles and Organogels from Foldamers: A Solvent
-Modulated Self-Assembling Process. J. Am. Chem. Soc. 2008, 130, 6936-6937.
[5] W. Cai, G.-T. Wang, P. Du, R.-X. Wang, X.-K. Jiang, Z.-T. Li. Foldamer Organogels: A Circular Dichroism Study
of Glucose-Mediated Dynamic Helicity Induction and Amplification. J. Am. Chem. Soc. 2008, 130, 13450-13459.
Brief Curriculum Vitae
Zhan-Ting Li was born in 1966 and received his A.B. degree in 1985 from Zhengzhou University. He earned his Ph.D. degree in fluorine chemistry in 1992 with Professor Qing-Yun Chen at Shanghai Institute of Organic Chemistry (SIOC). He did post- doctoral researches with Professor Jan Becher at the University of South Denmark and with Professor Steven C. Zimmerman at the University of Illinois at Urbana–Champaign. Since 2003, he has been a professor at SIOC. His researches are mainly concerned with the hydrogen bonding-related unnatural secondary structures, molecular recognition and self-assembly.
Molecular Recognition and Sensing of Peptides by Self-Assembled Receptors
Adam R. Urbach Department of Chemistry, Trinity University, San Antonio, Texas, USA, 78212
e-mail: [email protected]
Multivalent binding is believed to play a fundamental role in myriad biochemical processes, including
signal transduction, pathogenic infection and the immune response, and is involved in the bottom-up
molecular self-assembly of nanoscale structures. Challenges in this field include the synthesis of
well-defined multivalent receptors with predictable binding properties, as well as methods for measuring
their binding. This talk describes a biomimetic approach to the construction of multivalent receptors via
molecular self-assembly. This approach employs the organic macrocycle, cucurbit[8]uril (Q8), which has
the unusual property that it binds simultaneously and selectively to two different guests in aqueous solution.
In the monovalent case, Q8 binds to methyl viologen to form a Q8•viologen complex, which then binds to
tryptophan-containing peptides in a sequence-selective manner (Figure 1).
Fig. 1: Structures of Q8, methyl viologen (MV), and Trp, and a schematic of the Q8•MV•Trp complex
Multivalent receptors were formed by the assembly of multiple copies of Q8 onto scaffolds presenting
multiple viologen groups (Figure 2). These complexes bind peptides in a discrete multivalent fashion and
with increased binding affinity. The extent of valency is quantified directly by the built-in optical sensor,
which is based on a visible charge-transfer complex between viologen and indole groups. The predictable
behavior of this system and its relatively simple synthesis and analysis methods should make it well suited
to serve as a model for multivalent binding. Related studies and imminent directions will be discussed if
time permits.
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Fig. 2: Schematic illustration of the concept of a self-assembling modular receptor. A divalent scaffold
presenting multiple viologen groups (in red) recruits two equivalents of Q8, and the resulting receptor binds
in a divalent fashion to a peptide with two tryptophan residues (in blue).
Keywords: Multivalent binding, biomimetic, cucurbituril, host-guest interactions, charge transfer interactions, self-assembly References [1] J. J. Reczek, A. A. Kennedy, B. T. Halbert, A. R. Urbach, Multivalent recognition of peptides by modular
self-assembled receptors, J. Am. Chem. Soc. 2009, 131, 2408
[2] L. M. Heitmann, A. D. Taylor, P. J. Hart, A. R. Urbach, Sequence-selective recognition and cooperative dimerization
of N-terminal aromatic peptides in aqueous solution by a synthetic host, J. Am. Chem. Soc. 2006, 128, 12574
[3] M. E. Bush, N. D. Bouley, A. R. Urbach, Charge-mediated recognition of N-terminal tryptophan in aqueous solution
by a synthetic host, J. Am. Chem. Soc. 2005, 127, 14511
Brief Curriculum Vitae of the speaker Prof. Adam Urbach earned his Ph.D. (2002) in the field of bioorganic chemistry under the supervision of Peter Dervan at Caltech. He worked as a postdoctoral fellow under George Whitesides at Harvard University from 2002 to 2004 and then joined the faculty at Trinity University in San Antonio, Texas, where he is Assistant Professor of Chemistry. In 2007 he received a Distinguished Junior Faculty Award for Teaching and Research at Trinity University, and in 2008 a CAREER award from the National Science Foundation, USA. His research interests are focused on the design of molecules that selectively recognize, sense, and control
the properties of peptides, proteins, and DNA.
Threaded Structures Based on Crown Ether Derivatives
Feihe Huang *, Feng Wang, Kelong Zhu, Chuanju Zhang, Shijun Li, Ming Liu, Jinqiang Zhang, Chunlin He, Xichang Zhang, Ning Li
Department of Chemistry, Zhejiang University, Hangzhou, China, 310027 e-mail: [email protected]
We are focusing on the fabrication of threaded structures based on crown ether derivatives. There are three
main research projects. The first one is the improvement of host-guest complexation for the preparation of
large supramolecular systems. For example, we demonstrated that the complexation of paraquat could be
improved up to 219 times by the introduction of ion-pair recognition. The second one is the preparation of
novel supramolecular polymers based on host-guest complexation. For example, recently we prepared
supramolecular alternating copolymers from self-sorting organization of two heteroditopic monomers
(Scheme 1). The third one is the design and preparation of novel host-guest recognition systems. For a long
time, it has been widely accepted that a macrocycle needs at least 24 atoms for the threading of an alkyl
group into its cavity. However, we found that secondary dialkylammonium salts (SDS) are able to thread
through the cavity of benzo-21-crown-7 (B21C7) to form threaded structures (Scheme 2). Furthermore, we
also found that B21C7 can bind SDS much stronger than their traditional host dibenzo-24-crown-8.
O
O
O
O
O
O O
ON N
O
O
O O O O
O O O O2PF6
O
NH
O
O
PF6
O
self-sorting organization
105
Scheme 1: Formation of supramolecular alternating copolymers from self-sorting organization of heteroditopic monomers.
O
O
OO
O
O
O
NH2
HO
PF6
O O
O
Equimolar Benzo-21-Crown-7, Me3P, CH2Cl2, rtYield: 74%
NH2
O
PF6O
A Benzo-21-Crown-7-Based [2]Rotaxane Scheme 2: Preparation of a [2]rotaxane based on the benzo-21-crown-7/secondary ammonium salt recognition motif.
