Engineering chiral polyoxometalate hybrid metal-organic frameworks for asymmetric dihydroxylation of olefins

Article abstract of DOI:10.1021/ja401758c

Chiral metal-organic frameworks (MOFs) with porous and tunable natures have made them feasible for performing a variety of chemical reactions as heterogeneous asymmetric catalysts. By incorporating the oxidation catalyst [BW₁₂O₄₀]^5- and the chiral group, l- or d-pyrrolidin-2-ylimidazole (PYI), into one single framework, the two enantiomorphs Ni-PYI1 and Ni-PYI2 were obtained via self-assembly, respectively. The channels of Ni-PYIs were enlarged through a guest exchange reaction to remove the cationic chiral templates and were well modulated with hydrophilic/hydrophobic properties to allow molecules of both H ₂O₂ and olefin ingress and egress. The coexistence of both the chiral directors and the oxidants within a confined space provided a special environment for the formation of reaction intermediates in a stereoselective fashion with high selectivity. The resulting MOF acted as an amphipathic catalyst to prompt the asymmetric dihydroxylation of aryl olefins with excellent stereoselectivity.

Full text of DOI:10.1021/ja401758c

Communication
pubs.acs.org/JACS
Engineering Chiral Polyoxometalate Hybrid Metal−Organic
Frameworks for Asymmetric Dihydroxylation of Olefins
†
,‡
†
†
†
‡
,†
Qiuxia Han, Cheng He, Min Zhao, Bo Qi, Jingyang Niu, and Chunying Duan*
†State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, People’s Republic of China
‡School of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, People’s Republic of China
*
S Supporting Information
1
2,13
through the imbedded, regularly ordered chiral groups.
In
ABSTRACT: Chiral metal−organic frameworks (MOFs)
with porous and tunable natures have made them feasible
for performing a variety of chemical reactions as
heterogeneous asymmetric catalysts. By incorporating the
particular, the potential to directly blend both chiral ligands and
the metal ions endows MOFs with multiple functionalities and
new features that their components do not have.
1
4,15
Polyoxometalates (POMs) are well-known catalysts studied
5
−
oxidation catalyst [BW O ] and the chiral group, L- or
1
2
40
in the olefin epoxidation with excellent thermal and oxidative
D-pyrrolidin-2-ylimidazole (PYI), into one single frame-
work, the two enantiomorphs Ni-PYI1 and Ni-PYI2 were
obtained via self-assembly, respectively. The channels of
Ni-PYIs were enlarged through a guest exchange reaction
to remove the cationic chiral templates and were well
modulated with hydrophilic/hydrophobic properties to
allow molecules of both H O and olefin ingress and
16−18
stability toward oxygen donors.
The introduction of
POMs into these hierarchical frameworks at the molecular
level possibly increases the stability and corresponding
functions, providing a promising way to combine the organic
19−21
and inorganic catalytic components synergistically.
One of
the important issues in the petroleum industry is that the
oxidation reactions using POMs as catalysts often involve
reactants in immiscible liquid phases and aqueous oxidizing
agents. The attempt to find suitable amphipathic catalysts is an
important methodology for organic synthesis in both industrial
2
2
egress. The coexistence of both the chiral directors and the
oxidants within a confined space provided a special
environment for the formation of reaction intermediates
in a stereoselective fashion with high selectivity. The
resulting MOF acted as an amphipathic catalyst to prompt
the asymmetric dihydroxylation of aryl olefins with
excellent stereoselectivity.
2
2,23
and academic laboratories.
By incorporating a Keggin-type [BW O ] anion, nickel-
5
−
12
40
24
(
II) ions, and an asymmetric organocatalytic group, PYI,
within one single MOF, herein, we report the design and
synthesis of two new enantiomorphs of MOFs, Ni-PYI1 and
Ni-PYI2, for the asymmetric dihydroxylation of aryl olefins
atalytic asymmetric processes that exhibit high activity,
selectivity, and broad substrate generality under mild
reaction conditions are indispensable for producing enantio-
(
Scheme 1). We envisioned that the unique redox properties of
C
1
,2
Scheme 1. Synthetic Procedure of Ni-PYI1, Showing the
Guest Exchange and the Potential Amphipathic Channel for
the Asymmetric Olefin Dihydroxylation
merically enriched compounds in modern organic synthesis.
