Three-dimensional architectures incorporating stereoregular donor-acceptor stacks

Article abstract of DOI:10.1002/chem.201300762

We report the synthesis of two [2]catenane-containing struts that are composed of a tetracationic cyclophane (TC⁴⁺) encircling a 1,5-dioxynaphthalene (DNP)-based crown ether, which bears two terphenylene arms. The TC⁴⁺ rings comprise

Full text of DOI:10.1002/chem.201300762

FULL PAPER
DOI: 10.1002/chem.201300762
Three-Dimensional Architectures Incorporating Stereoregular
Donor–Acceptor Stacks
Dennis Cao,[a, b] Michal Jurꢀcˇek,[a] Zachary J. Brown,[a] Andrew C.-H. Sue,[a]
Zhichang Liu,[a] Juying Lei,[a] Anthea K. Blackburn,[a] Sergio Grunder,[a]
Amy A. Sarjeant,[a] Ali Coskun,[a, b] Cheng Wang,[a, c] Omar K. Farha,[a]
Joseph T. Hupp,[a] and J. Fraser Stoddart*[a, b]
Dedicated to the memory of Christian G. Claessens
Abstract: We report the synthesis of
two [2]catenane-containing struts that
are composed of a tetracationic cyclo-
phane (TC4+) encircling a 1,5-dioxy-
naphthalene (DNP)-based crown ether,
which bears two terphenylene arms.
The TC4+ rings comprise either 1) two
bipyridinium (BIPY2+) units or 2) a
by infinite donor–acceptor stacks in-
volving the [2]catenanes to produce in-
terpenetrated 3D architectures. As a
consequence of the planar chirality as-
sociated with both the DNP and hydro-
quinone (HQ) units present in the
crown ether, each catenane can exist as
four stereoisomers. In the case of the
nondegenerate (bistable) catenane, the
situation is further complicated by the
presence of translational isomers.
Upon crystallization, however, only
two of the four possible stereoiso-
ACHTUNGTRNEmNUNG ers—namely, the enantiomeric RR
and SS forms—are observed in the
crystals. An additional element of co-
conformational selectivity is present in
MOF-1051 as a consequence of the
substitution of one of the BIPY2+ units
by a DAP2+ unit: only the translational
isomer in which the DAP2+ unit is en-
circled by the crown ether is observed.
The overall topologies of MOF-1050
and MOF-1051, and the selective for-
mation of stereoisomers and transla-
tional isomers during the kinetically
driven crystallization, provide evidence
that weak noncovalent bonding inter-
actions play a significant role in the as-
sembly of these extended (super)struc-
tures.
BIPY2+ and a diazapyrenium (DAP2+
)
unit. These degenerate and nondegen-
erate catenanes were reacted in the
presence of CuACHTUNGTRENNUNG(NO3)2·2.5H2O to yield
Cu-paddlewheel-based MOF-1050 and
MOF-1051. The solid-state structures
of these MOFs reveal that the metal
Keywords: catenanes
· molecular
clusters serve to join the hepta
ACHTUNGTRNEpNUNG henyl-
recognition · pi–pi stacking · self-as-
sembly · stereochemistry
ACHTUNGTRENNUNGene struts into grid-like 2D networks.
These 2D sheets are then held together
Introduction
well-defined, extended architectures[3] of metal–organic
frameworks[4] (MOFs) and nanoporous coordination poly-
mers[5] (NCPs) in a quest to marry[6] the dynamics of SBRs
and MIMs with the robustness of MOFs and NCPs. The or-
ganic struts located between the metal secondary binding
units (SBUs) in MOFs serve as ideal platforms for the inser-
tion of SBRs and MIMs into the highly ordered three-di-
mensional (3D) scaffold of a MOF or an NCP.
Substrate-binding receptors[1] (SBRs) and mechanically in-
terlocked molecules[2] (MIMs) have been incorporated into
ˇ
[a] D. Cao, Dr. M. Jurꢀcek, Z. J. Brown, Dr. A. C.-H. Sue, Dr. Z. Liu,
J. Lei, A. K. Blackburn, Dr. S. Grunder, Dr. A. A. Sarjeant,
Prof. A. Coskun, Prof. C. Wang, Prof. O. K. Farha, Prof. J. T. Hupp,
Prof. J. F. Stoddart
Department of Chemistry, Northwestern University
2145 Sheridan Road, Evanston, Illinois 60208 (USA)
Fax : (+1)847-491-1009
We have shown[7] previously that rigid dicarboxylate
struts, containing degenerate p···p donor–acceptor (DA)
[2]catenanes, form—depending on the length of the struts—
either 2D or 3D Cu-based MOF-1011[7a] or MOF-1030,[7b] re-
spectively, in which the SBUs consist of a single CuI ion. It
transpires, however, that some of the acetylenic linkers used
to extend the backbone of the struts also coordinate to the
SBUs, resulting in a mode of binding in which each dicar-
boxylate strut is associated with three separate metal ions,
two with the carboxylates and one in which CuI ions coordi-
nate to an acetylenic linker in an h2 fashion. The catenanes
present in MOF-1011 form infinite DA stacks, while in
MOF-1030, pairs of catenanes, which are associated through
p···p stacking of their hydroquinone (HQ) units, are sand-
E-mail: stoddart@northwestern.ed
[b] D. Cao, Prof. A. Coskun, Prof. J. F. Stoddart
NanoCentury KAIST Institute and Graduate School of EEWS
Korea Advanced Institute of Science and Technology (KAIST)
373-1 Guseong Dong, Yuseong Gu
Daejeon 305-701 (Republic of Korea)
[c] Prof. C. Wang
College of Chemistry and Molecular Sciences
Wuhan University, Wuhan 430072 (P. R. China)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201300762.
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8457

wiched between phenylene/acetylene regions on adjacent
struts. In order to remove the complications involving h2
binding to triple bonds, struts free of reactive acetylenic
linkers are required to act as the building blocks. In re-
sponse to this requirement, we report herein 1) the incorpo-
ration of the [2]catenane-containing heptaphenylene struts,[8]
14+ and 24+ (Figure 1), into Cu paddlewheel-based[9] MOFs
Results and Discussion
The synthesis of 1·4PF6 and 2·4PF6, as well as the free
[36]crown-10-containing heptaphenylene strut 3, were ach-
ieved (Scheme 1) by a series of Miyaura borylations[12] and
Suzuki cross-couplings.[13] The methyl groups on the termi-
nal phenylene units are extremely important, since they
confer enough solubility to render[8] every neutral precursor
soluble in the chlorinated solvents employed in their
workup. Commercially available 4-bromo-3-methylbenzoic
acid (4) was esterified with tBuOH to yield the benzoic
ester 5. Subsequent borylation of 5 by treatment with
KOAc, bis(pinacolato)diboron, and [PdACTHNUTRGENUG(N dppf)Cl2] in
(CH3)2SO furnished the boronic ester 6 in 97% yield. Reac-
tion of 6 with a threefold excess of 4,4’-dibromobiphenyl in
the presence of [PdACHTUNRGTNEUNG(dppf)Cl2] and CsF in a p-dioxane/H2O
(3:1 v/v) solvent mixture yielded the terphenylene 7 in 24%
yield. This low yield is a consequence of a side reaction in
which both bromides on a single 4,4’-dibromobiphenyl mole-
cule react with 6, resulting in the formation of an unwanted
tetraphenylene diester. This byproduct, along with any
excess of unreacted 4,4’-dibromobiphenyl, can be separated
easily from the desired product—namely 7—by column
chromatography. Borylation at the remaining bromine site
in 7 afforded the terphenylene boronic ester 8, which was
then cross-coupled with a macrocyclic polyether, namely
NPP36C10-I2,[14] to yield the key intermediate 9 in 64%
yield. The hydroquinone (HQ) unit in the macrocyclic poly-
ether bears two terphenylene units para to each other such
that, in combination with the HQ ring, they constitute a
hepta(p-phenylene) backbone. Deprotection of the tert-butyl
ester groups by treatment with a mixture of trifluoroacetic
acid (TFA)/CH3CN (1:1 v/v) afforded the macrocyclic poly-
ether-containing diacid 3 in 96% yield.
