This article was published as part of the

2009 Metal–organic frameworks issueReviewing the latest developments across the interdisciplinary area of

metal–organic frameworks from an academic and industrial perspective Guest Editors Jeffrey Long and Omar Yaghi

Please take a look at the issue 5 table of contents to access the other reviews.

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Design and synthesis of metal–organic frameworks using metal–organic

polyhedra as supermolecular building blocksw

John J. Perry IV, Jason A. Perman and Michael J. Zaworotko*

Received 23rd October 2008

First published as an Advance Article on the web 3rd March 2009

DOI: 10.1039/b807086p

This critical review highlights supermolecular building blocks (SBBs) in the context of their

impact upon the design, synthesis, and structure of metal–organic materials (MOMs).

MOMs, also known as coordination polymers, hybrid inorganic–organic materials, and

metal–organic frameworks, represent an emerging class of materials that have attracted the

imagination of solid-state chemists because MOMs combine unprecedented levels of

porosity with a range of other functional properties that occur through the metal moiety

and/or the organic ligand. First generation MOMs exploited the geometry of metal ions or

secondary building units (SBUs), small metal clusters that mimic polygons, for the generation

of MOMs. In this critical review we examine the recent (o5 years) adoption of much larger

scale metal–organic polyhedra (MOPs) as SBBs for the construction of MOMs by highlighting

how the large size and high symmetry of such SBBs can afford improved control over the

topology of the resulting MOM and a new level of scale to the resulting framework

(204 references).

1. Introduction

Metal–organic materials, MOMs, (Fig. 1) are comprised of

metal moieties and organic ligands and are exemplified by a

diverse group of discrete (e.g. metal–organic polyhedra,

spheres or nanoballs, metal–organic polygons) or polymeric

structures (e.g. porous coordination polymers, PCPs,

metal–organic frameworks, MOFs, or hybrid inorganic–organic

materials).

Whereas MOMs have existed for several decades1–10 it

was not until the early 1990’s that they captured broad

attention as it became evident that MOMs are typically

facile to prepare, aesthetically pleasing and, because of

their inherent modularity, prototypal for a diverse range of

structures that are amenable to crystal engineering design

strategies.11–21 The foundation for today’s activity in

MOMs resides with the seminal work of A. F. Wells22–25

who introduced the simple and practically useful ‘‘node and

spacer’’ interpretation of inorganic crystal structures. Inorganic

crystal structures can thereby be described as networks defined

by metal ions (nodes) linked together via bonds (spacer or

edge). An important aspect of this approach is that the

resultant network topology is reliant on the geometry

Department of Chemistry, University of South Florida,4202 E. Fowler Ave. CHE 205, Tampa, FL 33620, USA.E-mail: xtal@usf.edu; Fax: +1(813) 974 3203;Tel: +1(813) 974 3451w Part of the metal–organic frameworks themed issue.

John J. Perry IV

John J. Perry IV was bornin Tampa, Florida. Heobtained a BA in mathe-matics and a BA in chemis-try, graduating with honorsfrom the University of SouthFlorida (USF) in 2003.He has since been workingtowards completion of aPhD degree in chemistry atUSF under the supervisionof Professor Michael J.Zaworotko. His researchinterests include crystalengineering, supramolecularchemistry, metal–organic

materials, polyhedra, and mathematical concepts applied tochemical systems.

Jason A. Perman

Jason A. Perman was born inTampa, Florida, and receivedhis BS degree from theUniversity of South Florida.After undergraduate work inthe laboratory of ProfessorMichael J. Zaworotko, Jasonjoined his research group as agraduate student in the springof 2006. He currently conductsresearch in co-crystal con-trolled solid state synthesiswith emphasis upon newligands for new metal–organicmaterials.

1400 | Chem. Soc. Rev., 2009, 38, 1400–1417 This journal is �c The Royal Society of Chemistry 2009

CRITICAL REVIEW www.rsc.org/csr | Chemical Society Reviews

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and coordination environment of the nodes as the spacer is

simply a linear connection between adjacent nodes. For

example, if a given metal ion preferably adopts a tetrahedral

geometry and two equivalents of a linear bifunctional ligand

are coordinated to this metal, then a cubic or hexagonal

diamondoid network is the likely outcome (Fig. 2). In a similar

vein, octahedral metals can sustain square grid or octahedral

nets depending upon the metal : ligand stoichiometry (Fig. 2).

Such an approach is inherently modular, meaning that any

existing network structure is in principle prototypal, i.e. it

might serve as a blueprint for the study of the crystallochemistry

of many compounds with the same topology but with a

different chemical composition.

2. Foundations

2.1 Design

In the early 1990’s, R. Robson26–33 and others34–48 applied the

‘‘node and spacer’’ approach to generate coordination polymers,

most typically via coordination of linear ditopic organic

molecules such as 4,40-bipyridyl to transition metal cations.

The resulting compounds can exist as 1-periodic, 2-periodic or

3-periodic nets that are at the very least rational based upon

the geometry of the node and the node : spacer stoichiometry.

0-Periodic structures based upon 4,40-bipyridyl and square

planar metal moieties were developed concurrently.49–51 These

‘‘molecular squares’’ and polygons served as precursors to the

Fig. 1 Metal–organic materials encompass discrete as well as extended structures with periodicity in one, two, or three dimensions. The latter

have also been referred to as coordination polymers, metal–organic frameworks, and hybrid inorganic–organic materials.

Fig. 2 Schematic illustration of the node (red) and linear spacer

(blue) approach for design of networks based upon tetrahedral

(above left cubic diamondoid, above right hexagonal diamondoid)

or octahedral metal nodes (below left square grid, below right

octahedral network).

Michael J. Zaworotko

Dr Mike Zaworotko is Pro-fessor in the Department ofChemistry at the Universityof South Florida, USF.He was born in Wales in1956 and received hisBSc and PhD degrees fromImperial College (1977) andthe University of Alabama(1982), respectively. Heserved at Saint Mary’sUniversity, Nova Scotia from1985–1998 and joined USFin 1999. Current researchinterests include crystalengineering, metal–organic

materials, supramolecular chemistry, co-crystals and greenchemistry. Dr Zaworotko has published over 260 peer reviewedpublications and he currently serves as Associate Editor ofCrystal Growth & Design.

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metal–organic polyhedra that are discussed below. 3-Periodic

nets such as the diamondoid net were studied27,52–56 through

judicious selection of a tetrahedral metal ion and two

equivalents of a spacer ligand, thereby affording a considerable

degree of predictability and control over the scale and

topology of the resulting compounds. Extension of this crystal

engineering57–65 paradigm across a wide range of metals and

organic ligands created a degree of chemical diversity greater

than that typically encountered in purely inorganic or purely

organic materials and in turn afforded a plethora of prototypal

MOMs. Indeed, given that crystal engineering design

principles are equally applicable to crystals that are sustained

by hydrogen bonds, there are also examples of diamondoid

networks sustained by multiple66–68 (i.e. nodes and spacers) or

single components69–72 (i.e. tectons) that are complementary in

terms of their hydrogen bonding.

2.2 Properties

As the nascent field of MOMs advanced, the level of complexity

increased and researchers began to address the functionality of

this emerging class of materials. There were early indications

that 3-periodic MOMs could survive guest exchange73 and, in

the late 1990’s, the research groups of O. M. Yaghi and

S. Kitagawa reported the first examples of MOMs that exhibit

permanent porosity.74,75 These new materials could aptly be

considered as second generation MOMs for which Yaghi and

Kitagawa coined the terms metal–organic frameworks

(MOFs)76,77 and porous coordination polymers (PCPs),

respectively.78,79 SubsequentMOMs possess the lowest densities

and highest surface areas per gram known to mankind.80,81

Furthermore, many of these MOMs exhibit air/water stability

and thermal stability that is much improved over that of first

generation MOMs. However, perhaps even more important

than any one particular MOM has been the realization that

such compounds are certainly rational if not predictable in

terms of their structure and porosity. For example, Yaghi and

O’Keeffe developed the versatile and fruitful design strategy

of reticular chemistry,82 a strategy that exploits secondary

building units (SBUs)83 as molecular polygons or polyhedra

for the construction of MOFs. An SBU (Fig. 3) is a metal

cluster or molecular complex which is rigid in nature, and,

when the points of extension are considered, prediction of

network topologies that might exist when these molecular

building blocks are linked via polytopic organic linkers is

relatively facile.

As discussed above, first generation MOMs consist of a

single metal ion node that is linked by polytopic organic

ligands. In this context the use of SBUs to generate porous

MOMs can be viewed as an important evolution in terms of

design and utility because the greater relative size of SBUs

afford much greater surface area and increased pore and cavity

sizes. Additionally, the use of multiple metal ions in a cluster

bridged by multiple coordinating ligands tends to enhance the

robustness of the MOM. SBUs are also important from a

design perspective as they provide a means of controlling the

coordination environment of otherwise promiscuous transition

metals which might be capable of adopting any of several

coordination modes. Thus, the inclusion of SBUs into the

chemists’ toolbox facilitated rapid development of MOMs

with enhanced properties and structures that can be readily

understood and exploited for design purposes. It should

therefore be unsurprising that interest in MOMs exploded as

their synthetic accessibility was soon combined with a range

Fig. 3 Examples of prototypal secondary building units (SBUs) commonly used in the construction of periodic MOMs. (a.) Cupric acetate is a

dimetal tetracarboxylate square paddlewheel cluster [M2(O2CR)4L2] (M = transition metal, L = axial ligand) which mimics a molecular square.

Basic chromium(III) acetate, a m3-oxo trimetallic hexacarboxylate cluster [M3O(O2CR)6L3] can be used as either a molecular triangle (b.) or a

triangular prism (d.). (c.) Basic zinc acetate is a m4-oxo tetrametallic hexacarboxylate cluster, [M4O(O2CR)6], that is prototypal for a molecular

octahedron.

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of functional properties: unprecedented levels of permanent

porosity;73,84–88 catalysis;86–92 molecular magnetism;93–96

chemical separations and sensing;97–103 luminescence;104–106

and NLO properties107,108 among others.109–111 Furthermore,

that MOMs are inherently modular and can be generated

through self-assembly means that they are amenable to

fine-tuning of both structure (e.g. scale, functional groups)

and bulk physical properties through either pre-synthetic or

post-synthetic modification.112–122 Indeed, today there is a

general realization that there already exist a plethora of

MOMs that are amenable to control over their structure–

property relationships in a manner that was hitherto

unprecedented in materials chemistry. This degree of control

means that the incorporation of more than one useful

property into a single material becomes feasible, i.e.

multi-functional MOMs.

