A novel copper(II) coordination polymer with carboxylate and isoindol backbones of a bifunctional ligand

Article abstract of DOI:10.1016/j.molstruc.2013.05.017

The reaction of a bifunctional ligand, 3-(1-oxo-1,3-dihydro-isoindol-2-yl)- propionic acid (Hpda) with Cu(NO₃)_{2 3}H ₂O in methanol-water in the presence of NaOH at room temperature produces a novel dinuclear copper(II) coordination polymer [Cu ₂(pda)4]n. The complex is fully characterized in the solid state as well as in solution using various analytical techniques including single crystal X-ray diffraction study. The single crystal X-ray structure analysis reveals that the monomeric unit of complex consists of Cu₂(O₂CR)4 paddlewheel building unit, where the two copper centers acquire a distorted square pyramidal geometry with amide oxygen of the isoindol ring of an adjacent Hpda ligand sitting on the axial positions.

Full text of DOI:10.1016/j.molstruc.2013.05.017

Journal of Molecular Structure 1047 (2013) 317–323
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
A novel copper(II) coordination polymer with carboxylate and isoindol
backbones of a bifunctional ligand
a
b
c,
⇑
b
a,
⇑
Ayan Patra , Tamal K. Sen , Ghezai T. Musie , Swadhin K. Mandal , Manindranath Bera
a
Department of Chemistry, University of Kalyani, Kalyani, Nadia, West Bengal 741 235, India
Department of Chemical Sciences, Indian Institute of Science Education & Research-Kolkata, Mohanpur, West Bengal 741 252, India
Department of Chemistry, The University of Texas at San Antonio, San Antonio, TX 78249, USA
b
c
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
ꢀ
ꢀ
ꢀ
A novel copper(II) coordination
polymer of a bifunctional ligand has
been prepared.
The complex consists of the square
2 2 4
Cu (O CR) paddlewheel secondary
building unit.
The complex shows axial binding of
amide oxygen of the isoindol moiety
with Cu(II) ions.
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction of a bifunctional ligand, 3-(1-oxo-1,3-dihydro-isoindol-2-yl)-propionic acid (Hpda) with
ꢁ3H
Cu(NO O in methanol–water in the presence of NaOH at room temperature produces a novel dinu-
clear copper(II) coordination polymer [Cu (pda) . The complex is fully characterized in the solid state as
well as in solution using various analytical techniques including single crystal X-ray diffraction study. The
single crystal X-ray structure analysis reveals that the monomeric unit of complex consists of Cu (O CR)
4
Received 22 March 2013
Received in revised form 9 May 2013
Accepted 13 May 2013
)
3 2
2
2
4 n
]
Available online 22 May 2013
2
2
paddlewheel building unit, where the two copper centers acquire a distorted square pyramidal geometry
with amide oxygen of the isoindol ring of an adjacent Hpda ligand sitting on the axial positions.
Ó 2013 Elsevier B.V. All rights reserved.
Keywords:
Carboxylate ligand
Isoindol functionality
Copper complex
Coordination polymer
Crystal structure
Spectral properties
1
. Introduction
There has been an increasing interest in the design and synthe-
and enhanced electrical conductivity, etc. [1–4]. One commonly
used synthetic strategy in building metal complexes with extended
structures is to employ appropriate bridging ligands which are
capable of binding to several metal centers and promoting mag-
netic spin interactions. The self-assembly of the ligands with versa-
tile coordination modes has lead to the formation of the
coordination polymers [5,6]. A wide variety of diverse architec-
tures with high structural stability have been prepared by connect-
ing rigid metallic building blocks with appropriate organic linkers.
In this context, the carboxylate ligands with their different coordi-
sis of polymeric coordination networks containing paramagnetic
metal ions. These class of complexes have potential applications
in the fields of molecular magnetic materials, biological catalysis,
⇑
Corresponding authors. Tel.: +91 33 25828282x306; fax: +91 33 25828282.
E-mail addresses: ghezai.musie@utsa.edu (G.T. Musie), mbera2009@klyuniv.a-
c.in (M. Bera).
0
022-2860/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molstruc.2013.05.017

3
18
A. Patra et al. / Journal of Molecular Structure 1047 (2013) 317–323
nation modes have played very important roles in the formation of
supramolecular assemblies [7–10]. Several complexes with multi-
ple carboxylic acid groups have proven to be good synthons for
supramolecular architectures and coordination polymers [11–15].
The use of polydentate carboxylate ligands, as the organic linkers,
have been studied extensively and reported in the literature [16–
1
8].