Figure 1. Structural formulas of the RR forms of the [2]catenanes 14+ and
24+, and the crown ether 3. All three molecules bear heptaphenylene
backbones terminated by carboxylic acid groups.
in which 2) separate, alternating, 2D layers in the solid state
are linked by means of DA p···p stacking interactions[10] in
3) a stereoregular manner, which 4) selects for the dual
planar chirality present in the catenanes in 5) the form of
syndiotactic-like arrays[11] in order to create stacks in which
RR and SS enantiomers alternate with each other.
The reaction of dicationic intermediate[15] 10·2PF6 with
1,4-bis(bromomethyl)benzene in the presence of 9 for three
Scheme 1. Synthesis of the [2]catenanes 1·4PF6 and 2·4PF6 and the macrocyclic polyether 3. Reagents and conditions: i) DMAP, tBuOH, THF, reflux. ii)
[Pd(dppf)Cl2], (Bpin)2, (CH3)2SO, KOAc, 808C. iii) [Pd(dppf)Cl2], p-dioxane/H2O (3:1 v/v), CsF, reflux. iv) TFA/CH3CN. v) NH4PF6/H2O. vi) HCl/
A
ACHTUNGTRENNUNG
CH3CN.
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Molecular Recognition
FULL PAPER
days under ambient conditions afforded the [2]catenane
12·4PF6 in 90% yield after purification by column chroma-
tography. De-esterification was achieved by treating 12·4PF6
with a solution of HCl in CH3CN (3:4 v/v). The purple pre-
cipitate that formed during the reaction was collected and
redissolved in H2O with the assistance of a small amount of
CH3OH. Addition of NH4PF6 to the aqueous solution pre-
cipitated a purple solid which was shown to be the [2]cate-
nane 1·4PF6. The [2]catenane 2·4PF6 was synthesized fol-
lowing a templation protocol similar to that employed in the
synthesis of 1·4PF6. The formation of the catenane was ach-
ieved by reacting 2,7-diazapyrene (14)—which was synthe-
sized[16] following a literature protocol (see the Supporting
Information)—with the dicationic intermediate[17] 11·2PF6 in
the presence of the macrocyclic polyether 9 as a template.
Column chromatography of the crude product yielded the
[2]catenane 13·4PF6, which was then converted into 2·4PF6
by treatment with a mixture of TFA and CH3CN (1:1 v/v).
Counterion exchange of the crude product furnished the
[2]catenane 2·4PF6 as a red solid in 76% yield over two
steps.
Both the HQ unit, which is located in the middle of the
heptaphenylene strut and the 1,5-dioxynaphthalene (DNP)
unit in the [36]crown-10 exhibit[14] planar chirality
(Figure 2). The assignment of absolute configuration of mol-
ecules with chiral planes involves,[18] in the first instance, the
selection of an out-of-plane “pilot atom” that is directly at-
tached to an atom which is located within the plane of the
planar chiral element in question. In the case of 1·4PF6 and
2·4PF6, any of the carbon atoms—highlighted by green cir-
cles in Figure 2—attached to the HQ and DNP unit oxygen
atoms will suffice. The next three atoms encountered, while
counting within the plane in question, are chosen by prece-
dence according to CIP rules,[19] as shown by a, b, and c in
Figure 2. When viewed from the pilot atom, if the a–b–c
array is clockwise, then the absolute configuration is R, and
if the array is counterclockwise, then the absolute configura-
tion is S. In the case of the [2]catenane strut illustrated in
Figure 3. a) A single layer of MOF-1050 as viewed from the [102] direc-
tion. The planar chiralities of the catenane sub-structures are assigned to
the descriptors RR and SS. The TC4+ rings and the crown ethers are illus-
trated in space-filling format while other atoms are portrayed in a stick
representation. b) Four stacked layers in the stick representation. The
DA stacks of catenanes and the layers are packed along the [102] axis.
Individual layers are highlighted by pale green and pale purple boxes.
Layers associated by DA interactions are of the same color and stacks of
catenanes are highlighted by orange squares. Inset: Cu paddlewheels.
Cu=gold/crown ethers=red/TC4+ =blue/organic struts=black. All hy-
drogen atoms have been omitted for the sake of clarity.
Figure 2, both the HQ and DNP units have R configura-
tions. The stereoisomers associated with the HQ unit cannot
undergo inversion simply because the overall length of the
strut is more than sufficient to prevent the passage of a ter-
phenylene unit through the middle of the [36]crown-10. On
the other hand, the DNP unit in the macrocyclic polyether
in 3 can undergo inversion of its planar chirality by a simple
pedaling motion: although this motion will be impaired in
the [2]catenanes 14+ and 24+, it can still happen[20] as a
result of the DNP units leaving the cavity of the tetracation-
ic cyclophane (TC4+) momentarily. In other words, in solu-
tion, the RR and SS enantiomers of 14+, 24+, and 3 are, in
principle at least, in equilibrium with their RS and SR enan-
tiomeric pair of diastereoisomers, respectively. Additionally,
in the case of 24+ in which the mechanically interlocked
Figure 2. Assignment of R configurations to both the HQ and DNP units
in one RR of the two enantiomeric [2]catenanes located within MOF-
1050. The green circles highlight the atoms which are utilized as “pilot
atoms” to conduct the assignment of planar chirality.
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J. F. Stoddart et al.
a major role in the assembly of the crystalline MOF despite
the fact that these interactions are considerably weaker than
the coordinative bonds which bind the organic struts to the
metal joints.
Moreover, in MOF-1051, the DAP2+ units reside exclu-
sively inside the cavity of the macrocyclic polyether, indicat-
ing that a co-conformational selection process is taking
place during the crystallization process in addition to the
diaACTHNUGRTENUNGstereoselective ones. This outcome is in stark contrast
with solution-state observations (Figure 5)—namely, that the
two different translational isomers of 24+ exist in a roughly
3:1 ratio in favor of encirclement of the DAP2+ unit. A
1
close inspection of the H NMR spectrum (Figure 5) of 24+
reveals peaks corresponding to the two different translation-
al isomers. The minor peaks can be assigned to the transla-
tional isomer in which the BIPY2+ unit is encircled by the
crown ether, while the other more intense peaks correspond
to the translational isomer in which the TC4+ encircles the
DAP2+ unit within the crown ether. Integration of the major
and minor peaks indicates that the translational isomers
exist in a roughly 3:1 ratio in favor of the one involving en-
circlement of the DAP2+ unit in the TC4+ by the crown
ether.
The catenanes in the alternating layers in these two
metal–organic frameworks exhibit (Figure 4a,b) extended
DA stacking interactions with each other, resulting in two
separate sets of layers, which are highlighted in purple and
green in Figure 3b. When viewed down the [102] direction,
each 2D layer is offset slightly—that is, staggered with re-
spect to those immediately above and below it. Every layer,
be it purple or green, is in register—that is, eclipsed—with
those either four above or four below it. Within any particu-
lar layer—purple or green—the catenanes are arranged in a
half-up/half-down manner, comprising RR and SS forms in
equal numbers inside each square, for which the sides are
approximately 3.6 nm in length. Analysis of these alternat-
ing purple and green (Figure 4a) layers reveals that within
any one layer, the catenanes exhibit one—either RR or SS—
Figure 4. DA stacks of four catenanes in a) MOF-1050 and b) MOF-1051.