2.3 Discrete metal–organic polyhedra

Notwithstanding the significant progress that has been made

in terms of de novo design of MOMs, crystal engineering of

MOMs with predictable structures and/or physical attributes

remains a daunting challenge. Indeed, diamondoid nets are

not the only network structures that can occur through linking

tetrahedral moieties since hexagonal diamond (Lonsdaleite)

can also occur.123 In this vein, design strategies that facilitate

new classes of MOMs with even greater ranges of scale and

control would represent a welcome addition to the field. This

critical review explores the opportunity represented by

using metal–organic polyhedra (MOPs) as SBBs. Such SBBs

typically start at the nanometre scale and possess high

symmetry, alluding to the possibility of a crystal engineering

strategy for MOMs that combines even greater levels of scale

with highly specific control over topology. Polyhedra are a

geometric construct which have been recognized for millennia

and in recent years they have been used as blueprints for

the design of discrete inorganic,124–132 organic,133–139 and

metal–organic49–51,140–152 nanoscale structures. Whereas inorganic

and organic polyhedra are in principle capable of serving as

SBBs, we will focus herein upon metal–organics because they

are so inherently amenable to exterior functionalization.

MOPs can be categorized as follows: Platonic solids,

Archimedean solids, faceted polyhedra and stellated polyhedra.

2.3.1 Platonic MOPs. Perhaps the simplest and most

widely recognized polyhedra are the five polyhedra

constructed from one type of regular polygon (equal angles

and edge lengths) meeting at identical vertices which are

known as the Platonic solids—the tetrahedron, hexahedron

(cube), octahedron, dodecahedron and icosahedron—all of

which belong to one of the highly symmetric point groups:

tetrahedral, icosahedral, or octahedral (Fig. 4).

There have been several examples of discrete metal–organic

tetrahedra reported in the literature. For example Yaghi et al.

reported a series of isoreticular metal–organic polyhedra

(IRMOP) based upon the common m3-oxo centered

Fe3O(CO2)6 trimer.149 Normally this SBU would be regarded

as a triangular prism, but the authors judiciously cap

three cofacial sites with sulfate groups, thereby affording a

triangular SBU with carboxylates oriented 601 from one

another. These molecular triangles are linked by ditopic

bridging ligands such as 1,4-benzene dicarboxylate,

4,40-biphenyl dicarboxylate, tetrahydropyrene-2,7-dicarboxylate,

or 4,40-terphenyldicarboxylate into what the authors refer to

as truncated tetrahedra. Separately, Fujita et al. reported

a number of examples of tetrahedral MOPs based upon

the strategy of molecular panelling.150–152 Fujita coupled

palladium ions with pyridyl based organic ligands designed

to act as molecular triangles, or panels, and his method has

been adopted by several other research groups. Oppel and

Focker reported a double walled tetrahedron153 which was

constructed from another triangular molecule capable of

acting as a ligand with transition metals. Specifically they used

a C3-symmetric ligand with a triaminoguanidinium core in

combination with zinc or cadmium metal ions to generate

various MOPs.

Another Platonic Solid which is well represented in MOPs is

the hexahedron as exemplified by the cube. Two distinct

strategies have been implemented to generate metal–organic

cubes. In the first strategy an octahedral metal is complexed to

coordinating ligands chosen so as to terminate along the three

so called exo directions, thus transforming a six coordinate

transition metal into one which is essentially three coordinate

and oriented such that each metal can act as a corner of the

cube. An interesting example of this strategy was described by

Thomas et al. in 1998, where the authors adopt ruthenium

metal ions complexed with [9]aneS3 and three 4,40-bipyridine

moieties at ca. 901 to one another to act as a single corner of

the cube.154 This complex was observed to be air and moisture

stable as a solid and dissolved in non-coordinating solvents.

Another example of a metal–organic cube was reported by

Eddaoudi and co-workers,155 who used a different strategy:

in situ blocking of one face of an octahedrally coordinated

metal to form a trigonal pyramidal building unit that can serve

as the corner of a cube. They implemented the strategy with

nickel ions and a bidentate bridging moiety, 4,5-imidazoledi-

carboxylic acid, that chelates to Ni ions in a fac-octahedral

fashion. The resulting anionic metal–organic cube exhibits a

distance from the center of the cavity to a non-hydrogen atom

of the imidazole ring of ca. 4 A, affording a small cavity of

B50 A3 with Th symmetry.

Chan et al. investigated the use of a tridentate ligand

capable of acting as the trigonal pyramidal corner of

a cube when combined with either square-planar or

octahedral metal ions. Specifically, they reported the

synthesis of a neutral, Oh-symmetric cube from Ni2+ metal

ions and 2,4,6-tri[(4-pyridyl)sulfanylmethyl]-1,3,5-triazine in

dimethylformamide.156 The pyridyl groups of eight ligands

coordinate equatorially with chloride ions in the axial

positions. The square-planar geometry of the metal centers

with respect to the bridging ligands occurs at the center of

the six faces of the cube, with the pyridyl pendant arms of the

ligands expanding diagonally along this face toward the

corners of the cube and the center of the ligand.

Finally, the octahedron represents a Platonic solid that

has been well explored in terms of MOPs. An aesthetically

pleasing example of an octahedral MOP was reported by

Eddaoudi and co-workers157 when they bridged 6 indium(III)

metal ions with 12 2,5-pyridinedicarboxylate ligands that

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exhibit both chelating and bridging coordination modes. The

six metal ions reside on the vertices of an octahedron, while the

ligands generate the edges. The resulting triangular windows

open the inner cavity of the octahedron, which in the single

crystal X-ray structure holds a single ethanol molecule. The

isolated MOP is anionic and adopts Th symmetry and

1,2-diammoniumcyclohexane cations serve as bridges by

linking the octahedra via hydrogen bonding into a 3-periodic

network.

2.3.2 Archimedean MOPs. A class of polyhedra that are

closely related to Platonic solids are the Archimedean solids, i.e.

geometrical structures generated from a single type of vertex

for which all of the faces are regular polygons. However,

unlike the Platonic solids there are at least two different

faces in each Archimedean polyhedron making them

semiregular solids. There are 15 Archimedean solids—the

truncated tetrahedron, cuboctahedron, truncated cube,

truncated octahedron, rhombicuboctahedron, snub cube

(plus enantiomer), icosidodecahedron, truncated cuboctahedron,

truncated dodecahedron, truncated icosahedron, rhombicosi-

dodecahedron, snub dodecahedron (plus enantiomer), and

truncated icosidodecahedron—two of which, the cuboctahedron

and icosidodecahedron, are also constructed from a single type

of edge and sometimes referred to as quasiregular. Archimedes

described 13 convex polyhedra constructed from two or more

types of regular polygons that meet at identical vertices. These

Archimedean solids (Fig. 4) are therefore distinct from Platonic

solids, which are composed of one type of polygon meeting in

identical vertices, and from the Johnson solids, whose regular

polygonal faces do not meet in identical vertices.

Fig. 4 Platonic and Archimedean solids. First row (left to right): tetrahedron, hexahedron (cube), octahedron, dodecahedron, and icosahedron.

Second row: truncated tetrahedron, cuboctahedron, truncated cube, truncated octahedron, and rhombicuboctahedron. Third row: truncated

cuboctahedron, snub cube, icosidodecahedron, and truncated dodecahedron. Fourth row: truncated icosahedron, rhombicosidodecahedron,

truncated icosidodecahedron, and snub dodecahedron.

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There are numerous examples of organic or metal–organic

polyhedra that would be considered Archimedean in nature,

i.e. composed of two or more different molecular polygons.

Stang et al. reported a series of what can best be described as

truncated tetrahedra (the simplest and most common

Archimedean MOP).142,158 In their method, the authors

adopt face-directed self-assembly of tritopic ligands such as

tris(pyridylethynyl)benzene or tris(p-cyanophenylethynyl)-

benzene with cis-platinum or cis-palladium bistriflate salts.

The resulting Archimedean MOPs were studied via solution

NMR experiments and single crystal X-ray diffraction. In each

structure six Pd2+ or Pt2+ ions self-assemble with four ligands

in such a manner that the metal ions act as the vertices and the

tritopic moieties act as the triangular (truncated) faces of

the truncated tetrahedron. Another example of a truncated

octahedron was provided by Yaghi and co-workers.159 In this

MOP, a dicarboxylate ligand with an angle of ca. 901 between

the carboxylate groups was employed to generate dimetal

tetracarboxylate square paddlewheel SBUs, six of which were

linked together. The location of the metal cluster coincides

with the vertices of an octahedron and the authors referred to

their compound (MOP-28) as a truncated octahedron.

Stang and co-workers reported160 cuboctahedra that are

constructed through self-assembly of 20 tridentate and bidentate

subunits to transition metals. In one example a triangular

tridentate ligand, 1,3,5-tris(40-Pt(PPh3)2OSO2CF3)ethynylbenzene,

and a bidentate ligand, 4,40-bispyridylacetal, were used.

In another example, 1,3,5-tris(4-pyridylethnynyl)benzene was

combined with bis(4-[trans-Pt(PPh3)3OSO2CF3]phenyl)-

ketone. Both spheroids were characterized in solution via

electrospray mass spectrometry and NMR and were estimated

to be ca. 5 nm in diameter. Fujita et al. reported a series of

MOP compounds that are of a roughly spherical shape

and possess the symmetry of the cuboctahedron.161 These

compounds are based upon palladium–pyridyl chemistry and

demonstrate a wide range of modularity; simple functionalization

of the bis(4-pyridyl)-bent ligand can lead to endohedral

functionalization of the inner cavity of the spheroid. The

ligand has a built-in angle of B1201 subtended between

pyridyl groups which coordinate to Pd2+ ions in a square-

planar fashion. In addition to being amenable to functionalizing

the inner cavity, this MOP can be ‘‘scaled-up’’ by adopting

expanded ligands that retain the bis-pyridyl moieties and

the 1201 angle, i.e. this MOP is prototypal for a series of

isoreticular structures.

Organic MOPs also exist as exemplified by the 1997 report by

Atwood and MacGillivray of an organic, hydrogen bonded

version of an Archimedean snub cube.162 In this spheroid, six

calix[4] resorcinarenes are combined with 8 water molecules

through 60 O–H� � �O hydrogen bonds to form a hydrogen

bonded capsule that is closely related to the snub cube. This

compound is stable in apolar organic solvents and has been

investigated via single crystal X-ray diffraction and 1H NMR

spectroscopy. The hollow interior of the spheroid is capable of

encapsulating guests with its internal volume cavity ofB1375 A3.

2.3.3 Faceted MOPs. A third class of discrete polyhedron

that is particularly salient to MOMs are those faceted

polyhedra that are sustained by vertex sharing of polygons

rather than the edge sharing observed in Platonic and

Archimedean solids. These nonconvex uniform polyhedra

differ from the convex, edge-sharing versions in that they

necessarily contain both closed faces (i.e. the polygon) and

open windows to the interior of the spheroid (Fig. 5). There

are nine examples of faceted polyhedra derived from

regular convex polygonal faces—the tetrahemihexahedron,

octahemioctahedron, and small icosihemidodecahedron are

constructed from triangles alone; the cubohemioctahedron,

small rhombihexahedron, and small rhombidodecahedron are

formed from squares alone; the small cubicuboctahedron is

constructed from a combination of triangles and squares; the

small dodecicosidodecahedron is generated from triangles and

pentagons; while the small dodecahemidodecahedron is

fashioned from the intersection of pentagons alone.

