Synthesis of coordination polymers with d10 metal ions and a new linear ligand: X-ray structural and luminescence studies

Article abstract of DOI:10.1016/j.poly.2012.06.055

Four new coordination polymers (CPs), {[Zn₂(L) ₄]·7H₂O}_n (1), {[Zn₂(L) ₄]·4H₂O}_n (2), {[Zn(L) ₂]·3/2H₂O}_n (3) and {[Cd(L) ₂

Full text of DOI:10.1016/j.poly.2012.06.055

Polyhedron 52 (2013) 1145–1152
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis of coordination polymers with d10 metal ions and a new linear ligand:
X-ray structural and luminescence studies
⇑
Musheer Ahmad, Parimal K. Bharadwaj
Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh 208016, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Available online 10 July 2012
Four new coordination polymers (CPs), {[Zn2(L)4]ꢀ7H2O}n (1), {[Zn2(L)4]ꢀ4H2O}n (2), {[Zn(L)2]ꢀ3/2H2O}n (3)
and {[Cd(L)2]ꢀ3H2O}n (4) (HL = 4-benzoimidazol-1-yl-methyl benzoic acid) have been synthesized under
hydrothermal conditions. All the complexes have been characterized by single crystal X-ray crystallogra-
phy (XRD), IR spectroscopy, elemental analysis and thermogravimetry (TGA). Complexes 1–4 show sim-
ilar 2D, non-interpenetrated, uninodal 4-connected layers that are further connected by H-bonding
interactions to 3D supramolecular structures. For the complexes 1–3, the overall architecture is con-
trolled by the template used. All complexes exhibit high thermal stability losing coordinated water mol-
ecules at ꢁ110 °C. Upon excitation at 343 nm, compounds 1–3 exhibit solid-state luminescence at room
temperature. The intensity of luminescence gradually decreases with an increase in the number of lattice
water molecules per Zn(II) center due to vibrational quenching by water molecules.
Dedicated to Alfred Werner on the 100th
anniversary of his Nobel prize in chemistry
in 1913.
Keywords:
Coordination polymer
d10 Metal ions
X-ray structural studies
Crystal structure
TGA
Ó 2012 Published by Elsevier Ltd.
Luminescence
1. Introduction
of mixed ligand CPs with different N-donor co-ligands did not lead
to results. However, nature of the co-ligands are found to influence
Recent years have witnessed an explosive growth in the con-
struction of coordination polymers (CPs) for their potential appli-
cations in gas adsorption [1–5], molecular storage [6,7],
heterogeneous catalysis [8–11], proton conduction [12–15], mag-
netism [16–20], luminescence [21,22] and so on. The design and
characteristic features of ligands such as rigidity and flexibility,
bulkiness, chirality and so on play important roles in dictating
overall topology of the CPs. Additionally, the tendency of metal
ions to adopt certain geometries and the external experimental
conditions imposed also influences the overall structure of the
frameworks. Most researchers have focused on the synthesis and
utilization of symmetric, bridging ligands [23] for the construction
of CPs. However, unsymmetrical ligands incorporating multiple
binding sites with different donors, can assembled metal centers
around to afford a variety of CPs with novel topological features
[24,25]. Usually ligands having both nitrogen [26] and carboxylate
[27–30] donors have been used extensively for this purpose. Moti-
vated by this, we have designed a semi-flexible linear ligand
flanked on either side by benzimidazole and carboxylate units
(Scheme 1). This design provides more conformational freedom
for the coordination environment around transition metal ions that
exhibit strong coordination preferences. Our attempted synthesis
the overall architecture. In this paper, we report the synthesis and
crystal structural description of four new coordination polymers of
Zn(II) and Cd(II) ions having the formula {[Zn2(L)4]ꢀ7H2O}n (1),
{[Zn2(L)4]ꢀ4H2O}n (2), {[Zn(L)2]ꢀ3/2H2O}n (3) and {[Cd(L)2]ꢀ3H2O}n
(4).
