Synthesis, characterization, and properties of copper and manganese complexes with 5-(benzimidazol-1-ylmethyl)isophthalate

Article abstract of DOI:10.1080/00958972.2012.712116

Four new complexes, [Cu(L)] (1), [Cu₂(L)(dpe) _0.5]2.5H₂O (2), [Mn(L)] (3), and [Mn(L)(pybim)] (4) [H₂L=5-(benzimidazol-1-ylmethyl)isophthalic acid, dpe=1,2-di(pyridin-4-yl)ethylene, pybim=2-(pyridin-2-yl)-1H-benzimidazole], have been synthesized under hydrothermal conditions and characterized by single-crystal and powder X-ray diffractions, FT-IR, and elemental analysis. The crystal structural analyses reveal that 1 and 4 are uninodal 3-connected 2-fold interpenetrated 2-D networks with (6³) topology, 2 shows an infinite 1-D double-stranded chain structure, and 3 exhibits a uninodal 4-connected 2-D network with (4⁴6²) topology. The factors influencing the structures of the coordination polymers are discussed. In addition, the thermal stabilities of 1-4, second-order non-linear optical effect of 1, and preliminary magnetic property of 3 have also been investigated.

Full text of DOI:10.1080/00958972.2012.712116

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Synthesis, characterization, and
properties of copper and manganese
complexes with 5-(benzimidazol-1-
ylmethyl)isophthalate
Hai-Wei Kuai a , Taka-Aki Okamura b & Wei-Yin Sun a
a State Key Laboratory of Coordination Chemistry, Coordination
Chemistry Institute, School of Chemistry and Chemical
Engineering, Nanjing National Laboratory of Microstructures ,
Nanjing University , Nanjing 210093 , China
b Department of Macromolecular Science , Graduate School of
Science, Osaka University , Toyonaka , Osaka 560-0043 , Japan
Accepted author version posted online: 16 Jul 2012.Published
online: 27 Jul 2012.
To cite this article: Hai-Wei Kuai , Taka-Aki Okamura & Wei-Yin Sun (2012) Synthesis,
characterization, and properties of copper and manganese complexes with 5-(benzimidazol-1-
ylmethyl)isophthalate, Journal of Coordination Chemistry, 65:18, 3147-3159, DOI:
10.1080/00958972.2012.712116
To link to this article: http://dx.doi.org/10.1080/00958972.2012.712116
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Journal of Coordination Chemistry
Vol. 65, No. 18, 20 September 2012, 3147–3159
Synthesis, characterization, and properties of
copper and manganese complexes with
5-(benzimidazol-1-ylmethyl)isophthalate
HAI-WEI KUAIy, TAKA-AKI OKAMURAz and WEI-YIN SUN*y
yState Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute,
School of Chemistry and Chemical Engineering, Nanjing National Laboratory of
Microstructures, Nanjing University, Nanjing 210093, China
zDepartment of Macromolecular Science, Graduate School of Science,
Osaka University, Toyonaka, Osaka 560-0043, Japan
(Received 19 April 2012; in final form 2 July 2012)
Four new complexes, [Cu(L)] (1), [Cu2(L)(dpe)0.5] ꢀ 2.5H2O (2), [Mn(L)] (3), and
[Mn(L)(pybim)] (4) [H2L ¼ 5-(benzimidazol-1-ylmethyl)isophthalic acid, dpe ¼ 1,2-di(pyridin-
4-yl)ethylene, pybim ¼ 2-(pyridin-2-yl)-1H-benzimidazole], have been synthesized under hydro-
thermal conditions and characterized by single-crystal and powder X-ray diffractions, FT-IR,
and elemental analysis. The crystal structural analyses reveal that 1 and 4 are uninodal
3-connected 2-fold interpenetrated 2-D networks with (63) topology, 2 shows an infinite 1-D
double-stranded chain structure, and 3 exhibits a uninodal 4-connected 2-D network with
(44 ꢀ 62) topology. The factors influencing the structures of the coordination polymers are
discussed. In addition, the thermal stabilities of 1–4, second-order non-linear optical effect of 1,
and preliminary magnetic property of 3 have also been investigated.
Keywords: Copper and manganese complexes; Crystal structure; Metal–organic frameworks;
NLO effect
1. Introduction
The crystal engineering of metal–organic frameworks (MOFs) has received attention
because of their intriguing structures, topologies, and potential applications in
magnetism, optical materials, catalysis, molecular/ionic recognition, and adsorption
[1]. Typically, construction of MOFs involves interconnections of metal centers and
bridging ligands to generate overall architectures, which can be influenced by factors
such as the nature of metal ions and ligands, auxiliary ligands, and reaction conditions
[2]. Structures and properties of the resultant coordination complexes may be closely
related to the intrinsic features of ligands [3]. Therefore, the design of ligands becomes
extremely important in this field. Among the well-employed organic ligands, N- and/or
*Corresponding author. Email: sunwy@nju.edu.cn
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online ß 2012 Taylor & Francis
http://dx.doi.org/10.1080/00958972.2012.712116

