On demand: The singular rht net, an ideal blueprint for the construction of a metal-organic framework (mof) platform

Article abstract of DOI:10.1002/anie.201201202

The exceptional nature of the rht-MOF platform, based on a singular edge-transitive net (the only net for the combination of 3- and 24-connected nodes), makes it an ideal target in crystal chemistry. The high level of control indicates an unparalleled blu

Full text of DOI:10.1002/anie.201201202

Angewandte
Chemie
DOI: 10.1002/anie.201201202
Metal–Organic Frameworks
On Demand: The Singular rht Net, an Ideal Blueprint for the
Construction of a Metal–Organic Framework (MOF) Platform**
Jarrod F. Eubank, Farid Nouar, Ryan Luebke, Amy J. Cairns, Lukasz Wojtas,
Mohamed Alkordi, Till Bousquet, Matthew R. Hight, Juergen Eckert, Jan P. Embs,
Peter A. Georgiev, and Mohamed Eddaoudi*
The need for tunable functional solid-state materials is ever
increasing because of the growing demand to address
persisting challenges in global energy issues, environmental
sustainability, and others.[1] It is practical and preferable for
such materials to be pre-designed and constructed to contain
the desired properties and specific functionalities for a given
targeted application. An emerging unique class of solid-state
materials, namely metal–organic frameworks (MOFs), has
the desired attributes and offers great promise to unveil
superior materials for many lasting challenges[2] since desired
functionality can be introduced pre- and/or post-synthesis.[3]
A remarkable feature of MOFs is the ability to build periodic
structures with in-built functional properties using the
molecular building block (MBB) approach, which utilizes
pre-selected organic and inorganic MBBs, with desired
function, that are judiciously chosen to possess the proper
geometry, shape, and directionality required to target given
underlying nets.[4]
of MOFs. Our analysis of edge-transitive nets revealed an
exceptional net, rht,[5] which met all of our requisite criteria.
The rht net is singular for the assembly of 24-connected
vertices (rhombicuboctahedral (rco) vertex figure) and 3-
connected vertices (triangular vertex figure). Though trian-
gular MBBs are common in MOF chemistry, we must employ
the supermolecular building block (SBB) approach, utilizing
externally functionalized metal–organic polyhedra (MOPs) as
SBBs, to access the high connectivity rco necessary for
constructing rht-MOFs,[7] like our original rht-MOF-
1 (Figure 1). The ability to target a single MOF from
An ideal blueprint starts with a net[5] that: 1) is singular,
exclusive for the assembly of given building units; 2) pref-
erably, encloses polyhedral cavities with 3D interconnecting
channels; and 3) is not susceptible to self-interpenetration
upon net expansion and/or decoration (it should be noted that
this confluence into one material is quite rare). Edge-
transitive nets (i.e., one kind of edge) are recognized as
suitable targets in crystal chemistry,[6] and, thus, are a prime
source to ascertain singular nets for the rational construction
Figure 1. a) Design strategy for the construction of rht-MOF-1: Rela-
tionship between the MBBs, SBB, and their corresponding building
units. b)–c) The two other polyhedral cavities in rht-type structures
resulting from the cubic packing of the tcz-MOP-based rhombicuboc-
tahedral SBB (green).
[*] R. Luebke, Dr. A. J. Cairns, Dr. M. Alkordi, Prof. Dr. M. Eddaoudi
KAUST Advanced Membranes & Porous Materials Center
King Abdullah University of Science and Technology
4700 King Abdullah University of Science and Technology
Thuwal 23955-6900 (Kingdom of Saudi Arabia)
E-mail: mohamed.eddaoudi@kaust.edu.sa
Dr. J. F. Eubank,[+] Dr. F. Nouar,[+] Dr. L. Wojtas, Dr. T. Bousquet,
M. R. Hight, Dr. J. Eckert, Prof. Dr. M. Eddaoudi
Department of Chemistry, University of South Florida
4202 East Fowler Avenue (CHE 205), Tampa, FL 33620 (USA)
particular MBBs and SBBs favors platform design and
facile tuning. The rht-MOF platform can readily be tuned
via four basic pathways: 1) expansion of the SBB; 2) spacing
of the distance between SBB and triangular MBB; 3) sub-
stitution of the triangular MBB; and 4) functionalization.