2. Experimental
2.1. General methods and materials
Benzimidazole (98%), methyl 4-(bromomethyl)benzoate (98%),
dabco, 1,2-di(4-pyridyl)ethylene (dpe), potassium iodide,
Zn(NO3)2ꢀ6H2O (98%) and Cd(NO3)2ꢀ4H2O (98%) were purchased
from Aldrich, USA and used as received. All solvents and anhydrous
K2CO3 were procured from S.D. Fine Chemicals, India. All solvents
were purified prior to use following standard methods.
Infrared spectra were recorded on a Perkin-Elmer Model 1320
spectrometer (KBr disk, 400–4000 cmꢂ1). 1H NMR spectra were re-
corded on a JEOL-ECX 500 FT (500 MHz) instrument in DMSO-d6
using Me4Si as the internal standard. ESI–mass spectra were
collected on
a WATERS Q-TOF Premier mass spectrometer.
Thermogravimetric analyses (TGA) were recorded using a Mettler
Toledo Star System (heating rate of 5 °C/min). Microanalyses for
the compounds were obtained using a CE-440 elemental analyzer
(Exeter Analytical Inc.). Solid-state photoexcitation and emission
⇑
Corresponding author. Tel./fax: +91 512 259 7436.
E-mail address: pkb@iitk.ac.in (P.K. Bharadwaj).
0277-5387/$ - see front matter Ó 2012 Published by Elsevier Ltd.
http://dx.doi.org/10.1016/j.poly.2012.06.055

1146
M. Ahmad, P.K. Bharadwaj / Polyhedron 52 (2013) 1145–1152
in ꢁ51% yield. The crystals were repeatedly washed with water fol-
lowed by acetone and air-dried. Anal. Calc. for C60H50N8O11Zn2: C,
60.56; H, 4.24; N, 9.42%. Found: C, 60.69; H, 4.35; N, 9.12%. IR
(KBr, cmꢂ1): 3414(m), 3089(m), 1605(s), 1561(s), 1513(s),
1485(w), 1381(s), 1296(m), 1265(w), 1206(w), 1179(m),
1134(m), 1114(w), 1018(m), 921(m), 799(s), 753(s), 627(m).
2.2.4. Synthesis of {[Cd(L)2]ꢀ3H2O}n (4)
A mixture containing HL (30 mg, 0.12 mmol), Cd(NO3)2ꢀ4H2O
(90 mg, 0.29 mmol) in 3 mL water and 0.1 mL of aq. ammonia solu-
tion were sealed in a Teflon-lined autoclave and heated under
autogenous pressure to 120 °C for three days and then allowed to
cool to room temperature at the rate of 1 °C per minute. Block-
shaped light-yellow crystals of 4 were collected in ꢁ50% yield.
The crystals were repeatedly washed with water followed by ace-
tone and air-dried. Anal. Calc. for C30H28N4O7Cd: C, 53.66; H, 4.20;
N, 8.34%. Found: C, 53.13; H, 4.28; N, 8.21%. IR (KBr, cmꢂ1):
3424(m), 3097(m), 1611(s), 1560(s), 1512(s), 1382(s), 1297(m),
1183(m), 1017(m), 923(s), 798(s), 750(s),693(w), 663(w).
Scheme 1. Schematic representation of ligand HL.
spectra were recorded using double UV–Vis-NIR spectrophotome-
ter (Varian Model Cary 5000) and Jobin Yvon Horiba Fluorolog-3
spectrofluorimeter at room temperature. Powder X-ray diffraction
2.3. X-ray structural studies
(Cu Ka radiation, scan rate 3 °/min, 293 K) was performed on a Bru-
ker D8 Advance Series 2 powder X-ray diffractometer.
Single crystal X-ray data on complexes 1–4 were collected at
100 K on a Bruker SMART APEX CCD diffractometer using graphite
monochromated Mo
Ka radiation (k = 0.71073 Å). The linear
2.2. Synthesis
absorption coefficients, scattering factors for the atoms, and the
anomalous dispersion corrections were taken from the Interna-
tional Tables for X-ray Crystallography [32]. The data integration,
reduction, empirical absorption correction and structure solution
were carried out as described earlier [33–36]. The H atoms were
refined as follows: the H atoms attached to C atoms were posi-
tioned geometrically and treated as riding atoms using SHELXL de-
fault parameters [37]. The hydrogen atoms of lattice water
molecules were located in difference Fourier maps and refined
freely keeping the O–H bond distances constrained to ꢁ0.85 Å with
the DFIX command. The crystal and refinement data are collected
in Table 1 while selective bond distances and angles are given in
Table S1 (supporting information).
