Coordination polymers and monomers based on new aminocarboxylate ligands: A cadmium(II) polymer containing dimeric aqua-bridged cadmium complex governed by polymeric chain

Article abstract of DOI:10.1016/j.ica.2011.06.018

The synthesis and characterization of novel coordination polymers [Co(HCCB)(H₂O)₂]_n (1), [Zn(HCCB)(H ₂O)₂]_n (2), {[Cd(HCCB)₂]·0. 5[Cd(μ-H₂O)(H₂O)₄

Full text of DOI:10.1016/j.ica.2011.06.018

Inorganica Chimica Acta 376 (2011) 195–206
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Coordination polymers and monomers based on new aminocarboxylate ligands:
A cadmium(II) polymer containing dimeric aqua-bridged cadmium complex
governed by polymeric chain
Rampal Pandey a, Mahendra Yadav a, Prashant Kumar a, Pei-Zhou Li b, Sanjay Kumar Singh b,
Qiang Xu b, Daya Shankar Pandey a,
⇑
a Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, U.P., India
b National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis and characterization of novel coordination polymers [Co(HCCB)(H2O)2]n (1),
Received 12 February 2011
Received in revised form 24 May 2011
Accepted 8 June 2011
[Zn(HCCB)(H2O)2]n (2), {[Cd(HCCB)2]ꢀ0.5[Cd(
l-H2O)(H2O)4]2}n (3) and [Cu(HCCB)(H2O)2]n (4) based on
3-(carboxymethylamino)-4-chlorobenzoic acid (H3CCB) and mononuclear complexes [Cu(HBCCB)(-
H2O)]ꢀH2O (5), [Co(HBCCB)(H2O)]ꢀH2O (6), [Zn(HBCCB)(H2O)] (7) and [Cd(HBCCB)(H2O)] (8) containing
3-bis(carboxymethylamino)-4-chlorobenzoic acid (H3BCCB) have been described. The compounds under
investigation have been characterized by elemental analyses, spectral studies and structures of 1–3 and 5
determined crystallographically. Structural data of 1 and 2 revealed that the deprotonated HCCB2ꢁ
bridges metal centers leading to a double stranded 1D chain. On the other hand, the HCCB2ꢁ coordinated
thorough carboxylate oxygen and amino nitrogen in 3 to afford a 1D chain whose charge neutrality is
Available online 16 June 2011
Keywords:
Aminocarboxylates
Coordination polymers
Supramolecular assemblies
Fluorescence
maintained by inclusion of aqua-bridged dimer [{Cd(
(2.754 Å) in 5 imposes a coordination geometry that is half-way between the square planar and square
l
-H2O)(H2O)4}2]4+. Strong Cuꢀ ꢀ ꢀCl interaction
pyramidal. The H3CCB, H3BCCB and 1–3 and 5 are fluorescent at rt. Thermal studies (TG and DSC) on
1–3 suggested higher stability of 2 relative to 1 and 3 [
D
Hf (kcal/mol),
DSf = 152.17, 0.60, 1; 195.56:
0.86, 2; 69.33:0.36, 3].
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
1,2,4,5-benzenetetracarboxylate, etc., have drawn special attention
[21,22]. In the construction of coordination polymers polycarboxy-
lates are preferably employed as bridging ligand owing to their
versatile coordination mode and high structural stability. Deproto-
nated carboxylates generally serve dual purpose, while acting as an
anionic ligand to occupy the coordination sites, these also compen-
sate overall charge [12,13,23,24].
The design and synthesis of novel coordination ligands is chal-
lenging and efforts are being made to tune the nature of interaction
between reactants and metal ions to obtain desired structures
[23–25]. To explore the possibility of formation of new coordination
polymers, aminocarboxylate ligands 3-(carboxymethylamino)-4-
chlorobenzoic acid (H3CCB) and 3-(bis-carboxymethylamino)-4-
chlorobenzoic acid (H3BCCB) have been synthesized and used in
the creation of coordination polymers and mononuclear complexes
based on Co(II), Zn(II), Cd(II) and Cu(II). It is well documented that
divalent zinc and cadmium ions frequently enhance structural
diversity due to the lack of crystal field stabilization, which allows
specific coordination environments responding to geometric and
steric requirement of the carboxylate ligands [26]. Further, most of-
ten aqua ligand exhibits terminal coordination mode however, com-
plexes containing aqua bridges are also known [27,28]. Although, a
The chemistry of coordination polymers have attracted a great
deal of current attention owing to their intriguing molecular archi-
tectures, topologies and potential applications in various areas
[1–8]. In this context, most of the work have been devoted toward
rational design of metal–organic frameworks (MOFs) with specific
structures and topologies displaying significant role in the devel-
opment of functional materials with desirable properties [9–11].
During past few decades numerous coordination polymers have
been successfully designed and synthesized through judicious
choice of the organic ligands and metal ions [12–16]. It has been
demonstrated that resultant structures are often affected by the
geometry of metal ions, nature of the organic ligands, metal to li-
gand ratio, solvent employed, counter anions and the pH of reac-
tion medium, etc. [17–20]. Among these, the choice of organic
ligand plays a crucial role in their synthesis. In this regard, multid-
entate O-donor ligands especially organic aromatic polycarboxy-
lates viz., 1,2-benzene-dicarboxylate, 1,3,5-benzenetricarboxylate,
⇑
Corresponding author. Tel.: +91 542 7602480.
E-mail address: dspbhu@bhu.ac.in (D.S. Pandey).
0020-1693/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2011.06.018