The first route depends upon expansion of the SBB, which
is based on the well-documented[8] truncated cuboctahedral
(tcz, 4^12.6^8.8^6)[5] MOP. The tcz-MOP consists of 12Cu2-
(O2CR)4 (Cu paddlewheels) MBBs joined by 24 isophthalate
(1,3-BDC) linkers [Cu24(5-R-BDC)24],[9] where the 5-position
of each bridging ligand (bent, 1208 angle) lies exactly on the
vertices of the requisite rco (24-connected). Interestingly, to
the best of our knowledge, the expanded version of the MOP,
Dr. J. P. Embs
Laboratory for Neutron Scattering, Paul Scherrer Institut (Switzer-
land)
Dr. P. A. Georgiev
Department of Structural Chemistry, University of Milan (Italy)
[+] These authors contributed equally to this work.
[**] We gratefully acknowledge the financial support of the NSF (DMR
0548117) and KAUST funds.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201201202.
Angew. Chem. Int. Ed. 2012, 51, 1 – 6
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
These are not the final page numbers!

.
Angewandte
Communications
which can be achieved by positioning isophthalate carbox-
ylates more distal while maintaining the necessary 1208 angle,
has never been reported, discrete or in rht-MOFs. The
interior of existing tcz-MOPs/SBBs remain relatively inac-
cessible, and expansion will give unprecedented large pores/
cavities.
From the exceptional nature of the rht-MOF, based on the
singular edge-transitive rht net, and ease of synthesis due to
controlled formation of the SBB and MBB in situ, it is evident
that this platform is amenable, par excellence, to expansion
without concern for interpenetration (Figure 2a), as well as
building block substitution/decoration and functionalization
(i.e., isoreticular chemistry).[10,11] Herein we report the con-
struction and properties of two novel expanded-SBB rht-
MOFs, as well as a series of predicted isoreticular rht-MOFs
with extra-large cavities, and confirm the power of the SBB
approach for the deliberate construction of rht-MOF as an
exemplary platform.
To generate the first rht-MOF having expanded SBBs
(i.e., expanded tcz cavities), we designed and synthesized only
the second such tetrazole-based ligand, 5’-(1H-tetrazol-5-yl)-
1,1’:3’,1’’-terphenyl-4,4’’-dicarboxylic acid (H3L2).[7] Longer
benzoate moieties in L2 replace the carboxylates of L1, in rht-
MOF-1, resulting in increased distance between carboxylates
while maintaining the 1208 angle, (i.e., expanded isophtha-
late). As anticipated, reaction between H3L2 and CuII results
in the first rht-MOF, based on expanded 24-connected SBBs
(generated in situ), [Cu6O(L2)3(NO3)·xsolv]n or rht-MOF-2
(Figure 2c). To the best of our knowledge, the discrete tcz-
MOP based on benzene-1,3-dibenzoate-type linkers has yet
to be isolated.[8]
The unprecedented expanded tcz-type SBBs (24 func-
tionalized expanded isophthalate-like ligands connected by
12 Cu paddlewheels), are assembled in situ from the benzene-
1,3-dibenzoate moieties. The enclosed cavity has a diameter
of 25.7 ꢀ, almost double the size of the original tcz built from
isophthalate moieties (ca. 15.9 ꢀ; Figure 2b). These extra-
large tcz are inter-connected through the expected trigonal
Cu-oxo trimers formed by each set of three tetrazolate
(N4CR) moieties to give the predicted expanded (3,24)-
connected rht-MOF.