À
C H···p and p···p interaction distances are denoted in a) and b), respec-
tively. In both MOFs, the struts are bent around the adjacent TC4+ rings.
The backbones of neighboring struts within a stack are offset by 868
from each other. The planes of chirality associated with the catenane sub-
structures are assigned to the descriptors R and S. c) Two adjacent 1D
chains of macrocyclic polyether-containing struts in MOF-1052. A single
CuII ion links each chain together. Cu=gold/crown ethers=red/TC4+
=
blue and magenta/organic struts=black. In c), a DMF molecule (white
and blue) is coordinated to each CuII ion. All hydrogen atoms have been
omitted for the sake of clarity.
TC4+ incorporates both bipyridinium (BIPY2+) and 2,7-di-
ACHTUNGTRENNUNG
azapyrenium (DAP2+) units, two translational isomers are
observed[21] in the approximate ratio of 3:1 in favor of the
isomer where the [36]crown-10 encircles the DAP2+
Single crystals of [Cu2(1)2A(H2O)2] (MOF-1050) and
[Cu2(2)2A(H2O)2] (MOF-1051) were obtained by heating (80–
858C) solutions of 1·4PF6 and 2·4PF6, respectively, and an
excess[22] of Cu
(NO3)2·2.5H2O in mixtures of diemthylforma-
.
CTHUNGTRENNUNG
CHTUNGTRENNUNG
ACHTUNGTRENNUNG
mide (DMF) or diethylformamide (DEF) in aqueous
EtOH—essentially the same conditions as those employed[7]
to produce MOF-1011 and MOF-1030. X-ray crystallogra-
phy carried out on the single crystals reveals[23] (Figures 3
and 4) that MOF-1050[24] and MOF-1051[25] are isostructural,
consisting of a 2D network (Figure 3) in which the struts are
joined together by copper paddlewheel[9] SBUs. Prior to the
formation of MOF-1050, a total of four stereoisomers—RR,
RS, SR, and SS, in which the first and second descriptors
refer to that of the HQ and DNP units, respectively—of the
catenanes are present[7b] in the crystallization solution. More
often than not,[26] DA catenanes crystallize to form continu-
ous p···p stacks in the solid state with the planar chirality as-
sociated with any individual stack being invariably offset by
a neighboring p···p stack adopting the opposite elements of
planar chirality. It is worth noting that, upon formation of
the extended structures, only one of the diasteroisomeric
pairs of enantiomers is present—namely, the RR and SS
Figure 5. 1H NMR spectrum (CD3CN, 500 MHz, 298 K) of 2·4PF6. The
resonances are assigned according to the labels in Figure 1. Peaks corre-
sponding to the minor isomer—namely, the one in which the bipyridini-
um unit is encircled by the macrocyclic polyether—are indicated by black
forms—indicating that diaACTHNUTRGENNGsU tereoACHTUTGNRENsNUGN election processes are
taking place during the crystallization of MOF-1050 and
MOF-1051. This diastereoselection suggests that the inter-
molecular p···p stacking of catenanes with each other plays
arrows. Parts of the spectrum have been omitted for the sake of ACHTUNGTRENNUNGclarity.
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Molecular Recognition
FULL PAPER
absolute configuration along one diagonal in which the cate-
nanes alternate up-down-up-down, while along the orthogo-
nal diagonal, in which the catenanes are either all up or all
down, the absolute configurations of the catenanes alternate
between RR and SS along the diagonal. The alternating
purple and green layers are conjugated (Figure 6) in a syn-
interactions with the closest phenylene rings and have dis-
tances (Figure 4a) typically of 2.72 and 2.84 ꢂ between the
plane of the phenylene ring and the hydrogen atoms. These
À
interstrut distances suggest that p···p and C H···p interac-
tions of the BIPY2+ and CH2N+ units with the adjacent
phenylene rings provide the driving force that leads to the
bent nature of the strut backbones and their orientations
with respect to the adjacent TC4+ rings. A consequence of
the alignment between the TC4+ rings and the oligo
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
are arranged at almost (ca. 868) right angles to each other.
The crossed alignment of the cyclophanes is rarely ob-
served[29] in TC4+-containing [2]catenanes. The distance be-
tween adjacent HQ centroids of RR and SS forms within a
DA stack is 13.8 ꢂ, while the distance between [2]catenanes
of the same stereochemistry is 27.6 ꢂ. These distances (Fig-
ure 4b) correspond[10] to a typical p···p stacking distance of
3.5 ꢂ between aromatic units. The net result is that the p···p
stacking interactions between alternating layers is optimal,
suggesting that DA self-assembly contributes to the forma-
tion of the interpenetrated extended (super)structures that
constitute MOF-1050 and MOF-1051. Despite this inter-
penetration, there are channels (Figure 7) running along the
a and c axes in MOF-1050 and MOF-1051 that constitute in
large measure the solvent-accessible voids,[30] which repre-
sent 57% of the crystal. The channels along the a axis are
19.4 ꢂ at their widest, while the smaller channels which run
along the c axis measure about 7.7 ꢂ across. By way of com-
Figure 6. Graphical representation of the MOF-1050 topology. DA inter-
actions hold the 2D MOF layers together. The layers are organized such
that every other layer—that is purple or green—experiences DA interac-
tions with each other. The purple layers stack together and the green
layers stack together.
diotactic-like manner[11] by p···p stacking interactions involv-
ing DA catenanes and their associated struts, such that the
RR forms alternate in the stacks with the SS forms. MOF-
1050 is reminiscent of “pillared” MOFs[27] in which bispyrid-
yl ligands coordinated to the metal paddlewheel SBUs are
used to create separation between 2D sheets. In the [2]cate-
nane-containing MOFs, however, the DA stacks take the
place of the bispyridyl ligands and extend the connectivity
of the organic struts beyond the second dimension into the
third one. The purple and green layers and their associated
DA stacks therefore constitute an interpenetrated 3D archi-
tecture in which noncovalent bonding assumes the role nor-
mally served by covalent and coordination bonds.
The methyl groups on the two terminal phenyl groups act
as steric barriers which induce a torsional twist of 50 and
1028 with respect to their contiguous aromatic rings. On the
other hand, the torsional angles between the remaining phe-
nylene rings and the central HQ unit vary only by between
22 and 288. The heptaphenylene backbones of the struts in
MOF-1050 and MOF-1051 are bent[28] by approximately 248,
and the struts themselves are lined up almost perfectly (68
displacement) with the BIPY2+ unit occupying the alongside
position in the neighboring catenane. The centroid-to-cent-
roid distance from an HQ unit to the nearest pyridinium
ring in an adjacent [2]catenane (Figure 4b) is 3.62 ꢂ. Simi-
larly, the other pyridinium unit that is not encircled by the
crown ether is within p···p stacking distance of one of the
phenylene rings attached to the HQ unit, with a centroid-to-
centroid distance (Figure 4b) of 3.65 ꢂ. Furthermore, the
Figure 7. The channels present in MOF-1050 as viewed along the a) a
and b) c axes. In both a) and b), Cu=gold/crown ethers=red/TC4+
=
blue/organic struts=black. All hydrogen atoms have been omitted for
the sake of clarity.
methylene protons in the TC4+ ring are engaged in C H···p
À
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J. F. Stoddart et al.