3148
H.-W. Kuai et al.
O-donor multi-dentate ligands are excellent building blocks for construction of
desirable frameworks. However, compared with other N- and/or O-donor ligands,
those containing both sterically hindered N-donors such as benzimidazolyl and
carboxylate may exhibit distinctive features and induce new structural evolution, which
may be helpful in the exploration of new crystalline materials and the study of
correlation between the reaction conditions and structures of resultant complexes [4].
Recently, we have focused our attention on utilization of benzimidazol-1-yl and
carboxylate-containing 5-(benzimidazol-1-ylmethyl)isophthalic acid (H2L) as a building
block for construction of coordination polymers with desirable structures and
properties. The arene-cored H2L exhibits a great advantage over other N- and/or
O-donors since it possesses two functional groups, carboxylate, and sterically hindered
benzimidazol-1-yl groups. Due to different coordination of carboxylates such as
ꢀ1ꢁꢁ1:ꢁ0-monodentate, ꢀ1ꢁꢁ1:ꢁ1-chelating and ꢀ2ꢁꢁ1:ꢁ1-bridging modes, H2L can act
as a multi-connector in assembly of complexes with diverse structures. Metal centers
may also be expected to be bridged by carboxylates to mediate magnetic interactions [5].
The sterically hindered benzimidazolyl group may induce new structural evolution and
maintain a specific coordination configuration [6]. As an aromatic dicarboxylate, L2–
can act as a bridging rod. The effect of steric hindrance of benzimidazolyl is important
in the assembly process. Herein, we report preparation and characterization of four
coordination polymers, [Cu(L)] (1), [Cu2(L)(dpe)0.5] ꢀ 2.5H2O (2), [Mn(L)] (3), and
[Mn(L)(pybim)] (4) [dpe ¼ 1,2-di(pyridin-4-yl)ethylene, pybim ¼ 2-(pyridin-2-yl)-1H-
benzimidazole]. The influence of auxiliary ligands, steric hindrance of ligands, and
solvent on the structures of coordination polymers will be discussed. Thermal stabilities
of 1–4, second-order non-linear optical (NLO) effect of 1, and preliminary magnetic
property of 3 have also been investigated.
2. Experimental
2.1. Materials and methods
All commercially available chemicals and solvents are of reagent grade and used as
received. According to the literature [7], a slight revised experimental procedure was
used to prepare the H2L. Elemental analyses of C, H, and N were taken on a Perkin-
Elmer 240C elemental analyzer at the analysis center of Nanjing University. The
content of metal in complexes was determined by measurements of inductively coupled
plasma (ICP) on a J-A1100 (Jarrell-Ash, USA) ICP spectrometer. Infrared spectra (IR)
were recorded on a Bruker Vector22 FT-IR spectrophotometer by using KBr pellets.
Thermogravimetric analyses (TGA) were performed on a simultaneous SDT 2960
thermal analyzer under nitrogen with a heating rate of 10ꢂC minꢁ1. Powder X-ray
diffraction (PXRD) patterns were measured on a Shimadzu XRD-6000 X-ray
˚
diffractometer with Cu-Ka (ꢂ ¼ 1.5418 A) radiation at room temperature. The
second-order NLO intensity was estimated by measuring a powder sample of
80–150 mm diameter in the form of a pellet relative to urea. A pulsed Q-switched
Nd:YAG laser at a wavelength of 1064 nm was used to generate a second-harmonic-
generation (SHG) signal from powder samples. The backscattered SHG light was
collected by a spherical concave mirror and passed through a filter that transmits only

