Pd uptake and H2S sensing by an amphoteric metal-organic framework with a soft core and rigid side arms

Article abstract of DOI:10.1002/anie.201408453

Molecular components of opposite character are often incorporated within a single system, with a rigid core and flexible side arms being a common design choice. Herein, molecule L has been designed and prepared featuring the reverse design, with rigid sid

Full text of DOI:10.1002/anie.201408453

Angewandte
Chemie
DOI: 10.1002/anie.201408453
Metal–Organic Frameworks
Pd Uptake and H S Sensing by an Amphoteric Metal–Organic
2
Framework with a Soft Core and Rigid Side Arms**
Jieshun Cui, Yan-Lung Wong, Matthias Zeller, Allen D. Hunter, and Zhengtao Xu*
Abstract: Molecular components of opposite character are
often incorporated within a single system, with a rigid core and
flexible side arms being a common design choice. Herein,
molecule L has been designed and prepared featuring the
reverse design, with rigid side arms (arylalkynyl) serving to
calibrate the mobility of the flexible polyether links in the core.
acceptors for binding Lewis bases as guests. Prompted by
the appeal of this concept as well as the potentially rich host–
guest chemistry, we aimed to achieve the formation of a MOF
system that simultaneously combines distinct donor and
acceptor characteristics, a topic that, to our knowledge, has
not yet been addressed.
II
Crystallization of this molecule with Pb ions led to a dynamic
Herein, we report that backfolded molecule L (Scheme 1)
II
metal–organic framework (MOF) system that not only exhibits
dramatic, reversible single-crystal-to-single-crystal transforma-
tions, but combines distinct donor and acceptor characteristics,
allowing for substantial uptake of PdCl2 and colorimetric
and Pb ions form a flexible framework that represents a step
towards our goal. This system displays distinct amphoteric
behavior, facilitated by the coexistence of free-standing sulfur
sensing of H S in water.
2
A
s in many domains in the arts and sciences, the integration
and interplay of opposing characters is a common thread in
chemistry. This interplay is reflected in the classical systems of
liquid crystals (with rigid and floppy components), surfactants
(
(
hydrophilic/hydrophobic components), and semiconductors
holes/electrons). More recent reports in this vein include
[
1]
frustrated Lewis acid–base pairs for H activation and
2
[2]
ditopic receptors for simultaneous anion and cation binding
ion-pair recognition). In the growing field of metal–organic
(
Scheme 1. Backfolded molecule L and compound M with the “star-
burst” form of a traditional dendrimer. The rigid phenylacetylene
(green) components act as the side chains in L but as the backbone
in M.
[3]
frameworks, this incorporation of components of opposite
character manifests itself in the combination of hard and soft
groups (e.g., carboxylate and sulfur/nitrogen donors), and in
various floppy side chains tethered to rigid backbones. Such
reports on bifunctional MOF systems generally aim to exploit
the tunable porous properties of MOFs to enhance the guest-
[
4]
[
5]
II
(and the alkyne and ether) donors and labile capped Pb
centers as accessible acceptor sites, which manifests itself in
[
5d,6]
binding properties for applications including separation,
sensing,
the effective uptake of both Lewis acid (such as PdCl ) and
2
[4d,7]
[6c,8]
and catalysis.
For example, thioether/thiol
Lewis base (such as H S) guests. Notwithstanding the
2
groups affixed to carboxylate building blocks tend to remain
freestanding in frameworks formed with hard metal ions
serendipitous nature of this discovery, molecule L is com-
posed of design elements that both follow and break from
previous works. First, the design carries over from the hard
and soft components strategy, as seen in the hard carboxy (as
the primary donors for framework formation) and soft donors
on the side arms. Also the side arms are backfolded, pointing
away from the carboxy groups, in contrast with the “starburst”
form of a traditional dendrimer (see Scheme 1 for example).
The backfolded configuration has been explored for network
IV
III
III
III
(
(
Zr , Al , Cr , Eu ), and thereby facilitate the uptake of
[
4a–c]
soft) metal species.
These donor-equipped MOF systems
[
9]
complement systems that feature open metal sites as
[
*] J. Cui, Y.-L. Wong, Dr. Z. Xu
Department of Biology and Chemistry
City University of Hong Kong
[
10]
83 Tat Chee Avenue, Kowloon, Hong Kong (China)
construction;
in the present case, it serves to minimize
E-mail: zhengtao@cityu.edu.hk
direct steric/chemical influence on the carboxy groups.