1.32 ppm, CD3SOCD3: dH 2.50 ppm, dC 39.52 ppm). The following abbre-
viations are used to explain the multiplicities: s, singlet; d, doublet; t,
triplet; br, broad peaks; m, multiplet or overlapping peaks. AA’BB’ and
AA’XX’ are used to denote para-phenylene and 4-substituted pyridinium
protons. The NMR spectra were processed using the MestReNova 7.1
chemistry software suite. High-resolution electrospray ionization (HR
ESI) mass spectra were measured on Agilent 6210 LC-TOF with Agilent
1200 HPLC introduction.
parison, the unit cell volumes of MOF-1011 and MOF-1030
are composed[7a,b] of only 0.2 and 35% solvent-accessible
voids, respectively.
The importance of noncovalent bonding interactions in
the formation of these MOFs is supported additionally by
the results of a control experiment in which the DA cate-
nanes in 14+ and 24+ have their tetracationic cyclophanes re-
moved to produce a strut 3, which incorporates only the
Synthesis of compound 6: A mixture of tert-butyl ester 5[37] (12.5 g,
46.0 mmol), bis(pinacolato)diboron (12.9 g, 50.8 mmol), [PdACHTUNGTRENNUNG(dppf)Cl2]
[36]crown-10. When 3 and Cu
608C in a mixture of DMF and aqueous EtOH, crystals of
[Cu(3)(H2O)2A(dmf)] (MOF-1052) were obtained. X-ray crys-
ACHTNUGTRNEN(NUG NO3)2·2.5H2O were heated to
(1.9 g, 2.3 mmol), KOAc (13.6 g, 139 mmol), and (CH3)2SO (200 mL) was
heated at 808C under N2 for 10 h. The reaction mixture was then cooled
to RT, diluted with CH2Cl2, and washed copiously with H2O to remove
(CH3)2SO and inorganic salts. The organic layer was dried (MgSO4), fil-
tered, and the solvent evaporated. The residue was then purified by
column chromatography on silica gel using EtOAc/hexanes (1:4 v/v) to
yield 6 (14.3 g, 97%) as an off-white solid. 1H NMR (CDCl3, 500 MHz,
298 K): d=7.72–7.78 (m, 3H), 2.56 (s, 3H), 1.59 (s, 9H), 1.35 ppm (s,
12H); 13C NMR (CDCl3, 125 MHz, 298 K): d=166.1, 144.8, 135.7, 133.8,
130.4, 125.5, 83.9, 83.7, 81.1, 28.4, 28.3, 25.2, 25.0, 22.3 ppm; HR MS
(ESI): m/z calcd for C18H27BO4: 317.2040 [M]+; found: 317.2039.
A
CHTUNGTRENNUNG
tallography reveals[23,31] that the organic struts are linked to-
gether by a single CuII ion so as to form 1D polymer chains
(Figure 4c) that are packed tightly together. The removal of
the enthalpic contributions provided by the DA stacks asso-
ciated with the catenanes in MOF-1050 and MOF-1051 re-
sults in a dramatic change in the solid-state (super)struc-
ture—that is, it would seem that noncovalent bonding inter-
actions are driving the formation of MOF-1050 and MOF-
1051.
Synthesis of compound 7: A mixture of boronic ester 6 (12 g, 38 mmol),
4,4’-dibromobiphenyl (14.7 g, 113 mmol), [Pd
ACHTUNGTERN(NUNG dppf)Cl2] (1.5 g, 1.8 mmol),
CsF (17.2 g, 113 mmol), and 3:1 (v/v) mixture of p-dioxane/H2O
a
(1300 mL) was heated under reflux under N2 for 16 h. After cooling to
RT, the reaction mixture was filtered. The filtrate was diluted with
CH2Cl2 and washed with H2O and brine. The organic layers were com-
bined, dried (MgSO4), filtered, and the solvent evaporated. The residue
was purified by column chromatography on silica gel using hexanes to
elute the excess of 4,4’-dibromobiphenyl and hexanes/CH2Cl2 (7:1 v/v) to
obtain 7 (5.4 g, 24%) as a white solid. 1H NMR (CDCl3, 500 MHz,
298 K): d=7.92 (s, 1H), 7.87 (dd, J=8.0, 1.7 Hz, 1H), 7.63 (AA’BB’, J=
7.0 Hz, 2H), 7.60 (AA’BB’, J=7.0 Hz, 2H), 7.52 (AA’XX’, J=8.2 Hz,
2H), 7.40 (AA’XX’, J=8.2 Hz, 2H), 7.32 (d, J=7.8 Hz, 1H), 2.36 (s,
3H), 1.63 ppm (s, 9H); 13C NMR (CDCl3, 125 MHz, 298 K): d=166.0,
145.6, 140.6, 140.6, 139.7, 139.0, 135.6, 132.0, 131.5, 131.0, 129.9, 129.7,
128.8, 127.0, 126.9, 121.8, 81.1, 28.4, 20.7 ppm; HR MS (ESI): m/z calcd
for C24H23BrO2: 445.0771 [M+Na]+; found: 445.0788.
Conclusion
The cumulative effect of noncovalent bonding interactions
in the shape of p···p stacks provided by suitably located
donor–acceptor catenanes can aid and abet the formation of
robust extended structures such that the two elements of
planar chirality associated with the stacked catenanes under-
go self-sorting into only one repeating enantiomer pair of
diastereoisomers. These observations demonstrate that it is
possible to call upon the tenets of supramolecular[32] and co-
ordination chemistry[33] to construct rigid, porous three-di-
mensional architectures that could play host to artificial mo-
lecular switches[34] and machines[35] one day, provided the
mechanically interlocked molecules are capable of undergo-
ing mechanostereochemical[36] dynamic motions in the solid
state.
Synthesis of compound 8:
A
mixture of tert-butyl ester
7 (5.3 g,
13 mmol), bis(pinacolato)diboron (3.6 g, 14 mmol), [PdAHCUTGNTR(EUNNNG dppf)Cl2] (0.5 g,
0.6 mmol), KOAc (3.8 g, 39 mmol), and (CH3)2SO (100 mL) was heated
at 808C under N2 for 10 h. The reaction mixture was then cooled to RT,
diluted with CH2Cl2, and washed copiously with H2O to remove
(CH3)2SO and inorganic salts. The organic layer was dried (MgSO4), fil-
tered, and solvent evaporated. The residue was then purified by column
chromatography on silica gel using CH2Cl2/hexanes (1:4 v/v) to yield 8
(4.15 g, 70%) as a white solid. 1H NMR (CDCl3, 500 MHz, 298 K): d=
7.94 (s, 1H) 7.93 (AA’BB’, J=8.0 Hz, 2H), 7.90 (AA’BB’, J=8.0 Hz,
1H), 7.70 (AA’XX’, J=8.6 Hz, 2H), 7.68 (AA’XX’, J=8.6 Hz, 2H), 7.41
(AA’BB’, J=8.0 Hz, 2H), 7.33 (AA’BB’, J=8.0 Hz, 1H), 2.38 (s, 3H),
1.63 (s, 9H), 1.38 ppm (s, 12H); 13C NMR (CDCl3, 125 MHz, 298 K): d=
165.9, 145.7, 143.4, 140.5, 140.0, 135.6, 135.4, 131.5, 130.9, 129.9, 129.6,
127.1, 127.0, 126.5, 84.0, 81.0, 28.3, 25.0, 20.7 ppm; HR MS (EI): m/z
calcd for C30H35BO4: 492.2548 [M+Na]+; found: 492.2557.