5-(Benzimidazol-1-ylmethyl)isophthalate
3149
532 nm radiation. The magnetic measurement in the temperature range 1.8–300 K was
carried out on a Quantum Design MPMS7 SQUID magnetometer in a field of 2000 Oe.
Diamagnetic corrections were made using Pascal’s constants.
2.2. Synthesis
2.2.1. Synthesis of [Cu(L)] (1). Reaction mixture of Cu(NO3)2 ꢀ 3H2O (24.1 mg,
0.1 mmol), H2L (29.6 mg, 0.1 mmol), 2 mL ethanol, and NaOH (8.0 mg, 0.2 mmol) in
12 mL of water was sealed in a 16 mL Teflon-lined stainless steel container and heated
at 180ꢂC for 3 days. After cooling to room temperature, dark-green platelet crystals of 1
were collected by filtration and washed by water and ethanol several times with a yield
of 32%. Anal. Calcd for C16H10N2O4Cu (%): C, 53.71; H, 2.82; N, 7.83; Cu, 17.76.
Found (%): C, 53.56; H, 2.62; N, 7.59; Cu, 17.60. IR (KBr pellet, cmꢁ1): 1622 (s), 1589
(m), 1517 (s), 1470 (s), 1428 (s), 1394 (m), 1356 (s), 1297 (w), 1255 (w), 1234 (w), 1196
(m), 1124 (w), 1107 (w), 980 (w), 934 (w), 900 (w), 816 (w), 752 (s), 735 (s), 592 (w),
478 (w).
.
2.2.2. Synthesis of [Cu2(L)(dpe)0.5] 2.5H2O (2). Reaction mixture of Cu(NO3)2 ꢀ 3H2O
(24.1 mg, 0.1 mmol), H2L (29.6 mg, 0.1 mmol), dpe (18.2 mg, 0.1 mmol), 2 mL ethanol,
and NaOH (8.0 mg, 0.2 mmol) in 12 mL of water was sealed in a 16 mL Teflon-lined
stainless steel container and heated at 180ꢂC for 3 days. After cooling to room
temperature, yellow block crystals of 2 were collected by filtration and washed by water
and ethanol several times with a yield of 36% based on H2L. Anal. Calcd for
C44H40N6O13Cu4 (%): C, 47.40; H, 3.62; N, 7.54; Cu, 22.82. Found (%): C, 47.26; H,
3.42; N, 7.59; Cu, 22.54. IR (KBr pellet, cmꢁ1): 3425 (m), 1613 (s), 1576 (s), 1512 (w),
1432 (w), 1398 (m), 1343 (s), 1297 (m), 1267 (m), 1234 (m), 1208 (m), 1187 (m), 1154 (w),
1102 (m), 980 (w), 841 (w), 748 (s), 638 (m), 613 (m), 554 (m), 431 (m).
2.2.3. Synthesis of [Mn(L)] (3). A mixture of MnCl2 ꢀ 4H2O (19.8 mg, 0.1 mmol), H2L
(29.6 mg, 0.1 mmol), and NaOH (8.0 mg, 0.2 mmol) in 12 mL of water was stirred for
10 min in air, and then transferred to a 16 mL Teflon-lined stainless steel container and
heated at 180ꢂC for 3 days. After cooling to room temperature, colorless block crystals
of 3 were collected by filtration and washed by water and ethanol several times with a
yield of 36%. Anal. Calcd for C16H10N2O4Mn (%): C, 55.03; H, 2.89; N, 8.02; Mn,
15.73. Found (%): C, 54.86; H, 2.99; N, 7.89; Mn, 15.56. IR (KBr pellet, cmꢁ1): 1621
(s), 1569 (s), 1545 (s), 1509 (s), 1453 (s), 1382 (s), 1291 (w), 1241 (w), 1185 (m), 1130 (w),
1104 (w), 967 (w), 912 (w), 871 (w), 806 (w), 775 (m), 760 (s), 740 (s), 725 (s), 679 (w),
649 (w), 593 (w), 527 (w).
2.2.4. Synthesis of [Mn(L)(pybim)] (4). Reaction mixture of MnCl2 ꢀ 4H2O (19.8 mg,
0.1 mmol), H2L (29.6 mg, 0.1 mmol), pybim (19.5 mg, 0.1 mmol), and NaOH (8.0 mg,
0.2 mmol) in 10 mL H2O was sealed in a 16 mL Teflon-lined stainless steel container and
heated at 180ꢂC for 3 days. After cooling to room temperature, pale yellow crystals of 4
were isolated by filtration and washed by water and ethanol several times in 42% yield
based on H2L. Anal. Calcd for C28H19N5O4Mn (%): C, 61.77; H, 3.52; N, 12.86; Mn,

