Catalytic transesterifications by a Zn-bissalen mof containing open pyridyl groups inside 1D channels

Article abstract of DOI:10.1002/ejic.201300208

The new ligand N,N′,N″,N″′-tetrakis[3-tert-butyl-5- (4-pyridinyl)salicylidene]-1,2,4,5-benzenetetraamine (bisSalen) containing four pyridyl groups in its periphery was prepared and subsequently used as an organic linker for a Zn-bisSalen MOF. A 2D undulated sheet structure was determined from single-crystal X-ray diffraction studies. The bisSalen ligands bridge two Zn^II ions, and one of the pyridyl groups on each side of the bisSalen ligand further coordinates to a bisSalen-coordinated Zn^II ion to provide a 2D sheet structure. The undulated 2D sheets are stacked closely together to form a 3D-like structure containing well-defined 1D channels, the orientation of which is perpendicular to the 2D sheets. The geometry of the bisSalen in the MOF is not planar. The remaining uncoordinated pyridyl groups point toward the 1D channels. Because of these openly accessible pyridyl groups in the channels, the Zn-bisSalen MOF is a very active catalyst for transesterifications. A 3D-like 2D Zn-bisSalen MOF {bisSalen = N,N′,N″,N″′-tetrakis[3-tert-butyl-5-(4-pyridinyl) salicylidene]-1,2,4,5-benzenetetraamine} with a large void space and Lewis-basic openly accessible pyridyl groups inside 1D channels was prepared and structurally investigated. The solvent-free Zn-bisSalen MOF contains a solvent-accessible void volume of 41.1 %. The as-prepared Zn-bisSalen MOF effectively catalyzes transesterifications.

Full text of DOI:10.1002/ejic.201300208

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Zn–bisSalen MOFs
W.-S. Kim, K. Y. Lee, E.-H. Ryu,
J.-M. Gu, Y. Kim,* S. J. Lee,*
A 3D-like 2D Zn–bisSalen MOF {bisSalen
=
N,NЈ,NЈЈ,NЈЈЈ-tetrakis[3-tert-butyl-5-(4-
S. Huh* ............................................. 1–7
pyridinyl)salicylidene]-1,2,4,5-benzene-
tetraamine} with a large void space and
Lewis-basic openly accessible pyridyl
groups inside 1D channels was prepared
and structurally investigated. The solvent-
free Zn–bisSalen MOF contains a solvent-
accessible void volume of 41.1%. The as-
prepared Zn–bisSalen MOF effectively ca-
talyzes transesterifications.
Catalytic Transesterifications by Zn–
a
BisSalen MOF Containing Open Pyridyl
Groups Inside 1D Channels
Keywords: Metal–organic frameworks
/
Salen ligands / Heterogeneous catalysis /
Metalloligands / Transesterification
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DOI:10.1002/ejic.201300208
Catalytic Transesterifications by a Zn–BisSalen MOF
Containing Open Pyridyl Groups Inside 1D Channels
Wan-Seok Kim,[a][‡] Kyung Yeon Lee,[b][‡] Eui-Hyun Ryu,[b]
Ja-Min Gu,[a] Youngmee Kim,*[c] Suk Joong Lee,*[b] and
Seong Huh*[a]
Keywords: Metal–organic frameworks / Salen ligands / Heterogeneous catalysis / Metalloligands / Transesterification
The new ligand N,NЈ,NЈЈ,NЈЈЈ-tetrakis[3-tert-butyl-5-(4-pyr- dulated 2D sheets are stacked closely together to form a 3D-
idinyl)salicylidene]-1,2,4,5-benzenetetraamine
(bisSalen)
like structure containing well-defined 1D channels, the ori-
entation of which is perpendicular to the 2D sheets. The ge-
ometry of the bisSalen in the MOF is not planar. The remain-
ing uncoordinated pyridyl groups point toward the 1D chan-
nels. Because of these openly accessible pyridyl groups in
the channels, the Zn–bisSalen MOF is a very active catalyst
for transesterifications.
containing four pyridyl groups in its periphery was prepared
and subsequently used as an organic linker for a Zn–bisSalen
MOF. A 2D undulated sheet structure was determined from
single-crystal X-ray diffraction studies. The bisSalen ligands
bridge two ZnII ions, and one of the pyridyl groups on each
side of the bisSalen ligand further coordinates to a bisSalen-
coordinated ZnII ion to provide a 2D sheet structure. The un-
contain dangling metal ions, not in the channels. In such a
case, however, the advantages of well-defined channels, for
example, substrate selectivity and enhanced efficiency of ca-
talysis, will be marginally effective.