Experimental Section
General information: Solvents were deoxygenated by passing Ar gas
through the solution for 30 min. Compound 4 and reagents were pur-
chased from Sigma–Aldrich and used as received, unless otherwise
noted. All reactions were performed under a N2 atmosphere and in dry
solvents, unless otherwise stated. All cross-coupling reactions were car-
ried out in deoxygenated solvents under N2 using the Schlenk technique.
Synthesis of compound 9: A mixture of boronic ester 8 (1.0 g, 2.1 mmol),
[14]
NPP36C10-I2
(0.81 g, 1.0 mmol), [PdACTHNGUTER(NNUG dppf)Cl2] (80 mg, 0.10 mmol),
[17]
Compounds 5,[37] NPP36C10-I2,[14] 10·2PF6,[15] and 11·2PF6 were all pre-
CsF (0.88 mg, 5.8 mmol), and a 3:1 (v/v) mixture of p-dioxane/H2O
(150 mL) was heated under reflux under N2 for 16 h. After cooling to
RT, the reaction mixture was filtered. The filtrate was diluted with
CH2Cl2 and washed with H2O and brine. The organic layers were com-
bined, dried (MgSO4), filtered, and evaporated. The residue was purified
by column chromatography on silica gel using CH2Cl2 then EtOAc/
CH2Cl2 (1:9 v/v) to yield 9 (780 mg, 64%) as an off-white solid. Although
9 exists presumably as a mixture of four stereoisomers, the signals for the
stereoisomers overlap within the resolution limits of both 1H and
13C NMR spectroscopic techniques. 1H NMR (CDCl3, 500 MHz, 298 K):
d=7.94 (s, 2H), 7.89 (dd, J=8.0, 1.8 Hz, 2H), 7.79 (AA’XX’, J=8.4 Hz,
2H), 7.72 (AA’BB’, 8.0 Hz, 4H), 7.70 (AA’BB’, 8.0 Hz, 4H), 7.67
pared following literature procedures. Analytical thin-layer chromatogra-
phy (TLC) was performed on aluminum sheets precoated with silica gel
60-F254 (Merck 5554). Column chromatography was carried out using
silica gel 60F (Silicycle 230–400 mesh). Nuclear magnetic resonance
(NMR) spectra were recorded at 298 K on a Bruker Avance III 500 spec-
trometer, with a working frequency of 500 MHz for 1H and 125 MHz for
13C. Chemical shifts are listed in ppm on the d scale and coupling con-
stants are recorded in Hertz (Hz). Deuterated solvents for NMR spectro-
scopic analyses were used as received. Chemical shifts are reported in d
relative to the signals corresponding to the residual non-deuterated sol-
vents (CDCl3: dH 7.26 ppm, dC 77.16 ppm, CD3CN: dH 1.94 ppm, dC
8462
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ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 8457 – 8465

Molecular Recognition
FULL PAPER
(AA’XX’, J=8.4 Hz, 4H), 7.43 (d, J=8.2 Hz, 4H), 7.36 (d, J=7.9 Hz,
2H) 7.19 (dd, J=8.0, 8.0 Hz, 2H), 6.97 (s, 2H), 6.63 (d, J=7.6 Hz, 2H),
5.30 (s, 2H), 4.16–4.07 (m, 4H), 4.05–3.95 (m, 4H), 3.93–3.88 (m, 4H),
3.78–3.57 (m, 20H), 2.40 (s, 6H), 1.63 ppm (s, 18H); 13C NMR (CDCl3,
125 MHz, 298 K): d=166.0, 154.3, 150.4, 145.8, 140.1, 140.0, 139.2, 137.4,
135.6, 131.5, 130.1, 130.3, 130.2, 129.9, 129.6, 127.0, 126.9, 126.8, 126.7,
125.1, 116.1, 114.6, 105.7, 81.1, 71.1, 71.0, 70.9, 70.9, 69.9, 69.8, 69.2, 68.0,
53.6, 28.4, 20.7 ppm; HR MS (ESI): m/z calcd for C80H86O14: 1288.6356
[M+NH4]+; found: 1288.6366.
(AA’XX’, J=8.0 Hz, 4H), 7.44 (AA’XX’, J=7.8 Hz, 2H), 7.24 (AA’XX’,
J=5.5 Hz, 2H), 7.18 (AA’XX’, J=6.8, 2.4 Hz, 2H), 6.89 (AA’XX’, J=
6.6, 2.3 Hz, 2H), 6.82 (AA’XX’, J=5.4 Hz, 2H), 6.34 (s, 2H), 6.13 (d, J=
7.8 Hz, 2H), 5.98–5.90 (m, 4H), 5.77–5.64 (m, 6H), 4.30–4.17 (m, 6H),
4.14–4.07 (m, 2H), 4.02–3.71 (m, 20H), 3.63 (t, J=9.6 Hz, 2H), 3.19 (br,
2H), 2.45 (s, 6H), 2.37 ppm (d, J=8.1 Hz, 2H); 13C NMR (CD3CN,
125 MHz, 298 K): d=167.9, 151.9, 150.6, 150.1, 146.9, 146.3, 145.9, 145.3,
144.7, 141.3, 140.2, 140.1, 137.6, 137.5, 136.9, 132.6, 132.0, 131.0, 130.9,
130.7, 130.3, 129.2, 129.1, 128.2, 127.7, 127.6, 126.8, 125.7, 125.4, 125.2,
124.6, 115.1, 109.3, 105.1, 72.2, 72.1, 71.7, 70.6, 70.4, 69.1, 69.0, 66.0,
20.8 ppm; HR MS (ESI): m/z calcd for C108H102F24N4O14P4: 984.3333
[MÀ2PF6]2+; found: 984.3343.
Synthesis of compound 3: A mixture of 9 (369 mg, 0.290 mmol), TFA
(20 mL), and CH3CN (20 mL) was stirred at room temperature for 19 h
before a white precipitate, which formed during this period, was filtered
off, washed with H2O, and dried in air to afford the pure product 3
(324 mg, 96%) as a white solid. Although 3 exists presumably as a mix-
ture of four stereoisomers, the signals for the stereoisomers overlap
within the resolution limits of both 1H and 13C NMR spectroscopic tech-
niques. 1H NMR (CD3SOCD3, 500 MHz, 298 K): d=12.96 (s, 2H), 7.92
(s, 2H), 7.85 (d, J=8.1 Hz, 2H), 7.83 (AA’XX’, J=7.8 Hz, 4H), 7.81–
7.74 (AA’BB’, 8H), 7.61 (d, J=8.4 Hz, 2H), 7.52 (AA’XX’, J=7.8 Hz,
4H), 7.41 (d, J=7.8 Hz, 2H), 7.20 (dd, J=8.0, 8.0 Hz, 2H), 7.06 (s, 2H),
6.67 (d, J=7.7 Hz, 2H), 4.14–3.98 (m, 8H), 3.85–3.65 (m, 8H), 3.65–3.52
(m, 16H), 2.37 ppm (s, 6H); 13C NMR (CD3CN, 125 MHz, 298 K): 167.3,
153.8, 149.8, 145.2, 139.4, 139.0, 138.0, 137.0, 135.4, 131.4, 130.1, 129.9,
129.7, 129.6, 129.1, 127.0, 126.5, 126.2, 125.9, 125.3, 115.3, 113.8, 105.7,
70.2, 70.1, 70.1, 70.0, 69.1, 68.8, 68.4, 67.7, 20.3 ppm; HR MS (ESI): m/z
calcd for C72H70O14: 1158.4766 [M]+; found: 1158.4750.