3150
H.-W. Kuai et al.
10.09. Found (%): C, 62.02; H, 3.80; N, 12.66; Mn, 10.32. IR (KBr pellet, cmꢁ1): 1624
(s), 1593 (s), 1537 (s), 1500 (m), 1457 (s), 1414 (s), 1383 (m), 1345 (s), 1290 (m), 1234 (m),
1197 (w), 1148 (w), 974 (m), 900 (w), 801 (m), 758 (s), 708 (s), 690 (m), 567 (w), 424 (m).
2.3. X-ray crystallography
The X-ray diffraction data for 1 were collected on a Rigaku Rapid II imaging plate area
˚
detector with Mo-Ka radiation (ꢂ ¼ 0.71075 A) using MicroMax-007HF microfocus
rotating anode X-ray generator and VariMax-Mo optics at 200 K. The structure of 1
was solved by direct methods with SIR92 [8] and expanded using Fourier techniques [9].
Crystallographic data collections for 2–4 were carried out on a Bruker Smart Apex
CCD area-detector diffractometer using graphite-monochromated Mo-Ka radiation
˚
(ꢂ ¼ 0.71073 A) at 293 K. The diffraction data were integrated using the SAINT
program [10], which was also used for intensity corrections for Lorentz and polarization
effects. Semi-empirical absorption correction was applied using SADABS [11]. The
structures were solved by direct methods and all non-hydrogen atoms were refined
anisotropically on F2 by full-matrix least-squares using the SHELXL-97 crystallo-
graphic software package [12]. In 1–4, all hydrogen atoms attached to carbon were
generated geometrically; hydrogen atoms in O5 in 2 and N3 in 4 were found at
reasonable positions in the difference Fourier maps and located there; part of the
hydrogen atoms in lattice water of 2 could not be located and thus were not included in
refinement. Details of crystal parameters, data collection, and refinements for the
complexes are summarized in table 1. Selected bond lengths and angles of 1–4 are listed
in table 2.
Table 1. Crystallographic data and structure refinement details for 1–4.
1
2
3
4
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
C16H10N2O4Cu C44H40N6O13Cu4 C16H10N2O4Mn C28H19N5O4Mn
357.80
200
1114.98
293(2)
349.20
293(2)
544.42
293(2)
Monoclinic
Pc
Monoclinic
P21/c
Monoclinic
P21/c
Monoclinic
P21/c
ꢂ
˚
Unit cell dimensions (A, )
a
b
c
6.697(6)
8.639(8)
11.398(11)
90.93(4)
659.3(10), 2
1.802
362
3.04–25.00
4670
7.078(5)
27.526(5)
11.604(5)
102.393(5)
2208.1(19), 2
1.677
8.2678(17)
11.577(2)
17.036(3)
119.033(7)
1425.7(5), 4
1.627
15.1916(19)
10.7173(14)
15.777(2)
114.051(2)
2345.6(5), 4
1.542
ꢃ
Volume (A ), Z
3
˚
Calculated density (g cmꢁ3
F(000)
)
1132
708
1116
ꢄ range (ꢂ)
Reflections collected
1.94–28.00
13,762
5260
2.23–27.81
8739
3314
2.37–27.71
14,808
5429
Independent reflections on F2 2140
Goodness-of-fit
R1 [I 4 2ꢅ (I)]a
wR2 [I 4 2ꢅ (I)]b
1.179
0.0687
0.1835
1.049
0.0588
0.1781
0.906
0.0340
0.0626
1.032
0.0539
0.1208
2
2
aR1 ¼ ÆjjFoj ꢁ jFcjj/ÆjFoj, bwR2 ¼ jÆw(jFoj ꢁ jFcj )j/Æjw(Fo)2j1/2, where w ¼ 1/[ꢅ2(Fo2) þ (aP)2 þ bP]; P ¼ (Fo2 þ 2Fc2)/3.