The ligand HL was synthesized following an earlier reported
[31] procedure with slight modifications, as given in supporting
information.
2.2.1. Synthesis of {[Zn2(L)4]ꢀ7H2O}n (1)
A mixture containing HL (20 mg, 0.08 mmol), Zn(NO3)2ꢀ6H2O
(60 mg, 0.20 mmol) in 3 mL water and 0.1 mL of aq. ammonia solu-
tion were sealed in a Teflon-lined autoclave and heated under
autogenous pressure to 120 °C for three days and then allowed to
cool to room temperature at the rate of 1 °C per minute. Block-
shaped pale-yellow crystals of 1 were collected in ꢁ40% yield.
The crystals were repeatedly washed with water followed by ace-
tone and air-dried. Anal. Calc. for C60H58N8O15Zn2: C, 57.11; H,
4.63; N, 8.88%. Found: C, 57.21; H, 4.72; N, 8.75%. IR (KBr, cmꢂ1):
3450(m), 3090(m), 1611(m), 1590(s), 1538(s), 1509(w), 1463(m),
1397(s), 1294(m), 1264(m), 1202(w), 1113(w), 1018(s), 977(w),
953(w), 912(w), 859(m), 799(m), 777(s), 751(s).
3. Results and discussion
The ligand is designed such that there is a possibility of rota-
tional degree of freedom about CꢂN bond to adopt different con-
formations to generate different coordination polymeric
structures with d10 metal ions. The IR spectra of 1–4 show strong
absorption bands between 1414 and 1611 cmꢂ1 attributable to
[38,39] coordinated carboxylate groups (see Supporting informa-
tion). The broad peak in the region, 3414–3476 cmꢂ1 indicates
[40] the presence of lattice water molecules.
2.2.2. Synthesis of {[Zn2(L)4]ꢀ4H2O}n (2)
A mixture of Zn(NO3)2ꢀ6H2O (50 mg, 0.17 mmol), HL (30 mg,
0.12 mmol) and dpe (10 mg, 0.06 mmol) in 3 mL H2O and 0.1 mL
aqueous Et4NOH solution were placed in a Teflon-lined stainless
steel autoclave and heated to 120 °C for three days under autoge-
nous pressure, and then allowed to cool to room temperature at
the rate of 1 °C per minute. Block-shaped pale-yellow crystals of
2 were collected in ꢁ43% yield. The crystals were repeatedly
washed with water followed by acetone and air-dried. Anal. Calc.
for C60H52N8O12Zn2: C, 59.66; H, 4.34; N, 9.28%. Found: C, 59.24;
H, 4.39; N, 9.56%. IR (KBr, cmꢂ1): 3476(m), 3090(m), 1591(s),
1540(s), 1463(s), 1398(s), 1294(s), 1264(s), 1203(m), 1018(s),
911(s), 859(s), 799(s), 777(s), 751(s).
3.1. Crystal structure of {[Zn2(L)4]ꢀ7H2O}n (1)
Compound 1 crystallizes in the monoclinic space group C2/c.
Single-crystal X-ray analysis reveals that the asymmetric unit of
1 contains one Zn(II), two Lꢂ1 and three and a half lattice water
molecules. The coordination mode of Lꢂ1 is given in Fig. 1. Here,
the metal ion shows distorted tetrahedral ZnN2O2 coordination
from two monodentate carboxylate
1.998(2) Å) and two benzimidazole
O
N
(Zn–O = 1.960(2)–
(ZnꢂN = 2.024(2)ꢂ
2.2.3. Synthesis of {[Zn(L)2]ꢀ3/2H2O}n (3)
A mixture containing HL (20 mg, 0.08 mmol), Zn(NO3)2ꢀ6H2O
(60 mg, 0.20 mmol) and dabco (10 mg, 0.08 mmol) in 3 mL water
and 0.1 mL of NaOH solution were sealed in a Teflon-lined auto-
clave and heated under autogenous pressure to 120 °C for three
days and then allowed to cool to room temperature at the rate of
1 °C per minute. Block-shaped yellow crystals of 3 were collected
2.042(3) Å) from four different Lꢂ1 ligand units.