Of the nine faceted polyhedra, the three that can be generated

via vertex-linking of squares represent especially viable

stargets for MOPs as square paddlewheel SBUs (Fig. 3a) are

ubiquitous in coordination chemistry. The only difference

between these three polyhedra is the angle subtended by the

vertices, a parameter that can be controlled by the synthetic

chemist when a ligand is chosen to link the square SBUs. The

cubohemioctahedron, small rhombihexahedron and small

Fig. 5 Faceted polyhedra. First row (left to right): tetrahemihexa-

hedron, octahemioctahedron, and small icosihemidodecahedron.

Second row: cubohemioctahedron, small rhombihexahedron, and small

rhombidodecahedron. Third row: small dodecahemidodecahedron,

small cubicuboctahedron, and small dodecicosidodecahedron.204

Fig. 6 The three faceted polyhedra that arise from vertex linking of

squares only: (a) cubohemioctahedron; (b) small rhombihexahedron;

(c) small rhombidodecahedron.

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rhombidodecahedron possess 12, 24, and 60 vertices, respectively

(Fig. 6), with the small rhombihexahedron, which has also

been termed a nanoball, of particular interest since the angle

between its vertices is 1201, i.e. it corresponds exactly to the

angle subtended by meta-substituted benzene rings. As such it

has been extensively studied by several research groups and it

can be regarded as the prototypal example of a metal–organic

faceted polyhedron.163,164

The first such example was constructed from 12 dimetal

tetracarboxylate square paddlewheel complexes, M2(bdc)2L2

(M: Cu(II); bdc: 1,3-benzene dicarboxylate and L: solvent

molecules or pyridine-type bases), vertex linked at 1201 by

the bdc ligands. The versatility of this nanoball is such that

multiple derivatives have been reported165–168 (Fig. 7). The

hydroxylated version of the nanoball has been studied in

solution169,170 and forms polymer composites171,172 whereas

the dodecyloxy derivative incorporates into a lipid membrane

and has been studied as a synthetic ion channel with selectivity

for smaller alkali metal cations.173 The small rhombihexahedron

shares the same edge skeleton as the Archimedean solid

known as the cuboctahedron and these terms have been used

interchangeably in the context of MOMs since the edge

skeleton defines the connectivity.

MOPs that can be described as small cubicuboctahedra have

also been characterized. In 2006, Sun and co-workers

reported174 a MOP constructed from Cu(ClO4)2�6H2O and

benzene-1,3,5-triacetic acid. Eight carboxylate ligands bind to

11 Cu2+ ions to form 5 square paddlewheel SBUs and one

mono-copper complex that adopts a square-planar geometry.

The triangular benzene-1,3,5-triacetate ligands are linked to

the five square paddlewheel SBUs and the mono-copper

moiety. The resulting MOP can therefore be regarded as six

square moieties bridged by eight triangles, i.e. it is a small

cubicuboctahedron. In 2008, Sun et al. reported175 a related

structure based upon a different triangular ligand, N0,N00,N0 0 0-

tris(pyrid-4-ylmethyl)-1,3,5-benzenetricarboxamide. In this

instance the authors chose a different copper salt,

Cu(BF4)2�6H2O, and the coordination is different from the

previous example in that pyridyl ligands coordinate to Cu2+ in

a square-planar fashion, but the MOP geometry remains the

same: triangular ligands linked at their vertices to the square

metal–ligand complexes so as to form what can be considered

a small cubicuboctahedron.

Another example of a faceted polyhedron was recently

reported by Mattay et al.176 In this contribution the authors

describe a cavitand-terpyridine subunit which can be viewed as

Fig. 7 The nanoball family portrait. Discrete nanoballs are based upon 12 paddlewheel SBUs and are therefore constructed from 24 Cu2+ ions

and 24 isophthalate molecules. A number of decorated nanoballs based upon substitution at the 5-position of the isophthalate ligands have been

crystallographically characterized.

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a molecular square. When combined with a zinc salt,

[Zn(NCMe)6](tetrakis(3,5-bis(trifluoromethyl)phenyl)borate)2,

in a 1 : 2 ratio of cavitand-to-metal, a cuboctahedron MOP in

which six cavitands are bridged by nearly linear Zn–terpyridine

linkages is formed. This MOP has been studied via ESI-MS,

small angle X-ray scattering (SAXS), diffusion NMR spectro-

scopy, and elemental analysis. However, no single crystal

X-ray structure was obtained. The authors assigned structure

based upon the aforementioned analyses and molecular

modeling. The predicted structure exhibits an outer diameter

of ca. 4.6 nm with large windows of ca. 0.77 nm that provide

access to an inner cavity of volume ca. 13.7 nm3.

2.3.4 Stellated MOPs. A fourth class of polyhedron that

has been exploited are the stellated polyhedra, in particular the

stella octangula.177 This MOP was first reported by Hardie

et al. and is constructed via self-assembly of ‘‘naked’’ Pd2+

ions and a derivative of a cyclotriveratrylene (CTV) macro-

cyclic host molecule. The authors exploited the rigid and

curved nature of the CTV derivative to impart molecular

recognition and increase the inner cavity volume over that of

a flat ligand counterpart. The bowls of the CTV ligands, which

occupy the eight triangular faces of an octahedron, orient

toward the inner cavity of the MOP with their rigid pyramidal

portions pointed outward away from the center. This is

why the authors interpret their structure not as a simple

octahedron, but rather a stellated version in which all of the

edges encompassing each face of the octahedron are extended

outward until they meet at a point away from that face,

generating a star-like prism. Each of these discrete stella

octangula is composed of six Pd2+ ions located at the vertices

of a simple octahedron, with eight C3-symmetric ligands based

upon the macrocycle, and results in an overall cationic com-

pound, which in this case is counter-balanced with nitrate ions.

The stella octangula are chiral and each individual complex is

composed of identical homochiral ligands. However, the bulk

solid exists as a racemic mixture. These MOPs were studied via

single crystal X-ray diffraction, 1H NMR, ESI-MS, and

diffusion ordered NMR spectroscopy (DOSY). The size

(ca. 3.1 nm) and octahedral symmetry of the complexes in

solution was thereby confirmed.

In principle, the aforementioned MOPs represent a toolbox

of SBBs for the construction of both low connectivity and high

connectivity nets. This contrasts with SBUs that are by their

geometric nature typically limited to the generation of 2-, 3-, 4-

and 6-connected nets. Furthermore, MOPs exhibit potential

for decoration around their periphery and therefore for

serving as an SBB through either cross-linking at exterior

metal sites or via cross-linking through the ligand (e.g. the

use of a tetracarboxylato ligand rather than a dicarboxylato

ligand). The remainder of this review addresses the use of such

MOPs and SBBs.

3. MOFs from MOPs: frameworks sustained by

supermolecular building blocks

For the purpose of this review we shall differentiate between

frameworks with polyhedral cages178 which share faces and

those constructed via polyhedral SBBs. In the case of the

former, HKUST can be considered an archetype.179 HKUST

is constructed from Cu2+ and trimesic acid in a 3 : 2 ratio with

the dicopper square paddlewheel SBU joining. HKUST

contains a nanoball but it is not isolated since it shares its

12 faces with additional nanoballs (Fig. 8). The nanoball does

not participate as a node but rather it can be regarded as an

assembly of 4- and 3-connected SBUs that generate void space

in a framework that exhibits a tbo topology. This review

focuses upon frameworks for which polyhedra serve as SBBs

via linking through multi-topic ligands rather than the sharing

of polygonal faces. One might view this situation as a natural

extension of the existing hierarchy: an SBB sustained

framework can be regarded as being constructed of nanoscale

MOPs; MOPs are constructed from SBUs; SBUs are

comprised of metal ions bridged by organic ligands. However,

whereas from the perspective of properties there might be a

greater level of complexity, from a design perspective the

bigger the SBB, the more likely that there will be a high level

of symmetry and a more limited number of topological

possibilities. Therefore, one might rationalize SBBs as simply

an extension to the SBU approach that facilitates a larger

length scale and a greater control over topology. The former is

obvious and consequential: the larger the building block one

exploits, the larger must be the resultant framework which in

turn means that even interpenetrated structures180–182 might

exhibit meaningful porosity. The latter is perhaps not quite so

obvious but it is also consequential. The SBB approach

provides a toolbox of building blocks capable of acting as

nodes with rare or even unprecedented connectivity sinceMOPs

offer coordination numbers higher than those possible with

simple inorganic metal clusters or molecular complexes.

Furthermore, that SBBs are designed from first principles

means that one might control or even customize the nature of

the resulting cavities (size, shape, and chemical functionality).

3.1 Platonic solids

3.1.1 Tetrahedra/supertetrahedra. Tetrahedra and super-

tetrahedra represent perhaps the earliest and most widely

studied SBBs. Yaghi et al. recently reported MOF-500183

([1], Table 1), a framework which is conceptually based

upon the linking of tetrahedra, and they also established

a synthetic method for the synthesis of metal–organic

tetrahedra composed from iron trimers based upon a trigonal

prismatic SBU (Fig. 3b and d). These tetrahedra (IRMOP

51–53)149 are synthesized from Fe2(SO4)3 in a solution of

Fig. 8 HKUST: sharing the same polygonal (SBU) face between

polyhedrons (shown here with small rhombihexahedrons) differs from

the SBB approach.

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N,N0-dimethylformamide and triethylamine in the presence

of 4,40-biphenyldicarboxylate and pyridine. Trigonal

[(Fe3O)(CO2)3(SO4)3] units are coordinated to three terminal

pyridine ligands. MOF-500 is built from these tetrahedral

SBBs by replacing the terminal pyridine groups with cis-1,2-

bis-4-pyridylethane, a ditopic bridging ligand capable of

linking the tetrahedra together. The resulting network exhibits

four different interconnected pores that are generated from

four types of porous tetrahedral SBBs with free pore diameters

ranging from 5.2 to 18.0 A. The solvent accessible free volume

of MOF-500 is B78% which is occupied by guests including

eight dimethylammonium cations that balance the charge of

the anionic framework. The arrangement of the tetrahedral

SBBs in MOF-500 affords b-cristobalite (SiO2) topology.

3.1.2 Hexahedra (cubes). MOPs exhibit several examples

of structures which can be regarded as cubes. Indeed, several

authors have chosen to adopt the nomenclature metal–organic

cubes (MOC), however such terminology can be ambiguous

since it does not necessarily address the fine details of the MOP

and its constituent parts. Nevertheless, such MOPs are capable

of serving as SBBs such as those first reported by Eddaoudi

and co-workers in 2004.155 This cube is constructed from Ni2+

ions and 4,5-imidazoledicarboxylic acid (Fig. 9), is anionic and

has the formula [Ni8L12]20� (H3L= 4,5-imidazoledicarboxylic

acid). The 8 Ni2+ ions reside at the vertices of a cube and

are linked through 12 L ligands which coordinate in a

bis-chelating fashion.