5-(Benzimidazol-1-ylmethyl)isophthalate
3151
3. Results and discussion
3.1. Preparation
Complexes 1–4 were obtained under hydrothermal conditions at 180ꢂC. NaOH was
used as alkaline reagent to neutralize the carboxylic acid. Reduction of Cu(II) to Cu(I)
occurred in formation of 2 as reported previously [13]. In addition, it was found that 2
can only be obtained in the water–ethanol system although several systems such as
water, water–methanol, water–DMF, and water–acetonitrile have been tried. This
implies that the solvent can subtly influence formation of coordination polymers.
Complexes 1–4 are stable in air in the solid state.
3.2. Structural description
3.2.1. Crystal structure of [Cu(L)] (1). The structural analysis shows that 1 crystallizes
in monoclinic acentric space group Pc with Flack parameter of ꢁ0.02(3). As exhibited
ꢂ
˚
Table 2. Selected bond lengths (A) and angles ( ) for 1–4
1
Cu(1)–N(12)
Cu(1)–O(3)#2
O(1)#1–Cu(1)–N(12)
O(4)#2–Cu(1)–N(12)
O(1)#1–Cu(1)–O(4)#2
1.933(8)
1.978(6)
101.8(3)
159.7(2)
98.6(3)
Cu(1)–O(1)#1
Cu(1)–O(4)#2
O(3)#2–Cu(1)–N(12)
O(1)#1–Cu(1)–O(3)#2
O(3)#2–Cu(1)–O(4)#2
1.893(7)
2.014(6)
94.2(3)
164.0(3)
65.5(3)
2
Cu(1)–O(1)
Cu(2)–N(11)
O(1)–Cu(1)–N(3)
1.831(3)
1.863(4)
171.82(19)
Cu(1)–N(3)
Cu(2)–O(3)#1
O(3)#1–Cu(2)–N(11)
1.870(4)
1.866(3)
175.23(19)
3
Mn(1)–O(1)
Mn(1)–O(4)#1
Mn(1)–O(3)#3
O(1)–Mn(1)–O(2)
O(1)–Mn(1)–N(12)#2
O(2)–Mn(1)–O(4)#1
O(2)–Mn(1)–O(3)#3
O(3)#3–Mn(1)–O(4)#1
2.1836(16)
2.0699(15)
2.0807(14)
59.10(5)
110.11(7)
89.80(6)
Mn(1)–O(2)
Mn(1)–N(12)#2
2.2201(15)
2.1366(17)
O(1)–Mn(1)–O(4)#1
O(1)–Mn(1)–O(3)#3
O(2)–Mn(1)–N(12)#2
O(4)#1–Mn(1)–N(12)#2
O(3)#3–Mn(1)–N(12)#2
130.50(6)
97.56(6)
101.50(7)
113.48(6)
90.91(6)
156.12(6)
103.97(6)
4
Mn(1)–O(1)
Mn(1)–N(2)
Mn(1)–O(3)#2
2.066(2)
2.197(3)
2.152(2)
Mn(1)–N(1)
Mn(1)–N(12)#1
Mn(1)–O(4)#2
2.497(3)
2.188(3)
2.468(2)
O(1)–Mn(1)–N(1)
O(1)–Mn(1)–N(12)#1
O(1)–Mn(1)–O(4)#2
N(1)–Mn(1)–N(12)#1
O(4)#2–Mn(1)–N(1)
O(3)#2–Mn(1)–N(2)
O(3)#2–Mn(1)–N(12)#1
O(3)#2–Mn(1)–O(4)#2
161.52(9)
95.71(10)
102.40(9)
85.70(10)
86.01(9)
142.25(10)
89.75(9)
56.19(8)
O(1)–Mn(1)–N(2)
O(1)–Mn(1)–O(3)#2
N(1)–Mn(1)–N(2)
O(3)#2–Mn(1)–N(1)
N(2)–Mn(1)–N(12)#1
O(4)#2–Mn(1)–N(2)
O(4)#2–Mn(1)–N(12)#1
92.24(10)
116.61(9)
70.35(10)
81.78(9)
112.26(10)
95.93(9)
145.78(8)
Symmetry transformations used to generate equivalent atoms: For 1, #1 x, y, 1 þ z; #2 ꢁ1 þ x, 2 ꢁ y, 1/2 þ z; for 2, #1 ꢁ1 þ x,
y, ꢁ1 þ z; for 3, #1 ꢁ x, 1/2 þ y, 3/2 ꢁ z; #2 ꢁ x, 1 ꢁ y, 1 ꢁ z; #3 x, 3/2 ꢁ y, ꢁ1/2 þ z; for 4, #1 x, ꢁ1 þ y, z; #2 x, 1/2 ꢁ y,
1/2 þ z.