Synthesis of compound 13·4PF6: A mixture of macrocyclic polyether 9
(0.450 g, 0.354 mmol), 2,7-diazapyrene 14[16] (0.216 g, 1.06 mmol),
[17]
11·2PF6
(0.863 g, 1.06 mmol), and DMF (20 mL) was stirred at RT
under N2 for 7 d before the solvent was removed under vacuum. The
solid residue was purified by column chromatography on silica gel using
(CH3)2CO and NH4PF6/ACTHUNTRGNEG(UN CH3)2CO (0.25 g/100 mL to 1.5 g/100 mL) as the
eluents. The fractions containing the product were combined, concentrat-
ed to a small volume, and an excess of H2O was added to precipitate the
product, which was then collected by filtration and washed several times
with H2O. After drying in air overnight, the pure product 13·4PF6 (0.72 g,
84%) was obtained as a red-purple solid. In solution, 13·4PF6 exists as a
3:1 (by 1H NMR spectroscopy) mixture of two translational isomers
(major-13·4PF6 and minor-13·4PF6). Both major-13·4PF6 and minor-
13·4PF6 exist presumably as a mixture of four stereoisomers, resulting in
complex NMR spectra for 13·4PF6. Most of the 1H and 13C NMR signals
of minor-13·4PF6 overlap with the signals of major-13·4PF6 or are broad-
Synthesis of compound 12·4PF6: Macrocyclic polyether
9
(0.77 g,
[15]
0.61 mmol), 10·2PF6
(0.87 g, 1.2 mmol), and a,a’-dibromo-p-xylene
1
ened, but some individual H NMR signals of minor-13·4PF6 can be iden-
(0.32 g, 1.2 mmol) were dissolved in DMF (40 mL). The reaction mixture
was stirred for 3 d at RT. The mixture was then poured directly onto a
silica gel column and flushed with (CH3)2CO to remove any remaining
uncharged compounds. The column was then eluted with
tified. The 1H and 13C NMR signals of minor-13·4PF6 could not be fully
1
assigned. Only the H and 13C NMR spectra of major-13·4PF6 are report-
ed (the signals of the stereoisomers of major-13·4PF6 overlap within the
resolution limits of both NMR spectroscopic techniques). Major-13·4PF6:
1H NMR (CD3CN, 500 MHz, 298 K): d=10.04 (s, 2H), 9.43 (s, 2H), 8.56
(AA’XX’, J=6.6 Hz, 2H), 8.51 (AA’XX’, J=6.4 Hz, 2H), 8.19–8.13 (m,
2H), 8.09 (dd, J=8.3, 1.9 Hz, 2H), 7.98 (d, J=1.7 Hz, 2H), 7.98–7.93 (m,
4H), 7.92–7.84 (m, 2H), 7.90 (AA’XX’, J=8.0 Hz, 4H), 7.87 (d, J=
9.5 Hz, 2H), 7.79 (AA’XX’, J=8.2 Hz, 4H), 7.65 (d, J=9.2 Hz, 2H), 7.57
(AA’XX’, J=8.0 Hz, 4H), 7.42 (AA’XX’, J=8.3 Hz, 4H), 7.42 (d, J=
8.1 Hz, 2H), 7.12 (AA’XX’, J=6.7, 2.4 Hz, 2H), 6.91 (AA’XX’, J=6.8,
2.4 Hz, 2H), 6.44 (d, J=13.7 Hz, 2H), 6.10 (AA’XX’, J=13.8 Hz, 2H),
5.73 (d, J=7.9 Hz, 2H), 5.70 (s, 2H), 5.65–5.62 (m, 4H), 5.60 (dd, J=7.9,
7.9 Hz, 2H), 4.44–4.36 (m, 2H), 4.35–4.26 (m, 4H), 4.14–3.62 (m, 22H),
3.60–3.49 (m, 4H), 2.43 (s, 6H), 1.76 (d, J=8.3 Hz, 2H), 1.63 ppm (s,
18H); 13C NMR (CD3CN, 125 MHz, 298 K): d=166.4, 151.0, 149.4, 146.6,
145.9, 145.6, 143.8, 142.3, 141.3, 140.2, 140.2, 139.9, 137.6, 137.4, 136.7,
136.3, 132.1, 132.1, 132.0, 130.9, 130.8, 130.7, 130.7, 130.3, 130.1, 129.2,
128.6, 128.5, 127.9, 127.7, 127.7, 127.6, 127.4, 127.1, 126.8, 125.7, 124.5,
123.2, 113.6, 107.2, 105.0, 81.8, 73.0, 72.9, 72.5, 71.1, 70.8, 70.4, 68.9, 68.9,
67.9, 66.1, 28.4, 20.8 ppm; HRMS (ESI): m/z calcd for
C120H118F24N4O14P4: 1064.3959 [MÀ2PF6]2+; found: 1064.3914.
NH4PF6/ACHTUNGTRENNUNG(CH3)2CO (0.10 mg/100 mL) to yield 12·4PF6 (1.3 g, 90%) as a
purple solid after counterion exchange with NH4PF6. Although 12·4PF6
exists presumably as a mixture of four stereoisomers, the signals for the
stereoisomers overlap within the resolution limits of both 1H and
13C NMR spectroscopic techniques. 1H NMR (CD3CN, 500 MHz, 298 K):
d=9.18 (AA’XX’, J=6.5 Hz, 2H), 8.77 (AA’XX’, J=6.7 Hz, 2H), 8.56
(AA’XX’, J=6.4 Hz, 2H), 8.51 (AA’XX’, J=6.7 Hz, 2H), 8.06–7.98 (m,
4H), 7.97 (br s, 2H), 7.91 (br s, 4H), 7.89 (AA’XX’, J=7.5 Hz, 2H), 7.87
(AA’XX’, J=8.3 Hz, 4H), 7.81 (AA’XX’, J=8.3 Hz, 4H), 7.58 (AA’XX’,
J=7.9 Hz, 4H), 7.56 (AA’XX’, J=7.9 Hz, 4H), 7.41 (AA’XX’, J=7.8 Hz,
2H), 7.25 (AA’XX’, J=5.2 Hz, 2H), 7.19 (AA’XX’, J=6.8, 2.4 Hz, 2H),
6.90 (AA’XX’, J=6.7, 2.4 Hz, 2H), 6.82 (AA’XX’, J=5.9 Hz, 2H), 6.34
(s, 2H), 6.13 (d, J=7.8 Hz, 2H), 5.95–5.87 (m, 4H), 5.75–5.61 (m, 6H),
4.28–4.15 (m, 6H), 4.11–4.03 (m, 2H), 4.00–3.68 (m, 20H), 3.59 (t, J=
10.1 Hz, 2H), 3.16 (br s, 2H), 2.41 (s, 6H), 2.34 (d, J=8.1 Hz, 2H),
1.62 ppm (s, 18H); 13C NMR (CD3CN, 125 MHz, 298 K): d=166.3, 151.7,
150.0, 146.3, 145.8, 145.8, 145.2, 144.6, 144.3, 141.2, 140.1, 140.0, 137.5,
137.4, 136.8, 136.6, 132.6, 132.1, 132.0, 130.8, 130.7, 130.6, 129.1, 129.0,
127.7, 127.6, 127.4, 126.7, 127.6, 127.4, 126.7, 125.6, 125.3, 125.1, 124.5,
115.0, 109.2, 105.0, 81.8, 72.1, 71.9, 70.6, 70.5, 70.3, 68.9, 68.9, 66.0, 28.3,
20.7 ppm; HR MS (ESI): m/z calcd for C116H118F24N4O14P4: 1040.3959
[MÀ2PF6]2+; found: 1040.4001.
