Fujita et al., 1994

Fujita et al.Nature, 1994

molecular "magic rings"

Fujita et al.

The stoichiometry will induce the right selection of the

fragments so as to afford a catenane

quantitatively

Fujita et al.

The complexes contain two identical ligands but each ligand is asymmetric: the ring is oriented

a catenane with two oriented rings

Is it a chiral compound?

a catenane with two 36-membered rings

Angew. Chem. Int. Ed. 2005, 44, 4896 –4899

Double-loop compound 2a was obtained by treating ligand 4 with bimetallic linker 5 in dimethyl sulfoxide (DMSO). Typically, ligand 4 (7.1

mg, 10 mmol) was treated with 5 (4.6 mg, 5.0 mmol) in DMSO (0.50 mL) for a few minutes at ambient temperature.

Subsequently, the catenation of 2a at both loops by adding water to the solution in DMSO was examined. The newly formed product was cyclic

dimer 3, which contains two catenated frameworks.

3 :

Why do we need to add water???

CPK modeling showed that an expanded conformation of 3 has an external diameter of approximately 4 nm (Figure 5). The

backbone of 3 comprises 238 non-hydrogen atoms

Guest = o-Carborane

1 23 4

5 67 8 9 10 11 12

* *

* *

N

N

N

N

NN

Pd

PdPd

O

O

OMe

MeO O

O

OO

OMe

MeO

MeOOMe

+

Free cage

Complexed cage

three very simple bridging ligands

Analogy with C60

Schematic representation of the self-assembly of coordinationnetworks from metal ions which favor a square-planar coordination geometry and

different bridging ligands. a) Linear ligands are expected to give 2D grid complexes. b) Slightly bent ligands are expected to lead to spherical finite

complexes.

The 1H NMR spectrum (aromatic region) of the productAssembled from Pd(NO3)2 and ligand 1a (2 equiv; 500 MHz,

[D6]DMSO, 258°C, TMS).

CSI-MS spectrum showing the formation of M12L24 product (PF6 salt).

a) Molecular structure 2a assembled from 24 bidentate ligands 1a and12 metal ions.

b) Schematic representation of the cuboctahedral frameworks of 2a.

a) STM image of individual spheres 2a on the graphite atroom temperature. b) Height profile of the STM image.

The crystal structure of 2b. Counterions and solventmolecules are omitted for clarity (green Pd, red O, blue N, gray C).

By attaching a functional group on each ligand, 24 functional groups are aligned equivalently at the periphery of the sphere. Metal–porphyrins are

known to collect light energy when they are aggregated as in light harvesting proteins or chlorophylls.

A molecular modeling study of 2d : Pd yellow , the porphyrin-based and pyridine-based units are green and purple, respectively

JACS, 2009

square planar Ni(II) and Co(II) complexes show spin crossover upon encapsulation by coordination cages of the general structure

1

The confined cavity of the hosts inhibits changes in the metal

coordination number or geometry and promotes configuration change

presumably via electronic interactions between the metal dz2 orbital and the

π orbitals of the aromatic cage panels.

UV-vis spectra of 1a⊃2 and 2 in solid state

MT vs T plots for 1a⊃2 and 2(~16% of the value expected for pure

HS configuration of Ni(II) : S=1)

Angew. Chem. Int. Ed., 2009, 48, 3418-3438

in this review article the contributions of Raymond, Rebek, Stang, Saalfrank and

others are also discussed

, 251

The Diels-Alder reaction of anthracenes in the absence of hosts is extremely well studied and generally yields an adduct bridging the

centre ring (9,10-position) of the anthracene framework as a consequence of the high localization of p-electron density at that site

Coordination cages (1 and 2), prepared by simple mixing of an exo-tridentate organic ligand and an end-capped Pd(II) ion in a 4:6 ratio in water.