3152
H.-W. Kuai et al.
in figure 1(a), there are one Cu(II) ion and one L2ꢁ ligand in the asymmetrical unit of 1.
Each Cu(II) is four-coordinate by one nitrogen atom from benzimidazolyl of one L2ꢁ
ligand and three carboxylate oxygen atoms from another two different L2ꢁ ligands to
furnish distorted square-planar coordination. Thus the Cu(II) center can be regarded as
a 3-connected node. Each L2ꢁ is a ꢀ3-connector using its two carboxylates with
ꢀ1ꢁꢁ1:ꢁ0-monodentate and ꢀ1ꢁꢁ1:ꢁ1-chelating coordination, respectively (scheme 1)
and benzimidazolyl. Infinite interconnection of metals and L2ꢁ leads to formation of a
2-D structural motif (figure 1b). From the perspective view of topology, if each Cu(II)
and L2ꢁ is treated as a node, the structure of 1 can be simplified into a uninodal
3-connected 2-D network (figure 1c). The flexible 2-D networks of 1 twist and distort to
some extent to interpenetrate each other. Thus 1 can be described as a uninodal
3-connected 2-fold interpenetrated 2-D net with (63) topology (figure S1).
.
3.2.2. Crystal structure of [Cu2(L)(dpe)0.5] 2.5H2O (2). When dpe was introduced into
the reaction system as an auxiliary ligand, 2 was obtained. It crystallizes in the
monoclinic P21/c space group. As shown in figure 2(a), the asymmetric unit of 2 consists
of two crystallographically independent Cu(I), one L2ꢁ ligand, half of dpe, and two and
a half lattice water molecules. Each Cu(I) in 2 is two-coordinate with a carboxylate
oxygen and a nitrogen atom from benzimidazolyl of L2ꢁ or dpe to generate a nearly
linear coordination geometry. An infinite 1-D chain is formed via interconnection of
Cu2 and L2ꢁ, which is further linked by dpe to give a 1-D neutral double-stranded
chain (figure 2b). Apart from the coordination, hydrogen-bonding interactions stabilize
resultant solid-state structure. According to their function in constructing the
supramolecule, we divide the hydrogen bonds into two groups: (1) O5–H16ꢀ ꢀ ꢀO2#1
and C18–H10ꢀ ꢀ ꢀO5. These interactions link adjacent double-stranded chains to form a
2-D network (figures S2a and S2b) and (2) C12-H6ꢀ ꢀ ꢀO4#2. Hydrogen bonds further
connect 2-D layers leading to a 3-D supramolecular structure (figures S2c and S2d). The
hydrogen-bonding data for 2 are summarized in table S1.
3.2.3. Crystal structure of [Mn(L)] (3). Complex 3 crystallizes in the monoclinic P21/c
space group with an asymmetric unit of 3 composed of one Mn(II) ion and one L2ꢁ
ligand. As shown in figure 3(a), each Mn(II) is five-coordinate with NO4 donor set by
one benzimidazolyl nitrogen atom from one L2ꢁ ligand and four carboxylate oxygen
atoms from another three different L2ꢁ ligands to furnish a distorted square-pyramidal
coordination geometry. The equatorial plane is defined by four oxygen atoms with
˚
˚
mean deviation of 0.24 A; Mn(II) deviates 0.49 A from this plane toward the apex. One
carboxylate of L2ꢁ in 3 adopts ꢀ1ꢁꢁ1:ꢁ1-chelating coordination, while the other one
exhibits ꢀ2ꢁꢁ1:ꢁ1-bridging mode (scheme 1) with Mn–O bond lengths of 2.0699(15) and
1
1
˚
2.0807(14) A (table 1). Two Mn(II) are linked by two ꢀ2ꢁꢁ :ꢁ -bridging carboxylates to
˚
form a [Mn2(COO)2] sub-unit with Mnꢀ ꢀ ꢀMn distance of 3.96 A, indicating that there
might be weak magnetic interactions within binuclear units (vide post). In 3, each L2ꢁ
bridges four different Mn(II)’s and each Mn(II) is coordinated by four different L2ꢁ
ligands. This linkage infinitely extends to form a 2-D network (figure 3b). The topology
for both Mn(II) and L2ꢁ can be regarded as 4-connecting nodes. As a result, 3 can be
simplified into a uninodal (4,4)-connected 2-D sql network with the point (Schlafli)
symbol of (44.62) (figure 3c).
¨

