Barium carboxylate metal-organic framework - Synthesis, x-ray crystal structure, photoluminescence and catalytic study

Article abstract of DOI:10.1002/ejic.201200417

A new 3D alkaline earth metal-organic framework (MOF), [Ba(Hdcp)H ₂O]_n (1) (H₃dcp = 3,5-pyrazoledicarboxylic acid), has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction ana

Full text of DOI:10.1002/ejic.201200417

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FULL PAPER
DOI: 10.1002/ejic.201200417
Barium Carboxylate Metal–Organic Framework – Synthesis, X-ray Crystal
Structure, Photoluminescence and Catalytic Study
Tanmoy Maity,[a] Debraj Saha,[a] Soma Das,[a] and Subratanath Koner*[a]
Keywords: Barium / Hydrothermal synthesis / Metal–organic frameworks / Heterogeneous catalysis / Aldol condensation /
Photoluminescence
A new 3D alkaline earth metal–organic framework (MOF),
[Ba(Hdcp)H2O]n (1) (H3dcp = 3,5-pyrazoledicarboxylic acid),
which adopts a μ3-η2:η1-bridging coordination mode to afford
a 3D network. Thermogravimetric analysis reveals that 1 is
has been hydrothermally synthesized and structurally char- thermally stable up to ca. 230 °C. An emission band at ca.
acterized by single-crystal X-ray diffraction analysis. A crys- 466 nm (λmax) was observed in the photoluminescence spec-
tallographic study reveals that each metal ion in 1 is coordi- trum of 1 in the solid state at room temperature. Compound
nated by eight O atoms and one N atom. Each 3,5-pyrazole-
dicarboxylato (Hdcp2–) ligand coordinates to six alkaline
earth metal centers through two carboxylate groups, each of
1 heterogeneously catalyzes the aldol condensation reactions
of various aromatic aldehydes with acetone, cyclohexanone,
acetophenone, and cyclopentanone.
room to predict and control their coordination geometry
and their tendency to form solvated metal centers, thus the
formation of typical alternating [M(H2O)6]L (M = alkaline
earth metal, L = ligand) organic–inorganic ionic layers.[9]
In this context, some recent studies concerning the catalytic
behavior of alkaline earth metal complexes deserve to be
mentioned.[10] Ana et al. studied alkene hydrogenation and
ketone hydrosilylation reactions over alkaline earth sulf-
onate metal–organic frameworks, which show 100% selec-
tivity towards ethylbenzene under homogeneous condi-
tions.[10e] They also reported the same reaction over an al-
kaline earth carboxylate metal–organic framework under
heterogeneous conditions.[10a] Choudary et al. studied an
aldol condensation reaction over nanocrystalline magne-
sium oxide, which showed high activity in the direct asym-
metric aldol condensation reaction under heterogeneous
conditions.[11] Baruah et al. studied an aldol condensation
reaction catalyzed by magnesium carboxylate compounds
under homogeneous conditions.[10g] Homogeneous cata-
lysts, however, suffer from recyclability problems as the sep-
aration of the catalyst from the reaction mixture is trouble-
some.