Most notable, however, is the configuration of the rigid
side arms (the phenylacetylene component) and the flexible
Dr. M. Zeller, Dr. A. D. Hunter
Department of Chemistry, Youngstown State University
One University Plaza, Youngstown, OH 44555 (USA)
[11]
backbone (the pentaerythritol ether hinges) in L, which
[**] This work is supported by City University of Hong Kong (Project no.
reverses the conventional design of flexible side arms
attached to rigid backbones (see molecule M in Scheme 1 as
9
1
667092) and the Research Grants Council of HKSAR (GRF
03413). The diffractometer was funded by NSF Grant 0087210, by
[5b]
an early example ). In particular, rigid units are widely
Ohio Board of Regents Grant CAP-491, and by Youngstown State
University.
[
12]
integrated as the linker backbone
because the shape
persistence and directionality often lead to networks of
robust pores and regular topologies. Herein, we place the
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201408453.
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
These are not the final page numbers!

.
Angewandte
Communications
rigid arylethynyl units in the side arms instead. By so doing,
we hope to achieve systematic control over the degree of
flexibility of the core unit, that is, bulky and stiff side arms
would limit the motion of the core unit, imposing structural
rigidity on the individual building blocks as well as the overall
network.
The synthesis of L is based on well-established procedures
(
see Scheme S1 in the Supporting Information). The efficient
Sonogashira coupling readily allows various alkynyl side arms
to be attached, thus facilitating the preparation of a versatile
linker system of tunable rigidity and functionality. Single
crystals of the framework BFMOF-1 (BF denotes back-
folded) suitable for X-ray diffraction studies were obtained by
solvothermal reaction between L and Pb(NO ) in a DMA/
3
2
H O mixture of solvents (DMA = N,N-dimethylacetamide;
2
detailed procedure given in the Supporting Information).
Elemental and thermogravimetric analyses (Figure S1) indi-
cates a composition of Pb O (C H O S ) (DMA) (H O)
6
2
69 48 12
4
2
3
2
2
for the as-prepared sample.
The proposed composition of the sample is also consistent
with the X-ray crystal structure of BFMOF-1 (Figures 1a and
[
13]
¯
2
a). The crystal structure adopts the space group P1, and
features the centrosymmetric Pb O (CO ) cluster
with the two edge-sharing Pb O tetrahedra
6
2
2 8
[
14]
(
Figure 1),
4
exhibiting short PbÀO bond lengths (i.e., 2.229, 2.251, 2.310,
Figure 2. The crystal-packing structures of a) BFMOF-1 and
b) BFMOF-1a, both shown along the a axis. The DMA guests are not
shown in (a). Atom colors: green=Pb; red=O; yellow=S; gray=C.
and 2.325 ꢀ). By comparison, the PbÀO distances from the
carboxy (-CO ) groups are longer, and vary more (for
2
example, from 2.401, 2.512, 2.620, and 2.714 ꢀ up to 2.981
and 3.065 ꢀ), indicating a weaker and more reversible nature
of the individual links. The asymmetric unit of the cell consists
of (Pb O)L(H O)·1.5DMA, with the H O being bound by
3
2
2
a Pb atom and the DMA molecules located in the voids. Two
II
of the Pb centers are weakly capped by two S atoms from the
side arms of L (distances: 3.329 and 3.954 ꢀ, respectively),
whereas the third Pb center is not capped—it appears to be
more open. The weakly bound and open Pb centers together
point to potential accessibility to guest donors. The other two
S atoms of the L molecule are not coordinated to the
II
Pb centers. As free-standing donors, they coexist with the
II
potentially accessible Pb centers, and suggest an amphoteric
character for the host network.
The BFMOF-1 grid can be viewed as a (4,8)-connected
net, with the L molecule and the Pb block being 4- and 8-
connected, respectively (Figure S2). The topology is that of
a distorted fluorite net (comparable to that of a Zr-based
[
15]
MOF ). This net can also be dissected as two diamondoid
(cubic ZnS) subnets fused at one set of the tetrahedral nodes.
When the as-prepared BFMOF-1 crystals were immersed
in ethanol (or other solvents, such as CH CN and CH Cl ), the
3
2
2
DMA guests were readily replaced. The resultant crystals,
upon exposure to air, quickly (i.e. within 30 minutes) trans-
form into a new crystalline phase (such as BFMOF-1a). The
[16]
quality of the X-ray crystal structure
for BFMOF-1a is
Figure 1. Crystal structures showing the local bonding environments of
somewhat poorer (for example with large residual electron-
density peaks near the Pb ions), which is likely caused by the
structural irregularities arising from the drastic transforma-
tion in the solid state. Nonetheless, the X-ray data clearly
indicate the retention of Pb O (CO ) cluster (but without the
the Pb O units in a) BFMOF-1 and b) BFMOF-1a. For each structure,
6
2
two of the eight associated L molecules are displayed in full. O16 in
(
a) is from the bound H O (PbÀO=2.981 ꢀ). Dashed lines denote
2
PbÀO contacts greater than 2.90 ꢀ and PbÀS contacts: a) Pb2ÀS2=
ÀS4=3.954 ꢀ; b) Pb3ÀS3=3.608 ꢀ, Pb2ÀS1=3.646 ꢀ.