5-(Benzimidazol-1-ylmethyl)isophthalate
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Figure 1. (a) The coordination environment of Cu(II) in 1 with ellipsoids drawn at the 30% probability level.
Hydrogen atoms are omitted for clarity. Symmetry codes: A, x, y, 1 þ z; B, ꢁ1 þ x, 2 ꢁ y, 1/2 þ z. (b) 2-D
network of 1. (c) Schematic representation of the uninodal 3-connected 2-D network with (63) topology of 1.
3.2.4. Crystal structure of [Mn(L)(pybim)] (4). Single-crystal X-ray diffraction analysis
revealed that 4 is also in the monoclinic P21/c space group. The asymmetric unit of 4
contains one Mn(II) ion, one L2ꢁ ligand, and one pybim. Each Mn(II) with N3O3 donor

3154
H.-W. Kuai et al.
Scheme 1. Coordination modes of L2ꢁ in 1–4.
Figure 2. (a) The coordination environment of Cu(I) in 2 with ellipsoids drawn at the 30% probability level.
Hydrogen atoms and lattice water molecules are omitted for clarity. Symmetry codes: A, ꢁ1 þ x, y, ꢁ1 þ z.
(b) The 1-D chain of 2.
set is six-coordinate by three carboxylate oxygen atoms from two different L2ꢁ ligands,
two nitrogen atoms from coordinated pybim, and one nitrogen atom from
benzimidazolyl of L2ꢁ with heavily distorted octahedral coordination geometry
(figure 4a). The equatorial plane is composed of two carboxylate oxygen atoms, one

5-(Benzimidazol-1-ylmethyl)isophthalate
3155
Figure 3. (a) The coordination environment of Mn(II) in 3 with 30% probability. Hydrogen atoms
were omitted for clarity. Symmetry codes: A, ꢁx, 1 ꢁ y, 1 ꢁ z; B, x, 3/2 ꢁ y, ꢁ1/2 þ z; C, ꢁx, 1/2 þ y, 3/2 ꢁ z.
(b) 2-D network of 3. (c) Schematic representation of the uninodal 4-connected 2-D network of 3 with (44 ꢀ 62)
topology.

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H.-W. Kuai et al.
Figure 4. (a) The coordination environment of Mn(II) in 4 with 30% probability. Hydrogen atoms were
omitted for clarity. Symmetry codes: A, x, ꢁ1 þ y, z; B, x, 1/2 ꢁ y, 1/2 þ z. (b) 2-D network of 4. (c) Schematic
representation of the uninodal 3-connected 2-D network of 4 with (63) topology.
benzimidazolyl nitrogen atom, and one nitrogen from pybim; the axial positions are one
carboxylate oxygen and nitrogen of pybim. One carboxylate of L2ꢁ in 4 adopts
ꢀ1ꢁꢁ1:ꢁ0-monodentate coordination while the other one is ꢀ1ꢁꢁ1:ꢁ0-chelating
(scheme 1). In 4, each L2ꢁ bridges three different Mn(II) ions and in turn each
Mn(II) is coordinated by three different L2ꢁ ligands. This connection extends infinitely
to form a 2-D network (figure 4b). Both L2ꢁ and Mn(II) in 4 can be regarded as
3-connectors, Thus the network of 4 can be simplified into a uninodal 3-connected 2-D
network with the point (Schlafli) symbol of (63) (figure 4c).
¨
3.2.5. Structural comparison of 1–4. Complexes 1–4 have diverse architectures from
1-D chain to 2-D networks with different topologies (vide supra). The different
structures of 1 and 2 as well as 3 and 4 can be ascribed to the effect of auxiliary ligand
since the other experimental conditions are the same. The difference between 1 and 3 is
caused by the different centers with different coordination number and geometry. Both
1 and 4 are 2-D networks with the same (63) topology; however, 1 shows a 2-fold
interpenetration, while no interpenetration was found in 4, perhaps due to steric
hindrance of pybim.
3.3. PXRD, IR, and TGA
The pure phases of 1–4 were confirmed by PXRD measurements. As shown in
figure S3, each PXRD pattern of the as-synthesized sample is consistent with the
simulated one.