These cubes were subsequently investigated by other

research groups and incorporated into framework MOMs.

In 2005, Xu and co-workers reported the assembly of

these cubes into a framework via bridging with Na+ cations

([2], Table 1).184 In Xu’s structure, the authors report that the

ligand is fully deprotonated (in contrast with the structure

reported by Eddaoudi) due to the use of a strong base, sodium

hydroxide. Two types of cavity were observed: the cavity of

the cube itself; a cavity generated by the linking of the cubes

into a 3-periodic array. The distance from the center of the

cube to the closest non-hydrogen atom of the imidazole ring is

3.236 A and the inner cavity of the cube exhibits a volume of

ca. 52 A3. The second cavity has a larger volume (B80 A3) as

the distance from the center to the closest Na+ is 3.717 A. The

authors reported a BET surface area of 147 m2 g�1 and a

micropore volume of 0.26 cm3 g�1 obtained from nitrogen

adsorption isotherms. In a separate contribution, Xu also

reported a related 3-periodic MOM in which the Ni cubes

are bridged by Li+ ions in lieu of sodium cations ([3],

Table 1).185 This structure is also porous with similar BET

surface area and micropore size (145 m2 g�1 and 0.28 cm3 g�1,

respectively).

Gao et al. reported a different strategy for the use of

4,5-imidazolate cubes as building blocks for higher order

structures.186 They reported a variation of the cube that

incorporates Co rather than Ni ([4], Table 1). The Co cations

are mixed-valent, six CoIII and two CoII, thereby affording an

anion of formula [Co8L12]14�. The authors envisioned using

the cubes as metalloligands for generation of extended

structures through either hydrogen bonding or coordination

to cationic molecular complexes and they reported a

crystal structure involving [Co8L12]14�, [Ni(cyclam)]2+ and

[Ni(cyclam)(H2O)2]2+. In the crystal lattice each cube interacts

with two [Ni(cyclam)]2+ cations along the b-axis through axial

coordination to two oxygen atoms diagonally across from one

another in the cube, resulting in a 1-periodic coordination

polymer along this direction (Fig. 10). Additionally the

cubes are involved in hydrogen bonding with two sets of

Table 1 A tabulation of MOMs derived from SBBs. Topology can be ambiguous depending upon how MBBs and SBBs are defined

Compound SBU Type SBB Type Topology Metal Ligand Author (ref. #)

[1] Trigonal prismatic Tetrahedron SiO2 (b-cristobalite) Fe(III) Carboxylate and dipyridine Yaghi183

[2] Square Cube Not determined Ni(II) 4,5-Imidazoledicarboxylate Xu184

[3] Square Cube Not determined Ni(II) 4,5-Imidazoledicarboxylate Xu185

[4] Square Cube 1-Periodic chains Co(II/III) 4,5-Imidazoledicarboxylate Gao186

[5] Square Octahedron pcu-a Cu(II) Pyridines Lah188

[6] Square Cubohemioctahedron fcu (nbo) Co(II) Tetracarboxylate Yaghi190

[7] Square Cubohemioctahedron fcu (nbo) Ni(II) Tetracarboxylate Eddaoudi/Zaworotko191

[8] Square Cubohemioctahedron fcu (nbo) Co(II) Tetracarboxylate Eddaoudi/Zaworotko191

[9] Square Cuboctahedron fcu Cu(I) Cyano Huang193

[10] Square paddlewheel Nanoball 1-Periodic chains Cu(II) Methoxycarboxylate Zaworotko194

[11] Square paddlewheel Nanoball bcu-a Cu(II) Sulfonatocarboxylate Zaworotko194

[12] Square paddlewheel Nanoball pcu-a Cu(II) Tetracarboxylate Zaworotko196

[13] Square paddlewheel Nanoball pcu-a Cu(II) Tetracarboxylate Zhou197

[14] Square paddlewheels/triangles

Nanoball rht Cu(II) Tetrazolecarboxylate Eddaoudi/Zaworotko200

[15] Square paddlewheel Nanoball rht Zn(II) Carboxylate Lah202

[16] Square paddlewheel Nanoball rht Cu(II) Carboxylate Schroder203

Fig. 9 An example of a discrete metal–organic cube consisting of 12

bis-chelating ligands around 8 metal cations occupying the vertices of

the cube.

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[Ni(cyclam)(H2O)2]2+ ions along the ac plane, leading to an

overall 3-periodic network if hydrogen bonding is taken into

consideration.

3.1.3 Octahedra. Lah’s group reported a face-driven

corner-linked polyhedron with C3-symmetric ligands and C4-

symmetric metals, a truncated octahedron [Pd6L8]12+

(Fig. 11).187 The ligandN,N0,N00-tris(3-pyridinyl)-1,3,5-benzene-

tricarboxamide can adopt conformational isomers and

afforded two polyhedra when crystallized: the syn-conformer

with cavity volume ca. 1600 A3 and the anti-conformer with a

cavity volume of ca. 1900 A3. NMR studies suggest that the

syn-conformer polyhedron dominates in solution. The stability

of these materials in dimethyl sulfoxide was addressed via

ESI-MS experiments that indicated a molecular weight of

4.8 kDa.

If the typical square planar metal is switched to an octahedral

metal such as Cu2+ with the same ligand and a different

4-pyridinylmethyl version of the ligand then an augmented

primitive cubic net ([5], Table 1) is generated because counter

nitrate ions link the copper vertices (Fig. 12).188 Two-fold

interpenetration of these nets is observed with p–p interactions

between the central benzene moieties of the ligands in adjacent

nets. Perchlorate counterions afforded an unusual cluster of

octahedra which resembles the chair form of cyclohexane

(Fig. 13).

3.2 Archimedean solids

3.2.1 Cuboctahedron (cubohemioctahedron). We have thus

far presented examples of four and six connected SBBs that

afford regular nets with transitivity 1111. An additional tiling

with transitivity 1112 is feasible with a polyhedron resembling

a cubohemioctahedron, also referred to as a cuboctahedron,

that is constructed from one type of edge and one type of

vertex 3.4.3.4.189 Such a polyhedron possesses 12 vertices and

may serve as a node if linked in such a manner that an

augmented face center cubic motif is generated. Three such

metal–organic networks have been generated through the use

of a tetracarboxylate ligand and either Co2+ or Ni2+ ([6], [7],

[8], Table 1).190,191 Six square faces meeting at 901 angles are

required from the metal–ligand coordination and the resulting

cubohemioctahedron is necessarily anionic when constructed

from M(II) and bdc: [M6(bdc)12]12�. This SBB is an exception

to the others discussed herein since it has yet to be reported as

a discrete moiety (Fig. 14).

Fig. 10 Chains of metal–organic cubes linked through Ni2+ cyclam

cations.

Fig. 11 Discrete metal–organic octahedron with blue faces representing

C3-ligands and green vertices representing metal ions.

Fig. 12 An augmented primitive cubic net constructed from metal–

organic octahedra that are linked via nitrate anions at the six vertices.

Fig. 13 Metal–organic octahedra behaving as a ditopic SBB joined

through perchlorate anions into a cyclohexane-like motif.

Fig. 14 An anionic metal–organic cubohemioctahedron constructed

from 12 isophthalate molecules and 6 M2+ ions.

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The SBU that sustains the SBB contains two crystallo-

graphically independent metal ions which exhibit distorted

octahedral geometry. The interior metal of the cubohemi-

octahedron SBB coordinates to four monodentate carboxylato

oxygen atoms in the equatorial positions and aqua ligands

in the axial sites. The two carboxylato ligands of bdc are

monodentate and afford an angle of B901. Additional metal

ions neutralize the charge of the ca. 1.8 nm SBB and are

coordinated to the exterior of the SBBs through an aqua

ligand and two of the four monodentate carboxylates

(Fig. 15 and 16). Three related MOMs were synthesized in

the presence of N,N0-dimethylformamide and water, either

solvothermally or by slow diffusion with the reactants.

The MOMs exhibit the same fcu topology (NbO net

when treating the metal and ligand as quadrilateral building

blocks), but a different scale because of the length of

the tetracarboxylate ligands; biphenyltetracarboxylate4�,

azobenzenetetracarboxylate4� and benzoimide phenanthroline

tetracarboxylate4� (BIPA-TC4�) (Fig. 17). In all three

structures, six cubohemioctahedra join at their square

faces so as to generate an octahedral cavity large enough to

accommodate 2700 A3, 5600 A3 and 36 000 A3 spheres,

respectively. The biphenyltetracarboxylate structure converts

from the square SBU to a tetrahedral SBU after prolonged

exposure to heat under mother liquor, thereby transforming

from an NbO net into a PtS net with reduced pore volume.190

The other twoMOMs constructed from the cubohemioctahedral

SBB and tetracarboxylate ligands adsorb gases and exchange

metal cations from solution without loss of crystallinity.191

The cuboctahedron is not limited to carboxylate based

materials and has been observed in several inorganic clusters

as exemplified by a structure that is sustained by a m4-Scoordination with Cu(I) (Fig. 18).192 Huang et al. generated

a face centered cubic net (fcu) from a cuboctahedral SBB

constructed from [Cu12(m4-SCH3)6]6+ using CN� ligands as

connectors between the copper vertices of the SBBs ([9],

Table 1).193 The vertices of the cuboctahedron are occupied

by twelve Cu(I) cations with sulfur atoms occupying the

centers of the six square faces. The fcu net does not form

under mild conditions, CuCl and cysteamine hydrochloride

afford a 44-net. Rather, it is generated under solvothermal

conditions (1401 C to 160 1C) that facilitate in situ synthesis

of both SCH3� (from NaSCN and methanol) and CN�

(from either NaSCN or acetonitrile). The octahedral cavity

generated from six linked SBBs can only accommodate a sphere

of volume ca. 90 A3 because methyl moieties extend into the

cavity. The solvent that occupies the tetrahedral and octahedral

cavities can be removed at elevated temperatures and the

resulting anhydrous material remains stable until 190 1C.

3.3 Faceted polyhedra

3.3.1 Nanoballs (truncated cuboctahedra). The prototypal

nanoballs of formula [Cu2(bdc2)L2]12 were first reported as

discrete MOMs in 2001 and their development as SBBs

followed shortly thereafter when decorated versions of the

Fig. 15 The SBU for the metal–organic cubohemioctahedron

consists of two metal cations (Ni2+ or Co2+) coordinated to four

carboxylato ligands.

Fig. 16 Face centered cubic (fcu) representation of the network

sustained by 12-connected metal–organic cubohemioctahedra.

Fig. 17 The biphenyltetracarboxylic acid (left), azobenzenetetracarboxylic acid (center) and benzoimide phenanthroline tetracarboxylic acid

(right) ligands used in the synthesis of metal–organic cubohemioctahedron-based fcu-like nets.

Fig. 18 The metal–organic cuboctahedron SBB built with m4-coordinated sulfur atoms (gold) and copper atoms (green).