The primary research avenues by which these goals are pursued
have successfully delivered vast numbers of new reactions over
many decades. On using either chiral metal complexes or chiral
small organic molecules to activate the target chemical bonds,
3,4
these reactions can also be rendered asymmetrically. In this
case, the combination of both chiral organic molecules and
metal complexes in a cooperative catalysis fashion attracted
much attention as a powerful method to generate catalysts for
5
,6
prospective practical applications. The major challenge in
achieving the enhanced catalytic activity and higher level of
stereodifferentiation thus goes beyond the synthesis of highly
functionalized complexes but includes the judicious selection of
appropriate catalytic combinations for compatibility between
7
the chiral organic and the inorganic catalysts.
Metal−organic frameworks (MOFs) are hybrid solids with
infinite networks built from organic bridges and inorganic
8
,9
connecting nodes. In addition to their potential applications
in many diverse areas, chiral MOFs are ideally suited for
heterogeneous asymmetrically catalytic conversions, since they
can impose size- and shape-selective restriction through readily
Received: February 18, 2013
Published: June 27, 2013
1
0,11
fine-tuned channels or pores
and high enantioselectivity
©
2013 American Chemical Society
10186
dx.doi.org/10.1021/ja401758c | J. Am. Chem. Soc. 2013, 135, 10186−10189

Journal of the American Chemical Society
Communication
5
−
[
BW O ] with its oxygen-enriched surface provided a
parallel fashion with both the active sites of the chiral directors
and the oxidation catalysts aligned in the channels (Figure 1a).
It is postulated that this kind of structure would render the
formation of the reaction intermediate of ethanediols coexisting
with the chiral sites and the hydroperoxy group in a well-
defined stereoselective fashion.
12
40
sufficient driving force for the transformation of catalytic
precursors to the active intermediate of the epoxidation.
addition, the chiral PYIs potentially acted as cooperative
catalytic sites to forge a crucial reaction center that enhanced
the activities of the oxidants and drove the catalysis in an
asymmetrical way.
hydrophobic properties of the MOFs consolidated by the
organic ligands and the POM anions was beneficial for the
amphipathic catalysis of the epoxidation processes.
25,26
In
2
7,28
In the meantime, the hydrophilic/
Most importantly, there are isolated PYI molecules that are
protonated and occupy the pores of channels. They can be
expediently replaced by soaking the crystals of Ni-PYI1 in a
dichloromethane solution containing diethylamine (Figure S7,
2
9,30
32
Solvothermal reaction of Ni H[BW O ] and 4,4′-bipyridine
Supporting Information). As a result, channels of Ni-PYI1
2
12 40
3
with L-tert-butoxycarbonyl-2-(imidazole)-1-pyrrolidine (L-
BCIP) gave Ni-PYI1 in a yield of 60%. Elemental analyses
and powder X-ray analysis (XRD) indicated the pure phase of
its bulk sample. Single-crystal structural analysis revealed that
were enlarged with accessible pores of about 1230 Å , as
33
calculated from PLATON analysis. Unlike the hydrophobic
channels within most MOFs, these channels in the guest-
exchanged Ni-PYI1 were consolidated by the hydrophilic
31
5−
Ni-PYI1 crystallized in the space group C2. Each of the two
[BW O ] anions and the hydrophobic organic ligands.
12
40
crystallographically independent Ni(II) ions connected four
Consequently, both the aryl olefin and the oxidant H O could
2 2
4
,4′-bipyridine bridges alternatively to produce a 2D sheet. In
take part in ingress and egress through these amphipathic
channels to interact with each other as well as the catalytically
active sites in the channels.
5−
addition, the [BW O ] anions were imbedded within the
1
2
40
polygons of the sheets (Figure S2, Supporting Information).
