Synthesis and crystal structure of bis [2-(4-methylphenyl)-1-phenethyl- 4(1H)-quinazolinone] dichlorocopper (II)

Article abstract of DOI:10.1016/j.poly.2012.10.002

The title complex, bis [2-(4-methylphenyl)-1-phenethyl-4(1H)-quinazolinone] dichlorocopper (II) was synthesized and characterized by single-crystal and powder X-ray diffraction, IR-UV spectra, elemental analyses, ¹H and ¹³C NMR and thermogravimetric analyses. Crystal structure determination reveals that the complex consists of mononuclear units with copper (II) ion coordinating in a bis-bidentate fashion. The copper (II) ion is located on the inversion center and has an octahedral coordination environment. The conformation of the dihydropyrimidine (DHPM) ring is almost planar unlike a sofa, as in the case of pure ligand. No classical hydrogen bonds were observed in the structure. The optimized geometrical parameters were calculated using the methods based on the density functional theory (DFT). A comparison of the molecular conformation and geometrical parameters obtained from the X-ray structure analysis and the theoretical study clearly indicates that the DFT calculations agree closely the X-ray structure. The investigated complex along with the ligand has been screened simultaneously for in vitro antibacterial and antifungal activities and compared with the drugs in use.

Full text of DOI:10.1016/j.poly.2012.10.002

Polyhedron 49 (2013) 145–150
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis and crystal structure of bis
[2-(4-methylphenyl)-1-phenethyl-4(1H)-quinazolinone] dichlorocopper (II)
a
b
G.Y.S.K. Swamy a, , K. Ravikumar , K.V.S. Ramakrishna
⇑
a Laboratory of X-ray Crystallography, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India
b Center for Nuclear Magnetic Resonance, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India
a r t i c l e i n f o
a b s t r a c t
Article history:
The title complex, bis [2-(4-methylphenyl)-1-phenethyl-4(1H)-quinazolinone] dichlorocopper (II) was
synthesized and characterized by single-crystal and powder X-ray diffraction, IR–UV spectra, elemental
analyses, 1H and 13C NMR and thermogravimetric analyses. Crystal structure determination reveals that
the complex consists of mononuclear units with copper (II) ion coordinating in a bis-bidentate fashion.
The copper (II) ion is located on the inversion center and has an octahedral coordination environment.
The conformation of the dihydropyrimidine (DHPM) ring is almost planar unlike a sofa, as in the case
of pure ligand. No classical hydrogen bonds were observed in the structure. The optimized geometrical
parameters were calculated using the methods based on the density functional theory (DFT). A compar-
ison of the molecular conformation and geometrical parameters obtained from the X-ray structure anal-
ysis and the theoretical study clearly indicates that the DFT calculations agree closely the X-ray structure.
The investigated complex along with the ligand has been screened simultaneously for in vitro antibacte-
rial and antifungal activities and compared with the drugs in use.
Received 23 August 2012
Accepted 3 October 2012
Available online 12 October 2012
Keywords:
Synthesis
Copper (II) complex
X-ray crystal structure
Density functional theory
NMR spectra
Antimicrobial activity
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
2. Experimental
Quinazoline, a heterocyclic compound which contains the
pyrimidine nucleus is reported to have physiological and pharma-
cological activities and applications in the treatment of several
diseases such as leprosy and mental disorders and also exhibit
wide range of activities, such as anti-bacterial [1] anti-fungal [2]
and anticancer [3]. Substituted quinazolines also show their po-
tent and specific inhibitory action against leukemia cells [4].
Structure analysis of these compounds provides an opportunity
to study the biological activity and its implications for the struc-
tural requirements for binding to the receptors. Further, the pir-
imidine ring conformation and the substituents of the ring often
play a crucial role in the structure–activity relationship of the
molecule [5,6]. In addition, metal-chelation to the molecule will
further enhance the potential of the anti-microbial activity [7,8].
In continuation of our work on quinazolines [9], herein, we report
the crystal structure, powder X-ray diffraction (PXRD), spectro-
scopic and thermogravimetric (TGA) analyses, geometry optimi-
zation using DFT and the antimicrobial activity of the copper
(II) complex.
2.1. Preparation of bis [2-(4-methylphenyl)-1-phenethyl-4(1H)-
quinazolinone] dichlorocopper (II) complex (I)
The complex was prepared by dissolving 2-(4-methylphenyl)-
1-phenethyl-4(1H)-quinazolinone (L) in methanol (10 mL). After
stirring for 10 min added CuCl2ꢀ2H2O (2 mmol) (taken in 5 mL
methanol), and the mixture was stirred for 20 min. Upon slow
evaporation, pale green color crystals were obtained at room tem-
perature. Anal. calc. for C46H40N4O2CuCl2: C, 67.78; H, 4.91; N, 6.87.
Found: C, 67.86; H, 4.82; N, 6.90%.
2.2. Materials and physical measurements
All materials and reagents were obtained commercially and
used without purification. The elemental analyses of C, H, and N
were carried out using American PE2400 II CHNS/O elemental ana-
lyzer. IR spectra were recorded on a Thermo Nicolet Nexus – 670
FT-IR spectrophotometer in the region 4000–400 cmꢁ1, using KBr
pellet. Electronic spectra were obtained using Varian Cary 5000,
UV–Vis spectrophotometer. Electrospray ionization-mass spectra
(ESI-MS) were recorded with quadrupole time-of-flight mass spec-
trometer (QSTAR XL, Applied Biosystems/MDS Sciex, Foster City,
CA, USA). The samples were introduced into the source by flow
⇑
Corresponding author. Tel.: +91 40 27191421.
E-mail addresses: swamygundimella@yahoo.com, swamy@iict.res.in (G.Y.S.K.
Swamy).
injection (10 lL loop) using MeOH as the mobile phase at a flow
0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2012.10.002