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Keywords: Thread structures, crown ethers, host-guest interactions, supramolecular polymers, self-assembly References [1] C. Zhang, S. Li, J. Zhang, K. Zhu, N. Li, F. Huang, Benzo-21-crown-7/Dialkylammonium Salt [2]Pseudorotaxane-
and [2]Rotaxane-Type Threaded Structures, Org. Lett. 2007, 9, 5553
[2] C. Zhang, K. Zhu, S. Li, J. Zhang, F. Wang, M. Liu, N. Li, F. Huang, Binding of secondary dialkylammonium salts by
pyrido-21-crown-7, Tetrahedron Lett. 2008, 49, 6917
[3] C. He, Z. Shi, Q. Zhou, S. Li, N. Li, F. Huang, Syntheses of cis- and trans-Dibenzo-30-crown-10 Derivatives via
Regioselective Routes and Their Complexations with Paraquat and Diquat, J. Org. Chem. 2008, 73, 5872
[4] F. Wang, C. Han, C. He, Q. Zhou, J. Zhang, C. Wang, N. Li, F. Huang, Self-Sorting Organization of Two Heteroditopic
Monomers to Supramolecular Alternating Copolymers, J. Am. Chem. Soc. 2008, 130, 11254
[5] K. Zhu, S. Li, F. Wang, F. Huang, Anion-Controlled Ion-Pair Recognition of Paraquat by a
Bis(m-phenylene)-32-crown-10 Derivative Heteroditopic Host, J. Org. Chem. 2009, 74, 1322
[6] K. Zhu, J. He, S. Li, M. Liu, F. Wang, M. Zhang, Z. Abliz, H. Yang, N. Li, F. Huang, Synthesis of
Bis(m-phenylene)-32-crown-10-Based Discrete Rhomboids Driven by Metal-Coordination and Complexation with
Paraquat, J. Org. Chem. 2009, 74, 3905
[7] F. Wang, B. Zheng, K. Zhu, Q. Zhou, C. Zhai, S. Li, N. Li, F. Huang, Formation of Linear Main-Chain
Polypseudorotaxanes with Supramolecular Polymer Backbones via Two Self-Sorting Host-Guest Recognition Motifs,
Chem. Commun. 2009, 4375
[8] S. Li, M. Liu, B. Zheng, K. Zhu, F. Wang, N. Li, X. Zhao, F. Huang, Taco Complex Templated Syntheses of a
Cryptand/Paraquat [2]Rotaxane and [2]Catenane by Olefin Metathesis, Org. Lett. 2009, 11, 3350
Brief Curriculum Vitae of the speaker Feihe Huang was born in China in 1973. He obtained his degree of Doctor of Philosophy in Chemistry from Virginia Polytechnic Institute and State University (VT) under the guidance of Prof. Harry W. Gibson in March 2005. Then he joined in Prof. Peter J. Stang’s group at University of Utah as a postdoctor. He became a Professor of Chemistry at Zhejiang University in December 2005. His current research interests are molecular machines, supramolecular polymers, templated synthesis and chemosensors. The awards he received up to now include William Preston Award for MS thesis from VT, 2004 Chinese Government Award for Outstanding Self-Financed Students Abroad, The Sigma Xi
Research Award for Ph.D. Degree Candidates from VT Chapter of Sigma Xi Research Society, Outstanding Ph.D. Dissertation Award from VT and Thieme Chemistry Journals Award. He has published more than 50 supramolecular chemistry papers in JACS, Angew Chem, Chem Commun, JOC, OL, Progress in Polymer Science, Macromolecules, etc.
N-Heterocyclic Carbenes: New Applications in Materials Chemistry
Christopher W. Bielawski Department of Chemistry & Biochemistry, The University of Texas, Austin, TX, 78712 USA
e-mail: [email protected]
Dynamic covalent polymers may be defined as materials whose monomeric constituents are linked through
reversible covalent connections. As such, they undergo spontaneous structural reorganizations through
assembly/disassembly processes in response to changes in external stimuli. Although polymer exchange
reactions have long been documented (e.g., transesterifications), the detailed study of reversible covalent
polymerizations has been challenged by the difficulties in finding suitable reactions that form covalent
bonds reversibly and with acute control. Our research program is broadly focused on understanding the
fundamental characteristics and chemistry of dynamic polymerizations with a particular attention directed
toward a new class of bis(carbene)s, which are comprised to two linearly opposed N-heterocyclic carbenes
annulated to a common linker. As shown in the graphic, these difunctional monomers have been (1)
homopolymerized to afford polyenetetraamines, (2) copolymerized with transition metals to form
main-chain organometallic polymers, and (3) copolymerized with various difunctional electrophiles to form
alternating copolymers. In many cases, the polymers obtained from these reactions were found to be
reversible and/or exhibit extensively delocalized structures. The synthesis, characterization, and
application of each of these dynamic materials and model complexes designed to gain further insight will
be discussed during the seminar.
N
NR
RN
NR
RN
NR
RN
NR
R
MN
NR
RN
NR
RnM
N
NR
RN
NR
RN
NR
RN
NR
Rn
N
NR
RN
NR
R
EN
NR
RN
NR
Rn
EE
E
arene linker
M transition metal
(1)
(2)
(3)
E electrophile
Fig. 1: Schematic illustration of the general methods for tuning the amphiphilicity of the building blocks.
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Keywords: N-heterocyclic carbenes, reversible chemistry, polymer chemistry, conjugated polymers, self-assembly References [1] D. J. Coady, D. M. Khramov, B. C. Norris, A. G. Tennyson, C. W. Bielawski, Adapting N-heterocyclic carbene/azide
coupling chemistry for polymer synthesis: Enabling access to aromatic polytriazenes, Angew. Chem. Int. Ed. 2009, 48,
5187.
[2] T. Tang, D. J. Coady, A. J. Boydston, O. L. Dykhno, C. W. Bielawski, C. W. Pro-ionomers: An anion metathesis
approach to amphiphilic block ionomers from neutral precursors, Adv. Mater. 2008, 20, 3096.
[3] A. G. Tennyson, J. W. Kamplain, C. W. Bielawski, C. W. Oxidation of poly(enetetramine)s: A new strategy for the
synthesis of conjugated polyelectrolytes, Chem. Commun. 2009, 2124.
Brief Curriculum Vitae of the speaker Prof. Christopher W. Bielawski began his studies in chemistry at the University of Illinois at Urbana-Champaign, where he worked as an undergraduate researcher in the laboratories of Prof. Jeffrey S. Moore on supramolecular systems. After receiving a BS degree in 1996, Prof. Bielawski enrolled in the graduate studies program at the California Institute of Technology. Under the aegis of Prof. Robert H. Grubbs, he created a series of designer metathesis catalysts for the synthesis of advanced polymeric materials, efforts for which he was awarded a PhD
degree in chemistry in 2003. After a short postdoctoral stint in the laboratories of Prof. David A. Tirrell (also at Caltech), he became an assistant professor of chemistry at the University of Texas at Austin in 2004 and was promoted to associate professor in 2009. Dr. Bielawski’s research program lies at the interface of polymer, synthetic organic, and organometallic chemistry.
Copper-Free Huisgen 1,3-Dipolar Cycloadditions in Crystals Mediated by Arene-Perfluoroarene Interaction
Yuguo Ma*, Benbo Ni, Chong Wang, Huixian Wu
Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P. R. China
Email: [email protected]
In the absence of transition metal catalysts, Huisgen 1,3-dipolar cycloadditions usually need elevated
temperature to achieve acceptable reaction rates and yields and show no regio-selectivity. Copper(I)
catalyzed azide-alkyne cycloaddition (CuAAC), with enhanced regio-selectivity and conversion, has been
one of the most powerful reactions in the “click” toolbox proposed by Sharpless. Unfortunately, the toxicity
of copper ions prohibits the application of this reaction in biology systems, which leads to great interest and
several recent reports in the copper-free 1,3-dipolar cycloaddition. However, few examples have realized
regioselectivity with terminal alkynes under mild conditions in the absence of transition metal catalysts.