Introduction
Currently, many research efforts are aiming for the prep-
aration and utilization of functional metal–organic frame-
works (MOFs).[1] Applications in catalysis[2] as well as in
gas sorption[3] and separation[4] make MOF systems a
unique class of crystalline, porous materials. Particularly for
catalysis applications, several strategies to prepare novel
MOF-based catalysts are being employed. The use of
Lewis-acidic metal ions as catalytic centers may be the most
popular approach.[5] There are many previous examples for
the utilization of Lewis-acidic catalytic centers. However, a
prerequisite of this type of MOF-based catalytic systems
is the presence of well-defined coordinatively unsaturated
openly accessible metal sites.[6] Otherwise, the catalytic reac-
tions mainly occur on the surfaces of MOFs, which may
On the other hand, the incorporation of Lewis-basic mo-
tifs in the framework is rather challenging because of their
reactivity toward metal ions during the preparation of the
corresponding MOFs. For example, nonfunctional, sym-
metric pillar ligands such as 1,4-diazabicyclo[2.2.2]octane
(DABCO) or 4,4Ј-bipyridyl (4,4Ј-bpy) tend to bridge two
metal ions by using two equivalent N-donor atoms to leave
no free basic site.[7] Nevertheless, we recently reported one
exceptional case, in which DABCO coordinates with only
one N atom to the metal center, and the other N atom is
not coordinating.[8] We may well attribute this unprece-
dented phenomenon to the geometric constraints of the ter-
phenyl-3,3Ј-dicarboxylate (3,3Ј-TPDC) bridging ligand
used in that case. The corresponding Zn MOF, Zn(3,3Ј-
TPDC)(DABCO), indeed exhibited catalytic activity for the
nitroaldol reaction in a size-dependent manner because of
the DABCO, which was orderly located in microporous 1D
channels.[9] Recently, Lewis-basic sites in the channels of
MOFs are thought to be beneficial for CO2 capture applica-
tions, because CO2 possesses a higher polarizability and a
larger quadrupole moment than N2, CH4, and H2.[10] As a
result, MOFs that have chemically accessible Lewis-basic
sites usually exhibit a high CO2 adsorption enthalpy.
There are numerous reports about postsynthetic frame-
work modifications with IRMOF-3, which consists of metal
ions and 2-aminobenzenedicarboxylate (NH2–BDC) bridg-
ing ligands.[11] The amino functionality remains intact dur-
[a] Department of Chemistry and Protein Research Center for
Bio-Industry, Hankuk University of Foreign Studies,
Yongin 449-791, Korea
Fax: +82-31-330-4566
E-mail: shuh@hufs.ac.kr
Homepage: http://www.hufs.ac.kr/
[b] Dept. of Chemistry, Research Institute for Natural Sciences,
Korea University,
5 Anam-dong, Sungbuk-gu, Seoul 136-701, Korea
Fax: +82-2-924-3141
E-mail: slee1@korea.ac.kr
Homepage: http://www.korea.ac.kr/
[c] Department of Chemistry and Nano Sceince, Ewha Womans
Univeristy,
Seoul 120-750, Korea
Fax: +82-2-3277-3419
E-mail: ymeekim@ewha.ac.kr
Homepage: http://www.ewha.ac.kr/
[‡] These authors contributed equally
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ing the MOF synthesis, and thus it can be subsequently C10) and (C22/C23/C24/C25/C26/C27), are 18° and 9°,
utilized for a wide range of chemical reactions to modify respectively.
the frameworks. Although these MOFs are good catalysts
for the Knoevenagel reaction of benzaldehyde because of
the free amino groups inside their channels, as reported by
Gascon et al.,[12] the number of publications of MOF-based
catalytic systems with functional groups other than NH2–
BDC inside the channels is still limited, because the intro-
duction of catalytically active organic functionalities is
much more challenging.