A 2D non-interpenetrated rectangular-grid is generated by
combination of four ligands and four metal centers. The dimension
of the rectangular-grid is approximately 6.3 ꢃ 8.1 Å. These 2D lay-
ers stack in ꢀꢀꢀABABꢀꢀꢀ fashion through
p p interactions (3.714(1) Å)
between aromatic rings of two parallel layers that is further
ꢀꢀꢀ

M. Ahmad, P.K. Bharadwaj / Polyhedron 52 (2013) 1145–1152
1147
Table 1
Crystal and structure refinement data for 1–4.
Complex
1
2
3
4
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C
60H58N8O15Zn2
C60H52N8O12Zn2
1207.83
C60H50N8O11Zn2
1189.81
monoclinic
C2/c
25.161(4)
11.539(2)
21.399(5)
90.000
123.182(5)
90.000
5199.7(17)
4
C30H28N4O7Cd
671.38
monoclinic
C2/c
24.987(5)
11.986(6)
22.025(4)
90.000
124.209(5)
90.000
1261.88
monoclinic
C2/c
25.349(6)
11.761(4)
21.405(5)
90.000
121.855(5)
90.000
5420(3)
4
triclinic
ꢀ
P1
11.779(5)
11.811(6)
20.942(3)
75.872(4)
81.890(5)
77.105(7)
2742.5(18)
2
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
U (Å3)
5455(3)
8
1.624
Z
qcalc (g/cm3)
1.544
0.966
1.460
0.947
1.517
0.996
l
(mmꢂ1
)
0.857
F(000)
2608
1244
2448
2704
Reflections collected
Independent reflections
Goodness-of-fit (GOF)
13466
3860
1.062
13899
7166
1.073
13138
3362
1.027
13819
3931
1.073
Final R indices [I > 2
R indices (all data)
CCDC
r(I)]
R1 = 0.0463
wR2 = 0.1202
R1 = 0.0576
wR2 = 0.1288
881367
R1 = 0.0793
wR2 = 0.1967
R1 = 0.0978
wR2 = 0.2142
786124
R1 = 0.0558
wR2 = 0.1387
R1 = 0.0796
wR2 = 0.1539
881368
R1 = 0.0455
wR2 = 0.1172
R1 = 0.0562
wR2 = 0.1254
881369
Fig. 1. Coordination modes of ligand Lꢂ1 in 1.
Fig. 3. 3D view along a-axis in 1 showing lattice water molecules in space-fill
model.
reinforced by strong non-covalent H-bonding interactions involv-
ing solvent molecules to form an overall 3D structure (Figs. 2 and
3).
Solvent accessible volume for 1, calculated with the PLATON [41]
program, is 12.0% of the total unit cell volume. Topological analysis
using the Topos software [42] shows that the structure can be de-
scribed as a uninodal 4-connected sql net with Schläfli symbol as
{44.62}. (Fig. 4).
3.2. Crystal structure of {[Zn2(L)4]ꢀ4H2O}n (2)
In this case, use of dpe as a co-ligand and the pH shifted to more
basic condition, led to the formation of a 2-fold interpenetrated 2D
coordination polymer. Interestingly, the co-ligand itself does not
bind to the metal. This compound crystallizes in the triclinic space
group P1. The asymmetric unit contains two Zn(II), four Lꢂ1 ligands
ꢀ
Fig. 2. Diagram showing
layers in 1.
pꢀꢀꢀp interactions between aromatic rings of two different
and four lattice water molecules. Both the Zn(II) metal ions show

1148
M. Ahmad, P.K. Bharadwaj / Polyhedron 52 (2013) 1145–1152
Fig. 6. ꢀꢀꢀABABꢀꢀꢀ stacking mode between two 2D sheets in 2.
