Two novel R- and S-malato-bridged coordination polymers by reacting lanthanide chloride and maleic anhydride, 1,10-phenanthroline at hydrothermal condition

Article abstract of DOI:10.1016/j.molstruc.2005.10.026

Two less common lanthanide coordination polymers, [Ln₂(fum)(malate)₂(phen)₂]_n ·n1.25H₂O (Ln=Eu, 1; Pr, 2. fum=fumarate, phen=1,10-phenanthroline) were synthesized and characterized by IR spectra and X-ray crystallography. Single crystal X-ray diffraction analysis shows that complex 1 is isostructural with complex 2. In the two complexes, we found a pair of enantiomers (R-malate and S-malate) which are obtained by addition reaction between maleate and water and fumarate which result from configurational tranformation of maleate. The two structures consist of coordination polymer chains along the c-axis which are held together solely through hydrogen bonding and π-π stacking. Three-dimension supramolecular structures are formed through the two types of weak interaction. The IR data are also described and compared with those of other similar complexes.

Full text of DOI:10.1016/j.molstruc.2005.10.026

Journal of Molecular Structure 787 (2006) 14–17
www.elsevier.com/locate/molstruc
Two novel R- and S-malato-bridged coordination polymers by reacting
lanthanide chloride and maleic anhydride, 1,10-phenanthroline
at hydrothermal condition
Li-Ping Zhang a,b, Liang Huang a, Ling-bo Qu a,b, Hua Peng a, Yu-Fen Zhao b,c,
*
a Department of Chemistry, Anyang Teachers College, Anyang 455002, China
b Key Laboratory of Chem-biology and Organic of Henan Province, Zhengzhou University, 450052, China
c Key Laboratory of Bioorganic Phosphorus Chemistry of the Education Ministry, Department of Chemistry,
School of Life Sciences and Engineering, Tsinghua University, Beijing 100084, China
Received 11 August 2005; received in revised form 16 October 2005; accepted 26 October 2005
Available online 20 February 2006
Abstract
Two less common lanthanide coordination polymers, [Ln2(fum)(malate)2(phen)2]n$n1.25H2O (LnZEu, 1; Pr, 2. fumZfumarate, phenZ1,10-
phenanthroline) were synthesized and characterized by IR spectra and X-ray crystallography. Single crystal X-ray diffraction analysis shows that
complex 1 is isostructural with complex 2. In the two complexes, we found a pair of enantiomers (R-malate and S-malate) which are obtained by
addition reaction between maleate and water and fumarate which result from configurational tranformation of maleate. The two structures consist
of coordination polymer chains along the c-axis which are held together solely through hydrogen bonding and p–p stacking. Three-dimension
supramolecular structures are formed through the two types of weak interaction. The IR data are also described and compared with those of other
similar complexes.
q 2005 Elsevier B.V. All rights reserved.
Keywords: Lanthanide; Maleic; Complex; Hydrothermal; Crystal structure
1. Introduction
changes into anti-configuration. So we selected maleic
anhydride, 1,10-phenanthroline as ligands coordinating to
lanthanide ions. We expected that maleic may react with
H2O at the position of CaC or change its configuration into
fumaric under 150 8C hydrothermal condition. In this paper,
two novel 3D supramolecular complexes [Eu2(fum) (malate)2
(phen)2]n$n1.25H2O 1 and [Pr2(fum)(malate)2(phen)2]n$-
n1.25H2O 2 were obtained. The two structures are very
interesting just because maleate does not exist in but fumarate,
R- and S-malates. To our knowledge, there is no similar
structure in the literature so far. Herein, we report the synthesis
and crystal structures of the two complexes which have 3D
supramolecular architecture assembled from 1D chains via
hydrogen bonding and p–p stacking.
Coordination polymers are of great interest due to their
physical properties and potential application in functional
materials [1–3]. Though the use of various saturated aliphatic
a,u-dicarboxylic acid to form bridges between metal centers
has been extensively studied [4], the use of unsaturated
aliphatic a,u-dicarboxylic acid is scanty in the literature [5].
Fumaric and maleic acid are the simplest unsaturated aliphatic
diacid. In our previous work, we reported three lanthanide
fumarate complexes containing 1,10-phenanthroline [6]. We
found that fumarate ligand is very stable at hydrothermal
condition. It is well known that maleic acid is at thermo-
dynamical unstable constitution. In some case, the double bond
of maleic has a tendency to react with electrophilic reagents as
Lewis base and the molecular syn-configuration may be
2. Experimental
2.1. Materials and apparatus
*
Corresponding author. Address: Department of Chemistry, Anyang
Teachers College, Anyang 455002, China. Tel.: C86 037 2290 3668; fax:
C86 037 2290 2048.
E-mail address: lpzhang@aytc.edu.cn (L.-P. Zhang).
LnCl3$6H2O (LnZEu or Pr) were prepared by dissolving
lanthanide oxide in dilute hydrochloric acid and then dried.
All other materials were purchased and used as received without
further purification. Infrared spectra were recorded with a
0022-2860/$ - see front matter q 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2005.10.026