The focus here is on a bifunctional ligand, Hpda consisting of an
Fig. 1. Chemical structure of the ligand Hpda.
ꢂ1
isoindol and carboxylate functionalities (Fig. 1). Similar bifunc-
tional carboxylate ligands have been used to assemble various me-
H, 5.93%; N, 6.20%. FTIR (KBr pellet, cm ):
m = 3106(b), 2967(b),
tal ions into aggregates including the paddlewheel Cu
units that show relevance in the area of supramolecular chemistry
19–22]. The dicopper tetracarboxylate system was of interest not
just because of the appealing square architecture of the Cu (O CR)
2
(O
2
CR)
4
1697(s), 1597(s), 1454(s), 1391(s), 1305(s), 1281(s), 1160(s),
1
1080(s), 987(s), 935(s), 827(s), 718(s), 661(s). H NMR (400 MHz,
[
D O, 25 °C): d 2.52 (t, 2H, ethylenic), 3.05 (t, 2H, ethylenic), 4.11
(s, 2H, ethylenic), 7.45 (t, 1H, aromatic), 7.48 (m, 2H, aromatic),
2
2
2
4
core and the strong axial ligating properties provided by the cop-
per(II) ions, but also because paddlewheel dicopper tetracarboxy-
lates are known to exhibit very strong antiferromagnetic
7.66 (d, 1H, aromatic).
2
.3.2. Synthesis of 3-(1-oxo-1,3-dihydro-isoindol-2-yl)-propionic acid,
Hpda
The ligand, Hpda was prepared following our published proce-
dure [28]. To a solution of the precursor ligand H cbal (0.500 g,
.242 mmol) in 15 ml of water at room temperature was slowly
added Zn(ClO O (0.417 g, 1.119 mmol) dissolved in 10 ml
ꢁ6H
9
coupling between the unpaired electrons of the d copper(II) ions
[
23–25]. Recently, we have reported a heptanuclear zinc complex
of a carboxylate and amide rich polydentate ligand undergoing
an intramolecular reaction between the N-alkylated amide and
the benzoate functionality at the half-end of the symmetrical li-
gand to yield an unsymmetrical ligand with an isoindol moiety
2
2
4
)
2
2
of water for a period of 15 min. After complete addition, a colorless
clear solution was observed. The whole reaction mixture was stir-
red for 2 h at room temperature. The solvent was then rotary evap-
orated. The off-white precipitate isolated was washed with
methanol followed by diethyl ether and hexane. The product was
recrystallized from a concentrated water solution of the com-
pound. The product was then dried in vacuo over anhydrous cal-
[
26]. In this paper, we report synthesis, structure, and spectral
properties of a new dinuclear copper(II) coordination polymer
incorporating the isoindol functionality.
2
. Experimental section
.1. Materials
-Carboxybenzaldehyde and b-alanine were purchased from
2
cium sulfate. Yield: 0.207 g (90%). Anal. Calcd. for C11
3
H11NO : C,
6
4.38%; H, 5.40%; N, 6.82%. Found: C, 64.14%; H, 5.57%; N, 6.64%.
ꢂ1
2
FTIR (KBr pellet, cm ):
m = 1695(s), 1595(s), 1371(s), 1339(s),
1
Sigma–Aldrich Chemie GmbH, Germany. Copper(II) nitrate trihy-
drate was obtained from SRL, India. Zinc(II) perchlorate hexahy-
drate was prepared from zinc(II) carbonate and 1:1 perchloric
acid. All other chemicals and solvents were reagent grade materials
and were used as received from the commercial sources without
further purification.
1220(s), 1173(s), 934(s), 826(s), 761(s). H NMR (400 MHz, D O,
25 °C): d 2.79 (t, 2H, ethylenic), 3.89 (t, 2H, ethylenic), 4.54 (s,
2
2H, methylenic protons of the isoindol ring), 7.51–7.73 (m, 4H, aro-
1
3
matic). C NMR (400 MHz, D
(1C, CH ), 49.17 (1C, CH of the iosindol ring), 126.50 (1C, aromatic
CH), 127.00 (1C, aromatic CH), 127.91 (1C, aromatic CH), 129.34
1C, aromatic CH), 134.10 (1C, aromatic CH), 135.72 (1C, aromatic
2 2
O, 25 °C): d 35.31 (1C, CH ), 42.88
2
2
(
CH), 171.56 (1C, C@O of the isoindol ring), 177.21 (1C, aliphatic
carboxylic).