To further confirm the power of the SBB approach and
the uniqueness of the rht based MOFs and implement our
strategy (i.e., construct an rht-MOF with increased distance
between the SBB and triangular MBB), we designed and
synthesized another novel tetrazolate ligand, 4’-(1H-tetrazol-
5yl)biphenyl-3,5-dicarboxylic acid (H3L3), where an extra
benzene moiety was deliberately placed between the tetra-
zole and isophthalic termini to increase the distance between
the tetrazolate-based MBBs and isophthalate-based SBBs,
generated in situ. As anticipated, reaction between H3L3 and
CuII produces the expected analogous/isoreticular rht-MOF-
3, [Cu6O(L3)3(NO3)·xsolv]n (Figure 2d). As expected, the
resulting truncated cuboctahedron cavity remains the same as
in rht-MOF-1 while the rdo-a cavity is enlarged to a diameter
of 27.2 ꢀ.
Figure 2. a) The expected increase in size of rht structures and related
cavities: (bottom) parent rht-MOF-1, (left) rht-MOF due to expansion
along the Y direction; (top); rht-MOF due to expansion along the X
direction; (right) rht-MOF due to expansion along both directions, X
and Y. b) (center) rht-MOF-1, used as a blueprint for design of new rht
nets where the length of H3L1 has been increased by additional
benzene rings in the X direction (left) leading to rht-MOF-3 (from
H3L3), and in the Y direction (right) leading to rht-MOF-2 (from H3L2).
Resulting cavities from the representative c) rht-MOF-2 and d) rht-
MOF-3: rdo-a (left), tcu (center), and expanded tcz (right).
thereof, resulting in a trefoil ligand (tL; i.e., trigonal tri-
isophthalate ligand; Figure 3a).[11,12] This feature, raising from
the singularity of the rht net, is the basis of our third strategy
and can be exploited via two different pathways: 1) utilization
of trefoil ligands that can permit the construction of rht-
MOFs based on covalently linked expanded SBBs, which
It was evident to us that the trigonal Cu-oxo trimer can be
replaced with an organic core while maintaining the iso-
phthalate termini and the essential trigonal positioning
2
www.angewandte.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2012, 51, 1 – 6
These are not the final page numbers!

Angewandte
Chemie
the design and synthesis of a flexible rht-MOF. To validate
this strategy, we utilized the flexible trefoil ligand, 5,5’,5’’-
[1,3,5-phenyl-tris(methoxy)]tris-isophthalic acid {5,5’,5’’-
[1,3,5-benzenetriyltris(methyleneoxy)]tris-1,3-benzenedicar-
boxylic acid} (H6tL1), which reacts with CuII to give the
expected rht-MOF-4a or [Cu3tL1(H2O)3·xsolv]n (Figure 3c).
Due to the comparable trefoil size (Figure 3a), all the cavities
in rht-MOF-4 are similar in size to the parent rht-MOF-
1 (15.9, 19.1, and 11.8 ꢀ vs. 15.9, 20.2, and 12.1 ꢀ, respec-
tively).
It should be noted that utilizing trefoil ligands permits the
deliberate construction of rht-MOFs based only on one type
of inorganic MBB, namely the paddlewheel, which eliminates
the need to form the Cu-oxo trimer inorganic MBB.[8] Thus,
this route offers potential to assemble rht-MOFs with various
other metals appropriate for paddlewheel formation,[8] but
not expected to generate a Cu-oxo-like trimer (e.g., Zn and
Co). Indeed, reactions between Zn or Co and H6tL1 result in
isostructural compounds [Zn3tL1(H2O)(DMF)2·xsolv]n (rht-
MOF-4b) and [Co3tL1(H2O)1.5(DMF)1.5·xsolv]n (rht-MOF-
4c), as determined by comparison of PXRD spectra and/or
single-crystal data (Supporting Information, Figure S22). The
exceptional versatility of our SBB-based approach and the
uniqueness of our rht-MOF platform, combined with the vast
library of organic syntheses, allow for facile incorporation of
multiple desired/targeted functions into the same structure/
material.
Figure 3. a) Trefoil moieties: The Cu-oxo trimer of the tetrazole-based
rht-MOFs can be substituted by an organic core. b) Dually expanded
trefoil organic ligand, tL3 (left), and select cavities in corresponding
rht-MOF-6. c) Trefoil tri-isophthalate organic ligand, tL1 (left), and
select cavities in corresponding rht-MOF-4.