Synthesis of compound 1·4PF6: Conc. HCl (30 mL) was added to a mix-
ture of the catenane 12·4PF6 (0.43 g, 0.18 mmol) and CH3CN (40 mL).
The reaction mixture was stirred for 30 min at RT, during which time a
purple precipitate formed. The precipitate was collected by filtration, dis-
solved in H2O with the assistance of a small amount of CH3OH, and
1·4PF6 (395 mg, 97%) was precipitated out of the solution as a purple
solid with the addition of NH4PF6. Although 1·4PF6 exists presumably as
a mixture of four stereoisomers, the signals for the stereoisomers overlap
within the resolution limits of both 1H and 13C NMR spectroscopic tech-
niques. 1H NMR (CD3CN, 500 MHz, 298 K): d=9.21 (AA’XX’, J=
6.2 Hz, 2H), 8.81 (AA’XX’, J=6.6 Hz, 2H), 8.59 (AA’XX’, J=6.4 Hz,
2H), 8.55 (AA’XX’, J=6.7 Hz, 2H), 8.04 (m, 4H), 8.02 (br s, 2H), 7.94
(AA’XX’, 8.0, 1.8 Hz, 2H), 7.91 (br s, 4H), 7.88 (AA’XX’, J=8.1 Hz,
4H), 7.81 (AA’XX’, J=8.2 Hz, 4H), 7.58 (AA’XX’, J=8.0 Hz, 4H), 7.57
Synthesis of compound 2·4PF6:
A mixture of 13·4PF6 (118 mg,
48.8 mmol), TFA (13 mL), and CH3CN (13 mL) was stirred at RT in the
dark for 3 d before the solvents were evaporated. After the addition a
3:2 mixture of H2O and CH3OH (50 mL) followed by aq. NH4PF6 (1.5m,
30 mL), the red precipitate that formed was collected by filtration,
washed with H2O, and dried in air to afford the pure product 2·4PF6
(102 mg, 90%) as a dark red solid. In solution, 2·4PF6 exists as a 3:1 (by
1H NMR spectroscopy) mixture of two translational isomers (major-
2·4PF6 and minor-2·4PF6). Both major-2·4PF6 and minor-2·4PF6 exist
presumably as a mixture of four stereoisomers, which results in complex
NMR spectra for 2·4PF6. Most of the 1H and 13C NMR signals of minor-
2·4PF6 overlap with the signals of major-2·4PF6 or are broadened, but
some individual 1H NMR signals of minor-2·4PF6 can be identified (Fig-
ure S4 in the Supporting Information). The 1H and 13C NMR signals of
minor-2·4PF6 could not be fully assigned. Only the 1H and 13C NMR
spectra of major-2·4PF6 are reported (the signals of the stereoisomers of
major-2·4PF6 overlap within the resolution limits of both NMR spectro-
scopic techniques). Major-2·4PF6: 1H NMR (CD3CN, 500 MHz, 298 K):
Chem. Eur. J. 2013, 19, 8457 – 8465
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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8463

J. F. Stoddart et al.
d=10.03 (s, 2H), 9.43 (s, 2H), 8.57 (AA’XX’, J=6.7 Hz, 2H), 8.51
(AA’XX’, J=6.5 Hz, 2H), 8.16 (dd, J=8.4, 1.9 Hz, 2H), 8.08 (dd, J=8.2,
1.9 Hz, 2H), 8.02 (d, J=2.1 Hz, 2H), 7.98–7.88 (m, 6H), 7.91 (AA’XX’,
J=8.1 Hz, 4H), 7.86 (d, J=9.0 Hz, 2H), 7.79 (AA’XX’, J=8.3 Hz, 4H),
7.64 (d, J=9.1 Hz, 2H), 7.58 (AA’XX’, J=8.0 Hz, 4H), 7.45 (d, J=
7.9 Hz, 2H), 7.43 (AA’XX’, J=8.5 Hz, 4H), 7.12 (AA’XX’, J=6.5,
2.4 Hz, 2H), 6.91 (AA’XX’, J=6.8, 2.4 Hz, 2H), 6.44 (d, J=13.7 Hz,
2H), 6.10 (d, J=13.7 Hz, 2H), 5.72 (d, J=7.9 Hz, 2H), 5.70 (s, 2H),
5.65–5.62 (m, 4H), 5.60 (dd, J=8.0, 7.9 Hz, 2H), 4.44–4.36 (m, 2H),
4.35–4.26 (m, 4H), 4.14–3.62 (m, 22H), 3.60–3.49 (m, 4H), 2.44 (s, 6H),
1.76 ppm (d, J=8.0 Hz, 2H); 13C NMR (CD3CN, 125 MHz, 298 K): d=
167.7, 151.0, 149.4, 147.0, 145.9, 145.6, 143.9, 142.3, 141.2, 140.3, 140.2,
139.8, 137.6, 137.4, 136.9, 136.3, 132.6, 132.6, 132.0, 131.0, 130.9, 130.7,
130.7, 130.3, 130.1, 129.2, 128.6, 128.2, 127.9, 127.8, 127.7, 127.6, 127.4,
127.2, 126.8, 125.7, 124.5, 123.2, 113.6, 107.2, 105.0, 73.0, 72.9, 72.5, 71.1,
70.8, 70.4, 68.9, 68.9, 67.9, 66.1, 20.8 ppm; HRMS (ESI): m/z calcd for
C112H102F24N4O14P4: 1008.3333 [MÀ2PF6]2+; found: 1008.3307.
M. B. LaLonde, R. Q. Snurr, O. K. Farha, J. T. Hupp, J. F. Stoddart,
J. Am. Chem. Soc. 2012, 134, 17436–17439.
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Synthesis of compound MOF-1050: CuACTHNUTRGNE(UNG NO3)2·2.5H2O (20 mg, 86 mmol)
and 1·4PF6 (10 mg, 4.4 mmol) were dissolved in a 3:3:2 (v/v/v) mixture
(1 mL) of DEF, EtOH, and H2O. The mixture was passed through a
0.45 mm filter into a 3 mL vial which was capped and heated in an iso-
thermal oven at 858C for 3 d, after which time it was removed from the
oven and cooled to room temperature, yielding a mixture of brown and
green crystals. The brown crystals of [Cu2(1)
characterized[24] by single-crystal X-ray crystallography.[23]
Synthesis of compound MOF-1051: Cu(NO3)2·2.5H2O (3.9 mg, 17 mmol)
2ACHTUNGTREN(NUNG H2O)2] (MOF-1050) were
AHCTUNGTRENNUNG
and 2·4PF6 (2.0 mg, 0.87 mmol) were dissolved in a 3:3:2 (v/v/v) mixture
(1 mL) of DEF, EtOH, and H2O. The mixture was passed through a
0.45 mm filter equally into three 1 mL crystallization tubes which were
capped in a 20 mL vial and heated in an isothermal oven at 808C for 2 d,
after which time they were removed from the oven and cooled to room
temperature, yielding a mixture of orange and green crystals. The orange
2ACHTUNGTRENNUNG
(H2O)2] (MOF-1051) were characterized[25] by single-
[5] a) G. J. E. Davidson, S. J. Loeb, Angew. Chem. 2003, 115, 78–81;
Angew. Chem. Int. Ed. 2003, 42, 74–77; b) D. J. Hoffart, S. J. Loeb,
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Loeb, Chem. Soc. Rev. 2007, 36, 226–235; e) V. N. Vukotic, S. J.