196
R. Pandey et al. / Inorganica Chimica Acta 376 (2011) 195–206
number of reports dealing with the coordination polymers based on
Cd(II) have appeared in literature, the polymers containing co-crys-
tallized aqua-bridged cadmium dimer governed by eight coordi-
nated cadmium polymeric chain has not been described [29–33].
Through this work we present the synthesis and characterization
of novel coordination polymers 1–4 based on H3CCB, mononuclear
complexes 5–8 containing H3BCCB and crystal structures of 1–3
and 5.
able for X-ray diffraction analyses, which were collected by filtra-
tion, washed with water/ethanol (1:1) and dried in air. Yield:
0.194 g, 60.2%. Anal. Calc. for C9H10NO6ClCo: C, 33.5; H 3.12; N,
4.34%. Found: C, 33.39; H, 3.02; N, 4.22%. IR (KBr pellet, cmꢁ1):
1610 s, 1551 s, 1382 s, 1340 m, 1245 w, 1035 m, 781 s. UV–Vis (so-
lid state, kmax nm): 295, 543.
2.5. Preparation of [Zn(HCCB)(H2O)]n
2
2. Experimental
It was synthesized following the above procedure for 1 except
that Zn(NO3)2ꢀ6H2O (0.297 g, 1 mmol) was used in place of Co(N-
O3)2ꢀ6H2O. Diffraction quality dirty white block shaped crystals
of 2 were obtained from the reaction mixture after cooling to room
temperature. These were separated by filtration, washed with
water/ethanol (1:1) and dried in air. Yield: 64.4% (0.419 g). Anal.
Calc. for C18H14N2O12Cl2Zn2: C, 33.19; H, 2.18; N, 4.36. Found: C,
33.08; H, 2.12; N, 4.26%. IR (KBr pellet, cmꢁ1): 1615 s, 1558 s,
1377 s, 1342 m, 1245 w, 1036 m, 779 s. UV–Vis (solid state, kmax
nm): 270, 319.
2.1. Materials and general methods
The reagents were procured from commercial sources and used
as received. Solvents were dried and distilled following the stan-
dard literature procedures [35]. IR and solid state electronic
absorption spectra were recorded on a Perkin–Elmer-577 and Shi-
madzu UV-1701 spectrometers, respectively. 1H NMR spectra in
CDCl3 was acquired on a JEOL AL 300 FT-NMR machine at an oper-
ating frequency of 300 MHz (1H). Chemical shifts (d) are given in
parts per million (ppm) relative to tetramethylsilane (TMS, d
0.00 ppm) and splitting patterns designated as s (singlet), d (dou-
blet). Elemental analyses for C, H and N were performed on an Ex-
ter CE-440 CHN analyser. Thermogravimetric (TG) and differential
scanning calorimetric (DSC) measurements were made on a Shi-
madzu DTG-60 simultaneous DTA-TG thermal analyzer at a heat-
ing rate of 1 °C/minꢁ1 under nitrogen flow (generally 60 mL/min)
and a Mettler Toledo DSC-25 with a flow rate of 30 mL/min, respec-
tively. Crystalline samples were heated from ꢂ25 to 600 °C at a
rate of 10 °C/min.
2.6. Preparation of {[Cd(HCCB)2]ꢀ0.5[Cd(l-H2O)(H2O)4]2}n 3
It was prepared following the above procedure for 1 using
Cd(NO3)2ꢀ4H2O (0.308 g, 1 mmol) in place of Co(NO3)2ꢀ6H2O. Color-
less block shaped crystals of 3 were separated by filtration, washed
with water/ethanol (1:1) and dried in air. Yield: 0.448 g, 59.0%.
Anal. Calc. for C18H14N2O13Cl2Cd2: C, 28.49; H, 1.60; N, 3.72. Found:
C, 28.38; H, 1.49; N, 3.64%. IR (KBr pellet, cmꢁ1): 1590 s, 1552 s,
1384 s, 1313 m, 1229 w, 1037 m, 792 s, 677 m. UV–Vis (solid state,
kmax nm): 270, 319.
2.2. Preparation of 3-(carboxymethyl-amino)-4-chlorobenzoic acid
(H3CCB)
2.7. Preparation of [Cu(HCCB)(H2O)]n
4
It was prepared following the above procedure for 1 except that
Cu(NO3)2ꢀ3H2O (0.232 g, 1 mmol) was used in place of Co(N-
O3)2ꢀ6H2O. It isolated as gray crystalline solid from the reaction
mixture after cooling to room temperature and was separated by
filtration, washed with water/ethanol (1:1) and dried in air. Yield:
74.1% (0.479 g). Anal. Calc. for C18H14N2O12Cl2Zn2: C, 33.35; H,
2.18; N, 4.32. Found: C, 33.18; H, 2.06; N, 4.24%. IR (KBr pellet,
cmꢁ1): 3226 m, 1626 s, 1565 s, 1429, 1385 s, 1325 m, 1269 w,
1044 m, 763 s. UV–Vis (solid state, kmax nm): 270, 319.
An aqueous solution (10 mL) of 3-amino-4-chlorobenzoic acid
(1.720 g, 10 mmol) was added dropwise to a solution of chloroace-
tic acid (1.880 g, 20.0 mmol) and KOH (1.120 g, 20.0 mmol) in
water (15 mL) over half an hour and heated under reflux for
12 h. After cooling to room temperature it gave a white precipitate
which was filtered, washed with water (20 mL) and air dried. Yield:
1.605 g, 69.8%. Anal. Calc. for C9H8NO4Cl: C, 47.08; H, 3.51; N, 6.10.
Found: C, 46.91; H, 3.49; N, 6.00%. 1H NMR (D2O, d ppm): 7.40 (d,
1H), 7.21 (d, 1H), 6.99 (s, 1H), 3.66 (s, 1H), 3.67 (s, 2H). IR data (KBr
pellet, cmꢁ1): 3404 s, 1689 s, 1597s, 1511 m, 1452 m, 1352 m, 1302
s, 1269 s, 1038 m, 758 s. UV–Vis (solid state, kmax nm): 360, 303.
2.8. Preparation of [Cu(HBCCB)(H2O)]ꢀH2O 5
A
mixture containing Cu(NO3)2ꢀ3H2O (0.232 g, 1.0 mmol),
2.3. Preparation of 3-(bis-carboxymethyl-amino)-4-chlorobenzoic acid
(H3BCCB)
H3BCCB (0.288 g, 1.0 mmol), KOH (0.112 g, 2.0 mmol) in H2O
(8 mL) was heated at 120 °C in a sealed tube for 24 h. Dark blue
block shaped crystals of 5 suitable for X-ray diffraction analysis
were obtained after cooling the reaction mixture to room temper-
ature. Yield: 0.243 g, 69%. Anal. Calc. for C11H12ClCuNO8: C, 34.30;
H, 3.14; N, 3.64. Found: C, 34.18; H, 3.02; N, 3.52%. IR (KBr pellet,
cmꢁ1): 1721 s, 1610 vs 1385 vs 1250 m, 935 m, 763 m. UV–Vis
(H2O, kmax nm): 263, 215.
The filtrate obtained after separation of H3CCB upon neutraliza-
tion with 0.01 M HCl gave H3BCCB as a white solid which was sep-
arated by filtration, washed with 3 ꢃ 20 mL of water and air dried.
Yield: 41.2% (1.188 g). Anal. Calc. for C9H8NO4Cl: C, 45.93, H, 3.50,
N, 4.87. Found: C, 45.71; H, 3.38; N, 4.80%. 1H NMR (D2O, d
ppm): 7.41 (d, 1H), 7.30 (d, 1H), 7.09 (s, 1H), 3.67 (s, 4H). IR (KBr
pellet, cmꢁ1): 3410 br, 1736 vs 1681 vs 1597s, 1437 s, 1291 s,
1230 m, 1154 m, 1037 m, 867 w, 764 s. UV–Vis (H2O, kmax nm):
242, 210.
2.9. Preparation of [Co(HBCCB)(H2O)]ꢀH2O 6
It was prepared following the above procedure for 4 using Co(N-
O3)2ꢀ6H2O (0.291 g, 1.0 mmol) in place of Cu(NO3)2ꢀ3H2O. It iso-
lated as pink crystalline solid which was separated by filtration,
washed with water/ethanol (1:1) and dried in air. Yield: 0.213 g,
56.2%. Anal. Calc. for C11H12ClCoNO8: C, 34.71; H, 3.18; N, 3.68.
Found: C, 34.45; H, 3.10; N, 3.55%. IR (KBr pellet, cmꢁ1): 1714 s,
1610 vs 1381 vs 1256 m, 1182, 931 m, 753 m.
2.4. Preparation of [Co(HCCB)(H2O)2]n
1
A
mixture of Co(NO3)2ꢀ6H2O (0.291 g, 1.0 mmol), H3CCB
(0.230 g, 1.0 mmol) and KOH (0.112 g, 2.0 mmol) in H2O (8 mL)
were heated in a sealed tube at 120 °C for 24 h. Upon cooling to
room temperature it afforded dark pink block shaped crystals suit-