3
.329 ꢀ, Pb3
6
2
2 8
Atom colors: green=Pb; red=O; yellow=S; gray=C.
associated H O) and the overall fluoride topology (Figure 1b
2
2
www.angewandte.org
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
These are not the final page numbers!

Angewandte
Chemie
and 2b). The unit cell parameters are, however, significantly
changed, with a shrinkage of the cell volume (by 12%) from
the additional electron density from the heavy PdCl species.
Qualitatively, the dark color can be ascribed to charge
transfer from the highest occupied molecular orbitals
(HOMOs) of L to the lowest unoccupied molecular orbitals
2
3
3
3
746.8(8) ꢀ in BFMOF-1 to 3306.5(19) ꢀ in BFMOF-1a.
The daughter phase BFMOF-1a is therefore less open, and
the fluoride net (Figure S2) is more distorted as compared
with the parent BFMOF-1. The crystal structure of BFMOF-
(LUMOs) of PdCl . The ether and thioether donors of L,
2
II
together with the low-lying 4d orbitals of the Pd center,
1
a contains no DMA molecules, as is also verified by
apparently favor such interactions. Under similar conditions,
thermogravimetric analysis (Figure S1) and FTIR spectros-
copy studies (Figure S3). The BFMOF-1a solid is stable in air
for months, as shown by powder X-ray diffraction (PXRD;
see pattern d in Figure 3).
AgBF molecules also diffuse readily into the BFMOF-1a
matrix (with an overall Ag:Pd ratio of 1.40:1, see the
Supporting Information), producing a brown color. However,
4
this brown color is lighter than that of the PdCl -loaded
2
sample (Figure S7). Further tests indicated a lower uptake for
HgCl , [PtCl (CH CN) ], and CdCl , with the number of
2
2
3
2
2
moles of the adsorbed Hg, Pt, or Cd ions being less than half
of that of Pb (see Supporting Information), and the BFMOF-
1
a host remaining strongly emissive (Figure S7). We suspect
II
I
that the uptake of Pd and Ag salts was facilitated by
p-complexation with the alkyne units on the host net, whereas
II
II
[18]
such interactions might be weaker for Hg and Cd ions. As
II
for Pt , its very low lability likely hinders the uptake.
Upon being placed in a H atmosphere, the crystals of
2
1
a-PdCl become gray, steadily turning into black within one
2
hour (Figure S5 and S6). This color change is consistent with
II
0
the reduction of the embedded Pd ions into Pd species.
Moreover, the PXRD pattern of the H -treated sample (that
2
is, 1a-Pd-H ) indicates retention of the crystalline order, with
2
no peaks corresponding to Pd particles or other crystalline
impurities detected (pattern g, Figure 3). Scanning electron
microscopy (Figure S8) images of the BFMOF-1a, 1a-PdCl2,
Figure 3. Powder X-ray diffraction patterns of BFMOF-1-related sys-
tems: a) calculated diffraction pattern from the single-crystal structure
of BFMOF-1; b) an as-prepared sample of BFMOF-1; c) pattern calcu-
lated from the single-crystal structure of BFMOF-1a (the desolvated
sample); d) BFMOF-1a; e) BFMOF-1’ (BFMOF-1a after being heated
in DMA at 1208C for 12 h); f) 1a-PdCl ; g) 1a-Pd-H ; h) 1a-H S.
and 1a-Pd-H solids indicate similar morphologies (that is,
2
with no extra particles present on the surface of the crystals of
0
1
a-Pd-H ), further supporting that the Pd species remain
2
embedded within the host net. Compound 1a-Pd-H will be
2
2
2
2
studied as a heterogeneous catalyst, for example in hydro-
genation reactions.
The solid sample of the desolvated phase of BFMOF-1a
The Lewis acid character of BFMOF-1a was revealed in
its interaction with H S (to form 1a-H S). Upon exposure to
shows no significant N sorption at 77 K. However, effective
2
2
2
CO uptake was measured at 273 K, as is shown in the highly
H S gas, the yellowish crystals of BFMOF-1a become dark
2
2
reproducible typical type-I gas adsorption isotherms (Fig-
ure S4). The corresponding surface area is found to be
red (Figure S9), with the bluish white emission (see the
spectra in Figure S10) being effectively suppressed. X-ray
photoelectron spectroscopy (XPS; Figure S11) studies indi-
cate a clear shift of the peaks attributed to Pb 4f7/2 and 4f5/2
2
À1
À1
3
18 m g , with pore volume being 0.107 ccg . The gas
sorption studies therefore indicate that dynamic, cooperative
diffusion processes can be achieved at higher temperatures
states toward lower energies after H S treatment. The dark
2
[
3k,17]
(
e.g., 273 K),
which can be attributed to the structural
color and the shift of the peak in the XPS spectrum are
flexibility built into the semirigid backbone of linker L.