Pair-selective encapsulation of two types of reactants, 9-hydroxymethylanthrancene (3a) and N-cyclohexylphthalimide(4a), within cage 1 and the subsequent Diels-Alder reaction leading to syn isomer of

1,4-adduct 5 within the cavity of 1

crystal structure of 1⊃5

with the "bowl" as container, the reaction pathway is totally different

experimental conditions : 10 mol % of 2, aqueous solution, r.t., 5 hours >99% yield of ➞ 6

Schematic representation of the catalytic Diels-Alder reaction of anthracenes and phthalimide in the presence of bowl 2. Autoinclusion of substrates into 2 (step a) and

autoexclusion of the product from 2 (step c)

6 / 2/ 3

formation of homotopic compounds must be avoided TEMPLATE

without template, 5 and 6 are obtained

X-ray structure of 6

X-ray structure of the host-guest complex: the triphenylene derivative forms an A-D complex with the cage (stacking)

1 : M12LA24

2 : M12LB24

LA : -R = -O-n-C3H7

LB : -R = -O-n-C6H13

When a fresh 1:1 mixture of 1 and 2 was immediately subjected to MS analysis, the peak intensities were

equivalent

When a 1:1 mixture of 1 and 2 in acetonitrile was allowed to stand at 23 °C overnight, the formation of mixed products

M12LA23LB (3) and M12LALB

23 (4) was not observed

Ligand exchange slowly occurs over 3 daysat room temperature, and new peaks, corresponding to 3

and 4, gradually appeared in the Mass spectrum.The mixed species 3 and 4 only appeared after 35 hours

LA : -R = -O-n-C3H7

LB : -R = -O-n-C6H13

The 1H NMR signals of free and coordinated pyridine are sharp and independently observed. However, using saturation transfer NMR spectroscopy, ligand equilibration can be observed. The exchange

rate, kobs, was determined to be 1.9x10-2 s-1, and the half-life was 36 s. The half-life of the mononuclear complex is thus smaller than that of

the M12L24 complex by a factor of 10∼ 5

pp. 53-56

Short nucleotide fragments such as mono- and dinucleotides are

generally unable to form stable hydrogen-bonded base pairs or

duplexes in water. Within the hydrophobic pockets of enzymes,

however, even short fragments form stable duplexes to transmit genetic

information. Here, we demonstrate the efficient formation of hydrogen

bonded base pairs from mononucleotides in water through enclathration

in the hydrophobic cavities of self-assembled cages.

The stable formation of DNA duplexes in water requires the association of at least four complementary nucleotide base pairs.

complementary base pair formation of mononucleotides is however possible within an artificial hydrophobic pocket.

the pyrazine-pillared coordination cage 1 provides a flat, hydrophobic pocket with an ideal interplanary distance (6.6A˚ ) for the binding of planar aromatic molecules

Stirring an aqueous solution of 5'-adenosine monophosphate(5, 2.0 mmol) and 5'-uridine monophosphate (6, 2.0 mmol) inthe presence of cage 1 (2.0 mmol) resulted in the formation of

the host–guest complex 1.(5⊃6)

A U

Molecular container compounds provide a new space for reaction chemistry, both literally and

figuratively, through the encapsulation of smaller guest molecules

M4L6 tetrahedral assemblies constructedfrom metal and ligand components

The tetrahedron assembles exclusively as the homochiral stereoisomer (that is, ΔΔΔΔ or ΛΛΛΛ), with its chirality generated by

the tris(bidentate) chelation of each of the four metal centers.

Left : schematic representation of the tetrahedral assembly. One ligand only is drawn

Right : CAChe model of [CpRu(η6-C6H6)⊂Fe4L6]11- with the guest molecule shown in a space-filling view

Acid Catalysis in Basic Solution : A Supramolecular Host Promotes Orthoformate Hydrolysis

Michael D. Pluth, Robert G. Bergman,* Kenneth N. Raymond*

SCIENCE, VOL. 316, 6 APRIL 2007, 85-88

Here, we report a highly charged, water-soluble, metalligandassembly with a hydrophobic interior cavity that thermodynamically

stabilizes protonated substrates and consequently catalyzes the normally acidic hydrolysis of orthoformates in basic solution, with rate

accelerations of up to 890-fold.

The naphthalene walls render the interior hydrophobic, whereas the tetra-anionic ligands, in combination with the trivalent metal

centers, confer a 12– overall charge to the assembly.

M : GaIII

11-

A model of [2-H+⊂1]11–

2 : N,N,N′,N′-tetramethyl-1,4-diaminobutane

pKa shift : ΔpKa~ 3.5 unitsfree amine : pKa~11complexed amine : pKa~14.5

In the presence of a catalytic amount of 1 in basic solution, triethyl orthoformate is quickly hydrolyzed (t1/2 ~ 12 min, pH = 11.0, 22°C) to the corresponding formate ester, HC(O)(OR),

and finally to formate, HCO2–