R. Pandey et al. / Inorganica Chimica Acta 376 (2011) 195–206
197
2.10. Preparation of [Zn(HBCCB)H2O] 7
COOH
COOH
It was prepared following the above procedure for 4 using
Zn(NO3)2ꢀ6H2O (0.297 g, 1.0 mmol) in place of Cu(NO3)2ꢀ3H2O.
After cooling the reaction mixture to room temperature it sepa-
rated as the white solid which was collected by filtration, washed
with water/ethanol (1:1) and air dried. Yield: 0.193 g, 52.5%. Anal.
Calc. for C11H10ClZnNO7: C, 35.80; H, 2.73; N, 3.80. Found: C, 35.55;
H, 2.61; N, 3.68%. IR (KBr pellet, cmꢁ1): 1689 s, 1606 vs 1386 vs
1263 m, 1206, 935 m, 776 m.
COOH
COOH
N
H
COOH
N
Cl
Cl
H3BCCB
H3CCB
Fig. 1. Structures of the ligands.
2.11. Preparation of [Cd(HBCCB)H2O] 8
It was prepared following the above procedure for 4 using
Cd(NO3)2ꢀ4H2O (0.308 g, 1.0 mmol) in place of Cu(NO3)2ꢀ3H2O.
The complex 8 separated as white powder upon cooling the reac-
tion mixture to room temperature and was collected by filtration,
washed with water/ethanol (1:1) and dried in air. Yield: 0.209 g,
50.3%. Anal. Calc. for C11H10ClCdNO7: C, 31.75; H, 2.42; N, 3.37.
Found: C, 31.57; H, 2.37; N, 3.28%. IR (KBr pellet, cmꢁ1): 1706 s,
1598 vs 1386 vs 1267 m, 1203, 933 m, 766 m.
3. Results and discussion
3.1. Syntheses and characterization
The ligands H3CCB and H3BCCB were prepared by reaction of 3-
amino-4-chlorobenzoic acid with chloroacetic acid under alkaline
conditions. Presence of both the aminocarboxylate (–N–CH2–
COOH) and carboxylate group enables it to form covalent/coordi-
nation bonds with the metal ions either through nitrogen and
carboxyl oxygen of the former or oxygen of the latter after
deprotonation (Fig. 1). Further, carboxyl oxygen and nitrogen
may easily get involved in intra- and intermolecular hydrogen
bonding interactions.
2.12. X-ray structure determinations
Single crystal X-ray data for 1, 2, 3 and 5 were collected on a
Rigaku R-AXIS RAPID II diffractometer at room temperature using
The complexes 1–4 were synthesized using H3CCB and metal(II)
nitrates under carefully controlled conditions (metal:ligand; 1:1,
120 °C). Treatment of the hydrated metal nitrates Co(NO3)2ꢀ6H2O,
Zn(NO3)2ꢀ6H2O and Cu(NO3)2ꢀ3H2O with H3CCB under alkaline
conditions afforded double-stranded 1D coordination polymers
[Co(HCCB)(H2O)]n (1), [Zn(HCCB)(H2O)]n (2) and [Cu(HCCB)(H2O)]n
(4). On the other hand, Cd(NO3)2ꢀ4H2O reacted with H3CCB under
analogous conditions to give entirely different complex
graphite-monochromated Mo K
crystallographic and refinement data for 1, 2, 3 and 5 are summa-
a radiation (k = 0.71073 Å). The
rized in Table 1. Structures were solved by direct methods (SHELXS
97) and refined by full-matrix least squares on F2
(SHELX 97)
[36,37]. Non-hydrogen atoms were refined with anisotropic ther-
mal parameters. All the hydrogen atoms were geometrically fixed
and refined using a riding model. Computer program PLATON
was used for analyzing the interaction and stacking distances
[38,39]. Powder X-ray diffraction data for 4 and 6–8 (PXRD) were
obtained on a Rigaku Rotoflux RTC-300 X-ray diffractometer
{[Cd(HCCB)]2ꢀ0.5[Cd(l-H2O)-(H2O)4]2}n (3). Although 1–4 have
been synthesized essentially under identical conditions, these ex-
hibit structural diversity, wherein both the aminocarboxylate and
employing Cu Ka (k = 1.5406 Å) radiation with a Ni filter.
Table 1
Crystal and structure refinement data for 1–3 and 5.
Compound
1
2
3
5
CCDC numbers
Empirical formula
Formula weight
Crystal system
743 407
C9H10ClCoNO6
322.56
747 607
C18H14Cl2N2O12Zn2
651.95
747 608
C18H12Cd2Cl2N2O13
760.00
787 720
C24H24Cl2Cu2N2O16
794.43
triclinic
triclinic
triclinic
triclinic
ꢀ
ꢀ
ꢀ
ꢀ
Space group
P1
P1
P1
P1
0
6.870(1)
7.573(2)
10.723(2)
6.860(1)
8.053(2)
8.223(2)
18.733(4)
7.493(2)
7.791(2)
13.097(3)
a (AÅ)
0
10.699(2)
15.073(3)
b (AÅ)
0
c (AÅ)
a
b (°)
c
V (ÅA3)
Z
(°)
89.21(3)
89.41(3)
77.86(3)
545.2(2)
88.94(3)
82.62(3)
89.72(3)
1096.9(4)
89.74(3)
78.98(3)
80.54(3)
1200.5(4)
84.71(3)
75.49(3)
69.52(3)
693.4(3)
(°)
0
2
2
2
1
T (K)
293
293
293
293
l
(mmꢁ1
)
1.838
1.964
5337
2465
0.0386
0.0920
1.224
2.502
1.974
10 626
4950
0.0754
0.2039
1.064
2.065
2.103
11 405
5368
0.0937
0.2417
1.051
1.812
1.902
2569
3147
0.0407
0.1069
1.078
Dcalc (g/cm3)
Reflections collected
Independent reflections
Rint
wR2 (all data)
Goodness-of-fit (GOF) on F2