5-(Benzimidazol-1-ylmethyl)isophthalate
3157
Complete deprotonation of H2L to give L2ꢁ in 1–4 was confirmed by crystal
structures and IR spectral data (see section 2) since no characteristic vibrations for
ꢁCOOH between 1680 and 1760 cmꢁ1 were observed [14].
Complexes 1–4 were subjected to TGA under nitrogen to ascertain their thermal
stability from 30ꢂC to 660ꢂC (figure S4). In the TGA curves of 1, 3, and 4, no obvious
weight loss was observed before decomposition of frameworks at ca 283ꢂC for 1, 538ꢂC
for 3, and 428ꢂC for 4, confirming no solvent in the architectures of these complexes.
For 2, a weight loss of 8.1% from 72ꢂC to 156ꢂC is assigned to release of lattice water
molecules (Calcd 8.1%), and the decomposition of the residue was observed at 270ꢂC.
3.4. NLO property of 1
Non-centrosymmetric structures may have second-order NLO effect [14, 15]. Complex
1 crystallizes in the acentric space group Pc which belongs to the polar point group C23.
Therefore, the optical properties were investigated to evaluate potential applications as
second-order NLO materials. Approximate estimations were carried out on a pulsed
Q-switched Nd:YAG laser at a wavelength of 1064 nm. The result obtained from a
powdered sample (80–150 mm diameters) as a pellet (Kurtz powder test) was compared
with those obtained for urea. The preliminary experimental results revealed that 1
exhibits modest powder SHG intensity compared to that for urea with a response of
0.8 times.
3.5. Magnetic property of 3
In 3, two Mn(II) ions are bridged by carboxylates to form a dinuclear [Mn2(COO)2]
˚
with Mnꢀ ꢀ ꢀMn distance of 3.96 A, which may mediate magnetic interactions [16].
Therefore, the magnetism of 3 was investigated from 1.8 to 300 K with a 2000 Oe
applied magnetic field. The magnetic behavior of 3 in the form of ꢆM, ꢆꢁM1, and ꢆMT
versus T are depicted in figure 5. The ꢆMT value of 5.52 emu K molꢁ1 at 300 K is higher
than the value expected for magnetically isolated Mn(II) (4.38 emu K molꢁ1, g ¼ 2.0),
suggesting the existence of magnetic interactions between neighboring Mn(II) centers.
As the temperature is gradually lowered, the ꢆMT value decreases continuously with an
extrapolated value which vanishes when T approaches 0; the ꢆM value increases
smoothly to reach 0.179 emu molꢁ1 at 1.8 K. The ꢆꢁM1 value (above 28 K) obeys the
Curie–Weiss law with a Weiss constant (ꢄ) of ꢁ18.36 K and a Curie constant (C) of
3.06 emu K molꢁ1. The negative value for ꢄ confirms antiferromagnetic interactions
between neighboring Mn(II) centers [17].
4. Conclusion
Hydrothermal reactions of the semi-rigid H2L with copper and manganese salts at
180ꢂC in the presence/absence of N-donor auxiliary ligands provide four coordination
polymers. Complex 1 shows a uninodal 3-connected 2-fold interpenetrated 2-D network
with (63) topology; 2 has a 1-D double-stranded chain structure, which can be extended
to 3-D supramolecular net by hydrogen-bonding; 3 exhibits a uninodal 4-connected 2-D

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H.-W. Kuai et al.
Figure 5. Temperature dependences of magnetic susceptibility of ꢆM, ꢆꢁM1, and ꢆMT for 3. The solid line
represents the fitted curve.
network with (44 ꢀ 62) topology; 4 displays a uninodal 3-connected 2-D network with
(63) topology. The results of this study not only imply that steric hindrance and
auxiliary ligands play an important role in construction of coordination polymers, but
also afford a good example of solvent controlled polymeric architecture, as previously
reported copper and manganese coordination polymers with benzenedicarboxylate
ligands [18].
Supplementary material
Crystallographic data for the structures reported in this article have been deposited with
the Cambridge Crystallographic Data Centre as Supplementary Publication Nos
CCDC-876693 (1), 876694 (2), 869284 (3), and 869285 (4). Copies of the data can be
obtained at http://www.ccdc.cam.ac.uk/conts/retrieving.html (or from the CCDC, 12
Union Road, Cambridge CB2 1EZ, UK; Fax:þ44 1223336033; E-mail:
deposit@ccdc.cam.ac.uk).
Acknowledgments
This work was financially supported by the National Natural Science Foundation of
China (Grant nos 91122001 and 21021062) and the National Basic Research Program
of China (Grant no. 2010CB923303).

5-(Benzimidazol-1-ylmethyl)isophthalate
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