In the course of our continuing investigation into the use
of MOFs in heterogeneous catalytic reactions, we have suc-
cessfully employed layered transition metals and lanthan-
ide-based MOFs to catalyze olefin epoxidation reac-
tions.[12] Recently, we have synthesized a 3D Mg–carboxyl-
ate framework, which catalyzes aldol condensation reac-
tions under heterogeneous conditions.[13] It is of interest to
study the catalytic efficacy of barium compounds in aldol
condensation reactions. There are several examples of bar-
ium-catalyzed C–C bond formation reactions[14] and some
instances of the catalysis of aldol condensation reac-
Introduction
The design and synthesis of functional materials based
on metal–organic frameworks (MOFs) have attracted much
attention primarily because of their fascinating architec-
tures and potential applications in catalysis,[1] magnetism,[2]
luminescence,[3] and gas adsorption and separation.[4] Di-
carboxylate ligands have received increased attention in the
construction of coordination-polymer arrays, and the more
rigid dicarboxylates in particular are useful building blocks
for preparing porous networks with metal ions throughout
the periodic system.[5] The ligand H3dcp (H3dcp = 3,5-pyr-
azoledicarboxylic acid) has six potential donor sites, which
involve two nitrogen atoms of the pyrazole ring and four
carboxylate oxygen atoms from two carboxylate groups
when it is fully deprotonated, and exhibits a multiple coor-
dination motif with the metal center.[6] A variety of coordi-
nation compounds of H3dcp has been reported, though the
majority of them concern transition metals and recently
some rare earth cations.[7] Attempts have been made to
study the coordination behavior of main group elements
both in aqueous and nonaqueous media, however, only a
few of them concern alkaline earth metals.[6,8] There are two
drawbacks in using s-block metals in MOF design: the
bonding interaction of s-block metal centers with carboxyl-
ate oxygen atoms is mainly ionic in nature due to the large
difference in their electronegativities, which provides little
[a] Department of Chemistry, Jadavpur University,
Kolkata 700032, India
Fax: +91-33-2414-6414
E-mail: snkoner@chemistry.jdvu.ac.in
Homepage: www.jaduniv.edu.in/view_department.php?deptid=64
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201200417.
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T. Maity, D. Saha, S. Das, S. Koner
tions.[14a,14b] However, to the best of our knowledge, there Table 1. Selected bond lengths [Å] and angles [°] for 1.
FULL PAPER
are no reports of barium-containing MOFs that catalyze
aldol condensation reactions under heterogeneous condi-
tions. This paper focuses on the preparation and structural
characterization of an alkaline-earth-metal-based MOF
that affords a new 3D structure involving barium and
H3dcp, namely [Ba(Hdcp)H2O]n (1). Notably, 1 also dem-
onstrates interesting photoluminescence properties.
Ba(1)–O(1) 2.848(3)
Ba(1)–O(4) 2.722(3)
Ba(1)–O(5) 2.900(3)
Ba(1)–cN(1) 2.823(3)
Ba(1)–eO(3) 2.859(3)
Ba(1)–gO(2) 2.864(3)
Ba(1)–hO(4) 2.781(3)
Ba(1)–iO(1) 2.935(3)
Ba(1)–iO(5) 2.817(4)
eO(3)–Ba(1)–O(4) 87.36(9)
gO(2)–Ba(1)–O(4) 126.40(9)
h
O(4)-Ba(1)- O(4) 85.05(9)
iO(1)–Ba(1)–O(4) 77.20(9)
O(4)–Ba(1)–iO(5) 63.60(9)
O(5)–Ba(1)–cN(1) 128.78(10)
eO(3)–Ba(1)–O(5) 126.17(9)
gO(2)–Ba(1)–O(5) 140.01(9)