The nickel(II) ions were coordinated in octahedral geometries
with four nitrogen atoms from four bpy ligands forming the
equatorial plane and with either two imidazole N atoms or two
acetonitrile N atoms occupying the axial positions, respectively
The transformation of the asymmetric dihydroxylation was
examined initially by using styrene and aqueous hydrogen
peroxide (15%) as oxidant in CH Cl , along with ex-Ni-PYI1
2
2
(0.7% mol ratio) in a heterogeneous manner at 40 °C, as shown
in Table 1. The result revealed the successful execution of our
(
Figure 1b). These coordinated PYI molecules were located
Table 1. Yields and Enantiomeric Excess (ee) Values of the
a
Asymmetric Dihydroxylation about the Aryl Olefins
b
c
entry
substrate
conversion (%)
ee (%)
1
2
3
4
5
styrene (1)
75
>95
67
2-chlorovinylbenzene (2)
76
3-chlorovinylbenzene (3)
79
>95
>95
nd
4-chlorovinylbenzene (4)
75
3,5-di-tert-butyl-4′-vinylbiphenyl (5)
<10
a
Reaction conditions: olefin, 55 mmol; ex-Ni-PYI1, 0.04 mmol; H O
2
2
b
(15%), 15 mL; CH Cl , 5 mL; 40 °C; 60 h. The conversions were
2 2
1
c
determined by H NMR spectroscopy of crude products. The ee
value was determined by chiral HPLC on a Chiralcel OD-H column.
MOF design, showing excellent enantioselectivity (ee > 95%)
for (R)-phenyl-1,2-ethanediol. In addition, the removal of ex-
Ni-PYI1 by filtration after 30 h shut down the reaction, and the
filtrate afforded only 5% additional conversion after stirring at
40 °C for another 30 h. These observations suggested that ex-
Ni-PYI1 was a true heterogeneous catalyst. Solids of ex-Ni-
PYI1 could be isolated from the reaction suspension by simple
filtration alone. In addition, the catalysts could be reused at
least three times with moderate loss of activity (from 75% to
Figure 1. (a) Crystal structure of Ni-PYI1 showing the stacking
pattern of the gridlike sheets and the 1D channels along the a axis with
5
−
[
BW O ] anions imbedded. (b) 2D network of Ni-PYI1 displaying
12 40
the coordination environments of Ni(II) ions. (c) CD spectra of the
crystalline powders Ni-PYI1 (black) and Ni-PYI2 (red), respectively,
showing the opposite Cotton effects.
6
8% of yield) and a slight decrease in the selectivity (ee values
above or beneath the 2D layer with the butoxycarbonyl of L-
BCIP being removed in the reaction simultaneously and the
pyrrolidine N atoms being protonated. Hydrogen bonds were
found between the protonated pyrrolidine N atoms and the
from >95% to 90%). The index of XRD patterns of the ex-Ni-
PYI1 bulky sample filtered off from the catalytic reaction
evidenced the maintenance of the crystallinity (Figure S8,
Supporting Information). The use of such a catalyst can be
extended to other chlorovinylbenzene substrates with com-
parable activity and asymmetric selectivity (Table 1).
In contrast to the smooth reactions of the substrates 1−4,
the asymmetric dihydroxylation catalytic reaction in the
presence of bulky olefin 5, 3,5-di-tert-butyl-4′-vinylbiphenyl,
5
−
imbedded [BW O ]
anion with N(9)···O(19A) and
1
2
40
N(9)···O(22) separations of about 3.24 and 3.27 Å, respectively
3
1
(
symmetry code A: / - x, − / + y, 1 − z) (Figure S4,
2
2
5
−
Supporting Information). Interacting with [BW O ]
1
2
40
through hydrogen bonds, the sheets were further stacked in a
1
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Journal of the American Chemical Society
Communication
gave less than 10% of conversion under the same reaction
conditions. The negligible adsorption by immersing ex-Ni-PYI1
into a solution of substrate 5, coupled with the fact that the
nitrogen atoms of bpy ligands. A terminal oxygen of the POM
and one water molecule (for Ni(1)) or partially occupied water
molecule or chloride (for Ni(2)) were on the axial positions,
respectively. As 4-connected nodes, the nickel ions were linked
together to form a 2D metal−organic gridlike sheet. These 2D
sheets were stacked along the crystallographic c axis and were
parallel to each other through the interactions between
34
molecule size of 5 is larger than that of the channels, revealed
that the substrate 5 is too large to be adsorbed in the channels.