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nanoballs were isolated (Fig. 7). Such decoration can occur at

either of two sites on the nanoball: (i) the vertices, by

decorating the 5-position of the bdc ligand; (ii) via ligand

coordination at the center of the square faces (Fig. 19), i.e. the

exterior apical position of the tetracarboxylate paddlewheel

SBUs. Zaworotko et al.194 reported the first such structures in

2004 and referred to their structures as being examples of

suprasupermolecular chemistry,195 thereby emphasizing the

controlled use of nanoscale nodes (the nanoball) to generate

extended coordination polymers (MOMs). A consequence of

the size of the nanoballs is the existence of up to 36 peripheral

sites for decoration. However, not all sites need to or should be

used since, although the ideal symmetry of the nanoball is Oh,

cross-linking can exploit only some decoration sites, thereby

resulting in lower levels of connectivity.

3.3.1.1 Chains of nanoballs. In principal every bdc ligand

might generate a nanoball although bdc ligands without

substituents in the 2-, 4- and 6-positions are preferred since

they are not as likely to sterically influence the torsion angle

between the carboxylate moieties. Zaworotko et al.194

reported that layering a solution of 5-methoxy-isophthalic

acid and 2,6-lutidine dissolved in methanol over a solution

of Cu(NO3)2 dissolved in methanol and nitrobenzene resulted

in nanoballs that could be described as being the result of

self-assembly of 70 species (24 Cu2+ ions, 24 5-MeO-bdc

ligands and 22 MeOH/H2O coordinated to 22 of the 24 axial

sites). The resulting nanoball exhibits a volume of B11.5 nm3

and participates as a node in a chain of nanoballs ([10],

Table 1) because two methoxy groups on each nanoball

coordinate to Cu2+ moieties on adjacent nanoballs

(Cu� � �Omethoxy 2.26 A) (Fig. 20).

3.3.1.2 bcu nets of nanoballs. Zaworotko et al. reported how

a methanol solution of the sodium salt of 5-sulfoisophthalic

acid and Cu(NO3)2 layered over a methanol solution of

4-methoxypyridine afforded a decorated anionic nanoball

sustained by 5-sulfonato-bdc ligands.194 The crystal structure

revealed that the nanoballs form an anionic body centered

cubic (bcu) net with nanoball nodes that are approximately

3.6 nm in diameter ([11], Table 1). The overall symmetry was

reduced to this level because 16 of the 24 sulfonates from

5-SO3-bdc pair with 8 [Cu(methoxypyridine)4]2+ cations to

crosslink the nanoballs (Fig. 21). The cavities contain 4-meth-

oxypyridinium cations and [Cu(methoxypyridine)4(H2O)2]2+

cations, thereby balancing the framework charge.

3.3.1.3 pcu nets of nanoballs. In 2007, Zaworotko and

co-workers reported a pcu-like net built from nanoball SBBs

([12], Table 1).196 Whereas the nanoball chains and the

nanoball bcu-like nets discussed above arise via coordination

bonds, this new pcu-like net was generated by covalent

cross-linking of the bdc ligands. An appropriate strategy for

such cross-linking of nanoballs involves the design of

tetracarboxylato ligands that are formed by linking at

the 5-position of bdc. Zaworotko et al. synthesized such a

Fig. 19 The metal–organic nanoball is modular in that it can be

functionalized at either the vertices (gray extension) or the square faces

(gold extensions).

Fig. 20 2-Connected nanoballs. A methoxy oxygen atom on a 5-MeO isophthalate ligand coordinates to the axial position on a dicopper

paddlewheel from an adjacent nanoball to form chains.

Fig. 21 Metal–organic nanoballs are cross-linked to eight adjacent

nanoballs through two coordinate covalent cross-links represented by

the gold rods thereby sustaining a bcu-like topology.

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tetracarboxylic acid with a flexible aryloxy linkage, 1,3-bis(5-

methoxy-1,3-benzene dicarboxylic acid)benzene (Fig. 22).

Reaction of this ligand with Cu(NO3)2 in a dimethyl

sulfoxide solution of o-dichlorobenzene and pyridine at

115 1C for 24 hours afforded blue-green prismatic crystals.

Single crystal X-ray crystallography revealed that the flexibility

of the ligand facilitated quadruple cross-linking, i.e. each

nanoball is cross-linked with six adjacent nanoballs through

four bridging ligands (Fig. 23).

The authors noted that four-fold cross-linking is feasible in

two modes: via all six of the ‘‘open’’ windows affording local

Oh symmetry; through two ‘‘open’’ windows and four square

faces affording local D4h symmetry. The nanoball nodes cross-link

in the latter fashion and the compound crystallized in the

tetragonal space group I422. The ligand adopted two crystallo-

graphically independent orientations: a syn-conformation

affording a cylinder of dimensions B7.24 A (Cu� � �Cu from

SBU) � 10.54 A (centroid–centroid of the bridging aryloxy

groups); an anti-conformation generating a cylinder of

dimensions B5.86 A (oxygen atoms that start the bridge) �17.88 A. The first cylinder is oriented along the a- and b-axes

and is filled with solvent molecules whereas the second

cylinder is oriented along the c-axis and results in a persistent

void that becomes a channel along this direction (Fig. 24). The

network contains large cavities of ca. 18.3 A along the

a,b-axes and 13.56 A along the c-axis. Unfortunately 2-fold

interpenetration mitigates this 1.8 � 1.8 � 1.4 nm cavity.

Zhou and co-workers utilized 5,50-methylene-diisophthalic

acid (Fig. 25) and Cu2+ to synthesize another 3-periodic

framework constructed from linking nanoballs into a pcu-like

network ([13], Table 1).197 Nanoballs are cross-linked to six

others along three orthogonal directions through four

bridging ligands. The authors identify the network as being

related to 3.44, or the linking of rhombicuboctahedra and

squares.198 This pcu net does not exhibit interpenetration,

presumably due to the shorter length of the bridge between

Fig. 22 1,3-Bis(5-methoxy-1,3-benzene dicarboxylic acid)benzene, a

flexible tetracarboxylate ligand.

Fig. 23 Illustration of the pcu-like topology of the quadruple cross-

linked metal–organic nanoball structure. Each nanoball is cross-linked

to six adjacent nanoballs through four covalent cross-links represented

by the purple cubes.

Fig. 25 5,50-Methylene-diisophthalic acid.

Fig. 24 (a.) The ab-pane contains large square cavities formed by quadruple cross-linking of nanoballs. (b.) Cross-linking as seen along a- and

b-axes, note that the ligands adopt a syn-conformation. (c.) Cross-linking as seen along the c-axis. Note here that the ligands adopt an

anti-conformation.

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1,3-bdc moieties. Nevertheless, the resulting surface area is

such that this compound reversibly stores the highest weight

percent of H2 at 1 bar and 77 K thus far observed in a MOM.

3.3.1.4 rht nets. Within the past year, two research groups

have independently reported topologically related examples of

extended MOMs for which nanoballs were used as SBBs. The

targeted network, the (3,24)-connected rht net, is a topology

only recently addressed by Delgado-Friedrichs and

O’Keeffe199 as the only edge transitive binodal net involving

triangles and rhombicuboctahedra (which shares the same

edge skeleton as the small rhombihexahedron). Eddaoudi

and Zaworotko200 presented the first metal–organic example

of an rht-like network. The authors realized that the nanoball

SBB could in principle serve as a 24-connected node if each of

24 vertices could be linked through trigonal 3-connected units,

thereby generating an rht-like network from first principles

([14], Table 1). Judicious chemical modification at the

5-position of bdc was performed to facilitate formation of a

trigonal SBU through coordination chemistry. The authors

synthesized 5-tetrazolylisophthalic acid (H3TZI) (Fig. 26)

which, when reacted with Cu(NO3)2�2.5H2O in DMF–EtOH

under solvothermal conditions, generated a framework

characterized as [Cu6O(TZI)3(H2O)9(NO3)]n�(H2O)15 in which

each nanoball is connected to a trigonal Cu3O(N4CR)3 unit

through each tetrazolate (N4CR) moiety (Fig. 27).

The authors noted that this compound could also be

described as a novel 3-periodic (3,3,4)-connected ternary

net201 which is based upon three geometrically different SBUs.

The framework contains three distinct open cages, the largest

of which contains a 2 nm diameter cavity when van der Waals

radii are considered. This cage is bordered by 24 square

paddlewheel SBUs and 8 trigonal SBUs such that it is

Fig. 26 5-Tetrazolylisophthalic acid.

Fig. 27 (Top) A single metal–organic nanoball shown with 24 Cu2+

tetrazole trimers (red triangle in scheme) around the periphery.

(Bottom) A single trimer connected to three nanoball SBBs. When

coupled these components highlight the (3,24)-connected nature of this

rht-like network.

Fig. 28 Illustration of the rht network from a tile perspective. The

central tile represents the largest cage formed from six surrounding

metal–organic nanoballs and the Cu3O(N4CR)3 trimers (red triangles)

linking them.

Fig. 29 C3-symmetric ligand: 5,50,500-[1,3,5-benzenetriyltris(carbonyl-

imino)]tris-1,3-benzene dicarboxylic acid.

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surrounded by 6 nanoballs (Fig. 28) and 8 tetrahedral-like

cages (which are deleted in Fig. 28 for clarity). The authors

estimate that the total solvent-accessible volume for this

MOM is B75% and they demonstrated that this material

possesses permanent porosity.

Lah and co-workers synthesized another example of an

extended MOM with rht-like topology202 by utilizing covalent

bonding. They synthesized a C3-symmetric facial ligand,

5,50,500-[1,3,5-benzenetriyltris(carbonylimino)]tris-1,3-benzene

dicarboxylic acid (Fig. 29), which can be regarded as three

1,3-bdc moieties linked through a trigonal organic unit. This

version of the rht net was synthesized in a one-pot reaction

involving Zn(NO3)2�6H2O, the C3-symmetric ligand described

above, and dimethylacetamide. The authors noted the

presence of large tetrahedral cavities interconnected with large

pores and a solvent-accessible free volume of B71%.

However, they did not explicitly identify the network as rht-like.

A third example of an extended MOM with rht-like

topology has been described by Schroder and co-workers.203

They exploited a rigid C3-symmetric hexacarboxylate ligand,

1,3,5-tris(30,50-dicarboxy[1,10-biphenyl]-4-yl)benzene, which is

in effect three 1,3-bdc units bridged by a trigonal organic

moiety. Combining this ligand with Cu(NO3)2�3H2O in a 5 : 1

N,N0-dimethylformamide : dimethyl sulfoxide solution (in the

presence of a small quantity of H2O) in a solvothermal

reaction resulted in blue octahedral-shaped single crystals in

high yield ([16], Table 1). The authors noted the large

cages and pores generated in their structure and reported a

solvent-accessible free volume ofB75% consistent with earlier

rht-like MOFs. While the H2 uptake at 1 bar and 77 K is

comparable to that of the rht-MOF reported by Eddaoudi and

Zaworotko [14] (2.3% vs. 2.4% total H2 uptake), at higher

pressures Schroder’s compound demonstrates a maximum

excess H2 uptake of 7.07% between 35 and 40 bar (total

uptake of 10.0 wt% at 77 bar) making it comparable to the

highest reported uptakes of H2 for any MOF at 77 K.