hO(4)–Ba(1)–O(5) 61.80(9)
iO(1)–Ba(1)–O(5) 68.94(9)
O(5)–Ba(1)–iO(5) 117.58(9)
eO(3)–Ba(1)–cN(1) 58.73(9)
gO(2)–Ba(1)–cN(1) 67.49(9)
hO(4)–Ba(1)–cN(1) 78.26(9)
iO(1)–Ba(1)–cN(1) 135.89(9)
iO(5)–Ba(1)–cN(1) 113.63(10)
gO(2)–Ba(1)–eO(3) 93.79(9)
eO(3)–Ba(1)–hO(4) 71.43(9)
iO(1)–Ba(1)–eO(3) 150.64(9)
eO(3)–Ba(1)–iO(5) 82.80(9)
iO(1)–Ba(1)–hO(4) 130.59(9)
hO(4)–Ba(1)–iO(5) 140.29(9)
iO(1)–Ba(1)–iO(5) 68.01(9)
O(1)–Ba(1)–O(4) 132.16(9)
O(1)–Ba(1)–O(5) 68.08(9)
O(1)–Ba(1)–cN(1) 73.41(9)
O(1)–Ba(1)–eO(3) 126.79(9)
O(1)–Ba(1)–gO(2) 87.82(9)
O(1)–Ba(1)–hO(4) 77.74(9)
O(1)–Ba(1)–iO(1) 81.02(9)
O(1)–Ba(1)–iO(5) 141.36(9)
O(4)–Ba(1)–O(5) 64.44(9)
O(4)–Ba(1)–cN(1) 145.44(9)
gO(2)–Ba(1)–hO(4) 145.42(9)
Results and Discussion
X-ray Structure of [Ba(Hdcp)(H2O)]n (1)
Single-crystal X-ray diffraction analysis reveals that 1
crystallizes in space group P21/c with Z = 4. Ba1 is coordi-
nated by nine atoms and has a distorted single capped
square-antiprism geometry (Figure 1, a): five oxygen atoms
i
i
(O1, O1, O4, O4, gO2) (g = –x, –y, –z; i = x, 1/2 – y,
1/2 + z) from five different carboxylate anions, two oxygen iO(1)–Ba(1)–gO(2) 76.35(9)
gO(2)–Ba(1)–iO(5) 63.43(10)
atoms (O5, iO5) from two bridged water molecules and one
oxygen (eO3) (e = 1 – x, –1/2 + y, 1/2 – z) and one nitrogen
atom (cN1) (c = –x, –1/2 + y, –1/2 – z) from one five-mem-
bered metallocyclic chelate. An ORTEP diagram with atom
numbering is shown in Figure S1, and selected bond lengths
and angles are collected in Table 1. The Ba–O (carboxylate)
bond lengths range from 2.720(3) to 3.047(2) Å, which are
consistent with other alkaline earth metal carboxyl-
ates.[10e,15,16] The Hdcp2– ligand has μ7 connectivity in this
structure and each ligand coordinates to six alkaline earth
metal centers through two carboxylate groups with a μ3-
η2:η1-bridging mode (Figure 1, b), which is similar to that
Symmetry transformation codes: (c) –x, –1/2 + y, –1/2 – z; (e) 1 –
x, –1/2 + y, 1/2 – z; (g) –x, –y, –z; (h) x, 1/2 – y, –1/2 + z; (i) x,
1/2 – y, 1/2 + z.
nated carboxylate oxygen atoms present in [Ba(Hpdc)-
(H2O)]. Amongst them, two water molecules and five carb-
oxylate oxygen atoms are in μ2 bridging mode. Although
one coordinated water and three carboxylate oxygen atoms
bridge different types of metals and others bind to the same
type of metals. In our case the coordinated water molecule
and two carboxylate oxygen atoms (O1 and O4) act as a
μ2-bridge to connect two metal centers. Here, barium(II)
ions are connected by O1, O4, and O5 atoms (and sym-
metry related ones) to result in a 1D zigzag inorganic chain
along the crystallographic c axis (Figure 1, c and d).
Bridged oxygen atoms (O1, O4, and O5 and symmetry re-
lated ones) share the faces of barium-containing polyhedra
of [Ba(Hpdc)(H2O)] [Hpdc2–
=
3,5-pyrazoledicarb-
oxylato].[8a] In the previously reported compound
[Ba(Hpdc)(H2O)], two types of barium with different coor-
dination numbers, viz. ten and nine, are connected through
an Hpdc2– ligand with μ7- and μ8-type connectivity. There
are three coordinated water molecules and eight coordi-
Figure 1. A segment of 1, showing (a) the local coordination envi-
ronment of barium(II) ion, (b) the coordination mode of the
Hdcp 2– ligand in 1, (c) 1D inorganic chain of 1 along the crystallo-
graphic a axis, and (d) along crystallographic c axis.
Figure 2. 3D framework of 1.