L.-P. Zhang et al. / Journal of Molecular Structure 787 (2006) 14–17
15
IR (KBr pellet, cmK1) for complex 1: 3442.12(m), 3065.89(w),
2922.67(w), 1598.69(vs), 1426.60(s), 1389.60(s), 1282.48(s),
1081.83(s), 990.93(w), 967.95(m), 839.94(s), 725.00(s),
662.61(s), 597.84(m), 491.73(m). IR (KBr pellet, cmK1) for
complex 2: 3448.53(m), 3065.20(w), 2925.98(w), 1594.64(vs),
1426.79(s), 1389.02(s), 1382.60(m), 1101.40(m), 1083.17(m),
840.48(s), 726.02(s), 661.51(s), 634.12(w), 596.67(w).
Table 1
Crystallographic data for complexes 1 and 2
1
2
Formula
Eu2 C36 H28.50 N4 O15.25
1065.05
Pr2C36 H28.50 N4O15.25
1042.95
Formula weight
Crystal size (mm)
Temperature (K)
Crystal system
Space group
0.20!0.20!0.15
293(2)
0.15!0.08!0.04
293(2)
Triclinic
Triclinic
PK1
P-1
2.3. Single-crystal X-ray diffraction
Unit cell dimensions
˚
a (A)
˚
b (A)
11.762(4)
12.687(4)
13.226(4)
75.635(6)
88.918(6)
71.647(5)
1810.9(10)
2
11.825(4)
12.742(4)
13.367(4)
75.684(6)
88.803(6)
71.601(6)
1848.1(11)
2
Single-crystal X-ray diffraction data were collected on a
Bruker SMART 1000 CCD diffractometer equipped with
˚
c (A)
a (8)
b (8)
g (8)
˚
graphite monochromatized Mo Ka radiation (lZ0.71073 A).
Semiempirical absorption corrections were applied using the
SADABS program. All calculations were carried out with use
of SHELXS-97 and SHELXL-97 programs [7]. The structures
were solved by the direct methods. All structures were refined
on F2 by full-matrix least-squares methods. The crystallo-
graphic data of the complexes are summarized in Table 1 and
the selected bond lengths in Table 2.
3
˚
V (A )
Z
Dcalc (Mg mK3
)
1.953
1.874
F(000)
m (mmK1
1041
1025
)
3.513
2.685
Limiting indices
K13%h%12
K15%k%14
K15%l%10
98.9(%)
K14%h%14
K13%k%15
K16%l%13
97.97(%)
Completeness to,
thetaZ25.01
Maximum and
minimum trans-
mission
3. Results and discussion
1.00 and 0.82
1.00 and 0.61
3.1. Structural description of [Ln2(fum)
(malate)2(phen)2]n$n1.25H2O
Data/restraints/par-
ameters
6298/24/532
0.925
7406/0/548
0.953
Single crystal X-ray diffraction studies reveal that
complexes 1 and 2 are isostructural and complex 1 will be
described in detail. There are two units of formula [Eu2(fum)
(malate)2(phen)2]$1.25H2O per cell in complex 1. The
asymmetric unit comprises of two independent Europium
atoms, one fumarate ligand, a pair of enantiomers (R-malate
and S-malate), two 1,10-phenanthroline ligands and three kinds
of lattice water molecules noted as O (15) (occupancy 0.5), O
(16) (occupancy 0.5) and O (17) (occupancy 0.25). As depicted
in Fig. 1, Eu (1) is nine-coordinated by two carboxylate oxygen
Goodness-of-fit on
F2
Final R indices [IO
2sigma(I)]
R1Z0.0494,
R1Z0.0500
wR2Z0.0751
R1Z0.1136
wR2Z0.0919
1.089 and K0.781
wR2Z0.0797
R1Z0.1082
wR2Z0.0938
1.377 and K0.799
R indices (all data)
Largest diff. peak
K3
˚
and hole (e A
)
Nicolet Avatar 360 FT-IR spectrometer. Elemental analyses
were obtained on a PE 2400 II CHNS/O elemental analyzer.
Table 2
˚
Selected bond distances (A) for complexes 1 and 2
2.2. Synthesis of complexes 1 and 2
Eu(1)–O(11)
Eu(1)–O(6)
Eu(1)–O(1)
Eu(1)–O(3)
Eu(1)–O(8)
Eu(1)–O(4)
Eu(1)–O(9)
Eu(1)–N(2)
Eu(1)–N(1)
Pr(1)–O(14A)
Pr(1)–O(9B)
Pr(1)–O(2)
Pr(1)–O(10)
Pr(1)–O(5)
Pr(1)–O(11)
Pr(1)–O(6)
Pr(1)–N(1)
Pr(1)–N(2)
2.336(8)
2.367(6)
2.393(6)
2.458(7)
2.47(6)
Eu(2)–O(2A)
Eu(2)–O(12)
Eu(2)–O(7B)
Eu(2)–O(9)
Eu(2)–O(4)
Eu(2)–O(5)
Eu(2)–O(10)
Eu(2)–N(3)
Eu(2)–N(4)
Pr(2)–O(1)
Pr(2)–O(13)
Pr(2)–O(7)
Pr(2)–O(8)
Pr(2)–O(12)
Pr(2)–O(6)
Pr(2)–O(10)
Pr(2)–N(4)
Pr(2)–N(3)
2.353(6)
2.354(7)
2.357(7)
2.515(6)
2.526(7)
2.528(7)
2.539(6)
2.567(8)
2.605(9)
2.392(6)
2.435(5)
2.449(5)
2.514(5)
2.518(5)
2.568(5)
2.578(5)
2.677(6)
2.703(7)
A mixture of EuCl3$6H2O (0.109 g), phenanthroline
(0.059 g), maleic anhydride (0.0294 g) and H2O (10 ml) was
placed in a Teflon-lined stainless steel autoclave (25 ml). The
pH value was adjusted to about five with sodium hydroxide
aqueous solution. After stirred, the mixture was sealed in the
bomb and heated at 150 8C for four days, then the bomb was
cooled slowly to room temperature. After filtration, the product
was washed with ethanol and then dried at room temperature.
Colorless needle-like crystals suitable to X-ray diffraction
analysis were obtained (45% yield). Elemental analysis
indicates that the formula of complex 1 is [Eu2(fum)
(malate)2(phen)2]n$n1.25H2O (Calcd (%): C, 40.60; H, 2.70;
N, 5.26. Found (%): C, 40.13; H, 2.79; N, 5.09). Similar
procedures were used to obtain green needles of [Pr2(fum)
(malate)2(phen)2]n$n1.25H2O 2 (yield: 30 %, Calcd (%): C,
41.46; H, 2.75; N, 5.37. Found (%): C, 41.24; H, 2.39; N, 5.60).
2.541(6)
2.558(7)
2.64 (9)
2.649(9)
2.396(5)
2.399(5)
2.402(5)
2.569(5)
2.571(5)
2.572(5)
2.581(5)
2.630(6)
2.669(7)
Symmetry transformations used to generate equivalent atoms: 1: A KxC2,
Ky, KzC1; B KxC2, Ky, KzC2. 2: A KxC1,KyC2,Kz; B KxC1,KyC
2,KzC1.