that 3 crystallizes in the monoclinic space group C2/c. The asym-
metric unit consists of one Zn(II), two Lꢂ1 and one and a half lattice
water molecules. The metal ions show distorted tetrahedral geom-
Fig. 4. Topological view of (4,4)-connected net in 1.
etry with ligation from two monodentate carboxylate
O
distorted tetrahedral geometry with ligation from two monoden-
tate carboxylate O (ZnꢂO = 1.950(3)ꢂ1.959(3) Å) and two benz-
imidazole N (ZnꢂN = 2.021(4)ꢂ2.014(4) Å) from four different
Lꢂ1 ligands. The structure consists of rectangular-grid 2D sheets
generated along the crystallographic ab plane through combina-
tion of four Lꢂ1 and four Zn (II) ions (Fig. 5).
These 2D interpenetrated sheets stack in ꢀꢀꢀABABꢀꢀꢀ fashion
through non-covalent interactions involving solvent molecules to
form an overall 3D structure (Figs. 6 and 7).
(ZnꢂO = 1.961(3) ꢂ 1.993(3) Å) and two benzimidazole N (ZnꢂN =
2.050(3)ꢂ2.061(3) Å) from four independent Lꢂ1 ligands. A non-
interpenetrated 2D sheet is formed along the crystallographic bc
plane by four Lꢂ1 and four Zn (II) ions (Fig. 9).
These 2D sheets further connect to give a 3D framework
through the multi-point H-bonding interactions between lattice
water molecules, non-coordinated carboxylate O atoms as well as
p p stacking interactions between adjacent layers (Fig. 10). The
ꢀꢀꢀ
solvent accessible volume again is very low; only 7.3% of the total
The four water molecules themselves form a linear chain via
strong H-bonding interactions (OW1ꢀ ꢀ ꢀOW2 = 2.939(11) Å),
(OW2ꢀ ꢀ ꢀOW3 = 2.797(9) Å) and (OW3ꢀ ꢀ ꢀOW4 = 2.788(11) Å). In
addition, both OW1 and OW4 (O8ꢀ ꢀ ꢀOW1 = 3.000(9), OW4ꢀ ꢀ ꢀO8 =
2.832(10) Å) show strong H-bonding interactions with the available
carboxylate O (Fig. 8). This structure like 1 is densely packed with
solvent accessible volume only 9.0% of the total unit cell volume.
unit cell volume.
3.4. Crystal structure of {[Cd(L)2]ꢀ3H2O}n (4)
Compound 4 also crystallizes in the monoclinic space group C2/c
as a non-interpenetrated structure. The asymmetric unit contains
two Lꢂ1, one Cd(II) and three lattice water molecules. Each Cd(II)
is six coordinated with a distorted octahedral geometry (Fig. 11),
with ligation from four O (CdꢂO = 2.270(3)–2.474(3) Å) of two
ligands Lꢂ1 in chelating mode and two N (CdꢂN = 2.262(3)–
2.273(3) Å) of two benzimidazole moieties. In this case also, a
non-interpenetrated 2D sheet is formed along the crystallographic
3.3. Crystal structure of {[Zn(L)2]ꢀ3/2H2O}n (3)
When dabco is used as a co-ligand with NaOH base, a different
structure is formed. Single crystal X-ray diffraction studies reveal
Fig. 5. 2D sheet view along ab plane in 2.

M. Ahmad, P.K. Bharadwaj / Polyhedron 52 (2013) 1145–1152
1149
Fig. 7. Water chain supported by carboxylate oxygen running along b axis in 2.