2
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Barium Carboxylate Metal–Organic Framework
with a Ba···Ba distance of 4.24 Å. Organic linkers further 40 nm in comparison to that of H3dcp. The redshift of the
connect the 1D chains to create a 3D network (Figure 2). emission spectra observed in 1 in comparison with that of
The metal centers are bridged by the organic Hdcp2– linkers the corresponding free ligand may be attributed to the de-
to construct a 3D MOF-based binodal 6,6-connected net- protonation of the ligand in 1.[18] This type of photolumi-
work, considering both the metal centers and Hdcp2– link- nescence can have potential applications in the design of
ers as six-connected nodes (Figure 1, a and b). Additional fluorescent materials.[19] However, examples of barium-
reinforcement in the networked structure is achieved by two based MOFs showing solid state photoluminescence at
types of intramolecular hydrogen bonds (Table S1) N2– room temperature are rare.[8b–8d]
H1···O2 (–x, 1/2 + y, –1/2 – z) and O5–H3···O3. Cheetham
et al. have introduced a notation rule to categorize the inor-
ganic and organic connectivities in framework structures.[17]
According to this rule the structure can be classified as I1O2
(I = inorganic and O = organic connectivity).
Catalytic Aldol Condensation Reaction
Environmentally friendly, heterogeneous catalytic pro-
cesses are attracting increasing attention in chemical indus-
tries. To find highly active solid Brønsted-type basic cata-
lysts able to perform C–C bond formation remains a chal-
lenge. The main drawbacks of using NaOH or KOH as
homogeneous catalysts are separation difficulties, corrosion
problems in the equipment, and the generation of a large
amount of waste. In order to overcome these disadvantages,
several efforts have been made to design new catalytic sys-
tems with controlled basic properties in order to increase
the process efficiency. The catalytic activity of 1 has been
studied in aldol condensation reactions under hetero-
geneous base-free conditions.
Catalytic reactions were performed (Scheme 1) with a
large excess of ketone to prevent self-condensation of the
aldehyde as well as for effective use of the aldehyde.[20]
Throughout the reaction, the temperature was maintained
in the range 0–5 °C. With increasing temperature, benzyl-
ideneketone (condensed product) was obtained from the β-
aldol. The catalytic reaction was performed in different
THF/H2O ratios (Table S2); the best result was obtained in
a 3:1 THF/H2O mixture, and results of the aldol condensa-
tion reactions are summarized in Tables 2 and S3. Under
all of the above conditions, aldehydes were converted into
their respective β-aldol product, which was the sole prod-
uct. In this study we noticed that the β-aldol products do
not undergo further transformation to form unsaturated
carbonyl compounds, which is generally observed.[21] The
yield of the β-aldol product decreased in the order p-Ͼ o-
Ͼ m-nitrobenzaldehyde. It may be realized that the nitro
substituent at the ortho/para position affords both a nega-
tive inductive effect and a negative mesomeric effect, which
increases the electrophilicity of the C=O group of these ni-
trobenzaldehydes, whereas substitution at the meta position
affords only a negative inductive effect. Between p- and o-
Thermogravimetric Analysis
Thermogravometric (TG) analysis confirmed that 1 is
thermally stable up to ca. 230 °C (Figure 3). The TG curve
indicates that 1 starts to lose water molecules at ca. 230 °C.
The mass loss of approximately 6% in the temperature
range 230–296 °C is in agreement with the theoretical value
of 5.8% and corresponds to the loss of one molecule of
water. The corresponding differential thermal analysis
(DTA) curve shows one endothermic peak at ca. 260 °C.
The loss of water at a relatively high temperature indicates
that the water molecules are tightly held to the metal cen-
ters through a coordination bond. On further heating, the
TG curve shows continuous mass loss up to 800 °C due to
decomposition of the compound.
Figure 3. TG-DTA curves of 1.
Photoluminescence Study
The electronic and photoluminescence spectra of H3dcp
and 1 were measured in the solid state (Figures S2 and S3).
The H3dcp ligand displayed very strong blue fluorescent
emission from 370 to 550 nm (λmax = 425 nm) upon exci-
tation at 270 nm, which is probably because of a π*Ǟπ
electronic transition. In the case of 1, the emission band
Scheme 1. Reaction scheme of the aldol condensation reaction cat-
was found at 466 nm (λmax) and was redshifted by around alyzed by 1.