Additionally, BFMOF-1a can be converted back into the
parent BFMOF-1 after being heated in DMA (pattern e in
Figure 3; the FTIR spectrum is given in Figure S3), illustrat-
ing further the dynamics and resilience of the host net.
The Lewis base character of the BFMOF-1a net was first
consistent with the binding of H S species as a strong electron
donor onto the Pb centers. Elemental analyses (see Support-
ing Information for the data) also indicate an increase of the
2
S content, with the composition of 1a-H S found to be
2
Pb O (L) (H S) (H O) . Each Pb O cluster thus appears to
6
2
2
2
2
2
4
6
2
associate with two H S molecules: the well-defined Pb O /
2
6
2
shown through interaction of the compound with PdCl . Upon
H S ratio indicates that the interaction with H S is regulated
2 2
2
contact with a solution of [PdCl (CH CN) ] in CH Cl , the
within the BFMOF-1a matrix: e.g., the capping thioether
S atoms on the Pb centers might serve to limit the uptake
2
3
2
2
2
slightly yellow crystals of BFMOF-1a turn brownish red, with
the color darkening over time (Figure S5 and S6). Inductively
coupled plasma (ICP) elemental analysis indicates a Pd:Pb
ratio of 2.51:1 for the PdCl -loaded sample (1a-PdCl ;
capacity under these conditions. The 1a-H S crystals remain
2
transparent (no cracking), with well-defined, sharp PXRD
peaks (pattern h, Figure 3) indicating a highly crystalline
phase. The peaks were, however, shifted to slightly higher
angles compared with those of BFMOF-1a, suggesting
2
2
composition = Pb O (L) (PdCl ) ). PXRD indicates that the
6
2
2
2 15
original lattice of BFMOF-1a (pattern f in Figure 3) is
retained but with a distinct intensity change as a result of
further compaction of the host lattice after H S treatment.
2
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3
These are not the final page numbers!

.
Angewandte
Communications
Single-crystal X-ray diffraction studies are underway to
Mahoney, A. M. Beatty, B. D. Smith, J. Am. Chem. Soc. 2001,
23, 5847 – 5848.
3] a) Y. Yan, S. Yang, A. J. Blake, M. Schrçder, Acc. Chem. Res.
1
further study the structure of 1a-H S.
2
[
The distinct color changes of the BFMOF-1a crystals in
2014, 47, 296 – 307; b) S. M. Cohen, Chem. Rev. 2012, 112, 970 –
response to H S binding point to potential sensing applica-
2
1000; c) W. L. Leong, J. J. Vittal, Chem. Rev. 2011, 111, 688 – 764;
tions. For example, the readily available single crystals of
BFMOF-1a provide a convenient and effective platform for
sensing and quantifying purposes as a disposable sensor for
d) S. T. Meek, J. A. Greathouse, M. D. Allendorf, Adv. Mater.
011, 23, 249 – 267; e) O. Shekhah, J. Liu, R. A. Fischer, C. Wçll,
2
Chem. Soc. Rev. 2011, 40, 1081 – 1106; f) D. Zhao, D. J. Timmons,
D. Yuan, H.-C. Zhou, Acc. Chem. Res. 2011, 44, 123 – 133;
g) M. H. Mir, L. L. Koh, G. K. Tan, J. J. Vittal, Angew. Chem. Int.
Ed. 2010, 49, 390 – 393; Angew. Chem. 2010, 122, 400 – 403; h) G.
Fꢁrey, Chem. Soc. Rev. 2008, 37, 191 – 214; i) S. Kitagawa, R.
Matsuda, Coord. Chem. Rev. 2007, 251, 2490 – 2509; j) Z. Xu,
Coord. Chem. Rev. 2006, 250, 2745 – 2757; k) D. Bradshaw, J. B.
Claridge, E. J. Cussen, T. J. Prior, M. J. Rosseinsky, Acc. Chem.
Res. 2005, 38, 273 – 282; l) S. Lee, A. B. Mallik, Z. Xu, E. B.
Lobkovsky, L. Tran, Acc. Chem. Res. 2005, 38, 251 – 261;
m) N. W. Ockwig, O. Delgado-Friedrichs, M. OꢂKeeffe, O. M.
Yaghi, Acc. Chem. Res. 2005, 38, 176 – 182; n) K. S. Suslick, P.
