metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
sionality and may provide potential supramolecular recogni-
tion sites for ꢀ±ꢀ stacking interactions (Chen et al., 2002;
Zhang et al., 2004) to form multi-stranded helices. Using
4-carboxyphenoxyacetic acid (H2cpoa) and 2,20-bipy, we have
hydrothermally prepared the title compound, [Cd(cpoa)-
(2,20-bipy)(H2O)]n, (I), which is a new neutral in®nite CdII±
dicarboxylate helical coordination polymer. The structure is
reported in this paper.
The asymmetric unit of (I) contains one CdII atom, one
cpoa2 ligand, one 2,20-bipy ligand and one aqua ligand
(Fig. 1). The Cd atom is coordinated by three O atoms from
one monodentate and one bidentate carboxylate group of two
cpoa2 ligands, the aqua ligand, and two N atoms from the
2,20-bipy ligand to furnish a distorted octahedral geometry.
The Cd1ÐO3i and Cd1ÐO4i bonds are longer than the Cd1Ð
O1 bond (see Table 1 for distances and symmetry codes). Each
pair of adjacent CdII atoms are bridged by cpoa2 ligands to
form a chiral helical chain running along the 21 axis in the c
ISSN 0108-2701
catena-Poly[[aqua(2,20-bipyridine-
j2N,N0)cadmium(II)]-l-4-carboxyl-
0
atophenoxyacetato-j3O:O4,O4 ]
Yan Yang,a Ming-Hua Zeng,b Fa-Yan Mengb and Hong
Liangb*
aCollege of Chemistry and Chemical Engineering, Central South University,
Changsha, Hunan 410000, People's Republic of China, and bSchool of Chemistry
and Chemical Engineering, Guangxi Normal University, Guilin, 541004, People's
Republic of China
Correspondence e-mail: zmh@mailbox.gxnu.edu.cn
Ê
direction with a pitch of 16.441 (5) 0A; this is longer than the
Ê
Received 31 May 2006
Accepted 11 July 2006
Online 11 August 2006
pitch of 11.25 (1) A in [Cu(ipa)(2,2 -bipy)]n.2nH2O (H2ipa is
isophthalic acid; Chen et al., 2002) because the cpoa2 dianion
is larger than the ipa2 dianion. These chains are decorated
with 2,20-bipy ligands, positioned alternately on two sides and
pointing outwards, as depicted in Fig. 2. The benzene rings of
the cpoa2 ions at each side of the helix are arranged in a
In the title compound, [Cd(C9H6O5)(C10H8N2)(H2O)]n, the
CdII atom is coordinated in a distorted octahedral fashion by
two carboxylate groups (one in a monodentate and one in a
bidentate fashion) from two 4-carboxylatophenoxyacetate
anions, two N atoms from a 2,20-bipyridine ligand and one
aqua ligand. The structure is a helix with a long pitch of
Ê
16.441 (5) A. A three-dimensional supramolecular network is
further constructed through ꢀ±ꢀ stacking and hydrogen-
bonding interactions between the helices.
Comment
It has been noted that employment of ¯exible or V-shaped
exobidentate organic bridges can improve the helicity of
polymeric chains (Ye et al., 2005). Therefore, we assumed that
Figure 1
A view of (I), shown with 30% probability displacement ellipsoids.
1
[Symmetry code: (i) x + , y + 1, z 12.]
2
the 4-carboxylatophenoxyacetate (cpoa2 ) anion, as a multi-
dentate ligand with two different carboxylate groups, one at a
¯exible site, may be useful in the formation of single-stranded
helical chains in the presence of aromatic chelate ligands, such
as 2,20-bipyridine (2,20-bipy) and 1,10-phenanthroline (phen).
These ligands are important in maintaining the one-dimen-
Figure 2
The chiral helical chain of (I).
m392 # 2006 International Union of Crystallography
DOI: 10.1107/S0108270106026783
Acta Cryst. (2006). C62, m392±m394
Yang, Van