It is suggested that the asymmetric dihydroxylations indeed
occur in the channels of the MOF, not on the external surface.
It is also found that when L-PYI and its hydrochloride salt were
used as catalysts, the reaction become inert under similar
conditions. In addition, employing Ni H[BW O ] and L-PYI
5−
[BW O ] and the nickel(II) centers, giving rise to 1D
12
40
channels along the a axis with a cross section of about 9.7 ×
12.4 Å2 (Figure 2). Since Ni-BPY possessed the similar
2
12 40
as homogeneous catalysts gave a conversion of 45% and an ee
value of 15%, which are far lower than those with ex-Ni-PYI1 as
catalyst. The higher conversion in the case of the ex-Ni-PYI1
system can possibly be attributed to the suitable distribution of
5−
pairs of the chiral PYI moiety and [BW O ] oxidant that
1
2
40
provides effective contacts with substrates at the same time.
The hydrolysis experiments demonstrate that the 0.7 mol %
loading of ex-Ni-PYI1 lead to the diol product in a conversion
of 87% from the racemic 2-phenyloxirane. It seems that Ni-
PYI1 is really a synergistic catalyst, enabling the concurrence of
3
5,36
the catalytic oxidation and hydrolysis reactions.
As the diols
obtained through the hydrolysis of the racemic 2-phenyloxirane
do not exhibit any stereoselectivity, the enantioselectivity of the
dihydroxylation can thus be mainly attributed to the
3
7,38
asymmetric behavior of the epoxidation.
From a mecha-
nistic point of view, the formation of hydrogen bonds between
the pyrrolidine N atom and the terminal oxygen atoms of the
5
−
Figure 2. Crystal structure of Ni-BPY showing the stacking pattern of
the gridlike sheet and the 1D channels along the a axis with
BW O
first activated the corresponding WO to
1
2
40
t
generate an active peroxide tungstate intermediate with H O ,
2
2
5
−
[
BW O ] anions imbedded.
12 40
ensuring the smooth progress of the reaction. At the same time,
the hydrogen bonds also enforced the proximity between the
conventional electrophilic oxidant and the chiral directors to
provide additional steric orientation, driving the catalysis to
channels constructed by the same organic linkers and the same
POM anions without any chiral directors, it is thus an excellent
reference for investigating the catalytic activity of Ni-PYIs in
the same dihydroxylation reaction.
Catalytic activities of Ni-BPY in the asymmetric dihydrox-
ylation experiments were carried out under the same conditions
by using styrene and aqueous hydrogen peroxide (15%). As
shown in Table 2, the ∼0.7% mole ratio loading of the catalyst
caused significant catalytic efficiency with conversion of up to
3
9
occur in a steroselective manner. The fact that the WO
t
bonds (greater than 1.71 Å) for both O(22) and O(19) of the
hydrogen-bonded terminal oxygen atoms were about 0.03 Å
(
on average) longer than other WO bonds gave preliminary
t
crystallographic evidence to support this hypothesis (Table S2,
Supporting Information).