Bhyrappa, J. H. Chou, M. E. Kosal, S. Nakagaki, D. W. Smi-
thenry, S. R. Wilson, Acc. Chem. Res. 2005, 38, 283 – 291;
o) O. M. Yaghi, G. M. Li, H. L. Li, Nature 1995, 378, 703 – 706;
p) G. B. Gardner, D. Venkataraman, J. S. Moore, S. Lee, Nature
H S species. Moreover, the BFMOF-1a solid is insoluble
2
(
whereas the commonly used lead acetate is soluble) in water
and is readily applicable in monitoring H S in water-based
2
[
19]
biological and environmental assays. For example, a light
but distinct red color (Figure 4) quickly developed even when
H S was present only at 17.6 mm (0.60 ppm). At the higher
2
concentrations of 35.2 mm (1.2 ppm), 88 mm (3.0 ppm), and
3
52 mm (12 ppm), the color darkens systematically, indicating
the potential for colorimetric analysis.
1995, 374, 792 – 795; q) L. R. MacGillivray, S. Subramanian, M. J.
Zaworotko, J. Chem. Soc. Chem. Commun. 1994, 1325 – 1326;
r) B. F. Hoskins, R. Robson, J. Am. Chem. Soc. 1989, 111, 5962 –
5
1
964; s) C. Wang, D. Liu, W. Lin, J. Am. Chem. Soc. 2013, 135,
3222 – 13234.
[
4] a) K.-K. Yee, N. Reimer, J. Liu, S.-Y. Cheng, S.-M. Yiu, J. Weber,
N. Stock, Z. Xu, J. Am. Chem. Soc. 2013, 135, 7795 – 7798; b) J.
He, K.-K. Yee, Z. Xu, M. Zeller, A. D. Hunter, S. S.-Y. Chui, C.-
M. Che, Chem. Mater. 2011, 23, 2940 – 2947; c) X.-P. Zhou, Z. Xu,
M. Zeller, A. D. Hunter, Chem. Commun. 2009, 5439 – 5441;
d) J. He, M. Zha, J. Cui, M. Zeller, A. D. Hunter, S.-M. Yiu, S.-T.
Lee, Z. Xu, J. Am. Chem. Soc. 2013, 135, 7807 – 7810; e) J. He, M.
Zeller, A. D. Hunter, Z. Xu, J. Am. Chem. Soc. 2012, 134, 1553 –
Figure 4. Photographs of the BFMOF-1 crystallites stirred for 0.5 hours
at 808C in solutions with H S at various concentrations: a) 0 ppm;
2
b) 0.6 ppm; c) 1.2 ppm; d) 3.0 ppm; e) 12 ppm and f) 60 ppm.
1
559; f) X.-P. Zhou, Z. Xu, J. He, M. Zeller, A. D. Hunter, R.
Clꢁrac, C. Mathoniꢃre, S. S.-Y. Chui, C.-M. Che, Inorg. Chem.
010, 49, 10191 – 10198; g) X.-P. Zhou, Z. Xu, M. Zeller, A. D.
In conclusion, an amphoteric metal–organic framework
has been characterized, with the donor and acceptor proper-
ties demonstrated in the uptake of metal salts (for example
PdCl ) and H S molecules, respectively. This material is
composed of a backfolded linker unit which has a soft core
and rigid arms, a feature that gives rise to the distinct
framework dynamics found. Rigid side arms and the back-
folded shape therefore appear to be linker features of interest
in the study of other frameworks.
2
Hunter, S. S.-Y. Chui, C.-M. Che, J. Lin, Inorg. Chem. 2010, 49,
7629 – 7631; h) E. D. Bloch, D. Britt, C. Lee, C. J. Doonan, F. J.
Uribe-Romo, H. Furukawa, J. R. Long, O. M. Yaghi, J. Am.
Chem. Soc. 2010, 132, 14382 – 14384; i) A. D. Burrows, C. G.
Frost, M. F. Mahon, C. Richardson, Chem. Commun. 2009,
2
2
4218 – 4220; j) X.-P. Zhou, Z. Xu, M. Zeller, A. D. Hunter, S. S.-
Y. Chui, C.-M. Che, Inorg. Chem. 2008, 47, 7459 – 7461.
[
5] a) S. Henke, R. A. Fischer, J. Am. Chem. Soc. 2011, 133, 2064 –
2067; b) Y.-H. Kiang, G. B. Gardner, S. Lee, Z. Xu, J. Am. Chem.
Soc. 2000, 122, 6871 – 6883; c) Y.-H. Kiang, G. B. Gardner, S.
Lee, Z. Xu, E. B. Lobkovsky, J. Am. Chem. Soc. 1999, 121, 8204 –
Received: August 22, 2014
Revised: October 9, 2014
Published online: && &&, &&&&
8215; d) M. Carboni, C. W. Abney, S. Liu, W. Lin, Chem. Sci.