198
R. Pandey et al. / Inorganica Chimica Acta 376 (2011) 195–206
M
M
M
O
O
O
O
O
O
M
N
M
HN
NH
Cl
O
Cl
O
Cl
O
M
O
O
O
(b)
(a)
(c)
M
M
M
O
HO
O
O
O
O
O
O
N
N
NH
O
M
Cl
O
M
Cl
Cl
O
O
O
M
(f)
O
(d)
O
(e)
O
Scheme 1. (a) and (b) coordination mode of H3CCB in complexes 1–4. (c–e) Other possible coordination modes of H3CCB and H3BCCB (f) coordination mode of H3BCCB in
complexes 5–8.
carboxylate groups of H3CCB are involved in bonding with the me-
tal centers (Scheme 1).
The ligand moieties in asymmetric unit assume ‘‘anti, anti’’ orienta-
tion. Each of the Co(II)/Zn(II) centers are connected with two bridg-
ing ligands to form a 14-membered macrocycle thus the structure
of 1 and 2 can be best described as a double stranded looped-chain
1D coordination polymer (Figs. 2a and 3a). Two types of metal–me-
tal distances occur in double stranded chain of 1 and 2; (i) sepa-
rated by bridging oxygen of the carboxylate groups (3.241 Å in 1;
3.294 Å in 2) and (ii) separated by HCCB2ꢁ 8.561 Å in 1; 8.479 Å
in 2) as shown in Scheme 2. The Co–O(carboxylate/aminocarboxyl-
ate) and Co–O(w) bond distances in 1 fall in the range of 2.057(3)–
2.049(3) and 2.084(4)–2.121(4) Å. Similarly, Zn–O(carboxylate-/
aminocarboxylate), Zn–O(w) bond distances in 2 are in the range
of 2.031(4)–2.094(4), 1.984(4)–2.054(4) Å. The Co–N and Zn–N
bond distances are 2.249(4) Å and 2.208(5)–2.255(4) Å, respec-
tively. These are normal and comparable to the bond distances ob-
served in other related systems [40–42]. The O(5)–Co(1)–O(6) and
O(5)–Zn(1)–O(11)/O(8)–Zn(2)–O(7) angles in 1 and 2 are 86.60(18)
and 95.61(16)–87.69(16)°. It suggested that the coordinated water
molecules are cis-disposed about the Co(II)/Zn(II) throughout poly-
meric chain. Complexes, 1 and 2 differ in empirical formula due to
dissimilar symmetry codes (Figs. 2a and 3a).
Under analogous conditions Cu(NO3)2ꢀ3H2O, Co(NO3)2ꢀ6H2O,
Zn(NO3)2ꢀ6H2O and Cd(NO3)2ꢀ6H2O reacted with H3BCCB (metal:li-
gand; 1:1, 120 °C) to afford mononuclear complexes [Cu(HBCCB)
(H2O)]ꢀH2O (5) [Co(HBCCB)(H2O)]ꢀH2O (6), [Zn(HBCCB)H2O] (7)
and [Cd(HBCCB)H2O] (8) in moderate to good yields. In 5–8 the
ligand H3BCCB interacted with the metal center through aminocar-
boxylate group, while carboxylate group remains uncoordinated
(Scheme 1e).
Characterization of the ligands and 1–8 have been achieved by
elemental analyses, spectral (FT-IR, 1H NMR, electronic absorption,
emission) and thermal (TG and DSC) studies. The structures of
coordination polymers 1–3 and representative mononuclear com-
plex 5 have been determined by single crystal X-ray diffraction
analyses. Information about the structures of 4 and 6–8 have also
been obtained by comparing their powder X-ray patterns (PXRD)
with the simulated patterns from single crystal X-ray data of 1
and 5.
3.2. Crystal structures of [Co(HCCB)(H2O)2]n 1 and [Zn(HCCB)(H2O)]n
The N(1)–C(2)–C(1) and N(2)–C(11)–C(10) angles in 1 and 2 are
113.4(4)° and 112.4(4)°, which strongly suggested that the N,O do-
nor sites of aminocarboxylate are almost planar with respect to
each other. The Co(1)–O(1)brid–Co(1) and Zn(1)–O(1)brid–Zn(2) an-
gles are 101.36(14)° and 103.53(2)°, respectively. An examination
of the crystal structures of 1 and 2 revealed the presence of two
types of cavities in their polymeric chain. Square shaped cavities
of the dimension [2.656(4) ꢃ 3.241(6) Å2, 1; 2.615(4) ꢃ
3.294(4) Å2, 2], created between two nearest metal centers sepa-
rated by V-shaped oxygen bridges of the ligand in polymeric chain.
Dimension has been measured by considering Mꢀ ꢀ ꢀM (Coꢀ ꢀ ꢀCo/
Znꢀ ꢀ ꢀZn) ꢃ O(1)ꢀ ꢀ ꢀO(1) distances. Ellipsoid cavities of the dimen-
sion [5.241 ꢃ 8.561 Å2, 1; 5.206 (3) ꢃ 8.479 (2) Å2, 2] are formed
between two Mꢀ ꢀ ꢀM (Coꢀ ꢀ ꢀCo/Znꢀ ꢀ ꢀZn) centers separated by
2
Coordination polymers 1 and 2 crystallize in triclinic crystal
ꢀ
system and P1 space group. The asymmetric units of these consists
of two metal ions (Co, 1; and Zn, 2), two deprotonated ligands
(HCCB2ꢁ) and four water molecules. Coordination geometry about
the metal centers in both 1 and 2 is distorted octahedral wherein
Co(II)/Zn(II) are coordinated by three oxygen donors from three
different carboxylates, amino nitrogen and two water molecules
(Figs. 2a and 3a). The ligand H3CCB in its deprotonated form
(HCCB2ꢁ coordinated to the respective metal center in two differ-
ent modes: (i) the aminocarboxylate interacted with two different
metal centers in
bonded through carboxyl oxygen in monodentate
l
–g
2–O(1),
g
1–N(1) mode, (ii) carboxylate group
1–O(4) fashion.
g

R. Pandey et al. / Inorganica Chimica Acta 376 (2011) 195–206
199
Fig. 2. (a) Crystal structure of 1 (hydrogen atoms omitted for clarity), Symmetry codes: i) x, y, z-1; ii) x, y, z + 1; iii) -x, -y + 1, -z + 1. (b) Overall 2D structure of 1 resulted by
intermolecular hydrogen bonding interactions. (c) A topological representation for 2D zig-zag double stranded chains in 1 through
created in 1 viewed down along crystallographic-‘b’ axis.
p–p stacking interactions. (d) Cavities
HCCB2ꢁ in the double stranded chains (Scheme 2). Dimension has
been calculated by distances between Mꢀ ꢀ ꢀM (Coꢀ ꢀ ꢀCo/Znꢀ ꢀ ꢀZn)
separated by ligands ꢃ centroid–centroid of the aromatic rings of
the bridged ligands.
tainly contribute towards overall stability of the 2D chains in 1 and
2.
The nearest Coꢀ ꢀ ꢀCo separations in 1 are 3.241, whereas Znꢀ ꢀ ꢀZn
distances in 2 are 3.294 Å (Scheme 2). Slightly longer distances in 2
may be due to smaller ionic radii of Zn(II) in comparison to Co(II).
Distances between
lO(1)ꢀ ꢀ ꢀ
lO(9) in 1 and 2 are 2.656 and 2.615 Å,
respectively. All the oxygen atoms of both 1 and 2 are involved
either in intra- or intermolecular hydrogen bonding interactions
(Table 3). Notably, these compounds contain both the Lewis basic
(the non-coordinated oxygen atoms) and acidic centers (the coor-
dinated Co(II)/Zn(II) ions with potentially good leaving coordinated
water molecules) in the same unit, may find potential application
as a bifunctional catalyst [43,44].
3.3. Supramolecular assemblies through weak bonding interactions
Double stranded chain lies parallel to each other through hydro-
gen bonding, C–Hꢀ ꢀ ꢀ
p and p–p interactions leading to 2D layers in
the bc-plane. Intermolecular O–Hꢀ ꢀ ꢀO hydrogen bonding interac-
tions in 1 and 2 leads to two dimensional (2D) repeated double
stranded chains along the crystallographic c-axis (Figs. 2b and
3b, Table 3). The distance(s) between Coꢀ ꢀ ꢀCo/Znꢀ ꢀ ꢀZn centers sep-
arated by HCCB2ꢁ in the chains are 6.870/7.564 Å. The intra- and
intermolecular hydrogen bonding distances are 2.570 and
3.048 Å, in 1 and 2.597 and 2.829 Å in 2, respectively [1,2]. Zig-
zag parallel chains with ellipsoidal cavities have been created from
3.4. Crystal structures of {[Cd(HL1)2]ꢀ0.5[Cd(l-H2O)(H2O)4]2}n 3
The crystallographic data of 3 suggested that it belongs to tri-
ꢀ
C–Hꢀ ꢀ ꢀ
p
and
p
–
p
interactions in 1 leading to a 2D network along
clinic crystal system with P1 space group. Its overall structure
crystallographic c-axis (Fig. 2c, S2 and S3, ESI). These interactions
in 2 lead to three parallel chains with ellipsoidal cavities along
crystallographic c-axis (Fig. 3c, S4). Intra- and intermolecular C–
shows 1D polymeric chain containing Cd(II) and HCCB2ꢁ alongwith
rhomboid dimeric cationic species [{Cd(l
-H2O)(H2O)4}2]4+ held be-
tween two polymeric chains. Cadmium in the polymeric chains are
eight, while those in dimeric unit are six coordinated [32,33]. The
local coordination environment about Cd(1) can be best described
as a distorted tetragonal antiprism consisting of six oxygen from
four different carboxylate groups of HCCB2ꢁ, adopting k2-COOꢁ
and k1-COOꢁ coordination mode and two nitrogen from different
ligands (Fig. 4a). The polymeric part incorporating bridging HCCB2ꢁ
creates a 14-membered macrocyclic ring alongwith rhomboid di-
meric unit, can also be ascribed as a double stranded looped chain.
The Cd–O distances (range 2.310(9)–2.630(11) Å) are similar to
those in other eight coordinated Cd(II) complexes [45,46].
Hꢀ ꢀ ꢀ
p distances (measured from hydrogen to centroid of the aro-
matic ring) are 3.311 and 3.473 Å, respectively in 1. Although, 1
and 2 have got similar structural framework, intramolecular C–
Hꢀ ꢀ ꢀ
p interactions are lacking in 2. Intra- and intermolecular p–p
stacking distances are 3.135 and 3.299 Å in 1 and 3.168 and
3.394 Å in 2, respectively. The centroid–centroid distances be-
tween aromatic rings of HCCB2ꢁ bridging two metal centers in 1
and 2 are 5.241 and 5.206 Å while, intra- and inter-chain aromatic
ring (centroid–centroid) distances are 4.415 and 4.586 Å. Shorter
inter-chain distances in comparison to intra chain separations cer-