2.2. Physical measurements
Microanalyses (C, H, N) were performed using a Perkin–Elmer
400 CHNS/O Series II elemental analyzer. FTIR spectra were ob-
2
2 4 n
2.4. Synthesis of the complex [Cu (pda) ]
tained on
a
Perkin–Elmer L120-000A spectrometer (200–
ꢂ1
4
000 cm ). The solution electrical conductivity was measured
A
water solution (15 ml) of Cu(NO
1.219 mmol) was slowly added dropwise at ambient temperature
to magnetically stirred solution of ligand Hpda (0.500 g,
3
)
2
ꢁ3H
2
O
(0.294 g,
with a Systronics digital conductivity meter 304 with a solute con-
ꢂ3
1
13
centration of about 10 M. H and C NMR spectra were obtained
on a Bruker AC 400 NMR spectrometer using TMS as the internal
standard. UV–vis spectra were recorded on a Shimadzu UV 1800
a
2.437 mmol) and NaOH (0.097 g, 2.437 mmol) in 15 ml methanol
during a period of 10 min. The whole reaction mixture was stirred
at room temperature for 1 h. It was then filtered to discard any
insoluble precipitate. The X-ray quality blue block shaped single
crystals were grown by slow evaporation of the clear filtrate at
room temperature after ꢃ10 days. Yield: 0.8739 g (76%). Anal.
(
190–1100 nm) (1 cm quartz cell) spectrophotometer. Fluores-
cence spectroscopy was performed using a Perkin Elmer-LS55
Spectrofluorimeter equipped with FLWINLAB software with a rect-
angular quartz cuvette of path length 1 cm. The room temperature
magnetic susceptibility in the solid state was measured using a
home built Gouy balance fitted with a polytronic d.c. power supply.
The experimental magnetic susceptibility was corrected for the
diamagnetic response using Pascal’s constants.
Calcd for C44
40
H N
4
O
2
12Cu : C, 55.99; H, 4.27; N, 5.94; Found: C,
ꢂ1
55.85; H, 4.35; N, 6.02. Molar conductance,
cm mol . FTIR (KBr pellet, cm ):
K
M
: (MeOH) = 30
X
-
2
ꢂ1
ꢂ1
m = 3338(b), 1634(vs), 1607(s),
1591(vs), 1567(s), 1385(vs), 1202(s), 1157(s), 1015(s), 951(s),
ꢂ1
8
91(s), 836(s), 724(s), 609(s). UV–vis (H
2
O): kmax
cm ) = 733 (137), 270 (5672) , 209 (35,317). eff (tot.): 2.18
eff/Cu: 1.54
(
e
, l mol
-
ꢂ1
sh
l
B
l ;
2
2
.3. Synthesis of the ligand, Hpda
l
B
l .
2
.3.1. Synthesis of N-(2-carboxybenzomethyl)–alanine, H cbal
2
The precursor ligand, H cbal was prepared according to the pre-
2.5. X-ray crystallography and data analysis
viously published procedure [27]. The product was confirmed by
elemental analysis, FTIR and 1H NMR spectroscopy. Anal. Calcd.
Crystal data as well as data collection and refinement for the
complex [Cu (pda) are summarized in Table 1. Selected bond
for C11
H
13NO
4
: C, 59.19%; H, 5.87%; N, 6.27%. Found: C, 59.08%;
2
4 n
]

A. Patra et al. / Journal of Molecular Structure 1047 (2013) 317–323
319
and maximum transmission factors. The data were merged to form
Table 1
a set of 2289 independent reflections with R = 0.0429. The residual
Crystal data and structure refinement parameters of the complex [Cu
2
(pda)
4
]
n.
ꢂ3
electron density is in the range +0.565 to ꢂ0.444 e Å . The struc-
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C
44
H
40
N
4
O
12Cu
2
ture was solved by direct methods and refined by full-matrix least-
943.9
Monoclinic
P2 /c
2
squares methods on F [32,33]. Hydrogen atom positions were ini-
tially determined by geometry and refined by a riding model. Non-
hydrogen atoms were refined with anisotropic displacement
parameters. All hydrogen atoms were generated at ideal positions
(CAH, 0.96 Å), and fixed with isotropic thermal parameters.