In this contribution, we prepared a new Zn–bisSalen
MOF by using the bridging ligand N,NЈ,NЈЈ,NЈЈЈ-tetrakis[3-
tert-butyl-5-(4-pyridinyl)salicylidene]-1,2,4,5-benzenetetra-
amine (bisSalen). The Zn–bisSalen MOF contains uncoor-
dinated Lewis-basic pyridyl groups inside its channels. The
intact, openly accessible pyridyl group acts as a catalytic
center for transesterification reactions with various sub-
strates.
These undulated 2D sheets are stacked closely together
to form a 3D-like structure containing 1D channels, as
shown in Figure 3. The remaining uncoordinated pyridyl
groups point toward these channels (Figure 2). The coordi-
nation environment of each ZnII ion is a distorted tetrago-
nal pyramid formed by an equatorial N2O2 unit from one
side of the bisSalen and an axial pyridyl N atom.
There are very few examples of MOFs containing free
pyridyl groups inside channels in the literature,[13,14] be-
cause they tend to coordinate metal ions during the MOF
synthesis whenever free metal ions are available. For in-
stance, Kim et al. reported a MOF having a free pyridyl
group exposed into a well-defined chiral channel that was
formed when they used pyridyl-functionalized d-tartric acid
as a bridging ligand.[13] The pyridyl group exposed toward
the channels catalyzed transesterifications in a substrate-
size-dependent manner. Chen et al. also prepared a lumi-
nescent Eu MOF with well-defined free pyridyl groups or-
derly located in MOF channels by using pyridine-3,5-di-
carboxylate as a bridging ligand.[14]
Results and Discussion
A Zn–bisSalen MOF was prepared by the reaction be-
tween Zn(NO3)2 and the bisSalen ligand N,NЈ,NЈЈ,NЈЈЈ-
tetrakis[3-tert-butyl-5-(4-pyridinyl)salicylidene]-1,2,4,5-
benzenetetraamine in N,N-diethylformamide (DEF) at
120 °C. The new bisSalen ligand was prepared according to
Scheme 1 by starting from 3-tert-butyl-2-hydroxybenzalde-
hyde. No additional ligand except the bisSalen was em-
ployed during the Zn–bisSalen MOF synthesis. We ob-
tained extremely small, red, block-shaped single crystals
(0.075 mmϫ0.068 mmϫ0.044 mm). The Zn–bisSalen
MOF crystallized in the monoclinic P21/c space group, and
its asymmetric unit comprises one half of a centrosymmet-
ric dinuclear complex and half a diethylamine solvate mole-
cule. The crystal was so small that we could not obtain
other useful information about the solvate molecules, except
one diethylamine group, which could be generated from
DEF solvent. The bisSalen ligand bridges two ZnII ions
(Figure 1), and one of the pyridyl groups on each side of
bisSalen further coordinates to a bisSalen-coordinated ZnII
ion of another dinuclear complex to provide a 2D sheet
structure, as depicted in Figure 2. The coordinated bisSalen
On the basis of a PLATON analysis,[15] the solvent-ac-
cessible void volume of the framework was calculated to be
41.1% for the solvent-free Zn–bisSalen MOF. According to
analytical data from elemental analysis and thermogravime-
tric analysis (TGA), there are four diethylamine (DEA) and
sixteen water molecules in a unit cell, although we could
not precisely locate these solvate molecules because of their
disorder in a large void space. Thus, the Zn–bisSalen MOF
possesses a very large void space. The as-prepared Zn–
bisSalen MOF gradually lost weight upon heating up to
445 °C, as shown in Figure 4. Four DEA and sixteen solv-
ate water molecules were completely lost at this tempera-
ture. Once the temperature was further increased, the
weight gradually decreased further. The bulk purity of the
as-prepared sample was confirmed by powder X-ray dif-
fraction (PXRD). As depicted in Figure 5, there is a good
agreement between the PXRD pattern of the bulk sample
and the pattern simulated from the single-crystal X-ray dif-
fraction data. Thus, the bulk sample was very pure.
