Five copper(II) metal–organic coordination
complexes with micro-channels based on flexible
bis(imidazole) and carboxybenzaldehyde ligands;
structural influence of experimental conditions on
their frameworks†
Hui Wang,
a
Vahid Safarifard,
b
Si-Yao Wang,
a
Ling-Hui Tu,
a
Hong-Ping Xiao,
*
a
Bi-Feng Huang,
a
Xin-Hua Li,
a
Mahmood Payehghadr
c
and Ali Morsali
*
b
Five new copper(II) metal–organic coordination complexes, [Cu
2
(1,2-bix)
2
(L)
4
] (1), [Cu(1,3-bix)(L)
2
]
n
$
nCH
3
OH$3H
2
O (2), [Cu(1,3-bix)(L)
2
]
n
$nH
2
O (3), [Cu
5
(1,3-bix)
2
(L)
6
(NO
3
)
2
(H
2
O)
2
(OH)
2
]$2H
2
O (4) and
[Cu(1,4-bix)(L)
2
]
n
(5), have been synthesized using 4-carboxybenzaldehyde (HL) and 1,n-bis(imidazol-l-yl-
methyl)benzene (1,n-bix; n ¼ 2, 3, 4) as ligands. These complexes were structurally characterized by
single-crystal X-ray crystallography and further characterized by FT-IR spectroscopy and
thermogravimetric analysis (TGA). Complex 1 is a symmetrical binuclear structure, and in compound 2
the 1D ladders are entangled through p–p stacking interactions to generate a 3D network with one-
dimensional micro channel. A 3D coordination framework 2 converted to network 3 by just increasing
the reaction temperature. Metal–organic polymer 3 is comprised of 1D corrugated double chains
structure. Complex 4 has a pentanuclear (Cu
5
) cluster structure and compound 5 shows a 1D zigzag
chain. The magnetic properties of the complexes 1 and 3 are reported briefly.
1. Introduction
Recently, the rational and controlled design multinuclear
metal–organic coordination polymers are still one of the most
focused areas of crystal engineering, due to their fascinating
architectures
1–6
and highly promising chemical and physical
application in many elds.
7–11
The construction of the unique
molecular architecture depends on the combination of several
factors, like the polarity of solvent, temperature, pH, template,
the coordination geometry of metal ions, nature of organic
ligands and counter-ions. In particular, the role of anions
proves important in the self-assembly processes, which is an
interesting and active theme in some studies.
12
For example, the
inuence of anions was investigated in three reports, and the
results showed that employing the similar systems using
different anions such as bromide, chloride, and iodide led to
the formation of three-, two- and one-dimensional coordination
polymer, respectively.
13–15
During the past decade, coordination complexes based on
diverse organic ligands with various chemical functionality
have drawn considerable attention in the development of
novel functional materials. Flexible bridging ligands, like
1,n-bis(imidazol-1-ylmethyl)-benzene (1,n-bix; n ¼ 2, 3, 4), are
widely used in the construction of the metal–organic coor-
dination polymers.
16–22
On the other hand, aromatic
carboxylic acid ligands such as 4-carboxybenzaldehyde (HL)
are also regarded a useful sort of organic ligands to construct
multi-nuclear cluster and metal–organic coordination
polymers.
23–26
Herein, we report the synthesis, crystal structures and
magnetic properties of ve copper(II) metal–organic coordi-
nation complexes [Cu
2
(1,2-bix)
2
(L)
4
](1), [Cu(1,3-bix)(L)
2
]
n
$n-
CH
3
OH$3H
2
O (2), [Cu(1,3-bix)(L)
2
]
n
$nH
2
O (3), [Cu
5
(1,3-
bix)
2
(L)
6
(NO
3
)
2
(OH)
2
(H
2
O)
2
]$2H
2
O(4), [Cu(1,4-bix)(L)
2
]
n
(5).
The inuence of chemical (solvents, starting materials,
anions, etc.) and process parameters (temperature and reac-
tion time) as well as coordination modes of L ligands and the
positional isomeric inuenced by 1,n-bix isomers, studied for
the system Cu(II)/HL/1,n-bix/solvent. The Results show that
the experimental conditions play an important role in
directing the nal structures and topologies.
a
College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou,
325035, P. R. China. E-mail: hp_xiao@126.com
b
Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box
14155-4838, Tehran, Iran. E-mail: morsali_a@modares.ac.ir; Fax: +98-21-
88009730; Tel: +98-21-82884416
c
Department of Chemistry, Payame Noor University, Karaj, Islamic Republic of Iran
† CCDC 966843, 966854, 966844, 966855 and 966856. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/c3ra47177b
Cite this: RSC Adv. , 2014, 4, 11423
Received 1st December 2013
Accepted 14th January 2014
DOI: 10.1039/c3ra47177b
www.rsc.org/advances
This journal is © The Royal Society of Chemistry 2014 RSC Adv. , 2014, 4, 11423–11429 | 11423
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