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crystals of [Cu2(2)
crystal X-ray crystallography.[23]
MOF-1052: Cu(NO3)2·2.5H2O (3.9 mg, 17 mmol) and
G
3
(1.0 mg,
0.79 mmol) were dissolved in a 3:3:2 (v/v/v) mixture (1 mL) of DMF,
EtOH, and H2O. The mixture was passed through a 0.45 mm filter equally
into three 1 mL crystallization tubes which were capped in a 20 mL vial
and heated in an isothermal oven at 608C for 5 d, after which time they
were removed from the oven and cooled to room temperature, yielding a
[6] H. Deng, M. A. Olson, J. F. Stoddart, O. M. Yaghi, Nat. Chem. 2010,
2, 439–443.
ˇ
´
[7] a) Q. Li, W. Zhang, O. S. Miljanic, C. B. Knobler, J. F. Stoddart,
O. M. Yaghi, Chem. Commun. 2010, 46, 380–382; b) Q. Li, C.-H.
Sue, S. Basu, A. K. Shveyd, W. Zhang, G. Barin, L. Fang, A. A. Sar-
jeant, J. F. Stoddart, O. M. Yaghi, Angew. Chem. 2010, 122, 6903–
6907; Angew. Chem. Int. Ed. 2010, 49, 6751–6755.
mixture of blue and green crystals. The blue crystals of [Cu(3)
(dmf)] (MOF-1052) were characterized[31] by single-crystal X-ray crystal-
lography.[23]
ACHTUGNTERN(NUGN H2O)2-
ACHTUNGTRENNUNG
[8] Recently, we introduced molecular gauge blocks based on 1–7 and
9–11 paraxylene rings as part of a homologous series of oligopara-
AHCTUNGTREGxNNUN ylenes with a view to providing a molecular tool box for the con-
Acknowledgements
struction of extended structures such as metal–organic frameworks;
see: S. Grunder, C. Valente, A. C. Whalley, S. Sampath, J. Portmann,
Y. Y. Botros, J. F. Stoddart, Chem. Eur. J. 2012, 18, 15632–15649.
These molecular gauge blocks have been incorporated into an isore-
ticular series of MOF-74 structures with pore aperatures ranging
from 14 to 98 ꢂ; see: H. Deng, S. Grunder, K. E. Cordova, C. Val-
ente, H. Furukawa, M. Hmadeh, F. Gꢅndara, A. C. Whalley, Z. Liu,
S. Asahira, H. Kazumorio, M. OꢃKeefe, O. Terasake, J. F. Stoddart,
O. M. Yaghi, Science 2012, 336, 1018–1023.
D.C. acknowledges the National Science Foundation (NSF) for a Gradu-
ate Research Fellowship. D.C. and J.F.S. were beneficiaries of the WCU
Program funded by the Ministry of Education, Science and Technology,
Korea (NRF R-31-2008-000-10055-0). D.C. gratefully acknowledges sup-
port from the Ryan Fellowship and the Northwestern University Interna-
tional Institute for Nanotechnology. M.J. gratefully acknowledges the
Netherlands Organisation for Scientific Research (NWO) and the Marie
Curie Cofund Action (Rubicon Fellowship) for financial support. S.G.
gratefully acknowledges the Swiss National Science Foundation for finan-
cial support. Z.J.B., J.T.H., and O.K.F. gratefully acknowledge financial
support from the Defense Threat Reduction Agency (grant Nos.
HDTRA1-09-1-0007 and HDTRA1-1-10-0023).
[9] The square paddlewheel is one of the most common clusters formed
between metal ions and carboxylates; see the following and referen-
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axial positions of the paddlewheels can be coordinated to a large va-
riety of ligands—typically, solvent molecules, such as H2O and
DMF, are present in freshly synthesized MOFs. Desolvating the pad-
dlewheels yields open metal sites which have been exploited for en-
hanced gas adsorption properties of the crystalline materials; see:
ˇ
´
[1] a) Q. Li, W. Zhang, O. S. Miljanic, C.-H. Sue, C. B. Knobler, Y.-L.
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˘
a) M. Dinca, J. R. Long, Angew. Chem. 2008, 120, 6870–6884;
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8464
www.chemeurj.org
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 8457 – 8465

Molecular Recognition
FULL PAPER
G. S. Walker, D. R. Allan, S. A. Barnett, N. R. Champness, M.
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,
monoclinic, space group P21/n (no. 14), a=12.6962(6), b=48.752(2),
c=26.1253(12) ꢂ, a=90.00, b=100.219(4), g=90.008, V=
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15914.1(13) ꢂ3, 1calcd =0.754 gcmÀ3
,
m
(CuKa)=0.524 mmÀ1
,
T=
99.99 K, orange blocks, 37477 measured reflections, F2 refinement,
R1 =0.1993, wR2 =0.4207, 7548 independent observed reflections (all
data), 1189 parameters.
[26] a) E. Alcalde, L. Pꢄrez-Garcꢀa, S. Ramos, J. F. Stoddart, S. A.
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[28] The angle was measured between the plane of the HQ ring and the
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122, 9300–9301.
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[30] The porosity of MOF-1050 was examined by CO2 adsorption at
273 K after the guest solvent molecules were removed using super-
critical CO2, and found to be about 350 m2gÀ1—the details of activa-
tion are located in the Supporting Information; also see: a) A. P.
Nelson, O. K. Farha, K. L. Mulfort, J. T. Hupp, J. Am. Chem. Soc.
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[31] Crystal data for MOF-1052: C153H165Cu2N3O35, Mr =2732.96 gmolÀ1
,
¯
triclinic, space group P1 (no. 2), a=13.4730(3), b=20.6981(4), c=
31.1920(6) ꢂ, a=100.4170(10), b=100.8960(10), g=108.7780(10)8,
V=7808.9(3) ꢂ3, 1calcd =1.162 gcmÀ3
,
m
(CuKa)=0.921 mmÀ1
,
T=
[20] S. A. Vignon, J. F. Stoddart, Collect. Czech. Chem. Commun. 2005,
70, 1493–1576.
224.99 K, blue blocks, 38206 measured reflections, F2 refinement,
R1 =0.1138, wR2 =0.2664, 24191 independent observed reflections
(all data), 1811 parameters.
[21] A similar ratio of translational isomers was observed in an analo-
gous [2]catenane without pendant terphenylene units; see: P. R.
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[22] The use of an excess of CuACTHNUTRGNE(NUG NO3)2·2.5H2O during the production of
À
MOF-1050 and MOF-1051 ensures that all the PF6 counterions are
exchanged for the NO3À counterions.
[23] CCDC-913139 (MOF-1050), CCDC-913140 (MOF-1051), and
CCDC-913141 (MOF-1052) contain the supplementary crystallo-
graphic 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.
[24] Crystal data for MOF-1050: C108H100CuN4O15, Mr =1757.46 gmolÀ1
,
monoclinic, space group P21/n (no. 14), a=12.7797(5), b=49.577(2),
c=26.7601(10) ꢂ, a=90.00, b=100.039(2), g=90.008, V=
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16695.1(11) ꢂ3, 1calcd =0.699 gcmÀ3
,
m
G
,
T=
224.98 K, brown blocks, 79708 measured reflections, F2 refinement,
R1 =0.2113, wR2 =0.4377, 17384 independent observed reflections
(all data), 1155 parameters.
Received: February 26, 2013
Published online: May 6, 2013
Chem. Eur. J. 2013, 19, 8457 – 8465
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
8465