1
13.113(3)
13.431(3)
11.246(2)
90.00
98.273(4)
90.00
b (Å)
c (Å)
a
(°)
b (°)
(°)
c
3. Results and discussion
Volume
Z
Density
Wavelength
Temperature
F(000)
Absorption coefficient
h range for data collection
Reflections collected
Independent reflections
1960.0(7)
4
3.1. Synthesis and characterization
1.599 Mg/m3
0.71073 Å
100 K
The Hpda ligand has been synthesized from a precursor unsym-
972
1.154 mm
1.57–27.00°
22,613
2289
metrical amino dicarboxylic ligand, N-(2-carboxybenzomethyl)-b-
alanine (H cbal) following our published procedure [27,28]
Fig. 2) and fully characterized by elemental analysis, FTIR,
ꢂ1
2
1
(
H
1
3
and C NMR spectroscopic analyses. The reaction of the precursor
ligand H cbal with Zn(ClO O in aqueous acidic medium at
ꢁ6H
ambient temperature afforded the bifunctional Hpda ligand. The
precursor ligand H cbal has undergone intra-cyclization reaction
R(F obsd data) [I > 2
wR(F2 all data)
Goodness-of-fit on F2
r
(I)]
0.0429
0.0807
1.040
2
4
)
2
2
2
3
Largest diff. peak and hole
+0.565 to ꢂ0.444 e/Å
between the secondary amine and the benzoate functionality to
produce Hpda consisting of an isoindol moiety. The 1-oxo-1,3-
dihydro-isoindol ring is most likely achieved via similarly known
mechanism that involves the activation of the secondary amine
and aromatic carboxylate backbone promoted by the zinc(II) ions
2
2
½wðF Þ ꢅg1=2.
2
2
wR2 ¼ f
r
½wðFo ꢂ F Þ2ꢅ=
r
c
o
R1 =
R
||Fo| ꢂ |Fc||/
R|Fo|.
distances and bond angles are given in Table 2. A clear blue block
shaped single crystal of the title complex with approximate dimen-
sions of 0.203 ꢄ 0.156 ꢄ 0.115 mm was selected for structural
analysis. Intensity data for this compound were collected using a
diffractometer with a Bruker SMART ccd area detector [29,30]
[
34,35]. It is noteworthy to see that under the specified reaction
conditions, Hpda remains uncoordinated to the zinc(II) ions in
solution. Corona et al. have reported the synthesis of a series of no-
vel isoindolone derivatives in goods yields via aza-Wittig reaction
of iminophosphoranes with dialdehydes under different reaction
conditions [36]. Recently, Dietrich et al. have also reported the
complexation behavior of isoindolone pincer ligands towards
Zn(II), Cd(II) and Pd(II) ions [37].
and graphite-monochromated Mo K
a radiation (k = 0.71073 Å). A
total of 22,613 data were measured with Miller indices hmin = ꢂ16,
h
1
max = 16, kmin = ꢂ17, kmax = 17, lmin = ꢂ14, lmax = 10, in the range
.57 < h < 27° using oscillation frames. The data were corrected
x
The reaction of Cu(NO
lar ratio in the presence of stoichiometric amounts of NaOH in
methanol–water at room temperature resulted in a blue solution
3
)
2
ꢁ3H
2
O with the ligand Hpda in 1:2 mo-
for absorption by the multi-scan method [31] giving minimum
Table 2
2 4 n
that was easily crystallized into a new polymeric [Cu (pda) ] com-
2 4 n
Selected bond lengths (Å) and angles (°) in the complex [Cu (pda) ] .
plex (Fig. 3). Molecular structure of the complex has been estab-
lished using the techniques such as elemental analysis, solution
electrical conductivity, FTIR, UV–vis, fluorescence spectroscopy,
room temperature magnetic moment measurement and single
crystal X-ray structure determination. The molar conductivity va-
Bond lengths (Å)
Cu(1)AO(1)
Cu(1)AO(2)
Cu(1)AO(3)
Cu(1)AO(4)
Cu(1)AO(5)
2.134(3)
1.964(2)
1.967(2)
1.962(2)
1.956(2)
ꢂ1
2
ꢂ1
lue of the complex in MeOH is 30
X
cm mol at room temper-
Bond angles (°)
ature, confirming the nonelectrolytic nature of the complex. The
room temperature magnetic moment per Cu in the monomeric
O(5)ACu(1)AO(4)
O(5)ACu(1)AO(2)
O(4)ACu(1)AO(2)
O(5)ACu(1)AO(3)
O(4)ACu(1)AO(3)
O(2)ACu(1)AO(3)
O(5)ACu(1)AO(1)
O(4)ACu(1)AO(1)
O(2)ACu(1)AO(1)
O(3)ACu(1)AO(1)
89.05(10)
87.46(10)
167.78(11)
168.45(10)
90.07(10)
91.01(10)
102.89(10)
97.67(10)
94.52(10)
88.63(10)
complex is 1.54
B
l indicating the strong antiferromagnetic cou-
pling between the two copper centers having one unpaired elec-
tron in each copper ion [38–40].