200
R. Pandey et al. / Inorganica Chimica Acta 376 (2011) 195–206
Fig. 3. (a) Crystal structure of 2 (hydrogen atoms omitted for clarity), Symmetry codes: i) x, y-1, z; ii) x, y + 1, z. (b) Overall 2D structure of 2 resulted by O-Hꢀ ꢀ ꢀO hydrogen
bonding interactions. (c) Topological representation for three parallel ribbons generated from
crystallographic-‘c’ axis.
pꢀ ꢀ ꢀ
p
interactions. (d) Two types of cavities differing in dimensions along
3.241 Å
8.561 Å
3.294 Å
8.479 Å
Zn
Zn
Zn
Zn
Zn
Co
Co
Co
Co
Co
Zn
Co
n
n,
(1)
(2)
Scheme 2. Metal–metal distances in two types of cavities present in the polymeric double stranded chain of 1 and 2.
The Cd(1)–N(1) and Cd(1)–N(2) distances are 2.651(11) and
2.572(12) Å, respectively which are comparable to those reported
in the literature [47,48]. The distorted octahedral coordination
geometry about Cd(2) is completed by four terminal and two
bridging aqua ligands (Fig. 4a and S6). This type of coordination
environment around Cd(II) in the same complex have not been ob-
served so far to the best of our knowledge in cadmium(II) polycar-
boxylate MOFs [32,33,49–51]. One can see that each ligand
connects two metal centers through three oxygens of the carboxyl-
ate group coordinated in k1-COOꢁ and k2-COOꢁ modes and the
nitrogen (Fig. 4a). Each Cd(1) in the polymeric chains are bonded
to four HCCB2ꢁ and forms a 1D chain, which in association with

R. Pandey et al. / Inorganica Chimica Acta 376 (2011) 195–206
201
Fig. 4. (a) Crystal structure of 3 (hydrogen atoms omitted for clarity), Symmetry code: i) -x + 1, -y, -z + 1; ii) x-1, y, z; iii) x + 1, y, z.; (b) Ellipsoidal (polymeric part) and squire
shape cavities (dimeric part) viewed down along crystallographic-‘c’ axis. (c) Arrangement of various atoms about Cd(1) and Cd(2). (d) Topological representation of dimeric
cadmium complex sandwiched between infinite double stranded chains in 3.
symmetrical aqua-bridged dimeric species leads to a 1D frame-
work and weak intermolecular interactions generate 2D as well
as 3D supramolecular network. According to the simplification
principle, the ligand HCCB2ꢁ in 3 can be viewed as a connector
and Cd(II) as four-connected nodes.
present (Fig. S5). The absence of inter-chain contacts through
p–
p
interactions may be attributed to the presence of dimeric units
between two polymeric chains. Intra-layer distances between the
centroids of aromatic ring of the ligand bridging two Cd(II) centers
are 5.241 Å, whereas inter-chain centroid–centroid distances are
4.415 Å. This type of contact contributes towards stability of the
chain.
The carboxylate groups having similar coordination mode (k1 or
k2) are trans-disposed. Aqua-bridged dimeric Cd(II) complex does
not contain H3CCB and completed its distorted octahedral geome-
try by aqua ligand in both the bridged and terminal mode. The Cd–
Oterminal bond distances lie in the range 2.211(10)–2.236(10) Å,
while Cd–Obridged are 2.357(8) Å. Comparison of bond distances re-
As described above, 1 and 2 adopted analogous, while 3 an en-
tirely different structure. The difference in overall structures may
be related to ability of the cadmium (4d metal) to adopt higher
coordination numbers. It is well established that Cd(II) in its com-
plexes can adopt coordination number 6–9 [52,53]. An inspection
of the structure of 3 revealed that each Cd(II) is linked to two
HCCB2ꢁ through nitrogen and oxygen of the aminocarboxylate
and other two through both the oxygen of carboxylate group after
deprotonation. The coordination of HCCB2ꢁ accumulates four neg-
ative charge on each cadmium center in the polymeric chain. Cad-
mium generally do not show oxidation states higher than two,
while from crystal structure it is obvious that each Cd(II) in the
polymeric chain bears four net negative charges. To balance the
charge in polymeric chain, aqua-bridged dimeric complex bearing
two net positive charges on each Cd(II) co-crystallizes with the
polymeric chain (observed dimeric/polymeric ratio; 0.5:1.0).
Among these three coordination polymers 3 is least stable. It
may be attributed to the easier collapse of aqua-bridged dimeric
vealed that the Cd(2)–O(9)bridged are longer than Cd(2)–Oterminal
.
Unlike 1 and 2, the complex 3 contains only ellipsoidal cavities
generated by neighboring Cd(II) bridged by HCCB2ꢁ in the poly-
meric double stranded looped chain. In this complex Cd(1) are sep-
arated from each other by 8.053 and Cd(2) by 3.650 Å.
The 1D double stranded 14-membered chain in 3 stacked along
crystallographic b-axis leading to a 3D supramolecular architecture
via strong OꢁHꢀ ꢀ ꢀO hydrogen bonding interactions involving
l-
aqua and terminal water molecules (O9, O10, O11, O12 and O13)
of the rhomboid dimers (Fig. 5a, S8, Table 3). Intermolecular C–
Hꢀ ꢀ ꢀ
a 2D layered network along crystallographic a-axis (Fig. 5d). Fur-
ther, 3 lacks inter-chain contacts through interactions, how-
ever, intramolecular stacking interactions (3.29 Å) are
p interactions (3.421(2) Å) in the polymeric chain generated
p–p
p–p