To prove this concept, we designed and synthesized the
azo-functionalized trefoil ligand, 5,5’,5’’-{4,4’,4’’-[1,3,5-phenyl-
tris(methoxy)]tris-phenylazo}tris-isophthalic acid (H6tL2)
where a phenylazo link was deliberately placed between the
benzene moiety and the isophthalate terminus of tL1. H6tL2
reacts with Zn to give the expected dinitrogen-functionalized
rht-MOF-5, [Zn3tL2(H2O)3·xsolv]n (Supporting Information,
Figure S17). As anticipated, the extra-large rdo-a and tcu
cavities (25.7 and 16.0 ꢀ vs. 19.1 and 11.8 ꢀ, respectively) are
lined with azo moieties. To demonstrate this approach in the
tetrazole-based rht-MOFs, we designed and synthesized an
amide-functionalized tetrazole-based ligand, 5’-(4-(1H-tetra-
zol-5-yl)benzamido)benzene-1,3-dioic acid (H3L4), which
gives the expected rht-MOF-8, [Cu6O(L4)3(NO3)·xsolv]n.
The effective implementation of our rational strategy
using rht-MOF as a platform, where cavity size, shape, and
functionality can be controlled and tuned with ease, is evident
by the successful design and construction of a series of rht-
MOFs with some of the lowest framework densities and free
volumes reported to date.[13] Unlike most previous low-
density MOFs,[13] rht-MOFs preclude the potential for inter-
penetration, resulting in one-step, deliberately open frame-
works with pores in the mesopore domain.[14] In fact,
calculated free volumes range from about 75% for rht-
MOF-4 to about 89% for the most open framework of the
series, rht-MOF-6. The various cavity sizes, apertures dimen-
sions, and accessible free volumes are summarized in the
Supporting Information, Table S1, as are surface areas.
The sorption isotherms (i.e., Ar, H2) for rht-MOF-2,-3,-4a
and descriptions are presented in the Supporting Information,
as well as inelastic neutron scattering data. The pore size
distribution for each shows the anticipated three different
substantiates strategy one; and 2) introduction of flexible
trefoil ligands which can impart flexibility into the resulting
rht-MOF. To apply this third strategy, based on the organic
substitution of the triangular inorganic MBB (i.e., tL vs.
Cu3O(L)3), several trefoil ligands have been synthesized and
utilized to generate rht-MOFs.[7b,11,12]
Herein, we report for the first time the covalent linking of
expanded SBBs by introducing a trigonal organic core and
replacing the carboxylic acid moieties of an isophthalate
terminus with benzoic acid moieties (Figure 3a). To imple-
ment this strategy, we designed and synthesized the expanded
tris-(4-(5’-ethynyl-1,1’:3’,1’’-terphenyl-4,4’’-dicarboxylic acid)-
phenyl)-amine (H6tL3), which reacts with CuII to give the
expected expanded SBB based rht-MOF-6, [Cu3tL3-
(H2O)3·xsolv]n (Figure 3b). The crystal structure is analogous
to the previous rht-MOFs; however, in this structure the SBBs
are covalently (vs. coordinately) interconnected through
trigonal tri-substituted organic moieties. Essentially, each
central amine core is triply covalently linked through
ethynylphenyl moieties to the 5-position of an expanded
isophthalate terminus. Thus, all components of the tcz cavity
in rht-MOF-6 remain the same as in rht-MOF-2, while the
triangular faces of the rdo-a and tcu cavities are now
delimited by purely organic moieties (e.g., Cu24[Cu3O(L2)3]4-
(O2CR)24 vs. Cu24(tL2)4(O2CR)24 for the tcu cavity; Fig-
ure 3a). As expected, all cavities are highly enlarged when
compared to rht-MOF-1 (25.7 and 16.0 ꢀ vs. 19.1 and 11.8 ꢀ,
respectively).
Introduction of the organic triangular core and ability to
target specifically rht-MOF from our SBB approach allows
Angew. Chem. Int. Ed. 2012, 51, 1 – 6
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3
These are not the final page numbers!