It is well known that benzene and hexafluorobenzene can form 1:1 co-crystals with a melting point of 23.7 oC, considerably higher than either of the two individual components. The binding energy of benzene with
hexafluorobenzene was estimated to be 3.7-4.7 kcal/mol in crystal. Similar alternating face-to-face stacking
motif of phenyl and perfluorophenyl units has also been found in crystal structures of other
arene-perfluoroarene-containing complexes. The alternating arrangement was attributed to the dispersion
and quadrupolar interactions between arenes and perfluoroarenes. More recently, arene-perfluoroarene
interactions have also been widely utilized in supramolecular chemistry, e.g., crystal engineering, rotaxane
synthesis, liquid crystallinity induction, and solid-state reactions.
Fig. 1: Schematic representation of strategy used for copper-free 1, 3-dipolar cycloaddition of azide and
alkyne facilitated by arene-perfluoroarene interaction.
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Herein, we demonstrate a copper-free 1,3-dipolar cycloaddition of azides and alkynes at room temperature
in the crystalline state, with the assistance of arene-perfluoroarene interaction (Fig. 1). Crystal packing
facilitated by arene-perfluoroarene interaction offered a desirable spatial arrangement of the azide and
alkyne functional groups, and thus realized a reasonably well-controlled cycloaddition polymerization in
the crystals. Hydrolysis of the imine-based “click” polymers yielded a soluble triazole degradation product,
which gave direct evidence for the highly regioselective copper-free 1,3-dipolar cycloaddition at room
temperature.
Keywords: Huisgen 1,3-Dipolar Cycloaddition, Arene-Perfluoroarene Interaction, Supramolecular Chemistry, Crystal Engineering; Self-assembly References [1] Huisgen, R. Angew. Chem. Int. Ed. Engl. 1963, 2, 565.
[2] (a) Rostovtsev, V. V.; Green, L. G.; Fokin, V. V.; Sharpless, K. B. Angew. Chem. Int. Ed. 2002, 41, 2596. (b) Tornøe, C. W.;
Christensen, C.; Meldal, M. J. Org. Chem. 2002, 67, 3057. (c) Kolb, H. C.; Finn, M. G.; Sharpless, K. B. Angew. Chem.
Int. Ed. 2001, 40, 2004.
[4] Coates, G. W.; Dunn, A. R.; Henling, L. M.; Ziller, J. W.; Lobkovsky, E. B.; Grubbs, R. H. J. Am. Chem. Soc. 1998, 120,
3641.
[5] Manetsch, R.; Krasiński, A.; Radić, Z.; Raushel, J.; Taylor, P.; Sharpless, K. B.; Kolb, H. C. J. Am. Chem. Soc. 2004, 126,
12809.
Brief Curriculum Vitae of the speaker Prof. Yuguo Ma obtained his B.Sc. degree with honor in 1994 and a Master degree in 1997 from College of Chemistry of Peking University. His research work is on liquid crystalline polymers under supervision of Prof. Qi-Feng Zhou. He continued his graduate study in the Department of Chemistry at University of Illinois at Urbana-Champaign with Prof. Steven C. Zimmerman, and obtained his Ph.D. in Organic/Polymer Chemistry in December 2002. From January 2003 to August 2005, he was a postdoc research associate with Prof. Geoffrey W. Coates in the Department of Chemistry and Chemical Biology of Cornell University. The main
focus of his postdoc work is on organometallic chemistry and catalysis. In September 2005, he returned to Peking University and has been an Associate Professor
in the Department of Polymer Science & Engineering at College of Chemistry. His current research interest includes: Supramolecular Chemistry, Self-Assembly & Molecular Recognition, Organic/Polymeric Functional Materials, and Organometallic Catalysis.
Metal Complexes with Multidentate Ligands: Structure Diversity and
Anion Exchange Property
Wei-Yin Sun *, Guan-Cheng Xu Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, School of
Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China e-mail: [email protected]
We focus our attention on assembly reaction, crystal structure and property of metal-organic frameworks
(MOFs) with flexible multidentate organic ligands, such as 1,3,5-tris(imidazol-1-ylmethyl)benzene (tib),
1,3,5-tris(imidazol-1- ylmethyl)-2,4,6-trimethylbenzene (titmb), etc. Systematic study of assembly
reactions of tib/titmb with varied metal salts was carried out, and coordination architectures with zero-, one-
(1D), two- (2D) and three-dimensional (3D) structures were obtained and their properties were investigated.
For example, flexible tripodal ligand tib was used to react with various zinc(II) salts ZnX [X = (BF4)2, SO4,
Cl2, Br2, I2] to afford a series of coordination polymers with different structures.
{[Zn(tib)2](BF4)2}n (1) has an infinite 2D cationic double layered structure, while {[Zn4(tib)3(SO4)4]·9H2O}n
(2) possesses a 3D framework structure with two different kinds of channels. The structure of
[Zn3(tib)2Cl6]n (3) is 2D network and the one of {[Zn3(tib)2Br6]·CH3OH}n (4) is an infinite 1D zigzag chain in
a plywood-like stacking fashion. {[Zn(tib)I]I}n (5) has 2D network structure which is further linked by
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hydrogen bonds to give rise to a fascinating 3D interlocked framework with 2-fold interpenetration. The
results demonstrated that the counteranions have remarkable effects on the structure of the coordination
polymers. On the other hand, the flexible ligand tib acts as a three-connecting node to connect three zinc(II)
centers with different conformations. In 1 and 5, tib has cis, cis, cis-conformation, while in 2, it adopts cis,
trans, trans-conformation. It is interesting that two different conformations (cis, cis, cis and cis, trans, trans)
of tib are coexist in 3 and in the case of 4, the ligand tib adopts a special cis, trans-conformation. The results
attest that the flexible ligand tib can adopt different conformations to form complexes with varied structures.
In addition, the uncoordinated tetrafluoroborate anions in 1 can be exchanged by nitrate or nitrite anions,
which mean that 1 has anion exchange property.
Keywords: Metal complexes, crystal structure, anion exchange, self-assembly References [1] Z. Su, J. Xu, J. Fan, D. J. Liu, Q. Chu, M. S. Chen, S. S. Chen, G. X. Liu, X. F. Wang, W. Y. Sun, Synthesis, Crystal
Structure and Photoluminescence of Coordination Polymers with Mixed Ligands and Diverse Topologies, Cryst.
Growth Des. 2009, 9, 2801-2811.
[2] Z. S. Bai, J. Xu, T. Okamura, M. S. Chen, W. Y. Sun, N. Ueyama, Novel dense organic-lanthanide hybrid architectures:
syntheses, structures and magnetic properties, Dalton Trans. 2009, 2528-2539.
[3] G. C. Xu, Q. Hua, T. Okamura, Y. J. Ding, Y. Q. Huang, G. X. Liu, W. Y. Sun, N. Ueyama, Cadmium(II) coordination
polymers with flexible tetradentate ligand 1,2,4,5-tetrakis(imidazol-1-ylmethyl)benzene: anion effect and reversible
anion exchange property, CrystEngComm 2009, 11, 261-270.
