Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
An effective approach for constructing acentric heterometallic-organic
framework with catalytic activity
Yan-Fei Chen , Yun-Cui Ma , Hua-Bin Zhang ⁎, Shu-Mei Chen a,b,⁎⁎
a,b
a
b,
a
College of Chemistry & Chemical Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, the Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
b
a r t i c l e i n f o
a b s t r a c t
Article history:
A new acentric heterometallic–organic framework, [CdMg (btec)(DMF)(H O) ] (1) (H btec = 1,2,4,5-benzene
tetracarboxylic acid), has been solvothermally synthesized. It features a 4-connected net with typical pts topol-
ogy. To the best of our knowledge, compound 1 is the first example of Cd–Mg heterometallic organic framework
2
3
4
Received 12 October 2013
Accepted 26 January 2014
Available online 3 February 2014
4
based on the H btec ligand. Compound 1 has potential unsaturated metal sites after the removal of coordination
water molecules, so it shows good catalytic activity on the diethylzinc addition to benzaldehyde. The
photoluminescent property of 1 is also investigated.
Keywords:
Metal–organic framework
Unsaturated metal sites
Catalytic property
Photoluminescence
©
2014 Elsevier B.V. All rights reserved.
Heterometallic-organic frameworks (HMOFs) are of great current
interest not only due to their many practical applications in lumines-
cence, magnetism, and heterogeneous catalysis [1–3], but also due to
their impressive structural diversity in architectures [4–7]. In particular,
acentric HMOFs offer many advantages on designing nonlinear optical
produce industrial phenylpropanol, and is also a typical reaction to eval-
uate the catalytic property of new MOF [20].
In addition, templated synthesis is of great importance in the design
and syntheses of functional materials [21]. A remarkable variety of
templates which include solvents [22] and ammonium cations [23]
have been utilized in the syntheses of HMOFs. Alkylammonium cations
are perhaps the popular ones among these various templates. They
have taken critical templating roles in the syntheses of artificial zeo-
lites [24,25]. However, so far templated HMOF materials with tetra-
alkylammonium cations are rarely synthesized.
(
NLO) materials [8,9]. Moreover, HMOF-based catalysis has become a
hot topic in recent years, but it is still in an immature phase [10]. A com-
mon structural feature of those reported HMOF-based catalysts is the
presence of coordinatively unsaturated metal sites (CUSs) as Lewis
acid sites [11,12]. CUSs can offer a promising tool in catalysis because
regular arrangements and well-defined environments of metal centers
in the pore channels induce regioselectivity and shape- or size-
selectivity towards guest molecules or reaction intermediates. In the
case of Lewis acid catalyzed reactions, the availability of CUSs is a key
requirement [13]. MOF materials with removable solvent molecules
occupying coordination sites of metals provide a versatile and conve-
nient route to produce these functional CUSs [14]. Thus, the generation
of CUSs by thermal activation is an effective approach for improving the
catalytic performance of MOFs. Some MOFs with CUSs, such as HKUST-1
and MIL-101 [15,16], have been successfully applied to catalyze some
organic reactions including the cyanosilylation of benzaldehyde [17]
and epoxide ring opening [18,19]. The asymmetric addition reaction of
diethylzinc with benzaldehyde is one of the convenient routes to
In this work, we report a new acentric heterometallic-organic
framework, [CdMg(btec)(DMF)(H
O) ] (1) (H btec = 1,2,4,5-benzene
2 3 4
tetracarboxylic acid), which is solvothermally synthesized and structur-
ally characterized by single-crystal X-ray diffraction, IR spectrum and
elemental analysis. The dehydrated sample has a good catalytic activi-
ty on the reaction of diethylzinc addition to benzaldehyde, so the
unsaturated metal sites may play the key role in the reaction. The
photoluminescent property of 1 is also investigated.
Compound 1 was solvothermally synthesized with the Cd(CH
COO) /Mg(NO /H btec/(Et) NBr/1,4-diazabicyclo[2.2.2]octane molar
ratio being 1:1:1:1:0.5 in mixed H O and DMF solvent (v: v = 1: 2) at
3
2
)
3 2
4
4
2
100 °C for 2 days. Single-crystal X-ray diffraction reveals that 1 crystal-
lizes in space group of Pna2(1) [30]. As shown in Fig. 1a, the asymmetric
4
−
unit of 1 consists of one Cd(II) ion, one Mg(II) ion, one btec ligand,
one coordinated DMF and three coordinated H O molecules. Cd1 is co-
2
ordinated by seven oxygen atoms from four carboxylate groups from
four ligands. Mg1 is octahedrally coordinated by six oxygen donors
⁎
Corresponding author.
from three waters, one DMF, and two carboxylate oxygen atoms from
⁎⁎ Correspondence to: S.-M. Chen, College of Chemistry & Chemical Engineering, Fuzhou
4−
two btec
ligands. The Cd\O and Mg\O bond lengths are normal.
The Cd centers and Mg centers are alternately linked by the carboxylate
(S.-M. Chen).
groups into an infinite linear chain along the b-axis. The distances