.
Angewandte
Communications
rht-MOF-2: Cu(NO3)2·2.5H2O (29 mg), H3L2 (11 mg), and DMF
(1 mL), added to 20 mL vial, heated to 808C/40 h to give blue-green
polyhedral crystals. Fm3m, a = 63.931 ꢀ.
pore sizes with the expected pore diameters in the mesopo-
rous domain for the expanded rht-MOFs. The values for the
exemplary trefoil-based rht-MOF-4a (7.2, 8.2, and 18.0 ꢀ)
deviate slightly from the calculated dimensions of the cavities
from the crystal structure. This phenomenon is attributed to
the inbuilt flexibility of the framework and reflected in the
isotherm, which exhibits an additional continuous uptake
starting at relatively low pressures with noticeable hysteresis.
To confirm this unique “breathing” behavior, we performed
CO2 sorption at high pressures.[15] The flexibility indeed
manifests in the isotherm, which shows a multistep uptake
behavior (Figure 4). In fact, it is apparent that additional
accessible volume is generated at higher pressures (28 bar and
273 K), and the total volumetric uptake approaches the
expected value (1.1 cm3 gÀ1) calculated from the original
crystal structure.
¯
rht-MOF-3: Cu(NO3)2·2.5H2O (39 mg), H3L3 (35 mg), and DMF
(1 mL) added to 20 mL vial, heated to 758C/40 h to give blue
¯
polyhedral crystals. Fm3m, a = 54.389.
rht-MOF-4a: Cu(NO3)2·2.5H2O (20 mg), H6tL1 (37 mg), DMF
(1 mL), and H2O (1 mL) added to 20 mL vial, heated to 858C/12 h,
¯
1058C/23 h, 1158C/23 h to give green polyhedral crystals. Fm3, a =
41.479 ꢀ.
rht-MOF-4b: Zn(NO3)2·6H2O (12 mg), H6tL1 (18 mg), DMF
(1 mL), and NMP (1 mL) added to 20 mL vial, heated to 858C/12 h to
give colorless polyhedral crystals. I4m, a = 29.3026 ꢀ, c = 41.672 ꢀ.
rht-MOF-4c: Co(NO3)2·6H2O (24 mg), H6tL1 (37 mg), DMF
(1 mL), and NMP (0.5 mL) added to 20 mL vial, heated to 858C/12 h,
1058C/23 h to give a few red cube crystals. I4m, a = 29.395 ꢀ, c =
41.638 ꢀ.
rht-MOF-5: Zn(NO3)2·6H2O (12 mg), H6tL2 (27 mg), DMF
(1 mL) and NMP (1 mL) added to 20 mL vial, heated to 858C/12 h,
¯
1058C/23 h to give a few orange cube crystals. Fm3, a = 56.798 ꢀ.
rht-MOF-6: H6tL3 (20 mg), Cu(BF4)2·6H2O (15 mg), DMF
(2 mL), HNO3 (0.2 mL, 3.5m in DMF) added to 20 mL vial, heated
¯
at 658C/3d to yield a few green-blue block crystals. Fm3m, a =
68.604 ꢀ.
rht-MOF-8: Cu(NO3)2·2.5H2O (39 mg), H3L4 (40 mg), DMF
(1 mL) added to 20 mL vial, heated to 758C/20 h, 858C/12 h to give
blue polyhedral crystals. I4m, a = 41.557, c = 59.003 ꢀ.
CCDC 866709 (rht-MOF-2), 866710 (rht-MOF-3), rht-MOF-4a
(866711), 866712 (rht-MOF-4b), 866713 (rht-MOF-4c), 866714 (rht-
MOF-5), 866715 (rht-MOF-6), and 884451 (rht-MOF-8) contain the
supplementary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Received: February 13, 2012
Published online: && &&, &&&&
Keywords: controlled porosity · hybrid materials · metal–
.
organic frameworks · reticular chemistry ·
supermolecular building blocks
Figure 4. CO2 high-pressure sorption isotherms for rht-MOF-4a.