Brief Curriculum Vitae of the speaker Prof. Wei-Yin Sun Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry (SKLCC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China Education:
BSc: 1986, East China Normal University, Shanghai, China MSc: 1990, Osaka University, Faculty of Science, Japan PhD: 1993, Osaka University, Faculty of Science, Japan
Professional Career:
1993 - 1995 Postdoctoral research fellow, Central Research Institute, Shionogi, Japan 1996 - present Professor, Nanjing University, China 2001.11 - 2002.4 CREST research fellow, Nagoya University, Japan
2004.11 - 2005.2 Visiting Professor, Institute for Molecular Science, Okazaki, Japan 2005.6 - 2005.8 Visiting Professor, Institute for Molecular Science, Okazaki, Japan
The Statics and Dynamics of Anion Supramolecular Chemistry:
Artificial Anion-Binding Motifs and Mechanistic Studies of Motion
Amar H Flood* Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
e-mail: [email protected]
The supramolecular chemistry of anions (e.g., halides, oxyanions, organic anions) is developing rapidly
after a long induction period. New receptors target fundamental questions, e.g., the strength of CH•••anion
hydrogen bonds, or seek to harness the associated recognition, such as anion-driven molecular machinery.
This talk will highlight both aspects thus illustrating the transition from the static, structural and
thermodynamic elements of supramolecular chemistry to the dynamic and stimuli responsive ones.
Fig. 1: Click chemistry generates privileged CH hydrogen-bonding triazoles: the latest addition to anion
supramolecular chemistry.
Click chemistry facilitated the synthetic creation of new receptors and thus, an opportunity to aid in the
recent re-examination of CH•••anion hydrogen bonding. This part of the talk will focus on the privileged
C–H hydrogen bond donor of the 1,2,3-triazole ring systems as elucidated from anion-binding studies with
macrocyclic triazolophanes (Fig. 1) and other receptors. Triazolophanes are shape-persistent and planar
macrocycles that direct four triazole and four phenylene CH groups into a 3.7 Å cavity. They display strong
(logK(Cl–) = 7), size-dependent halide binding (Cl– > Br– >> F– >> I–) and a rich set of binding equilibria.
For instance, the too large iodide (4.4 Å) can be sandwiched between two pyridyl-based triazolophanes
with extreme positive cooperativity. Computational studies verify the triazole’s hydrogen bond strength
indicating it approaches traditional NH donors. These examples, those of transport, sensing, templation,
and the versatile synthesis herald the use of triazoles in anion-receptor chemistry.
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Fig. 2: Redox-geneated anions drive motion along SN2- and SN1-like pathways
Molecular machines provide the means to control the relative location of molecular units, i.e., motion, and
have led to demonstrations of molecular valving and muscles. While it is true that one can dictate the start
and finish points, A and B, chemists have yet to control the pathway followed between the two points. Here
we describe a supramolecular prototype of a machine and the mechanism of motion between points A and
B. The findings show that the Cu(I)-based pseudorotaxane operates as a coordination complex when
switching forwards and then as a host-guest complex on the return stroke. We show that elucidation of
mechanism goes some way towards directing not only motions, but also designs for next generation
molecular machines.
Keywords: Click chemistry, hydrogen bonding, redox switching, mechanism, pseudorotaxanes References [1] Y. Li, A. H. Flood, Pure C–H hydrogen bonding to chloride ions: A preorganized and rigid macrocyclic receptor,
Angew. Chem. Int. Ed. 2008, 47, 2649-2652.
[2] K. A. McNitt, K. Parimal, A. I. Share, A. C. Fahrenbach, E. H. Witlicki, M. Pink, D. K. Bediako, C. L. Plaisier, N. Le, L.
P. Heeringa, D. A. Vander Griend, A. H. Flood, Reduction of a redox-active ligand drives switching in a Cu(I)
pseudorotaxane by a bimolecular mechanism, J. Am. Chem. Soc. 2009, 131, 1305-1313.
Brief Curriculum Vitae of the speaker Amar H Flood was educated at Otago University, New Zealand (BSc Honors, 1st Class, 1996 and PhD, 2001). Subsequently, he joined the group of Sir Fraser Stoddart (2002) at UCLA as a postdoctoral scholar conducting research on molecular machines. He started as an Assistant Professor at Indiana University (2005) conducting research on two areas including anion receptors using click chemistry, molecular switches that employ redox activation and molecular recognition with detection by surface-enhanced Raman scattering.
Highly Selective Photocyclodimerization of 2-Naphthalene Derivatives in Supramolecular Systems
Li-Zhu Wu*
Key laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of
Physics and Chemistry, the Chinese Academy of Sciences, Beijing 100190, China
email: [email protected]
Enzymes may bind substrates through multiple interactions in elaborate pockets, thereby forcing the substrates
into orientations that favor the specific reaction paths, representing the highest expression of chemical reaction. 1-2
The astonishing selectivity and efficiency that enzymes achieve at modest temperature have stimulated chemists
to mimic enzyme-like reactions that proceed within restricted cavities. 3-10 Cucurbit-[n]uril and cyclodextrin
represent two typical supramolecular systems that can encapsulate guest molecules in their cavity with desired
orientations. In this contribution, we will present our recent work on photocyclodimerization of 2-naphthalene
derivatives in supramolecular systems, including (1) highly efficient cucurbit[8]uril-templated intramolecular
photocycloaddition of 2-naphthalene-labelled poly(ethylene glycol) in aqueous solution; (2)
γ-cyclodextrin-directed enantioselective photocyclodimerization of methyl 3-methoxyl-2-naphthoate.
Keywords: photocyclodimerization of 2-naphthalene, cubane-like photocyclodimer, selectivity of
phototransformation, cucurbit[8]uril, γ-cyclodextrin
References
[1] Jencks, W. P. Catalysis in Chemistry and Enzymology; McGraw-Hill: New York, 1969.
[2] Sanders, J. K. M. Chem. Eur. J. 1998, 4, 1378.
[3] Breslow, R.; Dong, S. D. Chem. Rev. 1998, 98, 1997.
[4] Svoboda, J.; König, B. Chem. Rev. 2006, 106, 5413. [5] Ramamurthy, V.; Schanze, K. S. Eds. Molecular and Supramolecular Photochemistry; Marcel Dekker:
New York, 2001.
[6] Inoue, Y.; Ramamurthy, V. Eds.; Chiral Photochemistry; Marcel Dekker: New York, 2004.
[7] Lei, L.; Wu, L.-Z.; Wu, X.-L.; Liao, G.-H.; Luo, L.; Zhang, L.-P.; Tung, C.-H.; Ding, K.-L. Tetrahedron Lett.
2006, 47, 4725.
[5] Wu, X.-L.; Lei, L.; Wu, L.-Z.; Liao, G.-H.; Luo, L.; Shan, X.-F.; Zhang, L.-P.; Tung, C.-H. Tetrahedron 2007, 63, 3133.
[6] Lei, L.; Luo, L.; Wu, X.-L.; Liao, G.-H.; Wu, L.-Z.; Tung, C.-H. Tetrahedron Lett. 2008, 49, 1502.
[7] Wu, X.-L.; Luo, L.; Lei, L.; Liao, G.-H.; Wu, L.-Z.; Tung, C.-H. J. Org. Chem. 2008, 73, 491.