Fig. 8. 3D architecture showing embedded water molecules in space-fill model along a axis in 2.
position of the framework is achieved only above 350 °C. Com-
pound 2 exhibits a weight loss of 5.95% (expected = 5.96%) in the
range, 80–110 °C that corresponds to loss of four lattice water mol-
ecules and the framework decomposes above 310 °C. Compound 3
shows a weight loss of 2.27% (expected = 2.27%) due to removal of
lattice water molecules and the framework shows stability upto
350 °C. Likewise, 4 shows a weight loss of 8.05% (expected = 8.04%)
in the range, 80–120 °C corresponding to loss of lattice water mol-
ecules. It is also stable upto 350 °C and its decomposition starts be-
yond 350 °C. The complex 1 was heated at 110 °C under vacuum
for 4 h. The PXRD pattern of evacuated complex 1 (i.e., complex
10) shows that the framework remains intact upon removal of
water molecules (see Supporting information).
4. Luminescence properties
Complexes showing luminescence properties are of immense
current interest because of their variety of applications in photo-
chemistry, chemical sensors, as well as in electroluminescent dis-
plays [43–45]. Luminescence properties of complexes of d10
metal ions with nitrogen and carboxylate donor ligands have been
reported in the literature [46]. The luminescence properties of 1–4
and metal-free HL were investigated in the solid-state at room
temperature and are shown collectively in Fig. 14. Upon excitation
at 343 nm, 1–3 exhibit unsymmetrical emission as a pair of bands
at 510, 540 and 530 nm and correspondingly at 450, 440 and
420 nm, respectively. The emission bands at higher energy could
possibly be due to intra-ligand interaction as the profile of the
emission band is similar to that of HL, while the low energy band
probably originates from ligand-to-metal charge transfer [47]. For
complexes 1–3, the luminescence intensity gradually decreases as
the number of water molecules per Zn(II) center increases due to
Fig. 9. 2D view along bc plane in 3.
bc plane by four Lꢂ1 and four Cd(II) ions (Fig. 12). These 2D sheets
stack in ꢀꢀꢀABABꢀꢀꢀ fashion through non-covalent interactions
involving lattice water molecules to form an overall 3D structure
(Fig. 13). The 3D structure is further stabilized by a weak CꢂHꢀꢀꢀ
p
interactions (3.834(3) Å) between the benzimidazole moieties.
The solvent accessible volume again is quite low i.e., 10.7% of the
total unit cell volume.
Thermal stabilities of all the complexes were examined (see
Supporting information). Compound 1 shows a weight loss of
10.01% (expected = 9.99%) in the temperature range, 80–110 °C
corresponding to the loss of seven lattice water molecules. Decom-

1150
M. Ahmad, P.K. Bharadwaj / Polyhedron 52 (2013) 1145–1152
Fig. 10. 3D view along c-axis with lattice aqua molecules in space-fill model in 3.
vibrational quenching [48] by water molecules. To probe the effect
of water molecules on the intensity of luminescence, the evacuated
complex 10 is excited at 343 nm. The lower wavelength intra-li-
gand charge transfer band disappears with concomitant significant
increase in intensity of the longer wavelength band. This band,
attributed to ligand-to-metal charge transfer, is greatly enhanced
due to absence of vibrational quenching by lattice water molecules
as in 1. The red-shift of this band by ꢁ35 nm may be due to slight
changes in the structure around the metal ions upon removal of
lattice water molecules. Complex 4 also exhibits two emission
bands centering at ꢁ450 and 490 nm due to intra-ligand and li-
gand to metal charge transfer transitions [49] as in 1–3. Compared
with the ligand, which shows very less luminescence, the lumines-
cence enhancement in these complexes result from increased
rigidity of the ligand upon metal coordination that reduces loss
of energy by radiationless decay [50]. The ZnꢀꢀꢀZn (more than
6.6 Å) and CdꢀꢀꢀCd (more than 6.5 Å) distances are long enough to
contribute to cluster-centered transition caused by metalꢀꢀꢀmetal
interaction in these complexes.
Fig. 11. Coordination modes of ligand Lꢂ1 in 4.
Fig. 12. 2D view along bc plane in 4.

M. Ahmad, P.K. Bharadwaj / Polyhedron 52 (2013) 1145–1152
1151
Fig. 13. 3D view along c-axis with lattice water molecules in space-fill model in 4.
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: de-
posit@ccdc.cam.ac.uk. Supplementary data associated with this
article can be found, in the online version, at http://dx.doi.org/
10.1016/j.poly.2012.06.055.