2 4 n
3.2. Crystal and molecular structure of the complex [Cu (pda) ]
The solid state X-ray crystal structure reveals that the complex
adopts a three-dimensional network of coordination polymer with
Fig. 2. Synthesis of the ligand Hpda.

3
20
A. Patra et al. / Journal of Molecular Structure 1047 (2013) 317–323
2 4 n
Fig. 3. Synthesis of the complex [Cu (pda) ] .
Fig. 5. Stick representation of the molecular structure of the dimeric unit of
Cu (pda)
[
2
4 n
] .
Fig. 4. Labelled stick representation of the molecular structure of the monomeric
unit of [Cu (pda)
2
4 n
] .
ꢂ
ꢂ
two copper(II) ions and four (pda) ligands in the monomeric unit.
The structural view of the monomeric unit is depicted in Fig. 4. The
other (pda) ligand coming from a neighboring monomeric unit. In
this new dinuclear core, the two copper centers and all four car-
boxylate functionalities form a plane.
crystal structure of the monomeric unit consists of a neutral [Cu
2
(-
pda) ] species. The coordination geometry around each copper
4
The square base of the pyramid around the Cu(1) center is de-
ꢆ
ꢆ
center is best described by a distorted square pyramidal geometry.
Four carboxylate groups from four separate ligands bridge the two
fined by the O2, O3, O4 and O5 atoms. The axial position of the
square pyramidal geometry around the Cu1 center is occupied by
O1 atom coming from the amide oxygen of isoindol functionality.
For carboxylate coordination, the Cu(l)AO(2) bond distance
1
1
copper(II) ions in
2
g :g :l fashion placing the carboxylate oxygen
donor atoms at the equatorial positions of the five coordinate
square pyramidal copper centers. The remaining axial site on each
copper center is completed by a oxygen of the isoindol unit of an-
ꢆ
of 1.964(2) Å differs from the Cu(1) AO(4) bond distance of
1.962(2) Å by 0.002 Å. Again, the Cu(l)AO(3) bond distance of
2 4 n
Fig. 6. Stick representation of the molecular structure of the trimeric unit of [Cu (pda) ] .

A. Patra et al. / Journal of Molecular Structure 1047 (2013) 317–323
321
2 4 n
Fig. 7. A unit cell packing diagram of [Cu (pda) ] .
ꢆ
1
1
.967(2) Å differs from the Cu(1) AO(5) bond distance of
(Fig. 8a). The position of this band is consistent of a d–d transition
in copper(II) ions with the observed square-based geometry
around the copper centers. Two distinct charge transfer transitions
.956(2) Å by 0.011 Å. These differences in bond distances of the
two metal ions to the oxygen atoms of the syn–syn bidentate car-
boxylate bridges are usually not larger than 0.11 Å as in other diir-
on or dimanganese complexes [41,42] showing a high degree of
symmetry with respect to the carboxylate bridges. The non-bond-
ing Cuꢁ ꢁ ꢁCu distance is 2.635 Å, the value is within the range for
other reported paddlewheel tetracarboxylato dicopper(II) com-
plexes [20,23–25]. The Cu(1)AO(1) axial bond distance is quite
longer than the other CuAO equatorial bond distances
ꢂ1
ꢂ1
appear in the spectra at 270 nm (e, 5672 l mol cm ) and 209 nm
ꢂ1
ꢂ1
(e
, 35,317 l mol cm ) (Fig. 8b).
Upon excitation in the UV domain at 270 nm, the ligand Hpda
gives rise to a very low intense broad fluorescence spectrum at
401 nm in aqueous solution (Fig. 9). The fluorescence property of
the coordination polymer of Hpda with copper(II) ions has been
examined in aqueous solution. The copper(II) complex displays a
[
2.134(2) Å vs 1.962(2) Å]. The observed long CuAOamide axial bond
distance could be partly due to the participation of a loan pair of
electrons of the amide oxygen during the coordination with cop-
per(II) ions. This CuAOamide bond distance is in agreement with
the values reported in the literature for similar complexes [43].