2013, 4, 2396 – 2402.
[
6] a) Z. R. Herm, E. D. Bloch, J. R. Long, Chem. Mater. 2014, 26,
323 – 338; b) J.-R. Li, J. Sculley, H.-C. Zhou, Chem. Rev. 2012,
Keywords: donor–acceptor systems · host–guest systems ·
metal–organic frameworks · metal uptake · sensors
.
1
4
12, 869 – 932; c) Y. Liu, W. Xuan, Y. Cui, Adv. Mater. 2010, 22,
112 – 4135; d) R. Ahmad, A. G. Wong-Foy, A. J. Matzger,
Langmuir 2009, 25, 11977 – 11979; e) H. Wang, K. Yao, Z.
Zhang, J. Jagiello, Q. Gong, Y. Han, J. Li, Chem. Sci. 2014, 5,
620 – 624.
[
1] a) S. R. Flynn, D. F. Wass, ACS Catal. 2013, 3, 2574 – 2581;
b) G. C. Welch, R. R. S. Juan, J. D. Masuda, D. W. Stephan,
Science 2006, 314, 1124 – 1126.
[7] a) L. E. Kreno, K. Leong, O. K. Farha, M. Allendorf, R. P.
Van Duyne, J. T. Hupp, Chem. Rev. 2012, 112, 1105 – 1125;
b) S. S. Nagarkar, B. Joarder, A. K. Chaudhari, S. Mukherjee,
S. K. Ghosh, Angew. Chem. 2013, 125, 2953 – 2957; c) Y. Cui, H.
Xu, Y. Yue, Z. Guo, J. Yu, Z. Chen, J. Gao, Y. Yang, G. Qian, B.
Chen, J. Am. Chem. Soc. 2012, 134, 3979 – 3982; d) S. Pramanik,
C. Zheng, X. Zhang, T. J. Emge, J. Li, J. Am. Chem. Soc. 2011,
133, 4153 – 4155.
[
2] a) A. J. McConnell, P. D. Beer, Angew. Chem. Int. Ed. 2012, 51,
5052 – 5061; Angew. Chem. 2012, 124, 5138 – 5148; b) S. K. Kim,
G. I. Vargas-Zuniga, B. P. Hay, N. J. Young, L. H. Delmau, C.
Masselin, C.-H. Lee, J. S. Kim, V. M. Lynch, B. A. Moyer, J. L.
Sessler, J. Am. Chem. Soc. 2012, 134, 1782 – 1792; c) S.-K. Kim,
J. L. Sessler, Chem. Soc. Rev. 2010, 39, 3784 – 3809; d) J. M.
4
www.angewandte.org
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
These are not the final page numbers!

Angewandte
Chemie
[
[
8] a) A. Dhakshinamoorthy, M. Alvaro, H. Garcia, Chem.
Commun. 2012, 48, 11275 – 11288; b) X. Gu, Z.-H. Lu, H.-L.
Jiang, T. Akita, Q. Xu, J. Am. Chem. Soc. 2011, 133, 11822 –
Plater, J. M. S. Skakle, J. Chem. Soc. Dalton Trans. 2001, 1897 –
1903.
[15] M. Zhang, Y.-P. Chen, M. Bosch, T. Gentle III, K. Wang, D.
Feng, Z. U. Wang, H.-C. Zhou, Angew. Chem. Int. Ed. 2014, 53,
815 – 818; Angew. Chem. 2014, 126, 834 – 837.
11825; c) C. Wang, Z. Xie, K. E. de Krafft, W. Lin, J. Am. Chem.
Soc. 2011, 133, 13445 – 13454; d) D. T. Genna, A. G. Wong-Foy,
A. J. Matzger, M. S. Sanford, J. Am. Chem. Soc. 2013, 135,
[16] Crystal data for BFMOF-1a: C138H O Pb S , M = 3669.76,
96
26
6
8
r
10586 – 10589; e) L. Ma, C. Abney, W. Lin, Chem. Soc. Rev. 2009,
crystal dimensions: 0.327 ꢄ 0.213 ꢄ 0.101 mm, triclinic, space
¯
38, 1248 – 1256.
group P1, a = 13.079(4) ꢀ, b = 15.531(5) ꢀ, c = 17.946(6) ꢀ,
9] a) B. Chen, S. Xiang, G. Qian, Acc. Chem. Res. 2010, 43, 1115 –
124; b) Y.-S. Bae, C. Y. Lee, K. C. Kim, O. K. Farha, P. Nickias,
J. T. Hupp, S. T. Nguyen, R. Q. Snurr, Angew. Chem. Int. Ed.
012, 51, 1857 – 1860; Angew. Chem. 2012, 124, 1893 – 1896;
a = 101.700(6)8,
3306.5(2) ꢀ , Z = 1, 1
b = 106.280(7)8,
g = 100.948(6)8,
V=
=
3
À3
À1
1
= 1.843 gcm , m = 7.807 cm , 2qmax
calcd
50.708, GOF = 1.098. A total of 27434 reflections were collected
and 12026 are unique (Rint = 0.0535). R (wR ) = 0.0521 (0.1414)
2
1
2
c) A. L. Dzubak, L.-C. Lin, J. Kim, J. A. Swisher, R. Poloni, S. N.