[8] Liao, G.-H.; Luo, L.; Xu, H.-X.; Wu, X.-L.; Lei, L.; Tung, C.-H.; Wu, L.-Z. J. Org. Chem. 2008, 73, 7345. [9] Luo, L.; Liao, G.-H.; Wu, X.-L.; Lei, L.; Tung, C.-H.; Wu, L.-Z. J. Org. Chem. 2009, 74, 3506.
[10] Luo, L.; Cheng, S.-F.; Chen, B.; Tung, C.-H.; Wu, L.-Z. Langmuir 2009, in press.
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Acknowledgment: This work was supported by the National Natural Science Foundation of China, the Ministry of Science and Technology of China, and Bureau for Basic Research of the Chinese Academy of Sciences.
Brief Curriculum Vitae of the speaker
Professor Li-Zhu Wu got her Ph.D. (1995) in the field of organic photochemistry under the supervision of Professor Chen-Ho Tung, Institute of Photographic Chemistry, the Chinese Academy of Sciences, Beijing. She worked at Institute of Photographic Chemistry as a lecturer from 1996 to 1999. After a postdoctoral stay (1997-1998) at Hong Kong University working with Professor Chi-Ming Che on inorganic chemistry, she returned to the Technical
Institute of Physics and Chemistry, the Chinese Academy of Sciences. Since 1999, she is full Professor of Technical Institute of Physics and Chemistry, the Chinese Academy of Sciences. Her research interests are focused on supramolecular photochemistry, including photoinduced electron transfer, energy transfer and chemical reaction in supramolecular systems, photocatalytic reaction mimicing enzyme and supramolecular assembly.
Fluorescent Heteroditopic Ligands for Zinc Ion
Lei Zhu *, Lu Zhang, Robert J. Wandell, Ali H. Younes Department of Chemistry and Biochemistry, Florida State Univ., Tallahassee, FL 32306, USA
e-mail: [email protected]
Two distinct fluorescent heteroditopic ligand platforms were established where three coordination states
(free, mono-, and di-coordinated) of a ligand can be translated to three fluorescence states (non-fluorescent,
fluorescent at one wavelength, and fluorescent at another wavelength). The mechanistic insight of the
coordination-driven photophysical processes uncovered in this unique class of molecules will be described.
Such ligand platforms are ideally suitable for quantitative free zinc ion analysis over large concentration
ranges. The preliminary investigations on the suitability of these ligands as intracellular fluorescent probes
for free zinc ions will be presented.
Fig. 1: A cartoon showing the design principle of a fluorescent heteroditopic ligand for zinc ion. The
background is fluorescent live cell images in the presence of high concentration of zinc chloride enabled by
a heteroditopic indicator.
Keywords: heteroditopic ligand, zinc, fluorescence, photoinduced electron transfer, internal charge transfer, fluorescence resonance energy transfer, live cell fluorescence imaging
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References [1] L. Zhang, R. J. Clark, L. Zhu, A Heteroditopic Fluoroionophoric Platform for Constructing Fluorescent Probes with
Large Dynamic Ranges for Zinc Ions, Chem. Eur. J. 2008, 14, 2894
[2] L. Zhang, L. Zhu, Photochemically Stable Fluorescent Heteroditopic Ligands for Zinc Ion, J. Org. Chem. 2008, 73,
8321-8330.
[3] L. Zhu, L. Zhang, A. H. Younes, Mini Review: Fluorescent Heteroditopic Ligands of Metal Ions, Supramol. Chem.
2009, 21, 268-283.
Brief Curriculum Vitae of the speaker Lei Zhu was born in 1975 and grew up in the city of Nanjing, China. In 1997 he earned his BSc in chemistry from Peking University before moving to New York University for graduate study with Jim Canary in organic chemistry. After defending his Ph.D. dissertation in January 2003, Lei joined Eric Anslyn’s group at the University of Texas at Austin for postdoctoral training. Upon completing his postdoctoral appointment, Lei started his independent career as an Assistant Professor in the Department of Chemistry and Biochemistry at Florida State University in the fall of 2005.
Rapid Fabrication of Layer-by-Layer Assembled Functional Films
Junqi Sun *, Xiaokong Liu, Lianbin Zhang, Ling Zhang State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin
University, Changchun, China, 130021 e-mail: [email protected]
Layer-by-layer (LbL) assembly technique involves the alternate deposition of complementary materials to
fabricate composite films based on the driving force such as electrostatic interaction, hydrogen bonding,
coordination bonding and so forth. In the past decades, LbL assembly technique has developed as a group
of versatile and convenient methods for the construction of layered ultrathin films with precise control of
film thickness and composition. The LbL assembly technique is particularly suitable to fabricate ultrathin
films with a thickness less than 100 nm. It is time-consuming to employ LbL assembly technique to
fabricate micrometer-thick films. In some cases, ultrathin thin films suffer from the problems of poor
mechanical stability, low loading capacity for guest materials and difficulty in functional integration.
Therefore, it is necessary to develop ways to rapid fabrication of LbL assembled films with micrometer
thickness.
By the combination of solution self-assembly and interfacial LbL assembly, a facile way to enable the rapid
fabrication of micrometer-thick LbL assembled films has been developed. Polymeric complexes and
inorganic aggregates in solution were demonstrated to be useful building blokes for rapid fabrication of
highly transparent superhydrophobic coatings, anti-reflection & anti-fogging coatings, and foam coatings
with high loading capacity. We believe that the rapid LbL assembly method will provide a facile way to
fabricate advanced film materials with abundant functionalities because of the wide choices of building
blocks and the flexibility in controlling the film compositions and structures.
Fig. 1: Layer-by-layer deposition of polyelectrolyte complexes for the rapid fabrication of foam coating
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with micrometer thickness and its high loading capacity for organic dyes.
Keywords: layer-by-layer assembly, multilayer films, polyelectrolyte complexes, film materials References [1] L. Zhang, J. Q. Sun, Layer-by-Layer Deposition of Polyelectrolyte Complexes for the Fabrication of Foam Coatings
with High Loading Capacity, Chem. Commun. 2009, 3901–3903.
[2] Y. Li, F. Liu, J. Q. Sun, A Facile Layer-by-Layer Deposition Process for the Fabrication of Highly Transparent
Superhydrophobic Coatings, Chem. Commun. 2009, 2730–2732.
[3] X. K. Liu, B.. Y. Dai, L. Zhou, J. Q. Sun, Polymeric complexes as building blocks for rapid fabrication of
layer-by-layer assembled multilayer films and their application as superhydrophobic coatings, J. Mater. Chem. 2009,
19, 497–504.
[4] Y. M. Guo, W. Geng, J. Q. Sun, Layer-by-Layer Deposition of Polyelectrolyte-Polyelectrolyte Complexes for
Multilayer Film Fabrication, Langmuir 2009, 25, 1004-1010.