More interestingly, the solid state X-ray crystal structure of
title complex features the ligand’s carboxylate and amide oxy-
gens susceptible of being involved in a 3D coordination poly-
meric network (Figs. 5 and 6). In this network, the (pda)
ligand which axially coordinates to the copper(II) ions through
2 4
amide oxygen acts as the linker between the two [Cu (pda) ]
0.20
a
0.15
0.10
0.05
0.00
ꢂ
monomeric units and connect them to form the 3D coordina-
tion network. A unit cell packing diagram (Fig. 7) of the title
complex indicates the presence of four monomers in the asym-
metric unit cell.
500
600
700
800
900
3.3. Spectroscopic properties of the complex
Wavelength (nm)
The FTIR spectrum of the complex exhibits two strong bands at
591 and 1385 cm which are due to the asymmetric and sym-
4
.0
.5
.0
2.5
.0
1.5
.0
.5
0.0
b
ꢂ1
1
3
metric stretching vibrations of the carboxylate functionality of
ꢂ1
the ligand, respectively. The difference of ꢃ206 cm
between
3
the asymmetric and symmetric stretching vibrations is attributed
) mode of carboxylate
functionality [44,45]. The band at 1634 cm in the spectrum of
1
1
to the syn–syn bidentate bridging (
g
:g
:l
2
ꢂ1
2
the complex is assigned to C@O group of the isoindol functionality
[
46–48]. Comparing this amide carbonyl stretching band with that
ꢂ1
of the free ligand (ꢃ1695 cm ), it can be suggested that the amide
oxygen of the isoindol functionality is involved in strong coordina-
tion with copper(II) ion. The FTIR spectrum of the complex also
1
0
ꢂ1
shows a broad band at 3338 cm (stretching mode) [28] and a
ꢂ1
sharp band 1607 cm
(bending mode) [49] assignable to the
2
00 220 240 260 280 300 320 340
Wavelength (nm)
m
(OAH) vibrations of the water molecule coming from the mois-
ture of air.
The electronic spectra of the complex in aqueous solution dis-
2 4 n
Fig. 8. Electronic spectra of the complex [Cu (pda) ] in aqueous solution: (a)
1 ꢄ 10 (M) and (b) 1 ꢄ 10 (M).
ꢂ1
ꢂ1
ꢂ3
ꢂ4
play a single absorption band at 733 nm (
e
, 137 l mol cm
)

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A. Patra et al. / Journal of Molecular Structure 1047 (2013) 317–323
5
4
3
2
1
00
00
00
00
00
0
istry. A. P. thanks the University of Kalyani for providing a univer-
sity research fellowship.
References
[
1] L. Toma, R. Lescouezec, J. Vaissermann, F.S. Delgado, C. Ruiz-Perez, R. Carrasco,
J. Cano, F. Lloret, M. Julve, Chem. Eur. J. 10 (2004) 6130–6145.
2] M. Ohba, H. Okawa, Coord. Chem. Rev. 198 (2000) 313–328.
3] D. Gatteschi, Adv. Mater. 6 (1994) 635–645.
[
[
[
4] H.O. Stumpf, L. Ouahab, Y. Pei, D. Grandjean, O. Kahn, Science 261 (1993) 447–
449.
[
5] S. Majumder, S. Sarkar, S. Sasmal, E.C. Sanudo, S. Mohanta, Inorg. Chem. 50
(2011) 7540–7554.
[
[
[
[
6] S. Biswas, A. Ghosh, J. Mol. Struct. 1019 (2012) 32–36.
7] A. Distler, S.C. Sevov, Chem. Commun. (1998) 959–960.
8] P. Brandao, F.A.A. Paz, J. Rocha, Chem. Commun. (2005) 171–173.
9] N. Barooah, R.J. Sarma, A.S. Batsanov, J.B. Baruah, Polyhedron 25 (2006) 17–24.
3
50
400
450
[
[
10] G.M. Brown, M. George, R. Chidambaram, Acta Crystallogr. Sect. B 29 (1973)
2393–2403.
11] S.L. James, Chem. Soc. Rev. 32 (2003) 276–288.
Wavelength (nm)
ꢂ3
Fig. 9. Emission spectra of the ligand Hpda (– line; 1 ꢄ 10 M; kexi = 270 nm;
[12] R. Murugavel, M.G. Walawalkar, M. Dan, H.W. Roesky, C.N.R. Rao, Acc. Chem.
Res. 37 (2004) 763–774.
[13] K.S. Gavrilenko, S.V. Punin, O. Cador, S. Golhen, L. Ouahab, V.V. Pavlishchuk, J.
Am. Chem. Soc. 127 (2005) 12246–12253.