Maximoff, B. Smit, L. Gagliardi, Nat. Chem. 2012, 4, 810 – 816;
d) D. Liu, H. Wu, S. Wang, Z. Xie, J. Li, W. Lin, Chem. Sci. 2012,
for 829 parameters and 7750 reflections [I > 2s(I)]. CCDC-
1020278 contains the supplementary crystallographic data for
BFMOF-1a in 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.
3, 3032 – 3037; e) H. Wu, W. Zhou, T. Yildirim, J. Am. Chem. Soc.
2009, 131, 4995 – 5000; f) S. Xiang, W. Zhou, J. M. Gallegos, Y.
Liu, B. Chen, J. Am. Chem. Soc. 2009, 131, 12415 – 12419; g) Q.
Yang, C. Zhong, J. Phys. Chem. B 2006, 110, 655 – 658; h) Y.-W.
Li, J.-R. Li, L.-F. Wang, B.-Y. Zhou, Q. Chen, X.-H. Bu, J. Mater.
Chem. A 2013, 1, 495 – 499.
[17] a) X.-P. Zhou, Z. Xu, M. Zeller, A. D. Hunter, S. S.-Y. Chui, C.-
M. Che, Inorg. Chem. 2011, 50, 7142 – 7149; b) S. I. Swamy, J.
Bacsa, J. T. A. Jones, K. C. Stylianou, A. Steiner, L. K. Ritchie, T.
Hasell, J. A. Gould, A. Laybourn, Y. Z. Khimyak, D. J. Adams,
M. J. Rosseinsky, A. I. Cooper, J. Am. Chem. Soc. 2010, 132,
12773 – 12775; c) G. Huang, C. Yang, Z. Xu, H. Wu, J. Li, M.
Zeller, A. D. Hunter, S. S.-Y. Chui, C.-M. Che, Chem. Mater.
2009, 21, 541 – 546; d) P. D. Southon, L. Liu, E. A. Fellows, D. J.
Price, G. J. Halder, K. W. Chapman, B. Moubaraki, K. S. Murray,
J.-F. Lꢁtard, C. J. Kepert, J. Am. Chem. Soc. 2009, 131, 10998 –
11009; e) J. Tian, P. K. Thallapally, S. J. Dalgarno, J. L. Atwood,
J. Am. Chem. Soc. 2009, 131, 13216 – 13217; f) D. Tanaka, S.
Kitagawa, Chem. Mater. 2008, 20, 922 – 931; g) Y. Zhang, B.
Chen, F. R. Fronczek, A. W. Maverick, Inorg. Chem. 2008, 47,
4433 – 4435; h) M. Kawano, M. Fujita, Coord. Chem. Rev. 2007,
251, 2592 – 2605; i) L. J. Barbour, Chem. Commun. 2006, 1163 –
1168; j) L. Dobrzanska, G. O. Lloyd, H. G. Raubenheimer, L. J.
Barbour, J. Am. Chem. Soc. 2006, 128, 698 – 699; k) C. J. Kepert,
Chem. Commun. 2006, 695 – 700; l) J. L. Atwood, L. J. Barbour,
A. Jerga, B. L. Schottel, Science 2002, 298, 1000 – 1002.
[18] G. Frenking, N. Froehlich, Chem. Rev. 2000, 100, 717 – 774.
[19] a) S. K. Bae, C. H. Heo, D. J. Choi, D. Sen, E.-H. Joe, B. R. Cho,
H. M. Kim, J. Am. Chem. Soc. 2013, 135, 9915 – 9923; b) N.
Kumar, V. Bhalla, M. Kumar, Coord. Chem. Rev. 2013, 257,
2335 – 2347; c) G.-J. Mao, T.-T. Wei, X.-X. Wang, S.-y. Huan, D.-
Q. Lu, J. Zhang, X.-B. Zhang, W. Tan, G.-L. Shen, R.-Q. Yu,
Anal. Chem. 2013, 85, 7875 – 7881; d) L. A. Montoya, T. F.
Pearce, R. J. Hansen, L. N. Zakharov, M. D. Pluth, J. Org.