4. Concluding remarks and future prospects

It is an understatement to assert that the field of MOMs has

undergone explosive growth in the past 10 years. However,

MOMs are only beginning to exhibit their promise in terms of

design and functional properties. As such, new methods

and strategies for their design and synthesis are needed to

complement those that have been successful in the past. We

believe that the design strategy we address herein, the

exploitation of MOPs as SBBs for the generation of extended

MOMs, offers several attractive features that collectively make

a compelling case for further pursuit of such structures:

� They offer compositional diversity since they are inherently

modular in their nature. Indeed, the SBBs and MOMs

presented herein can all be regarded as prototypal, suggesting

the promise of fine-tuning or customizing the cavities and bulk

properties through judicious choice of metals, counterions or

ligands.

� High symmetry brings with it an ability to invoke crystal

engineering since SBBs of rare or unprecedented coordination

number offer improved or even exquisite control over network

topology.

� Such SBBs also offer structural diversity through the

ability to control connectivity between SBBs, thereby generating

multiple topologies from the same SBB (e.g. nanoballs can be

connected via linear or triangular connectors).

� The inherently facile and self-correcting nature of

synthetic approaches that rely upon self-assembly means that

one-pot processes from simple starting materials are the norm

rather than the exception.

This critical review is intended to act as a guide for those

interested in pursuing the SBB strategy for generation of

extended MOMs and to serve as validation that materials

designed through this strategy are not only of general interest

due to their inherent beauty and form, but that they are likely

to be of practical importance because of their scale and ready

accessibility. Indeed, the SBB strategy begs the following

question: what are the realistic limits of scale for MOMs in

terms of cavity size, pore size, and surface area?

References

1 J. H. Rayner and H. M. Powell, J. Chem. Soc., 1952, 319–328.2 R. Baur and G. Schwarzenbach, Helv. Chim. Acta, 1960, 43(3),

842–847.3 K. V. Krishnamurty and G. M. Harris, Chem. Rev., 1961, 61(3),

213–246.4 W. P. Griffin, Q. Rev., Chem. Soc., 1962, 16(2), 188–207.5 R. D. Billard and G. Wilkinson, J. Chem. Soc., 1963, 3193–3200.6 R. A. Walton, Q. Rev., Chem. Soc., 1965, 19(2), 126–143.7 T. Iwamoto, T. Nakano, M. Morita, T. Miyoshi, T. Miyamoto

and Y. Sasaki, Inorg. Chim. Acta, 1986, 2, 313–316.8 K. V. Krishnamurty, G. M. Harris and V. S. Sastri, Chem. Rev.,

1970, 70(2), 171–197.9 T. Iwamoto, M. Kiyoki, Y. Ohtsu and Y. Takeshige-Kato, Bull.

Chem. Soc. Jpn., 1978, 51(2), 488–491.10 A. E. Underhill and D. M. Watkins, Chem. Soc. Rev., 1980, 9(4),

429–448.11 B. Moulton and M. J. Zaworotko, Chem. Rev., 2001, 101(6),

1629–1658.12 S. L. James, Chem. Soc. Rev., 2003, 32(5), 276–288.13 N. L. Rosi, M. Eddaoudi, J. Kim, M. O’Keeffe and O. M. Yaghi,

CrystEngComm, 2002, 4(68), 410–404.14 M. J. Rosseinsky, Microporous Mesoporous Mater., 2004,

73(1–2), 15–30.15 G. K. H. Shimizu, J. Solid State Chem., 2005, 178(8), 2519–2526.16 A. K. Cheetham, C. N. R. Rao and R. K. Feller, Chem. Commun.,

2006, (46), 4780–4795.17 K. Biradha, M. Sarkar and L. Rajput, Chem. Commun., 2006,

(40), 4169–4179.18 S. R. Batten, Curr. Opin. Solid State Mater. Sci., 2001, 5(2–3),

107–114.19 A. Y. Robin and K. M. Fromm, Coord. Chem. Rev., 2006,

250(15–16), 2127–2157.20 M. J. Zaworotko, Cryst. Growth Des., 2007, 7(1), 4–9.21 R. Robson, Dalton Trans., 2008, (38), 5113–5131.22 A. F. Wells, Acta Crystallogr., 1954, 7(8–9), 535–544.23 A. F. Wells, Acta Crystallogr., 1954, 7(8–9), 545–554.24 A. F. Wells, in Three dimensional Nets and Polyhedra, Wiley,

New York, 1977.25 A. F. Wells, in Structural Inorganic Chemistry, Oxford University

Press, London, 5th edn, 1984.26 B. F. Hoskins and R. Robson, J. Am. Chem. Soc., 1989, 111(15),

5962–5964.27 B. F. Hoskins and R. Robson, J. Am. Chem. Soc., 1990, 112(4),

1546–1554.28 B. F. Abrahams, B. F. Hoskins and R. Robson, J. Chem. Soc.,

Chem. Commun., 1990, (1), 60–61.29 R. W. Gable, B. F. Hoskins and R. Robson, J. Chem. Soc., Chem.

Commun., 1990, (10), 762–763.30 R. W. Gable, B. F. Hoskins and R. Robson, J. Chem. Soc., Chem.

Commun., 1990, (23), 1677–1678.

1414 | Chem. Soc. Rev., 2009, 38, 1400–1417 This journal is �c The Royal Society of Chemistry 2009

Dow

nloa

ded

by U

nive

rsity

of

New

Ham

pshi

re o

n 23

Feb

ruar

y 20

13Pu

blis

hed

on 0

3 M

arch

200

9 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/B

8070

86P

View Article Online

31 B. F. Abrahams, B. F. Hoskins, J. Liu and R. Robson, J. Am.Chem. Soc., 1991, 113(8), 3045–3051.

32 B. F. Abrahams, B. F. Hoskins and R. Robson, J. Am. Chem.Soc., 1991, 113(9), 3603–3607.

33 S. R. Batten, B. F. Hoskins and R. Robson, J. Chem. Soc., Chem.Commun., 1991, (6), 445–447.

34 M. Fujita, Y. J. Kwon, M. Miyazawa and K. Ogura, J. Chem.Soc., Chem. Commun., 1994, (17), 1977–1978.

35 M. Fujita, Y. J. Kwon, S. Washizu and K. Ogura, J. Am. Chem.Soc., 1994, 116(3), 1151–1152.

36 M. Fujita, O. Sasaki, K.-Y. Watanabe, K. Ogura andK. Yamaguchi, New J. Chem., 1998, 22(2), 189–191.

37 S. Kitagawa, Nippon Kessho Gakkaishi, 1994, 36(1), 25–30.38 S. Kitagawa, S. Matsuyama, M. Munakata and T. Emori,

J. Chem. Soc., Dalton Trans., 1991, (11), 2869–2874.39 S. Kitagawa, S. Kawata, Y. Nozaka and M. Munakata, J. Chem.

Soc., Dalton Trans., 1993, (9), 1399–1404.40 S. Kawata, S. Kitagawa, M. Kondo, I. Furuchi and

M. Munakata, Angew. Chem., Int. Ed. Engl., 1994, 33(17),1759–1761.

41 C. T. Chen and S. Suslick, Coord. Chem. Rev., 1993, 128(1–2),293–322.

42 L. Carlucci, G. Ciani, D. M. Proserpio and A. Sironi, Inorg.Chem., 1997, 36(9), 1736–1737.

43 L. Carlucci, G. Ciani, D. W. von Gundenberg, D. M. Proserpioand A. Sironi, Chem. Commun., 1997, (6), 631–632.

44 A. J. Blake, N. R. Champness, S. S. M. Chung, W.-S. Li andM. Schroder, Chem. Commun., 1997, (11), 1005–1006.

45 M. Bertelli, L. Carlucci, G. Ciani, D. M. Proserpio and A. Sironi,J. Mater. Chem., 1997, 7(7), 1271–1276.

46 K. Biradha, Y. Hongo and M. Fujita, Angew. Chem., Int. Ed.,2000, 39(21), 3843–3845.

47 K. Biradha and M. Fujita, J. Chem. Soc., Dalton Trans., 2000,(21), 3805–3810.

48 K. Biradha and M. Fujita, Chem. Commun., 2001, (1), 15–16.49 M. Fujita, M. Tominaga, A. Hori and B. Therrien, Acc. Chem.

Res., 2005, 38(4), 371–380, and references therein.50 P. J. Stang and B. Olenyuk, Acc. Chem. Res., 1997, 30(12),

502–518, and references therein.51 M. Fujita, K. Umemoto, M. Yoshizawa, N. Fujita, T. Kusukawa

and K. Biradha, Chem. Commun., 2001, (6), 509–518.52 O. Ermer, Adv. Mater., 1991, 3(12), 608–611.53 T. Kitazawa, S. Nishikiori, R. Kuroda and T. Iwamoto, Chem.

Lett., 1988, 17(10), 1729–1732.54 B. F. Abrahams, M. J. Hardie, B. F. Hoskins, R. Robson and

G. A. Williams, J. Am. Chem. Soc., 1992, 114(26), 10641–10643.55 T. Otieno, S. J. Rettig, R. C. Thompson and J. Trotter, Inorg.

Chem., 1993, 32(9), 1607–1611.56 A. Michaelides, V. Kiritsis, S. Skoulika and A. Aubry, Angew.

Chem., Int. Ed. Engl., 1993, 32(10), 1495–1497.57 G. M. J. Schmidt, Pure Appl. Chem., 1971, 27(4), 647–678.58 M. C. Etter, Acc. Chem. Res., 1990, 23(4), 120–126.59 M. C. Etter, J. C. MacDonald and J. Bernstein, Acta Crystallogr.,

Sect. B, 1990, 46(2), 256–262.60 M. C. Etter, J. Phys. Chem., 1991, 95(12), 4601–4610.61 G. R. Desiraju, Angew. Chem., Int. Ed., 2007, 46(44), 8342–8356.62 G. R. Desiraju and A. Gavezzotti, J. Chem. Soc., Chem.

Commun., 1989, (10), 621–623.63 G. R. Desiraju, Acc. Chem. Res., 1991, 24(10), 290–296.64 G. R. Desiraju, Angew. Chem., Int. Ed. Engl., 1995, 34(21),

2311–2327.65 C. B. Aakeroy and K. R. Seddon, Chem. Soc. Rev., 1993, 22(6),

397–407.66 M. J. Zaworotko, Chem. Soc. Rev., 1994, 23(4), 283–288.67 S. B. Copp, S. Subramanian and M. J. Zaworotko, J. Am. Chem.