ꢂ3
k
k
emi = 401 nm) and the complex [Cu
emi = 402 nm) in aqueous solution.
2
(pda)
]
4 n
(– line; 1 ꢄ 10 M; kexi = 270 nm;
[
[
[
[
[
[
[
[
[
[
14] M. Eddaoudi, D. Moler, H. Li, B. Chen, T.M. Reineke, M. O’Keeffe, O.M. Yaghi,
Acc. Chem. Res. 34 (2001) 319–330.
15] M. Casarin, C. Corvaja, C.D. Nicola, D. Falcomer, L. Franco, M. Monari, L.
Pandolfo, C. Pettinari, F. Piccinelli, Inorg. Chem. 44 (2005) 6265–6276.
16] L.M. Zhao, Z.J. Zhang, S.Y. Zhang, P. Cui, W. Shi, B. Zhao, P. Cheng, D.Z. Liao, S.P.
Yan, Cryst. Eng. Commun. 13 (2011) 907–913.
17] D.J. Tranchemontagne, J.L. Mendoza-Cortes, M. O’Keeffe, O.M. Yaghi, Chem.
Soc. Rev. 38 (2009) 1257–1283.
18] C.N.R. Rao, S. Natarajan, R. Vaidhyanathan, Angew. Chem., Int. Ed. 43 (2004)
1466–1496.
highly intense broad emission band with maximum at 402 nm
upon excitation at 270 nm (Fig. 9). There is a significant increase
in the fluorescence intensity of the ligand Hpda upon addition of
copper(II) ions. Recently, it has been reported that the fluorescence
emission of various substrates containing fluorophores have signif-
icantly been enhanced due to the interaction with copper(II) ions
19] D.L. Reger, A. Debreczeni, B. Reinecke, V. Rassolov, M.D. Smith, R.F. Semeniuc,
Inorg. Chem. 48 (2009) 8911–8924.
20] D.L. Reger, A. Debreczeni, M.D. Smith, J. Jezierska, A. Ozarowski, Inorg. Chem.
[
50,51].
51 (2012) 1068–1083.
4
. Concluding remarks
21] M.V. Marinho, M.I. Yoshida, K.J. Guedes, K. Krambrock, A.J. Bortoluzzi, M.
Ho1rner, F.C. Machado, W.M. Teles, Inorg. Chem. 43 (2004) 1539–1544.
22] A. Enzmann, M. Eckert, W. Ponikwar, K. Polborn, S. Schneiderbauer, M. Beller,
W. Beck, Eur. J. Inorg. Chem. (2004) 1330–1340.
In conclusion, we have demonstrated that a bifunctional ligand
effectively promotes the formation of a novel dinuclear copper(II)
coordination polymer under specific experimental conditions.
The single crystal X-ray structure analysis reveals that the title
23] B. Bleaney, K.D. Bowers, Proc. Roy. Soc. London A 214 (1952) 451–465.
[24] F.A. Cotton, G. Wilkinson, C.A. Murillo, M. Bochmann, Adv. Inorg. Chem. (1999)
70–871.
[
[
8
25] O. Kahn, Molecular Magnetism, VCH Publishers, Inc., New York, USA, 1993.
26] M. Bera, G.T. Musie, D.R. Powell, Inorg. Chem. 48 (2009) 4625–4627.
2 2 4
complex consists of the square Cu (O CR) paddlewheel secondary
building unit, where the copper centers acquire distorted square
pyramidal geometry. The 3D coordination network of the polymer
is the result of the aggregation of the [Cu (pda) ] monomers con-
2 4
[27] G.T. Musie, X. Li, D.R. Powell, Inorg. Chim. Acta. 359 (2006) 1989–1996.
[
[
28] M. Bera, G.T. Musie, D.R. Powell, Inorg. Chem. Commun. 11 (2008) 293–299.
29] Data Collection: SMART Software Reference Manual, Bruker-AXS, 5465 E.
Cheryl Parkway, Madison, WI 53711–5373 USA, 1998.
nected by the isoindol oxygen on one side and carboxylate oxygen
on the other side of the ligand. The fluorescence spectroscopic
study indicates that the binding of copper(II) ions with this ligand
enhances its emission intensity. The current investigation shows
two different types of coordination modes of the bifunctional li-
gand that will positively contribute to the expansion of the field
of coordination and supramolecular chemistry.
[30] Data Reduction: SAINT Software Reference Manual, Bruker-AXS, 5465 E.
Cheryl Parkway, Madison, WI 53711–5373 USA, 1998.