146
G.Y.S.K. Swamy et al. / Polyhedron 49 (2013) 145–150
rate of 30
l
L/min. The thermal behavior was studied by TGA on a
sion 6.28a) [12]). Preliminary lattice parameters and orientation
matrices were obtained from three sets of frames. Intensity data
TGA/SDTA Mettler Toledo 851 analyzer (Zurich, Switzerland) with
open alumina crucible containing sample weighing about 8–10 mg
with a linear heating rate of 10 °C/min under N2 as purge gas. Pow-
der X-ray diffractograms were recorded on a Bruker-AXS D8-Ad-
were collected using graphite-monochromated MoK
a radiation
(k = 0.71073 Å) with the -scan method.
x
Integration and scaling of intensity data were accomplished
vance, X-ray diffractometer with graphite-monochromated Cu K
a
using SAINT [13] and absorption corrections were performed using
radiation (1.5406 Å) and 2h ranging from 5° to 50° with step size
0.005° and step time 13.5 s. The diffractometer is attached with
high sensitive Lynx-Eye detector. 1H and 13C NMR spectra were
measured with Varian Unity INOVA-500 MHz and Bruker
AVANCE-III 125 MHz spectrometers at ambient temperature in
DMSO-d6.
SADABS [14]. The structures were solved by direct methods and re-
fined by a full matrix least-squares procedure based on F2 [15].
Non-hydrogen atoms were refined with anisotropic displacement
parameters and hydrogen atoms were included in the models in
their calculated positions in the riding model approximation. The
details of the crystal data and refinement convergence are gathered
in Table 1. The geometrical calculations and molecular graphics
were computed using programs PARST [16], ORTEP-3 [17] and PLATON
[18].
2.3. Antimicrobial activity: antibacterial and antifungal screening
The minimum inhibitory concentration (MIC) was measured by
broth dilution method [10]. A Micro plate with nutrient broth med-
3. Results and discussion
ia (100
DMSO and concentration of 100
added to the first well, which is serially diluted from 1–8 and the
9th well acts as a control. A fixed volume of 100 l over night cul-
l
l) was added to (1–9). The test compound is dissolved in
ll/ml of the test compound is
3.1. Analytical and spectral studies
l
3.1.1. IR Spectra
ture is added in the entire well and incubated at 37 °C for 24 h.
After the incubation period the microplate was measured for tur-
bidity with spectrophotometer (Tecan M200 infinite Microplate
Reader). Penicillin and Streptomycin were used as positive control.
Neutrient broth was procured from M/s Himedia Laboratories,
Mumbai, India.
The IR spectra of the ligand and its Cu(II)-complex (Figs. S1 and
S2, supporting information), were recorded separately. IR spectra
of the complex show that the pyrimidine cC@N stretching fre-
quency in the free ligand at 1492 cmꢁ1 shifts to 1483 cmꢁ1, which
indicates that the imino nitrogen of the ligand coordinated to the
Cu(II) [19]. Similarly, the cC@O band of the quinazoline was shifted
to a little higher wave number (1666–1673 cmꢁ1) indicating coor-