The porosity of the Zn–bisSalen MOF was evaluated by
is tilted significantly, and the tilting angles between the mid- a standard volumetric N2 adsorption–desorption analysis
dle phenyl group and the side wings, (C5/C6/C7/C8/C9/ at 77 K. The as-prepared Zn–bisSalen MOF was immersed
Scheme 1. Preparation of the bisSalen ligand with four peripheral pyridyl groups.
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Figure 1. Dinuclear unit of the Zn–bisSalen MOF with atomic labelling. The displacement ellipsoids are shown at the 30% probability
level. Unlabelled atoms are related by the symmetry operator (–x, 1 – y, 1 – z).
Figure 2. Structure of the Zn–bisSalen MOF showing uncoordi-
nated pyridyl groups exposed toward 1D channels. Openly access-
ible pyridyl groups are highlighted as ball-and-stick models. Hydro-
gen atoms are omitted for clarity.
Figure 3. Packing diagram of the 2D sheets of the Zn–bisSalen
MOF along the c axis. Each layer is indicated with different colors.
in chloroform for solvent exchange before it was activated
at 120 °C for 1 h. Despite the large solvent-accessible void
of the solvent-free Zn–bisSalen MOF, the evacuated Zn–
bisSalen MOF only moderately sorbed N2, which was poss-
ibly due to the partial framework collapse after evacuation
of the solvent inside the channels. In fact, many known 2D
sheet-based frameworks are often flexible, and a change of
the original framework structure can be observed.[16] The
Brunauer–Emmett–Teller (BET) surface area was 175 m2/g,
and the total pore volume was 0.17 cm3/g. The N2 adsorp-
tion–desorption isotherms depicted in Figure 6 resemble
type I isotherms, which is indicative of the microporous Figure 4. TGA curve for the as-prepared Zn–bisSalen MOF.
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Figure 7. Timecourse of the transesterifications catalyzed by the as-
preapred Zn–bisSalen MOF.
Figure 5. PXRD patterns for the Zn–bisSalen MOF: (a) simulated
from single-crystal X-ray diffraction data, (b) obtained from as-
prepared Zn–bisSalen MOF, and (c) obtained from the Zn–
bisSalen MOF after transesterification.
It is noteworthy that p-nitrophenyl acetate is larger than
the other two substrates. Thus, the faster kinetics for p-ni-
range of the pore structure.[17] On the basis of the Horvath– trophenyl acetate may be attributable to electronic effects
Kawazoe (HK) method, the measured pore diameter was rather than to the substrate size dependence. This result can
0.92 nm.[18]
be accounted for by the fact that the void of the Zn–
Although the evacuated Zn–bisSalen MOF might par- bisSalen MOF is large enough to accommodate p-nitro-
tially lose its structure because of the flexible nature of its phenyl acetate. After the transesterification of p-nitrophenyl
framework, the as-prepared Zn–bisSalen MOF may act as acetate, we also checked the same reaction, using the hot-
an efficient heterogeneous Lewis-base catalyst because of filtered solution as a catalyst, to determine whether leached
the openly accessible pyridyl groups. Also the many solvent metal ions are the active catalyst or not. In comparison to
and water molecules that occupy the channels of the as- the original yield of 83%, only a low yield of 10% was
prepared Zn–bisSalen MOF can be easily exchanged during observed in this experiment. Therefore, the main catalytic
catalysis with solution containing substrate molecules, as sites are indeed the openly accessible pyridyl groups located
we previously observed in Zn(3,3Ј-TPDC)(DABCO) cataly- in the channels of the Zn–bisSalen MOF. However, in com-
sis.[9] We chose the transesterification reaction as a model parison to the as-prepared sample, the retrieved Zn–
reaction for the Zn–bisSalen MOF catalysis, because free bisSalen MOF catalyst exhibited a PXRD pattern with a
pyridyl groups were found to be very active for this reac- very reduced diffraction-peak intensity, as shown in Fig-
tion.[13] As depicted in Figure 7, three different acetate sub- ure 5. A partial collapse or amorphization of the flexible,
strates were used as substrates for the transesterification re- 3D-like framework of the Zn–bisSalen MOF induced by a
action in ethanol at 50 °C. The p-nitrophenyl acetate sub- delamination of the 2D sheets may be responsible for this
strate exhibited faster kinetics than phenyl acetate and vinyl change of the PXRD pattern. Nevertheless, the catalyst
acetate. Both phenyl acetate and vinyl acetate showed al- maintained its activity for more than 168 h in reagent-grade
most the same rate of reaction.