Brief Curriculum Vitae of the speaker Junqi Sun received a Ph.D in 2001 at Jilin University, majoring in polymer chemistry and physics. His Ph. D thesis work, under the direction of Professor Jiacong Shen and Professor Xi Zhang, investigated the construction and functionalization of layered ultrathin films. Between January of 2002 and August of 2003, he joined in Prof. Toyoki Kunitake’s group at RIKEN as a Postdoctoral Fellow. In September of 2003, he joined the faculty of Jilin University as a professor of chemistry. In 2003, he won the prize for the Author of National Excellent Doctoral Dissertation of P. R. China. He is also the winner of the 2007 Young Chemist Prize of Chinese Chemical Society. His main
research interests focuses on the fabrication of polymeric and polymeric/inorganic hybrid films and their functionalization.
Squaraine Dyes: Their Use in Supramolecular Chemistry and Trace Element Detection
Karl J Wallace* Department of Chemistry and Biochemistry, The University of Southern Mississippi,
Hattiesburg, MS USA e-mail: [email protected]
The coordination chemistry of heavy metals, for example, Fe3+, Pb2+, Cd2+, Hg2+, and Zn2+, is of interest, in
part because of their hazards and toxicity in biological, industrial, and agricultural applications.
Additionally, there is much interest in the detection and quantification of trace metals in the products of
chemical synthesis, in particular sensors for detecting Pd2+. There has been plethora of new molecular
sensors for the detection of heavy metals that utilize colorimetric or fluorescence mechanisms.
One interesting group of organic molecules, which constitute a unique class of dyes, is the squaraine
family of molecules. Squaraines have been used in applications such as optical recording, solar energy
conversion, electrophotography, nonlinear optics, photodynamic therapy, biochemical labeling,
chromo/fluorogenic probes, pH responsive probes, cation, anion, and neutral molecule recognition, and
self assembled aggregates. The squaraine dye backbone is a resonance stabilized, zwitterionic structure
(Scheme 1, 1a-c,).
Scheme 1: Resonance stabilized zwitterionic structure of the squaraine motif.
Strictly speaking, dyes are non responsive chemical species their color is imparted as a consequence of the
molecular properties. The systems described in this talk are classified as “indicators” since it is an
environmental response that changes the optical properties of the molecular receptors. This presentation
will discuss the use of squaraine molecules in the field of supramolecular chemistry, in particular trace
element detection.
Keywords: colorimetric receptors, host-guest recognition, trace-element detection, sensors squaraine
dyes
References:
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[1] Johnathan J. McEwen and Karl J. Wallace, Squaraine Dyes: Their use in Supramolecular Chemistry, Chem Commun, 2009, submitted [2] Karl J. Wallace, Molecular dyes used for the detection of biological and environmental heavy metals: highlights from 2004 to 2008, Supramolecular chemistry, 2009, 21, 89-102 [3] Ronald J.T. Houk , Karl J. Wallace, Himali S. Hewage, Eric V. Anslyn, A colorimetric chemodosimeter for Pd(II): a method for detecting residual palladium in cross-coupling reactions, Tetrahedron, 2008, 64, 8271-8278 [4] K. J. Wallace, M. Gray, Z. Zhong, V. M. Lynch and E. V. Anslyn, An Artificial Siderophore for the Detection of Iron(III), Dalton Transactions, 2005, 2436-2441.
Brief Curriculum Vitae of the speaker
Karl J. Wallace obtained an undergraduate degree (BSc, 1999) from the University of the West of England, Bristol and obtained a Ph.D. in supramolecular chemistry from King’s College, London, under the supervision of Prof. Jonathan W. Steed (2003). From 2003 to 2006, Dr. Wallace carried out post-doctoral work in the research lab of Prof. Eric V. Anslyn at the University of Texas at Austin. In the fall 2006, Dr. Wallace was appointed assistant professor at the University of Southern Mississippi. His current research interests are supramolecular chemistry, including host-guest recognition, synthesis of molecular sensors for trace element detection, chemical nerve agent detection, and explosives detection. Dr. Wallace is the co-author of a textbook
entitled “Core Concepts in Supramolecular Chemistry and Nanochemistry” (J. W. Steed, D. R. Turner & K. J. Wallace) Published by John Wiley & Sons (2007) and he is also a co-editor of the “Encyclopedia of Supramolecular Chemistry” (Eds. J. L. Atwood, J. W. Steed & K. J. Wallace) Publisher Taylor and Francis.
Synthesis and Supramolecular Self-Assembly of Responsive Polymers
Shiyong Liu *, Yanfeng Zhang, Hao Liu, Jian Xu Department of Polymer Science and Engineering, University of Science and Technology,
Hefei, Anhui Province, China, 230026 e-mail: [email protected]
Supramolecular self-assembly of block copolymers in aqueous solution has received ever increasing
interest over the past few decades due to diverse biological and technological applications in drug delivery,
imaging, sensing, and catalysis. In addition to relative block lengths, molecular weights and solution
conditions, chain architectures of block copolymers can also dramatically affect their self-assembling
properties in selective solvents. We present recent progresses in the synthesis of amphiphilic and double
hydrophilic block copolymers (DHBCs) possessing nonlinear chain topologies, including miktoarm star
polymers, dendritic-linear block copolymers, cyclic block copolymers and comb-shaped copolymer brushes,
via combinations of ring-opening polymerization, click chemistry, and controlled radical polymerizations.
Their supramolecular self-assembling behavior in aqueous solutions will also be reported.
Solution properties of linear poly(N-isopropylacryl- amide) (PNIPAM) have been well-known, which
possesses a lower critical solution temperature (LCST) at ~32 oC. We recently synthesized well defined
cyclic-PNIPAM via a combination of ATRP and click chemistry. Possessing no chain ends,
cyclic-PNIPAM exhibits unique thermal phase transition behavior, when compared to linear PNIPAM with
comparable MW. Typically, the former exhibits a lower LCST, stronger concentration dependences of
LCST and smaller enthalpic changes associated with the thermal phase transition. cyclic-PNIPAM also
possesses drastically different aggregation properties in aqueous solution above the LCST, as compared to
their linear counterpart.
In the context of double hydrophilic cyclic diblock copolymers, we recently developed a novel strategy for
the high-efficiency preparation of cyclic diblock copolymers at relatively high concentrations via the
combination of supramolecular self-assembly and “selective” click reactions, relying on the fine control of
spatial accessibility between terminal reactive groups. It was found that thermoresponsive cyclic diblock
copolymers typically self-assemble into aggregates at elevated temperatures, which possess higher CMC
values, smaller size, and lower average aggregation numbers, as compared to those of their linear
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precursors.
Dually responsive double hydrophilic Janus-type A7B14 heteroarm star copolymers with two types of
water-soluble polymer arms emanating from the two opposing sides of rigid toroidal β-CD core have been
prepared. Janus-type A7B14 star copolymers of N-isopropylacrylamide (NIPAM) and 2-(diethylamino)ethyl
methacrylate (DEA), (PDEA)7-CD-(PNIPAM)14, were synthesized by coupling ATRP and click chemistry
techniques, starting from well-defined β-CD derivative. Upon adjusting solution pH and temperatures, the
Janus star copolymer can reversibly self-assemble into two distinct types of polymeric vesicles with
“inverted” nanostructures in aqueous solution.