202
R. Pandey et al. / Inorganica Chimica Acta 376 (2011) 195–206
Fig. 5. (a) Environment of polymeric chains about cadmium centers in dimeric part. (b) Cadmium dimers about polymeric chain. (c) Topological view of the polymeric chains
with ellipsoidal cavities. (d) A 2D layered network constructed by CH. . .
contacts.
p
moiety as well as steric crowding around the Cd(II) in polymeric
chain.
the square pyramidal (sp) as suggested by coordination angles
interaction in 5 leads to a ladder network
incorporating water molecules (Fig. 6c).
(Fig. 6b). The C–Hꢀ ꢀ ꢀ
p
3.5. Structure of [Cu(HBCCB)(H2O)]ꢀH2O 5
3.6. X-ray powder diffraction studies
Mononuclear complex 5 crystallizes in triclinic crystal system
and P1 space group (Table 1). The asymmetric unit consists of
ꢀ
To acquire information about the structures of 4 and 6–8 pow-
der X-ray diffraction studies were made in the limited (2h, 15–50°)
PXRD data set. The powder patterns for these complexes (Fig. 7)
were compared with the simulated PXRD data obtained from sin-
gle crystal X-ray data of 1 and 5. Patterns in Fig. 7 reveal several
diffraction peaks in the range of 15–50° 2h that have acceptable
intensity indicating the bulk purity of samples. There is an accept-
able match with some minor differences between the simulated
and experimental patterns suggesting that 4 is structurally analo-
gous to 1 and 6–8 to 5.
one Cu(II), one HBCCB2ꢁ, one each of the coordinated and co-crys-
tallized water molecules. Each Cu(II) is four-coordinated with a
distorted square planar geometry, completed by nitrogen (N1)
from the HBCCB2ꢁ, two oxygen from different carboxylates of
HBCCB2ꢁ (O3 and O5) and one coordinated H2O molecule (O7)
(Fig. 6a). The Cu–O bond lengths are in the range [1.922(2)–
1.927(2) Å] and Cu–N bond length is 2.047(3) Å, while various
angles about the metal center fall in the range [84.70(10)–
172.49(12)°] (Table 2). Water molecule present in the lattice is
separated from Cu(II) center by ꢂ3.965 Å. (Fig. 6a). Notably,
carboxyphenyl group of the ligand is uncoordinated. The trans-
angles O3–Cu1–O5/N1–Cu1–O7 are 158.82(10)/172.49(12)° while
cis-close to 90° suggesting distorted square planar geometry about
the Cu(II) center. Distortion in geometry may be attributed to very
strong interaction between the Cu1 and Cl1 with a Cu1–Cl1 dis-
tance of 2.754(14) Å [34]. Such an interaction between copper
and chlorine atom attached to aromatic ring is rare and could be
considered as coordination bond (Fig. 6a and b). This strong inter-
action between is reflected by distorted square planar geometry.
The overall geometry about Cu(II) center seems very similar to
3.7. Spectral and thermal studies
Detailed description relating to the IR, electronic absorption,
and thermal studies are presented in ESI. Fluorescence properties
of the Zn(II) and Cd(II) coordination compounds and their potential
applications as new luminescent materials have drawn consider-
able current attention [54–59]. Photoluminescence properties of
the free H3CCB and 1–3 have been investigated in solid state at
room temperature. Upon excitation at k, 375 nm the ligand
H3CCB and 2 exhibited strong emissions at 422, and 428, 521 nm,

R. Pandey et al. / Inorganica Chimica Acta 376 (2011) 195–206
203
Fig. 6. (a) Crystal structure of 5 (hydrogen atoms omitted for clarity), Symmetry code: x,1 + y, z. (b) View of 5 showing that Cu (II) is in the same plane of coordinated atoms.
(c) Ladder view incorporating water molecules in 5 resulted by CHꢀ ꢀ ꢀ
p
interactions along crystallographic-‘b’ axis.
Table 2
Selected bond lengths (Å) and angles (°) in 1–3 and 5.
Complex 1
Co–O1
Co–O6
C8–Cl1
N1–C2–C1
O5–Co1–O6
O4–Co1–N1
2.057(3)
2.121(4)
1.748(5)
113.4(4)
86.6(2)
Co–O4
Co–N1
C2–N1
Co1–O1–Co1
O4–Co1–O6
O2–C1–O1
2.049(3)
2.249(4)
1.484(6)
101.4(1)
179.2(2)
125.4(4)
Co–O5
C1–O2
C1–O1
O1–Co1–O1
O1–Co1–O1
C3–N1–Co1
2.084(4)
1.235(6)
1.265(5)
78.6(1)
78.6(1)
114.5(3)
91.5(1)
Complex 2
Zn1–O1
Zn1–O11
Zn2–O8
C1–O2
N2–C11–C10
O5–Zn1–O11
O11–Zn1–N1
2.090(4)
2.065(4)
1.984(4)
1.236(6)
112.4(4)
95.6(2)
Zn2–O9
Zn1–O5
Zn2–O7
C1–O1
Zn1–O1–Zn2
O8–Zn2–O7
O2–C1–O1
2.094(4)
2.054(4)
2.352(4)
1.268(6)
103.5(2)
87.7(2)
Zn2–O3
Zn1–O6
Zn1–N1
2.031(4)
2.179(4)
2.208(5)
O4–C9–O3
O3–Zn2–O7
C3–N1–Zn1
126.2(5)
173.4(2)
115.2(3)
92.5(2)
124.8(5)
Complex 3
Cd1–O1
Cd1–O3
Cd2–O9
C1–O2
N2–C11–C10
O1–Cd1–O5
O5–Cd1–N2
O9–Cd2–O9
O4–C9–O3
2.349(8)
2.541(9)
2.357(8)
1.29(1)
115.4(11)
74.9(3)
68.1(3)
80.1(3)
119.3(12)
Cd1–O7
Cd1–O4
Cd2–O12
C10–O6
O1–C1–O2
O4–Cd1–O1
N2–Cd1–N1
O13–Cd2–O12
2.63(1)
2.33(1)
2.22(1)
1.21(2)
124.8(12)
129.6(3)
154.9(3)
97.0(4)
Cd1–O8
Cd1–N1
Cd2–O11
2.310(9)
2.651
2.21(1)
O7–Cd1–O8
O3–Cd1–O7
Cd2–O9–Cd2
O13–Cd2–O10
52.3(4)
162.0(3)
99.9(3)
178.3(4)
Complex 5
Cu1–O5
Cu1–N1
O5–Cu1–O7
O3–Cu1–N1
O3–Cu1–Cl1
1.922(2)
2.047(3)
93.98(10)
84.70(10)
110.82(8)
Cu1–O3
Cu1–Cl1
O3–Cu1–O7
O7–Cu1–N1
O7–Cu1–Cl1
1.924(2)
Cu1–O7
1.927(2)
158.82(10)
86.47(10)
85.86(8)
77.40(8)
2.7535(14)
97.27(11)
172.49(12)
95.15(10)
O5–Cu1–O3
O5–Cu1–N1
O5–Cu1–Cl1
N1–Cu1–Cl1