Soc., 1992, 114(22), 8719–8720.68 S. B. Copp, S. Subramanian and M. J. Zaworotko, J. Chem. Soc.,

Chem. Commun., 1993, (13), 1078–1079.69 O. Ermer, J. Am. Chem. Soc., 1988, 110(12), 3747–3754.70 O. Ermer and A. Eling, Angew. Chem., Int. Ed. Engl., 1988, 27(6),

829–833.71 M. Simard, D. Su and J. D. Wuest, J. Am. Chem. Soc., 1991,

113(12), 4696–4698.72 X. Wang, M. Simard and J. D. Wuest, J. Am. Chem. Soc., 1994,

116(29), 12119–12120.

73 G. B. Gardner, D. Venkataraman, J. S. Moore and S. Lee,Nature, 1995, 374(6525), 792–795.

74 O. M. Yaghi, G. Li and H. Li, Nature, 1995, 378(6558), 703–706.75 M. Kondo, T. Yoshitomi, K. Seki, H. Matsuzaka and

S. Kitagawa, Angew. Chem., Int. Ed. Engl., 1997, 36(16),1725–1727.

76 O. M. Yaghi, D. A. Richardson, G. Li, E. Davis and T. L. Groy,Mater. Res. Soc. Symp. Proc., 1995, 371, 15–19.

77 O. M. Yaghi and H. Li, J. Am. Chem. Soc., 1995, 117(41),10401–10402.

78 S.-i. Noro, S. Kitagawa, M. Kondo and K. Seki, Angew. Chem.,Int. Ed., 2000, 39(12), 2082–2084.

79 S. Shimomura, S. Horike and S. Kitagawa, Stud. Surf. Sci. Catal.,2007, 170B, 1983–1990.

80 G. Ferey, C. Mellot-Draznieks, C. Serre, F. Millange, J. Dutour,S. Surble and I. Margiolaki, Science, 2005, 309(5743), 2040–2042.

81 H. K. Chae, B. Y. Siberio-Perez, J. Kim, Y. B. Go, M. Eddaoudi,A. J. Matzger, M. O’Keeffe and O. M. Yaghi, Nature, 2004,427(6974), 523–527.

82 O. M. Yaghi, M. O’Keeffe, N. W. Ockwig, H. K. Chae,M. Eddaoudi and J. Kim, Nature, 2003, 423(6941), 705–714.

83 M. Eddaoudi, D. B. Moler, H. Li, B. Chen, T. M. Reineke,M. O’Keeffe and O. M. Yaghi, Acc. Chem. Res., 2001, 34(4),319–330.

84 M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Watcher,M. O’Keeffe and O. M. Yaghi, Science, 2002, 295(5554), 469–472.

85 A. J. Fletcher, K. M. Thomas andM. J. Rosseinsky, J. Solid StateChem., 2005, 178(8), 2491–2510.

86 T. K. Maji and S. Kitagawa, Pure Appl. Chem., 2007, 79(12),2155–2177.

87 D. J. Collins and H.-C. Zhou, J. Mater. Chem., 2007, 17(30),3154–3160.

88 M. Eddaoudi, H. Li and O. M. Yaghi, J. Am. Chem. Soc., 2000,122(7), 1391–1397.

89 J. S. Seo, D. Whang, H. Lee, S. I. Jun, J. Oh, Y. J. Jeon andK. Kim, Nature, 2000, 404(6781), 982–986.

90 P. M. Foster and A. K. Cheetham, Top. Catal., 2003, 24(1–4),79–86.

91 C.-D. Wu, A. Hu, L. Zhang andW. Lin, J. Am. Chem. Soc., 2005,127(25), 8940–8941.

92 S.-H. Cho, B. Ma, S. T. Nguyen, J. T. Hupp and T. E. Albrecht-Schmitt, Chem. Commun., 2006, (24), 2563–2565.

93 S. R. Batten and K. S. Murray, Coord. Chem. Rev., 2003,246(1–2), 103–130.

94 D. Maspoch, D. Ruiz-Molina and J. Veciana, J. Mater. Chem.,2004, 14(18), 2713–2723.

95 D. Maspoch, D. Ruiz-Molina, K. Wurst, N. Domingo,M. Cavallini, F. Biscarini, J. Tejada, C. Rovira and J. Veciana,Nat. Mater., 2003, 2(3), 190–195.

96 G. Ferey, Nat. Mater., 2003, 2(3), 136–137.97 S. Kitagawa and K. Uemura, Chem. Soc. Rev., 2005, 34(2),

109–119.98 L. Bastin, P. S. Barcia, E. J. Hurtado, J. A. C. Silva,

A. E. Rodrigues and B. Chen, J. Phys. Chem. C, 2008, 112(5),1575–1581.

99 Y.-S. Bae, K. L. Mulfort, H. Frost, P. Ryan, S. Punnathanam,L. J. Broadbelt, J. T. Hupp and R. Q. Snurr, Langmuir, 2008,24(16), 8592–8598.

100 C. Sanchez, B. Julian, P. Belleville and M. Popall, J. Mater.Chem., 2005, 15(35–36), 3559–3592.

101 B. Chen, L. Wang, F. Zapata, G. Qian and E. B. Lobkovsky,J. Am. Chem. Soc., 2008, 130(21), 6718–6719.

102 R. Custelcean and B. A. Moyer, Eur. J. Inorg. Chem., 2007, (10),1321–1340.

103 B. Chen, Y. Yang, F. Zapata, G. Lin, G. Qian andE. B. Lobkovsky, Adv. Mater., 2007, 19(13), 1693–1696.

104 R. J. Hill, D.-L. Long, P. Hubberstey, M. Schroder andN. R. Champness, J. Solid State Chem., 2005, 178(8), 2414–2419.

105 C. L. Cahill, D. T. de Lill and M. Frisch, CrystEngComm, 2007,9(1), 15–26.

106 M. Xue, G. Zhu, Y. Li, X. Zhao, Z. Jin, E. Kang and S. Qiu,Cryst. Growth Des., 2008, 8(7), 2478–2483.

107 O. R. Evans and W. Lin, Acc. Chem. Res., 2002, 35(7), 511–522.108 Y. Liu, G. Li, X. Li and Y. Cui, Angew. Chem., Int. Ed., 2007,

46(38), 6301–6304.

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Dow

nloa

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Feb

ruar

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blis

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on 0

3 M

arch

200

9 on

http

://pu

bs.r

sc.o

rg |

doi:1

0.10

39/B

8070

86P

View Article Online

109 U. Mueller, M. Schubert, F. Teich, H. Putter, K. Schierle-Arndtand J. Pastre, J. Mater. Chem., 2006, 16(7), 626–636.

110 C. Janiak, Dalton Trans., 2003, (14), 2781–2804.111 S. Kitagawa, R. Kitaura and S.-I. Noro, Angew. Chem., Int. Ed.,

2004, 43(18), 2334–2375.112 Z. Wang and S. M. Cohen, J. Am. Chem. Soc., 2007, 129(41),

12368–12369.113 Z. Wang and S. M. Cohen, Angew. Chem., Int. Ed., 2008, 47(25),

4699–4702.114 E. Dugan, Z. Wang, M. Okamura, A. Medina and S. M. Cohen,

Chem. Commun., 2008, (29), 3366–3368.115 K. K. Tanabe, Z. Wang and S. M. Cohen, J. Am. Chem. Soc.,

2008, 130(26), 8508–8517.116 M. J. Ingleson, J. P. Barrio, J.-B. Guilbaud, Y. Z. Khimyak and

M. J. Rosseinsky, Chem. Commun., 2008, (23), 2680–2682.117 M. Kawano, T. Kawamichi, T. Haneda, T. Kojima and

M. Fujita, J. Am. Chem. Soc., 2007, 129(50), 15418–15419.118 T. Haneda, M. Kawano, T. Kawamichi and M. Fujita, J. Am.

Chem. Soc., 2008, 130(5), 1578–1579.119 M. J. Zaworotko, Nature, 2008, 451(7177), 410–411.120 Y.-F. Song and L. Cronin, Angew. Chem., Int. Ed., 2008, 47(25),

4635–4637.121 J. S. Costa, P. Gamez, C. A. Black, O. Roubeau, S. J. Teat and

J. Reedijk, Eur. J. Inorg. Chem., 2008, (10), 1551–1554.122 W. Morris, C. J. Doonan, H. Furukawa, R. Banerjee and

O. M. Yaghi, J. Am. Chem. Soc., 2008, 130(38), 12626–12627.123 M. O’Keeffe and B. G. Hyde, in Crystal Structures: I. Patterns

and Symmetry, Mineralogical Society of America, Washington,DC, 1996, ch. 7, pp. 299–303.

124 S. Alvarez, Dalton Trans., 2005, (13), 2209–2233.125 C. Moiras and L. Cronin, in Organic Nanostructures, ed.

J. L. Atwood and J. W. Steed, Wiley-VCH, Weinheim, Germany,2008, ch. 11, pp. 275–289.

126 R. J. Gillespie, Chem. Soc. Rev., 1979, 8(3), 315–352.127 T. Z. Forbes, J. G. McAlpin, R. Murphy and P. C. Burns, Angew.

Chem., Int. Ed., 2008, 47(15), 2824–2827.128 Y. Feldman, G. L. Frey, M. Homyonfer, V. Lyakhovitskaya,

L. Margulis, H. Cohen, G. Hodes, J. L. Hutchison and R. Tenne,J. Am. Chem. Soc., 1996, 118(23), 5362–5367.

129 A. Muller, P. Kogerler and C. Kuhlmann, Chem. Commun., 1999,(15), 1347–1358.

130 A. Muller, E. Beckmann, H. Bogge, M. Schmidtman andA. Dress, Angew. Chem., Int. Ed., 2002, 41(7), 1162–1167.

131 A. M. Todea, A. Merca, H. Bogge, J. Van Slageren, M. Dressel,L. Engelhardt, M. Luban, T. Glaster, M. Henery and A. Muller,Angew. Chem., Int. Ed., 2007, 46(32), 6106–6110.

132 T. C. W. Mak and F.-C. Mok, J. Cryst. Mol. Struct., 1979, 8(4),183–191.

133 S. J. Dalgarno, N. P. Power and J. L. Atwood, in OrganicNanostructures, ed. J. L. Atwood and J. W. Steed, Wiley-VCH,Weinheim, Germany, 2008, ch. 14, pp. 317–346.

134 L. R. MacGillivray and J. L. Atwood, Angew. Chem., Int. Ed.,1999, 38(8), 1018–1033.

135 S. M. Biros and J. Rebek, Jr, Chem. Soc. Rev., 2007, 36(1),93–104.

136 M. D. Pluth and K. N. Raymond, Chem. Soc. Rev., 2007, 36(2),161–71.

137 F. Hof, S. L. Craig, C. Nuckolls and J. Rebek, Jr, Angew. Chem.,Int. Ed., 2002, 41(9), 1488–1508.

138 J. Rebek, Jr, Chem. Soc. Rev., 1996, 25(4), 255–264.139 M. M. Conn and J. Rebek, Jr, Chem. Rev., 1997, 97(5),

1647–1668.140 D. J. Tranchemontagne, Z. Ni, M. O’Keeffe and O. M. Yaghi,

Angew. Chem., Int. Ed., 2008, 47(28), 5136–5147.141 S. J. Dalgarno, N. P. Power and J. L. Atwood, Coord. Chem.