Keywords: Supramolecular chemistry, self-assembly, nonlinear block copolymers, controlled radical polymerizations, click chemistry References [1] C. H. Li, Z. S. Ge, J. Fang, S. Y. Liu, Synthesis and Self-Assembly of Coil-Rod Double Hydrophilic Diblock
Copolymer with Dually Responsive Asymmetric Centipede-Shaped Polymer Brush as the Rod Segment,
Macromolecules 2009, 42, 2916.
[2] Z. S. Ge, J. M. Hu, F. H. Huang, S. Y. Liu, Responsive Supramolecular Gels Constructed by Crown Ether-Based
Molecular Recognition, Angew. Chem. Int. Ed. 2009, 48, 1798.
[3] Z. S. Ge, Y. M. Zhou, J. Xu, H. W. Liu, D. Y. Chen, S. Y. Liu, High-Efficiency Preparation of Macrocyclic Diblock
Copolymers via Selective Click Reaction in Micellar Media, J. Am. Chem. Soc. 2009, 131, 1628.
Brief Curriculum Vitae of the speaker Prof. Shiyong Liu was born in Hubei Province, China in 1972. He obtained his B. S. degree in 1993 and M. S. degree in 1996 from Wuhan University, majoring in environmental chemistry and polymer chemistry, respectively. After obtaining his Ph.D. degree in 2000 from Fudan University under the direction of Prof. Ming Jiang, he spent three and a half years at University of Sussex and University of Delaware as postdoctoral fellow, working with Prof. Steven P. Armes and Prof. Eric W. Kaler, respectively. Since 2003, he has been a professor of Polymer Science & Engineering at the University of Science and Technology of
China. He was selected in the “One Hundred Talents Program” of CAS in 2003 and awarded the National Outstanding Youth Fund in 2004. Since 2008, he has served in the Editorial Advisory Board of Macromolecules (ACS). Currently, his research focuses on the design and synthesis of functional polymers, colloids, and stimuli-responsive polymeric assemblies with controlled properties for applications in imaging, sensing, and drug delivery.
Directed Assembly of Block Copolymer Materials Eungnak Han, Padma Gopalan*1
Department of Materials Science and Engineering, University of Wisconsin e-mail: [email protected]
An important aspect of self-assembly of block copolymers (BCPs) in thin-films is controlling the domain
orientation. The use of these self-assembled domains in thin-films as template for additive or subtractive
nanofabrication process is referred to as block copolymer lithography.1 BCP lithography has emerged as a
promising strategy to access feature sizes much smaller than what is achievable by conventional
lithography. In addition to the feature size, BCP lithography affords better control over critical dimension as
the assembly process is mainly thermodynamically driven.2
Typically in a diblock copolymer one of the domains prefers the substrate leading to parallel
orientation of domains. We have focused on developing chemistry to alter the substrate wetting
characteristics to make it non-preferential or neutral towards either block. In this approach, the interfacial
energy between the BCP and the substrate can be carefully controlled to prevent preferential wetting by one
block. In a seminal work, Mansky et al.3 demonstrated the use of hydroxy terminated PS-r-PMMA to
balance the interaction of the blocks of a BCP, and since then different types of third co-monomers have
been successfully incorporated by us4,5 and others6, into the random copolymer to create
substrate-independent surface modification layers.
We have demonstrated a new type of polymer brush with a distribution of a third polar monomer
which is capable of anchoring to an oxide surface4 or photo-crosslinking5 with itself to create a neutral
surface on substrates of arbitrary compositions. These brushes offer a number of advantages such as ease of
synthesis, fast kinetics and effectiveness in very thin layers which is desirable for pattern transfer. We
also report in a detailed study the compositional ranges of random copolymers that induce perpendicular
alignment in both symmetric and asymmetric PS-b-PMMA for three different types of random
copolymers.7 We found that symmetric and asymmetric BCPs have different perpendicular window and
overlap only in a narrow region. The thickness of the BCP film is equally important in defining the
perpendicular window. Within this well-defined perpendicular window, perpendicular orientation of
domains persists only up to a certain thickness of the film from the substrate (below 1.5Lo thickness). Our
latest results show that by using the right substrate modifying random copolymer composition and
processing conditions we can achieve perpendicular PMMA cylinders in very thick films opening up
potential applications in photovoltaic, electro-optics and membranes.
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We will also briefly present our effort in the area of developing new BCP materials8 for lithography
with improved etch selectivity between the blocks and the potential for using hierarchical structures7 to
access multiple length scales, using polyhedral oligomeric silsesquioxane (POSS) containing BCPs.
Keywords: directed assembly, block copolymers, POSS References: 1) Stoykovich, M. P.; Nealey, P. F. Materials Today 2006, 9 (9), 20-29. 2) Black, C. T. Acs Nano 2007, 1 (3), 147-150. 3) Mansky, P.; Liu, Y.; Huang, E.; Russell, T. P.; Hawker, C. Science 1997, 275 (5305), 1458-1460. 4) In, I.; La, Y. H.; Park, S. M.; Nealey, P. F.; Gopalan, P. Langmuir 2006, 22 (18), 7855-7860. 5) Han, E.; In, I.; Park, S. M.; La, Y. H.; Wang, Y.; Nealey, P. F.; Gopalan, P. Advanced Materials 2007, 19 (24), 4448-4452. 6) Ryu, D. Y.; Shin, K.; Drockenmuller, E.; Hawker, C. J.; Russell, T. P. Science 2005, 308 (5719), 236-239. 7) Han, E.; Stuen, K.; La, Y-H.; Nealey, P. F.; Gopalan, P. Macromolecules 2008; 41 (23); 9090–9097. 8) Hirai, T.; Leolukman, M.; Hayakawa, T.; Kakimoto, M.; Gopalan, P. Macromolecules 2008; 41(13); 4558-4560.
Brief Curriculum Vitae of the speaker
Prof. Gopalan received her Ph.D from Cornell University in Ithaca, NY, in Chemistry with Prof. Ober. Upon completion she conducted her postdoctoral work in Lucent Technologies, Bell Laboratories, NJ with Dr. Howard Katz. She is currently an Assistant Professor in the Department of Materials Science and Engg. at the University of Wisconsin-Madison, and holds an affiliate appointment in the Department of Chemistry. Currently her group consists of 8 graduate students and two postdoctoral fellows. She is a co-PI in both the NSF-NSEC and NSF-MRSEC centers on campus. Her research is primarily funded by NSF, DOE, ACS-PRF, and Intel Co. The
Gopalan group in engaged in the synthesis of fluorinated or low-loss EO polymers, hyperbranched EO polymers; nano-sturtural control of electro-optic properties; design of materials for optical imaging, imaging layers, self-assembly of block copolymers; and designer biointerfaces. She is the recipient of NSF-CAREER award for 2005 from the polymer program of Division of Materials Research (DMR).
Supramolecular Self-assembly of Hyperbranched Polymers
Yongfeng Zhou *, Deyue Yan School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University,
800 Dongchuan Road, Shanghai, 200240, P. R. China. e-mail: [email protected]
Molecular self-assembly is such a process that molecules or a part of molecules spontaneously form
ordered aggregates by intermolecular noncovalent interactions including van der Waals interaction,
Coulomb interaction, hydrophobic interaction, π-π stack, and so on. Previously, the reported precursor
molecules used in self-assembly often possess well-defined molecular structures, such as small amphiphiles,
dendrimers and linear block copolymers. Through the molecular self-assembly of these precursors, many
elaborate microscopic or mesoscopic supramolecular objects have been observed over the last two decades.