204
R. Pandey et al. / Inorganica Chimica Acta 376 (2011) 195–206
Table 3
Selected hydrogen bonds geometry (Å, °) in 1–3 and 5.
D–Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀH
Hꢀ ꢀ ꢀA
\DHA
Dꢀ ꢀ ꢀA
Complex 1
N1–H1ꢀ ꢀ ꢀO2
O5–H5Aꢀ ꢀ ꢀO3
O5–H5Bꢀ ꢀ ꢀO2
O6–H6Aꢀ ꢀ ꢀO2
O6–H6Bꢀ ꢀ ꢀO5
O6–H6Bꢀ ꢀ ꢀO6
0.86
0.82
0.86
0.82
0.82
0.82
2.49
1.85
2.25
1.97
2.60
2.33
134
146
163
176
115
146
3.154(5)
2.570(5)
3.056(5)
2.785(6)
3.033(6)
3.048(7)
Complex 2
O5–H5Aꢀ ꢀ ꢀO10
O6–H6Aꢀ ꢀ ꢀO10
O7–H7ꢀ ꢀ ꢀO2
0.82
0.82
0.82
2.23
2.01
1.95
150
175
162
2.967(6)
2.830(6)
2.740(6)
Complex 3
O10–H10ꢀ ꢀ ꢀO7
O11–H11ꢀ ꢀ ꢀO7
O12–H12ꢀ ꢀ ꢀO2
O13–H13ꢀ ꢀ ꢀO3
0.82
0.82
0.82
0.82
1.91
1.96
2.16
2.01
165
146
137
136
2.709(4)
2.815(5)
2.816(3)
2.667(6)
Fig. 8. Solid-state fluorescence spectra of H3CCB (kex 375, kem, 425 nm) and 2 (kex
375, kem, 422, 520 and 542 nm) at rt.
Complex 4
O(2)–H(2)ꢀ ꢀ ꢀO(4)
O(7)–H(7A)ꢀ ꢀ ꢀO(8)
O(7)–H(7B)ꢀ ꢀ ꢀO(6)
O(8)–H(8A)ꢀ ꢀ ꢀO(5)
O(8)–H(8B)ꢀ ꢀ ꢀO(4)
0.82
1.83
179
177(5)
165(4)
159(5)
170(6)
2.650(4)
2.669(4)
2.661(4)
2.883(4)
2.765(5)
0.92(4)
0.90(4)
0.77(6)
0.76(5)
1.75(4)
1.78(4)
2.15(6)
2.01(6)
exhibit red shifted emissions (>500 nm) in comparison to the
uncoordinated ligand, which may probably be due to
r-donation
from H3CCB to the metal(II) core. Fluorescence response of H3BCCB
and 5 were examined in water (1 ꢃ 10ꢁ4 M, Fig. 9). Upon excitation
at 325 nm H3BCCB displays a weak fluorescence at ꢂ445 nm, while
excitation at its absorption wavelength (kex 242 nm) did not exhi-
bit significant emission. Complex 5 displayed emission bands at
441 nm upon excitation at 325 nm. Fluorescence intensity in 5 is
almost three times greater than H3BCCB, which may be attributed
to the reduction of n–p⁄ transitions due to complex formation with
Cu(II) ion.
respectively. On the other hand, 1 and 3 weakly emit at 422, 520
and 426, 520, and 542 nm (Fig. 8 and S11). The emission band cen-
tered at 422 nm in the uncoordinated ligand may be ascribed to the
intra-ligand (ICT) transitions. Therefore, the bands at ꢂ520,
542 nm in the emission spectra of 1–3 may be attributed to LMCT
(ligand to metal charge transfer) transitions [58,59]. Further, 1–3
Fig. 7. Experimental powder XRD patterns of 6–8 (d) simulated with the PXRD pattern obtained from single crystal X-ray data of 5 (b) and 4 (c) simulated with the pattern
single crystal X-ray data of 1 (a).