References
[1] N.L. Rosi, J. Eckert, M. Eddaoudi, D.T. Vodak, J. Kim, M. OKeefe, O.M. Yaghi,
Science 300 (2003) 1127.
[2] M.K. Sharma, I. Senkovska, S. Kaskel, P.K. Bharadwaj, Inorg. Chem. 50 (2011)
539.
ˇ
[3] M. Dinca, J.R. Long, J. Am. Chem. Soc. 127 (2005) 9376.
[4] K. Biradha, A. Ramanan, J.J. Vittal, Cryst. Growth Des. 9 (2009) 2969.
[5] F. Nouar, J.F. Eubank, T. Bousquet, L. Wojtas, M.J. Zaworotko, M. Eddaoudi, J.
Am. Chem. Soc. 130 (2008) 1833.
[6] 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.
[7] H.-S. Choi, M.P. Suh, Angew. Chem., Int. Ed. 48 (2009) 6865.
[8] L. Ma, C. Abney, W. Lin, Chem. Soc. Rev. 38 (2009) 1248.
[9] C.J. Kepert, T.J. Prior, M.J. Rosseinsky, J. Am. Chem. Soc. 122 (2000) 5158.
[10] T. Ezuhara, K. Endo, Y. Ayoma, J. Am. Chem. Soc. 121 (1999) 3279.
[11] C.-D. Wu, W. Lin, Angew. Chem., Int. Ed. 46 (2007) 1075.
[12] A. Shigematsu, T. Yamada, H. Kitagawa, J. Am. Chem. Soc. 133 (2011) 2034.
[13] T. Yamada, M. Sadakiyo, H. Kitagawa, J. Am. Chem. Soc. 131 (2009) 3144.
[14] S.C. Sahoo, T. Kundu, R. Banerjee, J. Am. Chem. Soc. 133 (2011) 17950.
[15] T. Kundu, S.C. Sahoo, R. Banerjee, Chem. Commun. 48 (2012) 4998.
[16] M. Ahmad, M.K. Sharma, R. Das, P. Poddar, P.K. Bharadwaj, Cryst. Growth Des.
12 (2012) 1571.
Fig. 14. Solid-state emission spectra at room temperature.
5. Conclusion
In conclusion, we have described construction of four new coor-
dination polymers under hydrothermal conditions. We have cho-
sen unsymmetrical semi-flexible mixed donor based organic
ligand for construction of coordination polymers with d10 metal
ions. Solid-state emissions of the complexes have been achieved
at room temperature. We are in process to synthesize similar type
ligands for constructing coordination polymers for various
applications.
~
[17] P. Lama, A. Aijaz, E.C. Sanudo, P.K. Bharadwaj, Cryst. Growth Des. 10 (2010)
283.
[18] H.-L. Jiang, Q. Xu, Chem. Commun. 47 (2011) 3351.
[19] G.-C. Xu, W. Zhang, X.-M. Ma, Y.-H. Chen, L. Zhang, H.-L. Cai, Z.-M. Wang, R.-G.
Xiong, S. Gao, J. Am. Chem. Soc. 133 (2011) 14948.
[20] E. Coronado, J.R. Galán-Mascarós, C. Martí-Gastaldo, Inorg. Chem. 46 (2007)
8108.
[21] Y. Cui, Y. Yue, G. Qian, B. Chen, Chem. Rev. 112 (2012) 1126.
[22] M. Du, X.J. Xiang, X.J. Zhao, Inorg. Chem. 46 (2007) 3984.
[23] A. Aijaz, P. Lama, P.K. Bharadwaj, Inorg. Chem. 49 (2010) 5883.
[24] H. Wang, L.-H. Huo, Z.-P. Deng, H. Zhao, S. Gao, CrystEngComm 14 (2012) 3501.
[25] C. Ren, L. Hou, B. Liu, G.-P. Yang, Y.-Y. Wang, Q.-Z. Shi, Dalton Trans. 40 (2011)
793.
Acknowledgements
We gratefully acknowledge the financial support received from
the Department of Science and Technology, New Delhi, India (to
P.K.B.) and SRF from the CSIR to M.A.