In conclusion, we have described the design, synthesis, and
facile tuning of the rht-MOF platform by way of expansion of
the SBB, substitution of the triangular MBB, spacing of the
distance between SBB and triangular MBB, introduction of
various metals, and pre-synthesis functionalization. The
robust rht-MOFs with accessible cavities in the micro–
mesoporous range and 3D interconnecting channels, remain
open (no interpenetration) along with some of the lowest
reported crystalline framework densities and free volumes,
significant porosities, and observable differences in H2 uptake
and energetics depending on framework composition, pore
size, and functionality. The demonstration that numerous rht-
MOFs can readily be targeted and synthesized from a variety
of judiciously selected or designed ligands reveals a direct
pathway to specific functional solid-state materials. The
controlled production of a single product and the broad
application scope of this synthetic method heralds a new era
in functional materials design.
[1] a) Z. Wu, D. Zhao, Chem. Commun. 2011, 47, 3332 – 3338;
b) J. D. Sherman, Proc. Natl. Acad. Sci. USA 1999, 96, 3471 –
3478; c) E. Taarning, C. M. Osmundsen, X. Yang, B. Voss, S. I.
Andersen, C. H. Christensen, Energy Environ. Sci. 2011, 4, 793 –
804; d) A. Phan, C. Doonan, F. J. Uribe-Romo, C. B. Knobler,
M. OꢁKeeffe, O. M. Yaghi, Acc. Chem. Res. 2010, 43, 58 – 67;
e) P. L. Llewellyn, S. Bourrelly, C. Serre, A. Vimont, M. Daturi,
L. Hamon, G. De Weireld, J.-S. Chang, D.-Y. Hong, Y. K.
Hwang, S. H. Jhung, G. Fꢂrey, Langmuir 2008, 24, 7245 – 7250;
f) S. Ma, H.-C. Zhou, Chem. Commun. 2010, 46, 44 – 53; g) Z. R.
Herm, J. A. Swisher, B. Smit, R. Krishna, J. R. Long, J. Am.
Chem. Soc. 2011, 133, 5664 – 5667; h) S. R. Caskey, A. J. Matzger,
Mater. Matters 2009, 4.4, 111; i) U. Mueller, M. Schubert, F.
Teich, H. Puetter, K. Schierle-Arndt, J. J. Pastrꢂ, Mater. Chem.
2006, 16, 626 – 636.
[2] a) C. Volkringer, S. M. Cohen, Angew. Chem. 2010, 122, 4748 –
4752; Angew. Chem. Int. Ed. 2010, 49, 4644 – 4648; b) J. G.
Nguyen, S. M. Cohen, J. Am. Chem. Soc. 2010, 132, 4560 – 4561;
c) Z. Wang, S. M. Cohen, J. Am. Chem. Soc. 2009, 131, 16675 –
16677.
[3] Metal-Organic Frameworks: Design and Application, (Ed.: L.
MacGillivray), Wiley-VCH, Weinheim, 2010, and references
therein.
Experimental Section
Conditions and crystal data for the MOFs presented herein:
4
www.angewandte.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2012, 51, 1 – 6
These are not the final page numbers!

Angewandte
Chemie
[4] a) A. Stein, S. W. Keller, T. E. Mallouk, Science 1993, 259, 1558 –
1564; b) G. Fꢂrey, J. Solid State Chem. 2000, 152, 37 – 48; c) M.
Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. OꢁKeeffe,
O. M. Yaghi, Science 2002, 295, 469 – 472; d) S. Kitagawa, R.
Kitaura, S.-I. Noro, Angew. Chem. 2004, 116, 2388 – 2430;
Angew. Chem. Int. Ed. 2004, 43, 2334 – 2375.
[5] M. OꢁKeeffe, M. A. Peskov, S. J. Ramsden, O. M. Yaghi, Acc.
Chem. Res. 2008, 41, 1782 – 1789.
[6] N. W. Ockwig, O. Delgado-Friedrichs, M. OꢁKeeffe, O. M. Yaghi,
Acc. Chem. Res. 2005, 38, 176 – 182.