ethanol, which contains water (ca. 5%). To check the recycl-
Figure 6. (a) N2 adsorption–desorption isotherms for the Zn–bisSalen MOF at 77 K. (b) Horvath–Kawazoe (HK) pore-size-distribution
curve.
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9.98 (s, 1 H), 8.67 (d, 3JH-H = 6.1 Hz, 2 H), 7.81 (d, 3JH-H = 2.5 Hz,
2 H), 7.69 (d, JH-H = 2.5 Hz, 1 H), 7.48 (d, JH-H = 6.1 Hz, 1 H),
1.48 (s, 9 H) ppm.
ability of the catalyst, we ran the reaction three more times
by using the recovered catalyst. Although the conversion
of recycling experiment gradually became smaller than the
original one (1st recycle 65%; 2nd recycle 55%; 3rd recycle
53%), the Zn–bisSalen MOF indeed exhibited catalytic ac-
tivity.
3
3
Preparation of N,NЈ,NЈЈ,NЈЈЈ-Tetrakis[3-tert-butyl-5-(4-pyridinyl)-
salicylidene]-1,2,4,5-benzenetetraamine: To a solution of 1,2,4,5-
benzenetetramine tetrahydrochloride (0.223 g, 0.78 mmol) in pyr-
idine (10 mL) and ethanol (10 mL) was added dropwise a solution
of 3-tert-butyl-5-(4-pyridinyl)salicylaldehyde (1.0 g, 3.9 mmol) in
ethanol (20 mL) at room temperature. The mixture was heated to
reflux for 15 h. After cooling, the mixture was filtered, and the
solid was washed with ethanol three times and dried to afford
N,NЈ,NЈЈ,NЈЈЈ-tetrakis[3-tert-butyl-5-(4-pyridinyl)salicylidene]-
1,2,4,5-benzenetetraamine (bisSalen) as a red solid (0.630 g, 59%
Conclusions
We prepared and characterized a new rare example of
a Zn–bisSalen MOF containing a metalloligand[19–21] with
catalytically active, openly accessible pyridyl groups
pointing toward 1D channels. The planar bisSalen ligand is
severely distorted, which results in an interesting 2D sheet
structure. Although it is a 2D structure, the 2D sheets stack
together to form a 3D-like framework with open porosity.
The Zn–bisSalen MOF is an active catalyst for the transes-
terification of various acetate compounds in ethanol.
1
yield). H NMR ([D6]DMSO): δ = 12.05 (br., 4 H), 10.13 (s, 4 H),
8.75 (d, 3JH-H = 6.3 Hz, 8 H), 8.69 (s, 2 H), 8.29 (d, 3JH-H = 2.3 Hz,
3
3
4 H), 7.96 (d, JH-H = 2.3 Hz, 4 H), 7.95 (d, JH-H = 6.3 Hz, 8 H)
1.48 (s, 36 H) ppm. 13C NMR ([D6]DMSO): δ = 199.27, 161.72,
148.87, 139.05, 132.83, 132.10, 128.18, 127.85, 122.02, 121.78,
54.09, 35.44, 29.63 ppm. MS (MALDI-TOF): calcd. for [M]+
1087.356; found 1086.48.
Preparation of the Zn-bisSalen MOF: Zn(NO3)2·6H2O (0.015 g,
0.05 mmol) and the bisSalen ligand (0.027 g, 0.025 mmol) were dis-
solved in N,N-diethylformamide (10 mL). The reaction mixture was
heated at 120 °C in a Teflon-lined reactor for 3 d. Red microcrystals
were retrieved by filtration, washed with N,N-diethylformamide,
and dried in air. C86H142N12O20Zn2 (1794.9): calcd. C 57.55, H
7.97, N 9.36; found C 57.29, H 5.73, N 9.79.