Chem. 2013, 78, 6550 – 6557; e) H. Zhang, P. Wang, G. Chen, H.-
Y. Cheung, H. Sun, Tetrahedron Lett. 2013, 54, 4826 – 4829; f) F.
Zheng, M. Wen, F. Zeng, S. Wu, Polymer 2013, 54, 5691 – 5697;
g) L. A. Montoya, M. D. Pluth, Chem. Commun. 2012, 48, 4767 –
4769; h) V. S. Lin, C. J. Chang, Curr. Opin. Chem. Biol. 2012, 16,
595 – 601; i) H. Peng, W. Chen, Y. Cheng, L. Hakuna, R.
Strongin, B. Wang, Sensors 2012, 12, 15907 – 15946; j) A. R.
Lippert, E. J. New, C. J. Chang, J. Am. Chem. Soc. 2011, 133,
10078 – 10080.
[
[
[
10] a) Y.-Q. Sun, C. Yang, Z. Xu, M. Zeller, A. D. Hunter, Cryst.
Growth Des. 2009, 9, 1663 – 1665; b) Y.-Q. Sun, J. He, Z. Xu, G.
Huang, X.-P. Zhou, M. Zeller, A. D. Hunter, Chem. Commun.
2007, 4779 – 4781.
11] a) Y.-Q. Lan, S.-L. Li, H.-L. Jiang, Q. Xu, Chem. Eur. J. 2012, 18,
8076 – 8083; b) H. Kim, M. P. Suh, Inorg. Chem. 2005, 44, 810 –
812; c) Z. Guo, R. Cao, X. Wang, H. Li, W. Yuan, G. Wang, H.
Wu, J. Li, J. Am. Chem. Soc. 2009, 131, 6894 – 6895.
12] a) A. Santra, I. Senkovska, S. Kaskel, P. K. Bharadwaj, Inorg.
Chem. 2013, 52, 7358 – 7366; b) C. Zhang, M. Zhang, L. Qin, H.
Zheng, Cryst. Growth Des. 2014, 14, 491 – 499; c) C. Zhang, H.
Hao, Z. Shi, H. Zheng, CrystEngComm 2014, 16, 5662 – 5671;
d) L. Sarkisov, R. L. Martin, M. Haranczyk, B. Smit, J. Am.
Chem. Soc. 2014, 136, 2228 – 2231; e) Z. Wei, Z.-Y. Gu, R. K.
Arvapally, Y.-P. Chen, R. N. McDougald, J. F. Ivy, A. A.
Yakovenko, D. Feng, M. A. Omary, H.-C. Zhou, J. Am. Chem.
Soc. 2014, 136, 8269 – 8276.
[
13] Crystal data for BFMOF-1: C150H125N O Pb S , M = 3949.30,
3
30
6
8
r
crystal dimensions: 0.240 ꢄ 0.120 ꢄ 0.080 mm, triclinic, space
¯
group P1 with a = 13.316(2) ꢀ, b = 17.982(2) ꢀ, c =
8.910(2) ꢀ, a = 116.429(2)8, b = 98.931(2)8, g = 104.111(2)8,
1
3
À3
À1
V= 3746.8(8) ꢀ , Z = 1, 1calcd = 1.750 gcm
qmax = 52.748, GOF = 1.034. A total of 48491 reflections were
collected and 15282 are unique (Rint = 0.0354). R (wR ) = 0.0377
, m = 6.899 cm ,
2
1
2
(
0.1012) for 997 parameters and 12896 reflections [I > 2s(I)].
The same framework structure can be crystallized using DMF
N,N-dimethylformamide) in place of DMA. CCDC-1020276
(
and 1020277 contain the supplementary crystallographic data for
the two isoreticular structures of BFMOF-1 and BFMOF-1-
DMF in 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.
[
14] a) Z.-L. Xu, B. Liu, Q.-W. Wang, Z. Kristallogr. New Cryst.
Struct. 2011, 226, 515 – 517; b) M. R. St John Foreman, M. J.
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5
These are not the final page numbers!

.
Angewandte
Communications
Communications
Metal–Organic Frameworks
Yin and yang: A system incorporating
both rigid and flexible components has
been prepared in which traditional con-
figuration has been reversed by installing
rigid side arms onto a soft core (see
J. Cui, Y.-L. Wong, M. Zeller, A. D. Hunter,
Z. Xu*
&&&& — &&&&
II
Pd Uptake and H S Sensing by an
picture). After binding to Pb ions, the
2
Amphoteric Metal–Organic Framework
with a Soft Core and Rigid Side Arms
dynamic hard–soft (carboxy–thioether)
metal–organic framework has distinct
amphoteric character, with the donor-
acceptor properties enabling uptake of
PdCl and a sensitive colorimetric
2
response to H S.
2
6
www.angewandte.org
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2014, 53, 1 – 6
These are not the final page numbers!