[7] a) F. Nouar, J. F. Eubank, T. Bousquet, L. Wojtas, M. J.
Zaworotko, M. Eddaoudi, J. Am. Chem. Soc. 2008, 130, 1833 –
1835; b) R. Luebke, J. F. Eubank, A. J. Cairns, Y. Belmabkhout,
L. Wojtas, M. Eddaoudi, Chem. Commun. 2012, 48, 1455 – 1457.
[8] F. H. Allen, Acta Crystallogr. Sect. B 2002, 58, 380 – 388.
[9] a) M. Eddaoudi, J. Kim, J. B. Wachter, H. K. Chae, M. OꢁKeeffe,
O. M. Yaghi, J. Am. Chem. Soc. 2001, 123, 4368 – 4369; b) B.
Moulton, J. Lu, A. Mondal, M. J. Zaworotko, Chem. Commun.
2001, 863 – 864.
Zaworotko (University of South Florida), U.S. Pat. Appl. Publ.
US 20090143596A1, 2009 20090604 (Filed in 2007).
[12] Since publication of our original rht-MOF-1 and patent filing,
several examples based on our trefoil ligand strategy have
appeared: a) Y. Zou, M. Park, S. Hong, M. S. Lah, Chem.
Commun. 2008, 2340 – 2342; b) Y. Yan, X. Lin, S. Yang, A. J.
Blake, A. Dailly, N. R. Champness, P. Hubberstey, M. Schrçder,
Chem. Commun. 2009, 1025 – 1027; c) D. Zhao, D. Yuan, D. Sun,
H.-C. Zhou, J. Am. Chem. Soc. 2009, 131, 9186 – 9188; d) S.
Hong, M. Oh, M. Park, J. W. Yoon, J. S. Chang, M. S. Lah, Chem.
Commun. 2009, 5397 – 5399.
[13] H. Furukawa, Y. B. Go, N. Ko, Y. K. Park, F. J. Uribe-Romo, J.
Kim, M. OꢁKeeffe, O. M. Yaghi, Inorg. Chem. 2011, 50, 9147 –
9152.
[14] K. S. W. Sing, D. H. Everett, R. A. W. Haul, L. Moscou, R. A.
Pierotti, J. Rouquerol, T. Siemieniewska, Pure Appl. Chem.
1985, 57, 603 – 619.
[15] J. Rabone, Y.-F. Yue, S. Y. Chong, K. C. Stylianou, J. Bacsa, D.
Bradshaw, G. R. Darling, N. G. Berry, Y. Z. Khimyak, A. Y.
Ganin, P. Wiper, J. B. Claridge, M. J. Rosseinsky, Science 2010,
329, 1053 – 1057.
[10] O. M. Yaghi, M. OꢁKeeffe, N. W. Ockwig, H. K. Chae, M.
Eddaoudi, J. Kim, Nature 2003, 423, 705 – 714.
[11] “Supramolecular Assemblies and Building Blocks”: M.
Eddaoudi, F. Nouar, J. F. Eubank, L. Wojtas, T. Bousquet, M.
Angew. Chem. Int. Ed. 2012, 51, 1 – 6
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5
These are not the final page numbers!

.
Angewandte
Communications
Communications
Metal–Organic Frameworks
The exceptional nature of the rht-MOF
platform, based on a singular edge-tran-
sitive net (the only net for the combina-
tion of 3- and 24-connected nodes),
makes it an ideal target in crystal
chemistry. The high level of control
indicates an unparalleled blueprint for
isoreticular functional materials (without
concern for interpenetration) for targeted
applications.
J. F. Eubank, F. Nouar, R. Luebke,
A. J. Cairns, L. Wojtas, M. Alkordi,
T. Bousquet, M. R. Hight, J. Eckert,
J. P. Embs, P. A. Georgiev,
M. Eddaoudi*
&&&& — &&&&
On Demand: The Singular rht Net, an
Ideal Blueprint for the Construction of
a Metal–Organic Framework (MOF)
Platform
6
www.angewandte.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2012, 51, 1 – 6
These are not the final page numbers!