Circular dichroism (CD) of the bulk sample of Ni−PYI1
6
0% of the diol (entry 6). The catalytic reaction did not exhibit
presented Cotton effects at 284 (θ = −19.5°) and 340 nm (θ =
any obvious enantioselectivity. It should be concluded that the
7
.90°) (Figure 1c). The whole spectrum was quite different
activity of Ni-BPY in the catalytic dihydroxylation arises from
from that of the chiral precursor L-BCIP, which showed a
positive cotton effect at 268 nm. The difference in absorption
5−
40
the oxidative catalysis activity of [BW O ] , whereas the
12 40
stereoselectivity in the reactions was dominated by the presence
in the spectral region for the charge-transfer bands might be
41
indicative of the homochirality of the framework. The use of
Table 2. Yields and ee Values of the Dihydroxylation of
D-BCIP resulted in the formation of other enantiomorph, Ni-
a
Styrene
PYI2. It crystallizes in the same chiral space group C with the
2
42
same cell dimensions as for Ni-PYI1. The CD spectrum of
Ni-PYI2 exhibited Cotton effects opposite to those of Ni-PYI1,
as expected for a pair of enantiomers with a mirror-image
relationship between each other. Solids of Ni-PYI2 exhibited
similar catalytic activities but gave products with opposite
chiralities in the asymmetric dihydroxylation of styrene.
To further investigate the synergistic interactions between
the chiral amine and the inorganic POM, the reference MOF
Ni-BPY was assembled using the same starting components
with similar stoichiometries but different pH value (yield of
b
c
entry
cat.
yield (%)
ee (%)
1
5
6
7
8
Ni-PYI1
75
71
60
70
73
>95
Ni-PYI2
<−95
Ni-BPY
Ni-BPY/L-PYI
Ni-BPY/D-PYI
16
−20
65%) (Scheme S1, Supporting Information). It crystallized in
the space group P21 and was comprised of
a
Reaction conditions: styrene, 55 mmol; catalyst 0.04 mmol H O
2
2
5
+
5−
b
[
Ni H (bpy) (H O) (Cl) ] and [BW O ]
in an
2
1.5
5
2
1.5
0.5
12 40
(15%), 15 mL; CH Cl , 5 mL; 40 °C; 60 h. The conversions were
2 2
1
c
4
3
asymmetric unit. Both nickel ions reside in octahedral
determined by H NMR spectroscopy of the crude products. The ee
values were determined by chiral HPLC on a Chiralcel OD-H column.
geometries with the equatorial plane defined by the four
1
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Journal of the American Chemical Society
Communication
of the chiral directors and the chiral environment of the
channels, like those of Ni-PYIs.
(15) Banerjee, M.; Das, S.; Yoon, M.; Choi, H. J.; Hyun, M. H.; Park,
S. M.; Seo, G.; Kim, K. J. Am. Chem. Soc. 2009, 131, 7524−7525.
(16) Mizuno, N.; Kamata, K. Coord. Chem. Rev. 2011, 255, 2358−
Experiments on the asymmetric dihydroxylation also revealed
that the presence of excess chiral adduct L-PYI in the
aforementioned control reaction (entry 7) led to an increased
conversion but a slightly lower enantioselectivity (ee of 16%) of
the product. It seems that the formation of hydrogen-bonding
interactions between the protonated pyrrolidine rings absorbed
2
(
2
(
2
(
370.
17) Long, D. L.; Tsunashima, R.; Cronin, L. Angew. Chem., Int. Ed.
010, 49, 1736−1758.
18) Dolbecq, A.; Dumas, E.; Mayer, C. R.; Mialane, P. Chem. Rev.
010, 110, 6009−6048.
19) Zou, C.; Zhang, Z. J.; Xu, X.; Gong, Q. H.; Li, J.; Wu, C. D. J.
5−
within the pores and the [BW O ] anions could form a
Am. Chem. Soc. 2012, 134, 87−90.
1
2
40
novel mode for activation of the oxidant and improve the
catalytic activity. However, under the unconfined conditions,
these interactions occur in multiple ways with differing
(20) Ma, F. J.; Liu, S. X.; Sun, C. Y.; Liang, D. D.; Ren, G. J.; Wei, F.;
Chen, Y. G.; Su, Z. M. J. Am. Chem. Soc. 2011, 133, 4178−4181.
(21) Song, J.; Luo, Z.; Britt, D. K.; Furukawa, H.; Yaghi, O. M.;
5
−
Hardcastle, K. I.; Hill, C. L. J. Am. Chem. Soc. 2011, 133, 16839−
orientations of the ammonium salt and the [BW O ]
1
2
40
1
6846.
anion, which is likely to be deleterious to the enantioselectivity.