Experimental Section
General Methods: All commercially available starting materials and
solvents were purchased from Sigma–Aldrich, TCI, and Acros Co.
and were used without further purification. All of the reactions
and manipulations were carried out under N2 with standard inert-
gas and Schlenk techniques unless otherwise noted. The solvents
used in inert-gas reactions were dried by using standard procedures.
Flash column chromatography was carried out with 230–400 mesh
silica gel purchased from Sigma–Aldrich by using the wet-packing
method. All deuterated solvents were purchased from Sigma–Ald-
rich. 5-Bromo-3-tert-butyl-2-hydroxybenzaldehyde and 3-tert-but-
yl-5-(4-pyridinyl)salicylaldehyde were prepared according to modi-
fied literature procedures.[22,23]
Transesterification: A mixture of the as-prepared Zn–bisSalen
MOF catalyst (0.005 g, 0.0046 mmol), an ester of choice
[0.276 mmol (p-nitrophenyl acetate, 0.050 g; phenyl acetate, 0.038 g;
vinyl acetate, 0.024 g)], and n-nonane (10 μL, 0.056 mmol) as an
internal standard in ethanol (10 mL) was heated at 50 °C with con-
stant stirring for 168 h. The reaction progress was monitored at a
regular interval by taking an aliquot and analyzing it by gas
chromatography. A recycling experiment was performed by using
catalyst that was recovered from a previous reaction by centrifuga-
tion (9000 rpm, 20 min).
Preparation of 5-Bromo-3-tert-butyl-2-hydroxybenzaldehyde: To a
solution of 3-tert-butyl-2-hydroxybenzaldehyde (1.78 g, 9.98 mmol)
in acetic acid (5 mL) was added a solution of bromine (0.53 mL,
10.3 mmol) in acetic acid (2 mL) by using a dropping funnel over
the course of 15 min. The resulting mixture was stirred at room
temperature for 1 h. The mixture was diluted with CH2Cl2 (30 mL)
and subsequently washed with H2O (10 mL), saturated aqueous
Na2CO3, saturated aqueous NaHCO3 (10 mL), and brine (10 mL).
The organic phase was dried with Na2SO4, and the solvents were
evaporated to afford pure 5-bromo-3-tert-butyl-2-hydroxybenzalde-
Physical Measurements: NMR spectra were recorded with a Varian
AS400 (399.937 MHz for 1H and 100.573 MHz for 13C) spectrome-
1
ter. H chemical shifts were referenced to the proton resonance re-
sulting from the protic residue in the deuterated solvent, and 13C
chemical shifts were recorded downfield in ppm relative to the car-
bon resonance of the deuterated solvent. Matrix-assisted laser-de-
sorption-ionization time-of-flight mass spectra (MALDI-TOF)
were obtained with a Bruker Daltonics LRF20 MALDI-TOF mass
spectrometer at the Industry-Academic Cooperation Foundation,
Yonsei University. The N2 adsorption–desorption analysis was per-
formed with a Belsorp-miniII at 77 K (BEL Japan). The CHCl3
exchanged sample was dried at 120 °C for 1 h prior to the measure-
ment. Powder X-ray diffraction patterns were obtained by using a
Rigaku MiniFlex (30 kV, 15 mA). Thermogravimetric analyses
were carried out with a TGA Q5000 (TA Instruments) under nitro-
gen. Elemental analyses were performed at the Organic Chemistry
Research Center (Seoul, Korea) by using an EA1112 (CE Instru-
ments, Italy).
1
hyde as a yellow solid (2.28 g, 89% yield). H NMR (CDCl3): δ =
3
11.73 (s, 1 H), 9.81 (s, 1 H), 7.58 (d, JH-H = 2.4 Hz, 1 H), 7.52 (d,
3JH-H = 2.4 Hz, 1 H), 1.40 (s, 9 H) ppm.