However, little attention has been paid to the molecular self-assembly of ill-defined polymers.
Hyperbranced polymers (HBPs) are a new type of polymers with great advantages of facile fabrication,
highly branched topology and a large population of terminal functional groups, in spite of their irregular
architecture compared with well-defined dendrimers. Recently, there has been an explosive growth of
interest in supramolecular self-assembly of HBPs. Many impressive molecular aggregates at all scales and
dimemsions, such as macroscopic tubes, physical gels, micro- or nano-vesicles, fibers, spherical micelles,
honeycomb films and large compound vesicles, have been reported by direct solution self-assembly,
interfacial self-assembly, and hybrid self-assembly. Compared with the linear block copolymers, HBPs
have demonstrated several advantages or specialties in self-assembly behaviors, including controllable
morphologies and structures, special properties, characteristic self-assembly mechanism and facile
functionalization process. Especially, a small change in the molecule architecture of HBPs will give rise to
a big change in topology due to an enlarged effect of the highly branched structure, which leads to a
variable of designable self-assembly morphologies and structures. Such an enlarged effect is very useful
and attractive to prepare highly complicated surparmolecular structures and increase the complexity of the
self-assembly systems.
In addition, it was also found the self-assembly of HBPs has displayed great potentials in several
application areas, for example, the model membranes to mimic biomembrane structures and cellular
processes; intelligent drug carriers and nanoreactors, hierarchical self-assembly, and so on. In short,
although still being at the early stage, self-assembly of HBPs has provided a new avenue for the
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development of supramolecular chemistry.
Keywords: molecular self-assembly, hyperbranched, block copolymers. References [1] Yan, D.; Zhou, Y.; Hou, J. Supramolecular self-assembly of macroscopic tubes, Science, 2004, 303, 65.
[2] Zhou, Y.; Yan, D. Supramolecular self-assembly of amphiphilic hyperbranched polymers at all scales and
dimensions: progress, characteristics and perspectives, Chem. Commun. 2009, 1172.
[3] Zhou, Y.; Yan, D. Real-time membrane fission of giant polymer vesicles, Angew. Chem. Int. Ed., 2005, 44, 3223.
[4] Zhou, Y.; Yan, D. Real-time membrane fusion of giant polymer vesicles, J. Am. Chem. Soc., 2005, 127, 10468.
Brief Curriculum Vitae of the speaker Yongfeng Zhou received BS and Ms degree in chemistry of Harbin Institute of Technology. In 2005, he obtained his PhD in polymer chemistry and physics at Shanghai Jiao Tong University under the supervision of Prof. Deyue Yan. Then, he worked in the same university as a lecturer and was promoted to be an associate professor there. His current research interests include the controllable synthesis and self-assembly of block copolymers, especially the hyperbrancehd multiarm copolymers. .
List of Participants
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A Adam R. Urbach Department of Chemistry, Trinity University, San Antonio, Texas, USA, 78212 e-mail: [email protected] Amar H. Flood Department of Chemistry, Indiana University, Bloomington, IN 47405, USA e-mail: [email protected]
C Canping Du National Natural Science Foundation of China e-mail: [email protected] Christopher W. Bielawski Department of Chemistry & Biochemistry, The University of Texas, Austin, TX, 78712 USA e-mail: [email protected] Chuan-Feng Chen Institute of Chemistry, Chinese Academy of Sciences, Beijing, China, 100190 e-mail: [email protected]
D Daoben Zhu Institute of Chemistry, Chinese Academy of Sciences, Beijing, China, 100190 e-mail: [email protected]
E Elsa C. Y. Yan Department of Chemistry, Yale University, New Haven, CT06511 e-mail: [email protected]
F Feihe Huang Department of Chemistry, Zhejiang University, Hangzhou, China, 310027 e-mail: [email protected] Feixue Gao National Natural Science Foundation of China e-mail: [email protected]
G Guangtao Li Department of Chemistry, Tsinghua University, Beijing, China, 100084 e-mail: [email protected]
H Huaping Xu Department of Chemistry, Tsinghua University, Beijing, China, 100084 e-mail: [email protected]
J Janice M. Hicks Executive Officer, Division of Chemistry,Senior Executive Service, National Science
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Foundation, 4201 Wilson Blvd, Arlington VA 22230 e-mail: [email protected] Jianhua Dong National Natural Science Foundation of China e-mail: [email protected] Jiannian Yao Vice President of National Natural Science Foundation of China e-mail: [email protected] José M. Rivera Department of Chemistry, University of Puerto Rico, Río Piedras Campus, San Juan, Puerto Rico 00931 e-mail: [email protected] Jovica D. Badjic Department of Chemistry, The Ohio State University, Columbus, OH 43228 USA e-mail: [email protected] Junlin Yang National Natural Science Foundation of China e-mail: [email protected] Junqi Sun State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, China, 130021 e-mail: [email protected]
K
K. Travis Holman Department of Chemistry, Georgetown University, Washington, DC, USA, 20057 e-mail: [email protected] Karl J. Wallace Department of Chemistry and Biochemistry, The University of Southern Mississippi, Hattiesburg, MS USA E-mail: [email protected]
L Lei Zhu Department of Chemistry and Biochemistry, Florida State Univ., Tallahassee, FL 32306, USA e-mail: [email protected] Linda S. Shimizu Department of Chemistry and Biochemistry, University of South Carolina, SC, USA, 29208 e-mail: [email protected] Li-Zhu Wu Key laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, the Chinese Academy of Sciences, Beijing 100190, China email: [email protected]
M Minghua Liu Institute of Chemistry, The Chinese Academy of Sciences, Beijing, China, 100091 e-mail: [email protected]
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P Padma Gopalan
Department of Materials Science and Engineering, University of Wisconsin e-mail: [email protected]
Q Qing Chang National Natural Science Foundation of China e-mail: [email protected]
R Ronald K. Castellano Department of Chemistry, P. O. Box 117200, University of Florida, Gainesville, FL 32611, USA e-mail: [email protected]
S Shiyong Liu Department of Polymer Science and Engineering, University of Science and Technology, Hefei, Anhui Province, China, 230026 e-mail: [email protected]
T Thomas H. Lane, Ph.D. President of American Chemical Society, N.W. Washington, D.C. 20036 e-mail: [email protected]
W
Wei-Yin Sun Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China e-mail: [email protected] Wenping Liang National Natural Science Foundation of China e-mail: [email protected]
X Xi Zhang Department of Chemistry, Tsinghua University, Beijing, China, 100084 e-mail: [email protected]
Y Yongfeng Zhou School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China. e-mail: [email protected] Yongjun Chen Department of Chemical Science, National Natural Science Foundation of China e-mail: [email protected] Yuguo Ma Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry, Peking University,
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Beijing, 100871, China e-mail: [email protected]
Z Zhan-Ting Li State Key Laboratory of Bioorganic and Natural Products Chemistry Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences 354 Fenglin Lu, Shanghai 200032, China e-mail: [email protected]
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US-China Workshop for Early Career Chemical Scientists ——Supramolecular Chemistry
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