Rev., 2008, 252(8–9), 825–841.142 S. Leininger, J. Fan, M. Schmitz and P. J. Stang, Proc. Natl.

Acad. Sci. U. S. A., 2000, 97(4), 1380–1384.143 S. Leininger, B. Olenyuk and P. J. Stang, Chem. Rev., 2000,

100(3), 853–907.144 T. Murase and M. Fujita, in Organic Nanostructures, ed.

J. L. Atwood and J. W. Steed, Wiley-VCH, Weinheim, Germany,2008, ch. 8, pp. 205–222.

145 O. Ugono, J. P. Moran and K. T. Holman, Chem. Commun.,2008, (12), 1404–1406.

146 D. L. Caulder and K. N. Raymond, Acc. Chem. Res., 1999,32(11), 975–982.

147 M. D. Ward, in Organic Nanostructures, ed. J. L. Atwood andJ. W. Steed, Wiley-VCH, Weinheim, Germany, 2008, ch. 9,pp. 223–250.

148 T. D. Hamilton and L. R. MacGillivray, Cryst. Growth Des.,2004, 4(3), 419–430.

149 A. C. Sudik, A. R. Millward, N. W. Ockwig, A. P. Cote, J. Kimand O. M. Yaghi, J. Am. Chem. Soc., 2005, 127(19), 7110–7118.

150 K. Umemoto, K. Yamaguchi and M. Fujita, J. Am. Chem. Soc.,2000, 122(29), 7150–7151.

151 M. Yoshizawa, M. Nagao, K. Umemoto, K. Biradha andM. Fujita, Chem. Commun., 2003, (15), 1808–1809.

152 D. K. Chand, K. Biradha, M. Kawano, S. Sakamoto,K. Yamaguchi and M. Fujita, Chem.–Asian J., 2006, 1(1–2),82–90.

153 I. M. Oppel (nee Muller) and K. Focker, Angew. Chem., Int. Ed.,2008, 47(2), 402–405.

154 S. Roche, C. Haslam, S. L. Heath and J. A. Thomas, Chem.Commun., 1998, (16), 1681–1682.

155 Y. Liu, V. Ch. Kravtsov, R. D. Walsh, P. Poddar, H. Srikanthand M. Eddaoudi, Chem. Commun., 2004, (24), 2806–2807.

156 M. Hong, Y. Zhao, W. Su, R. Cao, M. Fujita, Z. Zhou and A. S.C. Chan, J. Am. Chem. Soc., 2000, 122(19), 4819–4820.

157 Y. Liu, V. Ch. Kravtsov, R. D. Walsh, D. A. Beauchamp,J. F. Eubank and M. Eddaoudi, J. Am. Chem. Soc., 2005,127(20), 7266–7267.

158 M. Schweiger, T. Yamamoto, P. J. Stang, D. Blaser and R. Boese,J. Org. Chem., 2005, 70(12), 4861–4864.

159 Z. Ni, A. Yassar, T. Antoun and O. M. Yaghi, J. Am. Chem. Soc.,2005, 127(37), 12752–12753.

160 B. Olenyuk, J. A. Whiteford, A. Fechtenkotter and P. J. Stang,Nature, 1999, 398(6730), 796–799.

161 M. Tominaga, K. Suzuki, T. Murase andM. Fujita, J. Am. Chem.Soc., 2005, 127(34), 11950–11951.

162 L. R. MacGillivray and J. L. Atwood, Nature, 1997, 389(6650),469–472.

163 B. Moulton, J. Lu, A. Mondal and M. J. Zaworotko, Chem.Commun., 2001, (9), 863–864.

164 M. Eddaoudi, J. Kim, J. B. Wachter, H. K. Chae, M. O’Keeffeand O. M. Yaghi, J. Am. Chem. Soc., 2001, 123(18), 4368–4369.

165 H. Abourahma, A. W. Coleman, B. Moulton, B. Rather,P. Shahgaldian and M. J. Zaworotko, Chem. Commun., 2001,(22), 2380–2381.

166 Y. Ke, D. J. Collins and H.-C. Zhou, Inorg. Chem., 2005, 44(12),4154–4156.

167 H. Furukawa, J. Kim, K. E. Plass and O. M. Yaghi, J. Am. Chem.Soc., 2006, 128(26), 8398–8399.

168 H. Furukawa, J. Kim, N. W. Ockwig, M. O’Keeffe andO. M. Yaghi, J. Am. Chem. Soc., 2008, 130(35), 11650–11661.

169 R. W. Larsen, G. J. McManus, J. J. Perry IV, E. Rivera-Oteroand M. J. Zaworotko, Inorg. Chem., 2007, 46(15), 5904–5910.

170 R. W. Larsen, J. Am. Chem. Soc., 2008, 130(34), 11246–11247.171 K. Mohamed, H. Abourahma, M. J. Zaworotko and

J. P. Harmon, Chem. Commun., 2005, (26), 3277–3279.172 K. Mohamed, T. G. Gerasimov, H. Abourahma,

M. J. Zaworotko and J. P. Harmon, Mater. Sci. Eng., A, 2005,A409(1–2), 227–233.

173 M. Jung, H. Kim, K. Baek and K. Kim, Angew. Chem., Int. Ed.,2008, 47(31), 5755–5757.

174 H.-F. Zhu, J. Fan, T.-a. Okamura, Z.-H. Zhang, G.-X. Liu,K.-B. Yu, W.-Y. Sun and N. Ueyama, Inorg. Chem., 2006,45(10), 3941–3948.

175 Y. Wang, T.-a. Okamura, W.-Y. Sun and N. Ueyama, Cryst.Growth Des., 2008, 8(3), 802–804.

176 T. Schroder, R. Brodbeck, M. C. Letzel, A. Mix, B. Schnatwinkel,M. Tonigold, D. Volkmer and J. Mattay, Tetrahedron Lett., 2008,49(41), 5939–5942.

177 T. K. Ronson, J. Fisher, L. P. Harding and M. J. Hardie, Angew.Chem., Int. Ed., 2007, 46(47), 9086–9088.

178 H. Chun, J. Am. Chem. Soc., 2008, 130(3), 800–801.179 S. S.-Y. Chui, S. M.-F. Lo, J. P. H. Charmant, A. G. Orpen and

I. D. Williams, Science, 1999, 283(5405), 1148–1150.180 S. R. Batten and R. Robson, Angew. Chem., Int. Ed., 1998,

37(11), 1460–1496.

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181 L. Carlucci, G. Ciani and D. M. Proserpio, Coord. Chem. Rev.,2003, 246(1–2), 247–289.

182 G. J. McManus, J. J. Perry IV, M. Perry, B. D. Wagner andM. J. Zaworotko, J. Am. Chem. Soc., 2007, 129(29), 9094–9101.

183 A. C. Sudik, A. P. Cote, A. G. Wong-Fey, M. O’Keeffe andO. M. Yaghi, Angew. Chem., Int. Ed., 2006, 45(16), 2528–2533.

184 R.-Q. Zou, L. Jiang, H. Senoh, N. Takeichi and Q. Xu, Chem.Commun., 2005, 3526–3528.

185 R.-Q. Zou, H. Sakurai and Q. Xu, Angew. Chem., Int. Ed., 2006,45(16), 2542–2546.

186 A.-L. Cheng, N. Liu, J.-Y. Zhang and E.-Q. Gao, Inorg. Chem.,2007, 46(4), 1034–1035.

187 D. Moon, S. Kang, J. Park, K. Lee, R. P. John, H. Won,G. H. Seong, Y. S. Kim, G. H. Kim, H. Rhee and M. S. Lah,J. Am. Chem. Soc., 2006, 128(11), 3530–3531.

188 J. Park, S. Hong, D. Moon, M. Park, K. Lee, S. Kang, Y. Zou,R. P. John, G. H. Kim andM. S. Lah, Inorg. Chem., 2007, 46(24),10208–10213.

189 O. Delgado-Friedrichs, M. D. Foster, M. O’Keeffe,D. M. Proserpio, M. J. Treacy and O. M. Yaghi, J. Solid StateChem., 2005, 178, 2533–2554.

190 B. Chen, N. W. Ockwig, F. R. Fronczek, D. S. Contreras andO. M. Yaghi, Inorg. Chem., 2005, 44(2), 181–183.

191 A. J. Cairns, J. A. Perman, L. Wojtas, V. Ch. Kravtsov,M. H. Alkordi, M. Eddaoudi and M. J. Zaworotko, J. Am.Chem. Soc., 2008, 130(5), 1560–1561.

192 R. V. Parish, Z. Salehi and R. G. Pritchard, Angew. Chem., Int.Ed. Engl., 1997, 36(3), 251–253.

193 D. Li, T. Wu, X.-P. Zhou, R. Zhou and X.-C. Huang, Angew.Chem., Int. Ed., 2005, 44(27), 4175–4178.

194 G. J. McManus, Z. Wang and M. J. Zaworotko, Cryst. GrowthDes., 2004, 4(1), 11–13.

195 G. R. Newkome, E. He and C. N. Moorefield, Chem. Rev., 1999,99(7), 1689–1746.

196 J. J. Perry IV, V. Ch. Kravtsov, G. J. McManus andM. J. Zaworotko, J. Am. Chem. Soc., 2007, 129(33), 10076–10077.

197 X.-S. Wang, S. Ma, P. M. Forster, D. Yuan, J. Eckert,J. L. Lopez, B. J. Murphy, J. B. Parise and H.-C. Zhou, Angew.Chem., Int. Ed., 2008, 47(38), 7263–7266.

198 M. O’Keeffe and B. G. Hyde, in Crystal Structures: I. Patternsand Symmetry, Mineralogical Society of America, Washington,DC, 1996, ch. 7, p. 356.

199 O. Delgado-Friedrichs and M. O’Keeffe, Acta Crystallogr., Sect.A, 2007, A63(4), 344–347.

200 F. Nouar, J. F. Eubank, T. Bousquet, L. Wojtas,M. J. Zaworotko and M. Eddaoudi, J. Am. Chem. Soc., 2008,130(6), 1833–1835.

201 Z. Wang, V. Ch. Kravtsov and M. J. Zaworotko, Angew. Chem.,Int. Ed., 2005, 44(19), 2877–2880.

202 Y. Zou, M. Park, S. Hong and M. S. Lah, Chem. Commun., 2008,(20), 2340–2342.

203 Y. Yan, X. Lin, S. Yang, A. J. Blake, A. Dailly,N. R. Champness, P. Hubberstey and M. Schroder, Chem.Commun., 2009, (9), 1025–1027.

204 Faceted polyhedra from Fig. 5 were created using Robert Webb’sGreat Stella Software: http://www.software3d.com/Stella.php.

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