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nitrobenzaldehyde, more steric crowding at the ortho posi- Table 2. (Continued)
tion may lead to lower conversion for the ortho variety. In
the case of chloro-substituted benzaldehyde, the β-aldol
product obtained from o-chlorobenzaldehyde predominates
over m-chlorobenzaldehyde, which is usual for the effective
negative inductive effect in the ortho position. Whereas the
lower electronegativity of the bromo variety compared to
the chloro one causes a lower yield in the case of m-bro-
mobenzaldehyde. On the other hand, the presence of an
electron-donating group on the ring in the case of the
methyl-substituted benzaldehyde, the yield decreases and
demonstrates the lowest conversion. Interestingly, in the
case of p-methoxybenzaldehyde, the yield was still very
good. We assume that the methoxy group may interact with
Table 2. Reactions of various aromatic aldehydes and acetone/cy-
clohexanone catalyzed by 1.[a]
barium and facilitates the reaction.[22] The yields of β-aldol
products showed a similar trend with acetone, cyclohex-
anone, acetophenone, and cyclopentanone. The aldehydes
were converted into the desired products in aldol reactions
catalyzed by 1 in short reaction times compared to those
of other alkaline-earth-metal-catalyzed aldol condensation
reactions.[10g,11] The isolated yields of the products are also
higher than those of the magnesium-carboxylate-catalyzed
aldol condensation reactions under homogeneous condi-
tions or nanocrystalline-magnesium-oxide-catalyzed asym-
metric aldol condensation reactions under heterogeneous
conditions. Shibasaki et al. studied similar types of aldol
condensation reactions over a barium catalyst under homo-
geneous conditions, which showed impressive conversion
(up to 99%), however the turnover frequencies (TOF) of
these reactions are low (0.32–1 h–1).[24] Besides, the aldol
condensation reactions catalyzed by magnesium carboxyl-
ate under homogeneous conditions also demonstrate lower
TOF values (2–5 h–1) than that of 1.[10g]
The BET (Brunauer–Emmett–Teller)[23] surface area of 1
was calculated from the N2 adsorption isotherm. The ad-
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Barium Carboxylate Metal–Organic Framework
sorption–desorption isotherm of 1 is shown in Figure S4. five successive aldol reaction runs has been studied (Table
The adsorption of N2 follows a type II isotherm with a S4). The catalytic efficacy of the recovered catalyst re-
surface area (SBET) of 56 m2 g–1. This is a consequence of mained almost the same in each run.
sorption on the surface, not in the framework. Therefore,
catalytic reactions clearly take place on the surface of the
catalyst rather than in the pores.
Conclusions
We have synthesized a new MOF, [Ba(Hdcp)H2O]n,
through a hydrothermal route, which is thermally stable up
to ca. 230 °C. The compound demonstrates excellent cata-
lytic activity in aldol condensation reactions and displays
high yields with 100% selectivity under base free hetero-
geneous conditions in water/THF. The surface area ob-
tained in the nitrogen sorption measurement indicates that
the compound is not porous enough to accept guest mole-
cules in the bulk of the solid. Therefore, the aldol condensa-
tion reaction takes place on the surface of the catalyst.
However, the advantage of our system is that the catalyst is
not air or moisture sensitive; hence, there is no need to
carry out reactions under an inert atmosphere. The catalyst
can be easily recovered by filtration and can be reused sev-
eral times without any significant loss of catalytic activity.
Future work will continue to focus on constructing alka-
line-earth-metal-based frameworks for higher catalytic ac-
tivity.
Separation, Catalyst Reuse, and Heterogeneity Test
To ascertain that the catalysis was indeed heterogeneous,
we performed a hot filtration test. The solid catalyst was
filtered when the catalytic reaction was 30–40% complete,
and the residual activity of the supernatant solution after
separation of the catalyst was studied. The supernatant
solution was kept under the reaction conditions for another
8 h, and the composition of the solution was analyzed from
time to time. No reaction progress was observed during this
period, which excludes the presence of active species in the
solution. This experiment clearly demonstrates that there
was no leaching of Ba from the solid catalyst during the
reactions. Furthermore, atomic absorption spectrometric
analysis of the supernatant solution of the reaction mixture
collected by filtration confirmed the absence of Ba in the
liquid phase.