Preparation of 3-tert-Butyl-5-(4-pyridinyl)salicylaldehyde: To a solu-
tion of 5-bromo-3-tert-butyl-2-hydroxybenzaldehyde (1.0 g,
3.89 mmol) in dioxane (100 mL) were added 4-pyridinylboronic
acid (0.7 g, 4.28 mol), a solution of K2CO3 (1.34 g, 9.73 mmol) in
H2O (20 mL), PPh3 (0.1 g, 0.4 mmol), and PdCl2(PPh3)2 (0.28 g,
0.4 mmol). The mixture was degassed with N2 for 10 min and
stirred at 90 °C under N2 for 3 h. After cooling, the resulting mix-
ture was diluted with CH2Cl2 (100 mL) and washed with H2O and
brine two times. The organic layer was separated and dried with
anhydrous MgSO4. After filtration, the filtrate was concentrated to
dryness by using a rotary evaporator. The residue was purified by
silica-gel column chromatography (CH2Cl2/hexanes = 1:4, v/v) to
afford pure 3-tert-butyl-5-(4-pyridinyl)salicylaldehyde as a yellow
X-ray Crystallography: A clear, red, block-shaped single crystal of
Zn–bisSalen MOF (C74H66N9O4Zn2) with the approximate dimen-
sions of 0.075 mmϫ0.068 mmϫ0.044 mm, was used for the X-ray
crystallographic analysis. The X-ray intensity data were measured
with a Bruker AXS X8 Prospector system equipped with a
multilayer monochromator and a Cu IμSTM microfocus sealed-tube
X-ray source (λ = 1.54178 Å). A total of 2031 frames were col-
1
solid (0.850 g, 59% yield). H NMR (CDCl3): δ = 11.93 (s, 1 H),
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cation, Science and Technology (20100010096, 20110008018,
20120002285, NRF-20100020209, NRF-2008-331-C00149) and the
RP-Grant 2013 of the Ewha Womans University are gratefully ac-
knowledged. The authors thank Bruker for single-crystal X-ray
data collection.
Table 1. Selected bond lengths [Å] and angles [°].
Zn(1)–O(1)
Zn(1)–N(3)#1
Zn(1)–N(1)
1.935(11)
2.084(14)
2.100(13)
Zn(1)–O(2)
Zn(1)–N(2)
1.956(12)
2.098(14)
–
–
O(1)–Zn(1)–O(2)
94.8(5)
O(1)–Zn(1)–N(3)
#1
101.7(5)
[1] T. R. Cook, Y.-R. Zheng, P. J. Stang, Chem. Rev. 2013, 113,
734.
[2] S. T. Meek, J. A. Greathouse, M. D. Allendorf, Adv. Mater.
2011, 23, 249.
[3] K. Sumida, D. L. Rogow, J. A. Mason, T. M. McDonald, E. D.
Bloch, Z. R. Herm, T.-H. Bae, J. R. Long, Chem. Rev. 2012,
112, 724.
O(2)–Zn(1)–N(3)#1 106.2(5)
O(1)–Zn(1)–N(2)
N(3)#1-Zn(1)–
N(2)
O(2)–Zn(1)–N(1)
N(2)–Zn(1)–N(1)
159.3(5)
97.1(5)
O(2)–Zn(1)–N(2)
88.2(5)
O(1)–Zn(1)–N(1)
89.9(5)
149.5(5)
77.5(5)
N(3)#1-Zn(1)–N(1) 102.3(5)
[4] Y. He, W. Zhou, R. Krishna, B. Chen, Chem. Commun. 2012,
48, 11813.
lected. The total exposure time was 27.46 h. The frames were inte-
grated with the Bruker SAINT software package by using a wide-
frame algorithm. The integration of the data with a monoclinic
unit cell yielded a total of 11994 reflections to a maximum θ angle
of 44.50° (1.10 Å resolution), of which 3123 were independent
(average redundancy 3.976, completeness = 90.7%, Rint = 7.54%,
Rsig = 15.17%) and 1441 (46.14%) were larger than 2σ(F2). The
final cell constants of a = 10.4189(12) Å, b = 18.863(2) Å, c =
22.224(3) Å, β = 91.451(9)°, V = 4366.3(9) Å3, are based upon the
refinement of the XYZ centroids of 3258 reflections above 20σ(I)
with 6.146°Ͻ2θϽ85.72°. The data were corrected for absorption
effects by using the multiscan method (SADABS). The ratio of
minimum/maximum apparent transmission was 0.825. The struc-
ture was solved and refined by using the Bruker SHELXTL Soft-
ware Package in the space group P21/c with Z = 2 for the formula
unit C74H66N9O4Zn2. The final anisotropic full-matrix least-
[5] L.-X. Shi, C.-D. Wu, Chem. Commun. 2011, 47, 2928.