16
L.-P. Zhang et al. / Journal of Molecular Structure 787 (2006) 14–17
fumarate, one carboxylate oxygen atom [O (2A)] from
S-malate (1A) which is generated through symmetry trans-
formation (KxC2, Ky, KzC1) from R-malate (1), and one
carboxylate oxygen atom [O (7B)] from R-malate (1B) which
is generated through symmetry transformation (KxC2, Ky,
KzC2) from S-malate (1). Eu (III) ions are connected into 1D
chains by R- and S-malate ligands (Fig. 2). One carboxylate
group of fumarate ligand coordinates to Eu (III) ions in
bridging bidentate mode, and the other protrude from the chain
hydrogen bonding to hydroxyl groups from neighboring chain.
Phen ligands coordinate to Eu (III) ions in chelating mode and
protrude from the polymeric chain. Two types of p–p stacking
interactions exist between two adjacent chains (Fig. 3). The
average distances between two phen ligands from two
S-malate (1A)
R-malate (1B)
˚
neighboring chains are 3.2779 and 3.2771 A, respectively.
Besides, weak C–H–O hydrogen bonds are observed between
phen and malate ligands from different chains, and between
phen and lattice water molecules. Relevant hydrogen bond
parameters are listed in Table 3. The coordinates of hydrogen
atoms marked with an asterisk from lattice water could not be
specified because of disordered state. So we can only guess the
probably hydrogen bonding interactions between lattice water
and uncoordinated carboxylate group from fumarate. The
complicated hydrogen bonding and p–p stacking interactions
between chains result in 3D supramolecular structure (Fig. 3).
R-malate (1)
S-malate (1)
Fig. 1. Coordination environment of Eu(III) ions in complex 1 showing 50%
thermal ellipsoids. All H atoms and C atoms from phen are omitted for clarity.
atoms [O (1) and O (4)] and one hydroxyl oxygen atom [O (3)]
from R-malate (1), two carboxylate oxygen atoms [O (6) and O
(9)] and one hydroxyl oxygen atom [O (8)] from S-malate (1),
one carboxylate oxygen atom [O (11)] from fumarate and two
nitrogen atoms [N (1) and N (2)] from phen. Eu (2) is also nine-
coordinated but with different environment. Eu (2) is
coordinated by two carboxylate oxygen atoms [O (4) and O
(5)] from R-malate (1), two carboxylate oxygen atoms [O (9)
and O (10)] from S-malate (1), two nitrogen atoms [N (3) and N
(4)] from phen, one carboxylate oxygen atom [O (12)] from
3.2. IR spectra
In both spectra, C–H (from phen) stretching vibrations
appear above 3000 cmK1 and characteristic C–H out-of-plane
bending vibrations are seen at about 840 and 725 cmK1
indicating the presence of phen ligands [8]. The O–H (from
,
Fig. 2. Projection of complex 1 down b-axis showing hydrogen bonding between carboxylate of fumarate and hydroxyl of malate from two adjacent chains (all C and
H atoms from phen are omitted for clarity).