In order to check the stability of the catalyst, we charac-
terized the recovered material. After the catalytic reactions
were completed, the solid catalyst was recovered by centri-
fugation, washed thoroughly with dichloromethane, and
dried under vacuum at 100 °C. The recovered catalyst was
then subjected to powder XRD analysis. Comparison of the
XRD patterns (Figure 4) of the pristine compound and re-
covered catalyst convincingly demonstrated that the struc-
tural integrity of the compound was unaltered after the re-
action.
Experimental Section
Materials: Barium nitrate, 3,5-pyrazoledicarboxylic acid monohy-
drate, and substituted benzaldehydes were purchased from Sigma–
Aldrich and used without further purification; other chemicals
were purchased from Merck (India). Benzaldehyde, acetone, and
tetrahydrofuran were distilled before use. Benzaldehyde was kept
over NaA molecular sieves to trap possible traces of benzoic acid.
[Ba(Hdcp)H2O]n (1): Compound 1 was synthesized through a hy-
drothermal route. The compound was obtained as colorless block-
shaped crystals in a 25 mL teflon-lined Parr acid digestion bomb
at 150 °C for 3 d followed by slow cooling to room temperature.
The initial reaction mixture was prepared by mixing 3,5-pyrazoled-
icarboxylic acid monohydrate (0.087 g, 0.5 mmol), lithium hydrox-
ide monohydrate (0.020, 0.5 mmol), and barium nitrate (0.130 g,
0.5 mmol) in milliQ water (8 mL). The crystals obtained were fil-
tered by suction and washed several times with distilled water and
then with acetone to remove unreacted materials and dried in air.
For characterization of the bulk compound, IR spectroscopy and
elemental analysis were undertaken. Selected IR (KBr disk): ν =
˜
–
–
1574 (νas, CO2 ), 1410, 1353 (νs, CO2 ), 1261, 1210, 996, 791 (C–O
and O–C–O), 3600 (m, O–H) cm–1. C5H4BaN2O5 (309.44): calcd.
C 19.41, H 1.30, N 9.05; found C 19.4, H 1.4, N 9.0.
X-ray Crystallography: X-ray diffraction data for 1 was collected at
293(2) K with a Bruker SMART APEX CCD X-ray diffractometer
using graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å).
Determination of integrated intensities and cell refinement were
performed with the SAINT[25] software package using a narrow-
frame integration algorithm. An empirical absorption correction
(SADABS)[26] was applied. The structure was solved by direct
methods and refined using the full-matrix least-squares technique
against F2 with anisotropic displacement parameters for non-hy-
drogen atoms with the programs SHELXS97 and SHELXL97.[27]
Figure 4. X-ray powder diffraction pattern of virgin and recovered
catalyst and calculated diffraction lines for 1.
For the recyclability study, aldol condensation reactions
were performed using p-nitrobenzaldehyde with acetone, cy-
clohexanone, acetophenone, and cyclopentanone. After the
first reaction cycle, the catalyst was recovered as mentioned
earlier. The performance of the recycled catalyst in up to Hydrogen atoms were placed in calculated positions using suitable
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FULL PAPER
riding models with isotropic displacement parameters derived from
their carrier atoms. In the final difference Fourier maps, there were
no remarkable peaks except the ghost peaks surrounding the metal
centers. A summary of the crystal data and relevant refinement
parameters for 1 is given in Table 3.
(4 mmol), tetrahydrofuran (3 mL), water (1 mL), and catalyst
(5 mg) were combined in a round-bottomed flask. It was then
placed in an ice bath and the temperature was maintained at 0–
5 °C. To this solution, the requisite amount of aldehyde (2 mmol)
was added and the reaction mixture was stirred for 8 h (Scheme 1).