In contrast, in the case of Ni-PYIs as catalysts, the interactions
between them are confined and fixed orientationally. In other
words, the enantioselectivities of Ni-PYIs are superior to those
of simply mixing the corresponding MOFs with the chiral
adduct originating from the integration of POM and chiral
(
22) Hashimoto, T.; Maruoka, K. Chem. Rev. 2007, 107, 5656−5682.
(23) Yin, P. C.; Li, D.; Liu, T. B. Chem. Soc. Rev. 2012, 41, 7368−
7
383.
(24) Dias, L. C.; Marchi, A. A.; Ferreira, A. B.; Aguilar, A. M. J. Org.
Chem. 2008, 73, 6299−6311.
(25) Mizuno, N.; Yamaguchi, K.; Kamata, K. Coord. Chem. Rev. 2005,
249, 1944−1956.
3
0,44
directors into a single MOF.
(26) Duncan, D. C.; Chambers, R. C.; Hecht, E.; Hill, C. L. J. Am.
Chem. Soc. 1995, 117, 681−691.
27) Matsumoto, K.; Oguma, T.; Katsuki, T. Angew. Chem., Int. Ed.
009, 48, 7432−7435.
28) Marigo, M.; Franzen
K. A. J. Am. Chem. Soc. 2005, 127, 6964−6965.
(29) Kawamoto, R.; Uchida, S.; Mizuno, N. J. J. Am. Chem. Soc. 2005,
ASSOCIATED CONTENT
Supporting Information
Text, figures, tables, and CIF files giving crystal data,
experimental details, and characterization data. This material
is available free of charge via the Internet at http://pubs.acs.org.
■
(
2
(
*
S
́
, J.; Poulsen, T. B.; Zhuang, W.; Jørgensen,
1
27, 10560−10567.
30) Duan, C. Y.; Wei, M. L.; Guo, D.; He, C.; Meng, Q. J. J. Am.
Chem. Soc. 2010, 132, 3321−3330.
31) Data for Ni-PYI1: C H BN NiO W , M = 3610.63,
(
AUTHOR INFORMATION
Corresponding Author
E-mail for C.D.: cyduan@dlut.edu.cn.
■
*
(
3
8
52
11
42 12
r
monoclinic, space group C2, a = 25.266(3) Å, b = 11.490(1) Å, c =
3
Notes
22.880(2) Å, β = 90.49(1)°, V = 6642(1) Å , Z = 4, 18459 total
reflections, 11426 unique reflections (Rint = 0.034), final R1 (with I >
The authors declare no competing financial interest.
2
σ(I)) = 0.038, wR2 (all data) = 0.0792, S = 1.021.
(
32) Lin, X. M.; Li, T. T.; Chen, L. F.; Zhang, L.; Su, C. Y. Dalton
ACKNOWLEDGMENTS
■
(
Trans. 2012, 41, 10422−10429.
We gratefully acknowledge financial support from the NSFC
Nos. 91122031 and 21025102).
(33) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7−13.
(34) The molecular size (8.3 × 6.5 Å) was calculated by using the
program Chem3D.
(
2
(
35) Jonsson, S. Y.; Farnegardh, K.; Backvall, J. E. J. Am. Chem. Soc.
001, 123, 1365−1371.
36) Andersson, M. A.; Epple, R.; Fokin, V. V.; Sharpless, K. B.
Angew. Chem., Int. Ed. 2002, 41, 472−475.
37) Nielsen, L. P. C.; Stevenson, C. P.; Blackmond, D. G.; Jacobsen,
E. N. J. Am. Chem. Soc. 2004, 126, 1360−1368.
38) Zhu, C. F.; Yuan, G. Z.; Chen, X.; Yang, Z. W.; Cui, Y. J. Am.
Chem. Soc. 2012, 134, 8058−8061.
39) Aggrawal, V. K.; Lopin, C.; Dandrinelli, F. J. Am. Chem. Soc.