[
31] G.M. Sheldrick, SADABS, Program for Multi-Scan Absorption Correction of Area
Detector Data, University of Göttingen, Germany, 2002.
[32] G.M. Sheldrick, SHELXTL; Version 6.10 Reference Manual. Bruker AXS, 5465 E.
Cheryl Parkway, Madison, WI 53711–5373 USA, 2000.
[
[
[
[
33] International Tables for Crystallography, Vol. C, Tables 6.1.1.4, 4.2.6.8, and
.2.4.2, Kluwer, Boston, 1995.
34] M. Kunishima, K. Hioki, T. Moriya, J. Morita, T. Ikuta, S. Tani, Angew. Chem. Int.
Ed. 45 (2006) 1252–1255.
4
35] M. Pohmakotr, N. Yotapan, P. Tuchinda, C. Kuhakarn, V. Reutrakul, Tetrahedron
6
3 (2007) 4328–4337.
36] D. Corona, E. Dıaz, A. Guzman, C.K. Jankowskib, Spectrochim. Acta A 61 (2005)
788–2795.
Supplementary material
2
CCDC 930040 contains the supplementary crystallographic data
in CIF format for the [Cu (pda) ] . This data can be obtained free of
2 4 n
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:
deposit@ccdc.cam.ac.uk.
[37] B.L. Dietrich, J. Egbert, A.M. Morris, M. Wicholas, O.P. Anderson, S.M. Miller,
Inorg. Chem. 44 (2005) 6476–6481.
[
38] H. Uekusa, S. Ohba, T. Tokii, Y. Muto, M. Kato, S. Husebye, O.W. Steward, S.C.
Chang, J.P. Rose, J.F. Pletcher, I. Suzuki, Acta. Cryst. B48 (1992) 650–667.
[39] T. Kawata, H. Uekusa, S. Ohba, T. Furukawa, T. Tokii, Y. Muto, M. Kato, Acta
Cryst. B48 (1992) 253–261.
[
40] O.W. Steward, R.C. McAfee, S.C. Chang, S.R. Piskor, W.J. Schreiber, C.F. Jury, C.E.
Taylor, J.F. Pletcher, C.S. Chen, Inorg. Chem. 25 (1986) 771–777.
[
41] Y. Gultneh, A. Farooq, S. Liu, K.D. Karlin, J. Zubieta, Inorg. Chem. 31 (1992)
3
607–3611.
Acknowledgements
[42] A.S. Borovic, M.P. Hendrich, T.R. Holman, E. Munck, V. Papaefthymiou, L. Que
Jr., J. Am. Chem. Soc. 112 (1990) 6031–6038.
[
43] L.M. Hyman, C.J. Stephenson, M.G. Dickens, K.D. Shimizu, K.J. Franz, Dalton
Trans. 39 (2010) 568–576.
44] V. Zelenak, M. Sabo, W. Massa, J. Cernak, Acta Cryst. C60 (2004) m85–m87.
The authors thank the Department of Science and Technology
DST) (Grant No.: SR/FT/CS-067/2009), New Delhi for funding and
(
[
financial support. The instrumental facilities provided by the
DST-FIST and UGC-SAP in the Department of Chemistry are greatly
appreciated. The authors also acknowledge the Contingency Grant
provided by the DST-PURSE program in the Department of Chem-
[45] V. Zelenak, Z. Vargova, K. Gyoryova, Spectrochim. Acta A. 66 (2007) 262–272.
[
46] M.G. Arnaudov, B.B. Ivanova, S.T. Todorov, S.I. Zareva, Spectrochim. Acta A. 63
2006) 491–500.
(
[
47] J. Smolikova, M. Havel, S. Vasickova, A. Vitek, M. Svoboda, K. Blaha, Coll. Czech.
Chem. Commun. 39 (1974) 293–306.

A. Patra et al. / Journal of Molecular Structure 1047 (2013) 317–323
323
[
[
[
48] H.E. Hallam, C. Jones, J. Mol. Struct. 5 (1970) 1–19.
49] M. Falk, Spectrochim. Acta A. 40 (1984) 43–48.
50] S.S. Bag, R. Kundu, S. Talukdar, Tetrahedron Lett. 53 (2012) 5875–5879.
[51] O. Garcia-Beltran, N. Mena, L.C. Friedrich, J.C. Netto-Ferreira, V. Vargas,
F.H. Quina, M.T. Nunez, B.K. Cassels, Tetrahedron Lett. 53 (2012) 5280–
5283.