L.-P. Zhang et al. / Journal of Molecular Structure 787 (2006) 14–17
17
Fig. 3. Packing diagram of complex 1 viewed along c-axis. All H atoms are omitted for clarity.
Table 3
Hydrogen bonds parameters (A, 8) for complexes 1
˚
D–H
d(D–H)
d(H/A)
:DHA
d(D/A)
Position of A
O(3)–H(3A)
O(8)–H(8A)
C(8)–H(8)
0.930
0.930
0.930
0.930
0.930
0.930
1.663
1.723
2.482
2.691
2.575
2.599
146.8
141.3
144.4
128.5
152.6
128.8
2.494
2.517
3.284
3.350
3.428
3.263
2.651
2.727
2.554
2.833
O(14) [xK1,y,z]
O(13) [xK1,y,z]
O(1) [KxC2,KyC1,KzC1]
O(6) [x,yK1,z]
O(17)
C(15)–H(15)
C(5)–H(5)
C(18)–H(18)
O(16)–H(16*)
O(16)–H(16*)
O(17)–H(17*)
O(17)–H(17*)
O(16)
O(13) [x,yK1,z]
O(13) [KxC3,KyK1,KzC2]
O(14) [xK1,yC1,z]
O(14) [KxC2,KyC1,KzC1]
* The hydrogen atoms marked with asterisks are disordered which coordinations could not be specified.
lattice water molecules or hydroxyl of malate ligands)stretching
bands centered at 3442 cmK1 are broadened by hydrogen
bonding [9]. Asymmetric and symmetric C–O stretching bands
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The crystallographic data have been deposited at Cambridge
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Science Research Project of the Education Department of
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