[6] S. Neogi, M. K. Sharma, P. K. Bharadwaj, J. Mol. Catal. A
2009, 299, 1.
[7] T. Gadzikwa, B.-S. Zeng, J. T. Hupp, S. T. Nguyen, Chem.
Commun. 2008, 3672.
[8] J.-M. Gu, T.-H. Kwon, J.-H. Park, S. Huh, Dalton Trans. 2010,
39, 5608.
[9] J.-M. Gu, W.-S. Kim, S. Huh, Dalton Trans. 2011, 40, 10826.
[10] R. Vaidhyanathan, S. S. Iremonger, G. K. H. Shimizu, P. G.
Boyd, S. Alavi, T. K. Woo, Science 2010, 330, 650.
[11] Z. Wang, S. M. Cohen, Chem. Soc. Rev. 2009, 38, 1315.
[12] J. Gascon, U. Aktay, M. D. Hernandez-Alonso, G. P. M.
van Klink, F. Kapteijn, J. Catal. 2009, 261, 75.
[13] J. S. Seo, D. Whang, H. Lee, S. I. Jun, J. Oh, Y. J. Jeon, K. Kim,
Nature 2000, 404, 982.
[14] B. Chen, L. Wang, Y. Xiao, F. R. Fronczek, M. Xue, Y. Cui,
G. Qian, Angew. Chem. 2009, 121, 508; Angew. Chem. Int. Ed.
2009, 48, 500.
squares refinement on F2 with 393 variables converged at R1
=
[15] A. L. Spek, PLATON – A Multipurpose Crystallographic Tool,
Utrecht University, Utrecht, The Netherlands, 2004.
[16] P. Kanoo, R. Sambhu, T. K. Maji, Inorg. Chem. 2011, 50, 400.
[17] M. Kruk, M. Jaroniec, Chem. Mater. 2001, 13, 3169.
[18] G. Horvath, K. Kawazoe, J. Chem. Eng. Jpn. 1983, 16, 470.
[19] M. C. Das, S. Xiang, Z. Zhang, B. Chen, Angew. Chem. 2011,
123, 10696; Angew. Chem. Int. Ed. 2011, 50, 10510.
[20] S.-C. Xiang, Z. Zhang, C.-G. Zhao, K. Hong, X. Zhao, D.-R.
Ding, M.-H. Xie, C.-D. Wu, M. C. Das, R. Gill, K. M.
Thomas, B. Chen, Nat. Commun. 2011, 2, 204.
[21] M. C. Das, Q. Guo, Y. He, J. Kim, C.-G. Zhao, K. Hong, S.
Xiang, Z. Zhang, K. M. Thomas, R. Krishna, B. Chen, J. Am.
Chem. Soc. 2012, 134, 8703.
12.47% for the observed data and at wR2 = 29.49% for all data.
The goodness-of-fit was 1.096. The largest peak in the final differ-
ence-electron-density synthesis was 0.653 e–/Å3, and the largest
hole was –0.484 e–/Å3 with an RMS deviation of 0.127 e–/Å3. On
the basis of the final model, the calculated density was 0.971 g/cm3
and F(000), 1330 e–. Selected bond lengths and angles are listed in
Table 1. CCDC-896260 contains 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.
[22] M. Cavazzini, A. Manfredi, F. Montanari, S. Quici, G. Pozzi,
Eur. J. Org. Chem. 2001, 4639.
Acknowledgments
[23] G. A. Morris, S. T. Nguyen, Tetrahedron Lett. 2001, 42, 2093.
The Basic Science Research Program through the National Re-
search Foundation of Korea (NRF) funded by the Ministry of Edu-
Received: February 12, 2013
Published Online: ᭿
Eur. J. Inorg. Chem. 0000, 0–0
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