After the reaction, the catalyst was separated by filtration, and the
filtrate was concentrated in vacuo. The products were purified by
column chromatography over silica gel (mesh 60–120) using an n-
hexane/ethyl acetate mixture as eluent and were analyzed by 1H
NMR spectroscopy, elemental analysis, and by comparing them
with authentic samples.
Table 3. Crystallographic data and structure refinement parameters
for 1.
Empirical formula
Formula weight
Crystal system
Space group
a [Å]
b [Å]
c [Å]
C5H4BaN2O5
309.44
monoclinic
P21/c
10.0456(3)
10.5616(3)
7.1981(2)
90.00
Supporting Information (see footnote on the first page of this arti-
cle): ORTEP diagram of 1, results of catalytic reactions in specific
condition in tabular form, UV/Vis spectra, N2 adsorption iso-
therm, 1H NMR spectra of all products of known compounds,
elemental analysis study of the isolated products.
α [°]
β [°]
101.3810(10)
90.00
748.68(4)
4
γ [°]
[a] Reaction conditions: Aldehyde (2 mmol), ketone (4 mmol),
tetrahydrofuran (3 mL), water (1 mL), and catalyst (5 mg); T = 0–
5 °C. Yields were isolated after 8 h of reaction. [d] Turn over
number (TON): number of mol converted/mol of active site.
V [Å3]
Z
Temperature [K]
293(2)
2.745
Dcalc [gcm–3]
Absorption coefficient [mm–1] 5.296
F(000)
576
–13 Յ h Ն 13
–13 Յ k Ն 13
Intervals of reflection indices
Acknowledgments
–8 Յ l Ն 9
11829
1736
1755
R1 = 0.0310, wR2 = 0.0805
R1 = 0.0315, wR2 = 0.0809
0.0160
0.667
–3.293
1.210
We acknowledge the Department of Science and Technology (DST)
, Government of India for funding a project (to S. K.) (SR/S1/IC-
01/2009). T. M. thanks the Council of Scientific and Industrial Re-
search (CSIR), New Delhi, for awarding him a fellowship. Ms. N.
Khatun is thanked for her help with NMR spectroscopy. The au-
thors also thank the DST for funding the Department of Chemis-
try, Jadavpur University to procure a single-crystal X-ray facility
and NMR spectrometer under the FIST programme.
Measured reflections
Reflections with [IϾ 2σ(I)]
Independent reflections
Final R indices[IϾ 2σ(I)]
R indices (all data)
Rint
Δρmax [eÅ–3]
Δρmin [eÅ–3]
Goodness-of-fit on F2
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and photoluminescence spectra were recorded with a Shimadzu
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Catalytic Reactions: The catalytic reactions were carried out in a
glass batch reactor according to the following procedure. Ketone
6
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Job/Unit: I20417
/KAP1
Date: 28-08-12 16:38:59
Pages: 8
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Received: April 26, 2012
Published Online: ᭿
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7

Job/Unit: I20417
/KAP1
Date: 28-08-12 16:38:59
Pages: 8
T. Maity, D. Saha, S. Das, S. Koner
FULL PAPER
Metal–organic frameworks
The aldol condensation reaction of various
aromatic aldehydes is catalyzed by a new
3D alkaline earth metal–organic frame-
work (MOF), [Ba(Hdcp)H2O]n (H3dcp =
3,5-pyrazoledicarboxylic acid). It demon-
strates excellent catalytic yields with high
selectivity in water/THF under hetero-
geneous conditions. The catalyst can be re-
cycled and reused several times without sig-
nificant loss of activity.
T. Maity, D. Saha, S. Das,
S. Koner* .......................................... 1–8
Barium
Carboxylate
Metal–Organic
Framework
–
Synthesis, X-ray Crystal
Structure, Photoluminescence and Cata-
lytic Study
Keywords: Barium / Hydrothermal syn-
thesis / Metal–organic frameworks / Het-
erogeneous catalysis / Aldol condensation /
Photoluminescence
8
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