R. Pandey et al. / Inorganica Chimica Acta 376 (2011) 195–206
205
c.uk/data_request/cif. Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/
j.ica.2011.06.018.
References
[1] P. Przychodzén, T. Korzeniak, R. Podgajny, B. Sieklucka, Coord. Chem. Rev. 250
(2006) 2234.
[2] A. Beghidja, P. Rabu, G. Rogez, R. Welter, Chem. Eur. J. 12 (2006) 7627.
[3] R. Wang, J. Zhang, L. Li, Inorg. Chem. 48 (2009) 7194.
[4] R. Fu, S. Xiang, S. Hu, L. Wang, Y. Li, X. Huang, X. Wu, Chem. Commun. 42
(2005) 5292.
[5] W. Yang, X. Lin, A.J. Blake, C. Wilson, P. Hubberstey, N.R. Champness, M.
Schröder, Inorg. Chem. 48 (2009) 11067.
[6] Takamizawa, T. Saito, T. Akatsuka, E.-I. Nakata, Inorg. Chem. 44 (2005) 1421.
[7] J.S. Seo, D. Whang, H. Lee, S.I. Jun, J. Oh, Y.J. Jeon, K. Kim, Nature 404 (2000) 982.
[8] O. Hallale, S.A. Bourne, K.R. Koch, New J. Chem. 29 (2005) 1416.
[9] D. Bradshaw, J.B. Claridge, E.J. Cussen, T.J. Prior, M.J. Rosseinsky, Acc. Chem.
Res. 38 (2005) 273.
Fig. 9. Fluorescence spectra of H3BCCB (kex 325, kem, 445 nm) and 5 (kex 325, kem,
441nm) in water at rt.
[10] S. Kitagawa, K. Uemura, Chem. Soc. Rev. 34 (2005) 109.
[11] K. Uemura, S. Kitagawa, K. Fukui, K. Saito, J. Am. Chem. Soc. 126 (2004) 3817
(and references therein).
[12] A.N. Khlobystov, A.J. Blake, N.R. Champness, D.A. Lemenovskii, A.G. Majouga,
N.V. Zyk, M. Schröder, Coord. Chem. Rev. 222 (2001) 155.
[13] M. Eddaoudi, D.B. Moler, H. Li, B. Chen, T.M. Reineke, M. O’Keeffe, O.M. Yaghi,
Acc. Chem. Res. 34 (2001) 319.
[14] G.R. Desiraju, Angew. Chem., Int. Ed. 34 (1995) 2311.
[15] R. Kitaura, S. Kitagawa, Y. Kubota, T.C. Kobayashi, K. Kindo, Y. Mita, A. Matsuo,
M. Kobayashi, H.C. Chang, T.C. Ozawa, M. Suzuki, M. Sakata, M. Takata, Science
298 (2002) 2358.
[16] R. Matsuda, R. Kitaura, S. Kitagawa, Y. Kubota, R.V. Belosludov, T.C. Kobayashi,
H. Sakamoto, T. Chiba, M. Takata, Y. Kawazoe, Y. Mita, Nature 436 (2005) 238.
[17] B.-C. Tzeng, T.-H. Chiu, B.-S. Chen, G.-H. Lee, Chem.-Eur. J. 14 (2008) 5237.
[18] R. Banerjee, A. Phan, B. Wang, C. Knobler, H. Furukawa, M. O’Keeffe, O.M. Yaghi,
Science 319 (2008) 939.
4. Conclusions
In summary, through this work we have successfully synthe-
sized four novel coordination polymers using a new aminocarbox-
ylate ligand H3CCB and four mononuclear complexes based on
H3BCCB. Spectral and structural studies suggested that the synthe-
sis of a variety of coordination polymers can be achieved in the
same solvent under analogous reaction conditions. Further, it has
been demonstrated that in 1 and 2 the metal centers are bridged
by HCCB2ꢁ to form a rigid double stranded 1D chain. In these sys-
tems the O–Hꢀ ꢀ ꢀO hydrogen bonding, C–Hꢀ ꢀ ꢀ
p
and
p p interac-
ꢀ ꢀ ꢀ
[19] T.K. Prasad, M.V. Rajasekharan, Cryst. Growth Des. 8 (2008) 1346.
[20] A.A. Mohamed, A.P. Mayer, H.E. Abdou, M.D. Irwin, L.M. Perez, J.P. Fackler,
Inorg. Chem. 46 (2007) 11165.
tions construct 2D supramolecular networks possessing square
and ellipsoidal cavities of different size. On the other hand, 3
exhibited inclusion of cadmium dimer governed by eight coordi-
nated cadmium coordination polymer. In this system, a 3D supra-
molecular network resulted from O–Hꢀ ꢀ ꢀO hydrogen bonding
interactions between dimeric unit and double stranded polymeric
[21] H. Eddaoudi, M. Li, M. O0Keeffe, O.M. Yaghi, Nature 402 (1999) 276.
[22] S.S.Y. Chui, S.M.F. Lo, J.P.H. Charmant, A.G. Orpen, I.D. Williams, Science 283
(1999) 1148.
[23] B. Kesanli, W. Lin, Coord. Chem. Rev. 246 (2003) 305.
[24] S. Mandal, S. Natarajan, Inorg. Chem. 47 (2008) 5304.
[25] S. Furukawa, K. Hirai, K. Nakagawa, Y. Takashima, R. Matsuda, T. Tsuruoka, M.
Kondo, R. Haruki, D. Tanaka, H. Sakamoto, S. Shimomura, O. Sakata, S.
Kitagawa, Angew. Chem., Int. Ed. 48 (2009) 1766.
[26] Y. Dai, E. Ma, E. Tang, J. Zhang, Z. Li, X. Huang, Y. Yao, Cryst. Growth Des. 5
(2005) 1313.
[27] S. Paul, R. Clerac, N.G.R. Hearns, D. Ray, Cryst. Growth Des. 9 (2009) 4032.
[28] P.K. Nanda, V. Bertolasi, G. Aromí, D. Ray, Polyhedron 28 (2009) 987.
[29] T. Chattopadhyay, K.S. Banu, S. Chattopadhyay, A. Banerjee, S. Mondal, E.
Suresh, D. Das, Inorg. Chem. Commun. 12 (2009) 26.
chain. The C–Hꢀ ꢀ ꢀ
p
and
p p interactions led to 2D parallel double
ꢀ ꢀ ꢀ
layers incorporating dimeric complex. Thermal studies indicated
higher stability of 2 in comparison to 1 and 3. Further, four mono-
nuclear complexes based on H3BCCB have been prepared and the
representative complex 5 structurally characterized. Significant
fluorescence behavior of H3CCB and 1–3 has been observed in solid
state, where the intensity of ligand is strong relative to the com-
[30] H. Aghabozorg, N. Ilaie, M. Heidari, F. Manteghic, H. Pasdarb, Acta Crystallogr.,
Sect. E 64 (2008) m1351.
[31] K.S. Hagen, R. Lachicotte, A. Kitaygorodskiy, J. Am. Chem. Soc. 115 (1993)
12617.
plexes. Likewise, H3BCCB and
temperature.
5 also fluoresces at room
[32] X.-J. Ke, D.-S. Li, J. Zhao, C.-X. Meng, X.-N. Zhang, Q.-F. He, C. Li, Y.-Y. Wang,
Inorg. Chem. Commun. 13 (2010) 484.
[33] K.H. Chung, E. Hong, Y. Do, C.H. Moon, J. Chem. Commun. (1995) 2333.
[34] H.-P. Xiao, L.-G. Zhu, Acta Crystallogr., Sect. E 59 (2003) m964.
[35] D.D. Perrin, W.L.F. Armango, D.R. Perrin, Purification of Laboratory Chemicals,
Pergamon, Oxford, UK, 1986.
[36] G.M. Sheldrick, SHELXL-97, Program for X-ray Crystal Structure Refinement,
Göttingen University, Göottingen, Germany, 1997.
[37] G.M. Sheldrick, SHELXS-97, Program for X-ray Crystal Structure Solution,
Göttingen University, Göttingen, Germany, 1997.
Acknowledgments
Thanks are due to the Department of Science and Technology,
New Delhi, India for financial support through the scheme SR/S1/
IC-15/2006. One of the authors (R.P.), thanks the Council of Scien-
tific and Industrial Research, New Delhi, India for a Senior Research
Fellowship. We are also grateful to the Department of Chemistry,
Faculty of Science, Banaras Hindu University, Varanasi, India for
extending laboratory facilities and the National Institute of Ad-
vanced Industrial Science and Technology (AIST), Osaka, Japan for
single crystal X-ray diffraction facility.
[38] A.L. Spek, PLATON, A Multipurpose Crystallographic Tools, Utrecht University,
Utrecht, The Netherlands, 2000.
[39] A.L. Spek, Acta Crystallogr., Sect. A 46 (1990) C31.
[40] M.-H. Zeng, X-L. Feng, W.-X. Zhang, X.-M. Chen, Dalton Trans. (2006) 5294.
[41] V.R. Pedireddi, S. Varughese, Inorg. Chem. 43 (2004) 450.
[42] W.M. Singh, J.B. Baruah, Dalton Trans. (2009) 2352.
[43] J.S.M. Samec, J.-E. Backvall, P.G. Andersson, P. Brandt, Chem. Soc. Rev. 35
(2006) 237.
Appendix A. Supplementary material
[44] J.H. Choi, Y.H. Kim, S.H. Nam, S.T. Shin, M.-J. Kim, J. Park, Angew. Chem., Int. Ed.
41 (2002) 2373.
1H NMR spectra of the ligands H3CCB and H3BCCB, figures for
supramolecular assemblies in 1–3, TG-DSC curves for 1–3 and fluo-
rescence spectra of 1 and 3. CCDC 743407, 747607, 747608 and
787720 contain the supplementary crystallographic data for (1),
(2), (3) and (4). These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.a-
[45] R.-Q. Zhong, R.-Q. Zou, D.S. Pandey, T. Kiyobayashi, Q. Xu, Inorg. Chem.
Commun. 11 (2008) 951.
[46] R.-Q. Zou, R.-Q. Zhong, M. Du, D.S. Pandey, Q. Xu, Cryst. Growth Des. 8 (2008)
452.
[47] Y. Qiu, Y. Li, G. Peng, J. Cai, L. Jin, L. Ma, H. Deng, M. Zeller, S.R. Batten, Cryst.
Growth Des. 10 (2010) 1332.
[48] D.P. Martin, M.R. Montney, R.M. Supkowski, R.L. LaDuca, Cryst. Growth Des. 8
(2008) 3091.

206
R. Pandey et al. / Inorganica Chimica Acta 376 (2011) 195–206
[49] P. Mukherjee, M.G.B. Drew, C.J. Gómez-Garcia, A. Ghosh, Inorg. Chem. 48
[55] S.L. Zheng, J.H. Yang, X.L. Yu, X.M. Chen, W.T. Wong, Inorg. Chem. 43 (2004)
830.
z
(2009) 4817.
[50] A. Castin´ eiras, R. Pedrido, Inorg. Chem. 47 (2008) 5534.
[51] T.C. Stamatatos, G.C. Vlahopoulou, C.P. Raptopoulou, A. Terzis, A. Escuer, S.P.
Perlepes, Inorg. Chem. 48 (2009) 4610.
[56] T. Hirano, K. Kikuchi, Y. Urano, T. Nagano, J. Am. Chem. Soc. 124 (2002) 6555.
[57] J. Cui, A. Wang, N.L. Edleman, J. Ni, P. Lee, N.R. Armstrong, T. Marks, J. Adv.
Mater. 13 (2001) 1476.
[52] S.-L. Li, Y.-Q. Lan, J.-F. Ma, J. Yang, G.-H. Wi, L.-P. Zhang, Z.-M. Su, Cryst. Growth
Des. 8 (2008) 675.
[58] R.C. Evans, P. Douglas, C.J. Winscom, Coord. Chem. Rev. 250 (2006) 2093.
[59] S.V. Ganesan, S. Natarajan, Inorg. Chem. 43 (2004) 198.
[53] L. Wang, W. You, W.C. Huang, Wang, X.-Z. You, Inorg. Chem. 48 (2009) 4295.
[54] L. Fabbrizzi, M. Licchelli, G. Rabaioli, A. Taglietti, Coord. Chem. Rev. 205 (2000)
85.