[26] O. Ohmori, M. Fujita, Chem. Commun. 14 (2004) 1586.
[27] M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O’Keeffe, O.M. Yaghi,
Science 295 (2002) 469.
[28] T. Devic, C. Serre, N. Audebrand, J. Marrot, G. Férey, J. Am. Chem. Soc. 127
(2005) 12788.
[29] S.-S. Chen, Y. Zhao, J. Fan, T.-A. Okamura, Z.-S. Bai, Z.-H. Chen, W.-Y. Sun,
CrystEngComm 14 (2012) 3564.
Appendix A. Supplementary data
[30] S.S. Nagarkar, A.K. Chaudhari, S.K. Ghosh, Inorg. Chem. 51 (2012) 572.
[31] M.V. Lucky, S. Sivakumar, M.L.P. Reddy, A. Kumar Paul, S. Natarajan, Cryst.
Growth Des. 11 (2011) 857.
CCDC 786124, 881367–881369 contain the supplementary
crystallographic data for 1–4. These data can be obtained free of

1152
M. Ahmad, P.K. Bharadwaj / Polyhedron 52 (2013) 1145–1152
[32] International Tables for X-Ray Crystallography, vol. III, Kynoch Press,
Birmingham, England, 1970, pp. 257.
[33] SAINT, version 6.02, Bruker AXS., Madison, WI, 1999.
[34] G.M. Sheldrick, SADABS, Empirical Absorption Correction Program, University of
Göttingen, Göttingen, Germany, 1997.
[41] A.L. Spek, PLATON, The University of Utrecht, Utrecht, The Netherlands, 1999.
[42] V.A. Blatov, M. O’Keeffe, D.M. Proserpio, CrystEngComm 12 (2010) 44.
[43] J.E. McGarrah, Y.J. Kim, M. Hissler, R. Eisenberg, Inorg. Chem. 40 (2001) 4510.
[44] Q. Wu, M. Esteghamatian, N.X. Hu, Z. Popovic, G. Enright, Y. Tao, M. D’Iorio, S.
Wang, Chem. Mater. 12 (2000) 79.
[35] XPREP, version 5.1, Siemens Industrial Automation Inc., Madison, WI, 1995.
[36] G.M. Sheldrick, SHELXTL Reference Manual, version 5.1, Bruker AXS, Madison,
WI, 1997.
[37] G.M. Sheldrick, SHELXL-97: Program for Crystal Structure Refinement, University
of Göttingen, Göttingen, Germany, 1997.
[45] M.D. Allendorf, C.A. Bauer, R.K. Bhakta, R.J.T. Houk, Chem. Soc. Rev. 38 (2009)
1330.
[46] N.S. Gunning, C.L. Cahill, Dalton Trans. (2005) 1518.
[47] Y. Zhou, W.X. Mingyan, A. Lan, L. Zhang, R. Feng, F. Jiang, M. Hong, Inorg. Chem.
Commun. 15 (2012) 140.
[38] L. Lisnard, P. Mialane, A. Dolbecq, J. Marrot, J.M.-J. Clemente, E. Coronado, B.
Keita, P. de Oliveira, L. Nadjo, F. Secheresse, Chem. Eur. J. 13 (2007) 3525.
[39] X.-J. Li, X.-Y. Wang, S. Gao, R. Cao, Inorg. Chem. 45 (2006) 1508.
[40] D. Dobrzynska, L.B. Jerzykiewicz, J. Jezierska, M. Duczmal, Cryst. Growth Des. 5
(2005) 1945.
[48] K.-L. Wong, G.-L. Law, Y.-Y. Yang, W.-T. Wong, Adv. Mater. 18 (2006) 1051.
[49] S.L. Li, Y.Q. Lan, J.F. Ma, J. Yang, G.H. Wei, L.P. Zhang, Z.M. Su, Cryst. Growth Des.
8 (2008) 675.
[50] S.L. Zheng, J.H. Yang, X.L. Yu, X.M. Chen, W.T. Wong, Inorg. Chem. 43 (2004)
830.