003, 125, 7596−7601.
40) Wu, P. Y.; He, C.; Wang, J.; Peng, X. J.; Li, X. Z.; An, Y. L.;
REFERENCES
■
(
1) Melchiorre, P.; Marigo, M.; Carlone, A.; Bartoli, G. Angew. Chem.,
Int. Ed. 2008, 47, 6138−6171.
2) Piovesana, S.; Scarpino Schietroma, D. M.; Bella, M. Angew.
Chem., Int. Ed. 2011, 50, 6216−6232.
3) D’Souza, D. M.; Muller, T. J. J. Chem. Soc. Rev. 2007, 36, 1095−
104.
4) Dondoni, A.; Massi, A. Angew. Chem., Int. Ed. 2008, 47, 4638−
660.
5) Marinetti, A.; Jullien, H.; Voituriez, A. Chem. Soc. Rev. 2012, 41,
(
(
(
1
(
4
(
4
(
(
̈
(
(
2
(
884−4908.
Duan, C. Y. J. Am. Chem. Soc. 2012, 134, 14991−14999.
41) Crassous, J. Chem. Soc. Rev. 2009, 38, 830−845.
6) Allen, A. E.; MacMillan, D. W. C. Chem. Sci. 2012, 3, 633−658.
(
(
7) Xiao, W.; Jin, R. H.; Cheng, T. Y.; Xia, D. Q.; Yao, H.; Gao, F.;
42) Data for Ni-PYI2: C H BN NiO W , M = 3610.63,
3
8
52
11
42 12
r
Deng, B. X.; Liu, G. H. Chem. Commun. 2012, 48, 11898−11900.
8) An, J.; Farha, O. K.; Hupp, J. T.; Pohl, E.; Yeh, J. I.; Rosi, N. L.
Nat. Commun. 2012, 604−606.
9) Perry, J. J., IV; Perman, J. A.; Zaworotko, M. J. Chem. Soc. Rev.
009, 38, 1400−1417.
10) Ma, L. Q.; Falkowski, J. M.; Abney, C.; Lin, W. B. Nat. Chem.
010, 2, 838−846.
11) Jiang, H. L.; Feng, D. W.; Liu, T. F.; Li, J. R.; Zhou, H. C. J. Am.
Chem. Soc. 2012, 134, 14690−14693.
12) Yoon, M.; Srirambalaji, R.; Kim, K. Chem. Rev. 2012, 112,
196−1231.
13) Seo, J. S.; Wang, D.; Lee, H.; Jun, S. I.; Oh, J.; Jeon, Y. J.; Kim,
K. Nature 2000, 404, 982−986.
14) Cohen, S. M. Chem. Rev. 2012, 112, 970−1000.
monoclinic, space group C2, a = 25.187(4) Å, b = 11.483(2) Å, c =
(
3
2
2.862(4) Å, β = 90.37(1)°, V = 6612(2) Å , Z = 4, 18571 total
reflections, 11366 unique reflections (Rint = 0.048), final R1 (with I >
σ(I)) = 0.0490, wR2 (all data) = 0.1073, S = 1.003.
43) Data for Ni-BPY: C H45.50BCl0.50N Ni O W , M = 3810.62,
(
2
(
2
2
(
50
10
2
42 12
r
monoclinic, space group P2 , a = 13.414(1) Å, b = 14.924(1) Å, c =
1
3
2
0.062(1) Å, β = 102.67(1)°, V = 3918.5(2) Å , Z = 2, 18409 total
reflections, 10227 unique reflections (Rint = 0.0621), final R1 (with I >
σ(I)) = 0.0576, wR2 (all data) = 0.1412, S = 1.000.
44) Wu, P. Y.; He, C.; Wang, J.; Peng, X. J.; Li, X. Z.; An, Y. L.;
(
2
(
(
1
(
Duan, C. Y. J. Am. Chem. Soc. 2012, 134, 14991−14999.
(
1
0189
dx.doi.org/10.1021/ja401758c | J. Am. Chem. Soc. 2013, 135, 10186−10189