dination of the carbonyl oxygen to the metal atom. This can be
attributed to the minimum effect of the pyrimidine ring conjuga-
tion on the carbonyl bond (C@O 1.234(2) Å (1.231(3) Å in the
ligand)). A medium intensity band appears at 3177 cmꢁ1 in the
Agar cup bioassay (SMART (Version 5.625) [11]) was employed
for testing antifungal activity. Solutions were prepared by dissolv-
ing the compound in DMSO and different concentrations (100
lg
and 150 g) were made. After inoculation, 6 mm sterile disk were
l
scooped out with 6 mm sterile cork borer and the lids of the dishes
were replaced. Controls were maintained with DMSO and Clotrim-
azole B (50 lg/mL). The treated and the controls were kept at 27° C
for 48 h. Inhibition zones were measured and the diameter was
calculated in millimeter. Three replicates were maintained for each
treatment. Media Potato Dextrose broth and Potato Dextrose agar
were procured from M/S Himedia Laboratories, Mumbai, India.
ligand which is assigned to
c(NH) stretching of the quinazoline
ring, completely disappeared in the complex molecule. This may
be due to deprotonation of the amino nitrogen upon coordination
with Cu(II). This result is further confirmed by X-ray and 1H NMR
studies. New bands with medium to weak intensities at 425–
510 cmꢁ1 are tentatively assigned to c(MꢁO)/(MꢁN) [20].
2.4. Crystal structure determination
3.1.2. Uv
The electronic spectrum of the ligand shows a strong band at
241 nm (n ? p⁄) and a relatively weak band at 357 nm ( p⁄
p ? )
X-ray single crystal data collected was performed at room tem-
perature with a Bruker SMART Apex CCD area detector (SAINT (Ver-
for C@O and C@N chromophores. On complexation, these bands
were shifted to 206 and 306 nm respectively, indicating the metal
coordination to the carbonyl oxygen and the pyrimidine nitrogen
(N1) [21], agreeing with X-ray diffraction.
Table 1
Crystallographic data and data collection parameters.
Empirical formula
Formula weight
Crystal system
Space group
Unit cell dimensions
a (Å)
C46H40N4O2CuCl2
815.30
orthorhombic
Pbcn
3.1.3. ESI – mass spectra
The positive ion ESI mass spectrum of the ligand showed the
protonated molecular ion, [M+H]+ at m/z 343 and [M+Na]+ ion at
m/z 365. The spectrum of the prepared Cu(II)-complex with the li-
gand did not show intact complex with two chlorides. The spec-
trum showed only the species without chlorides at m/z 743
corresponding to [Cu+2L–2H]+ ion. The isotopic distribution of
the ion m/z 743 matching well with the simulated spectrum ob-
tained for [C46H40N4O2Cu]+. The spectrum clearly confirms dehy-
drogenation of the ligand during complex formation as observed
by X-ray diffraction. The oxidation state of Cu in the ion m/z 743
is +1, where the Cu might have reduced from Cu(II) to Cu(I) during
ESI ionization. These assignments are based on 63Cu.
19.0406(12)
9.4385(06)
22.5152(14)
4046.3(4)
4
1.3383
0.7151
0.71073
1692
2.1–25.00
27205
b (Å)
c (Å)
V (Å3)
Z
Dcal (Mg/m3)
l
(mmꢁ1
)
Radiation (Mo K
a
) (Å)
F(000)
h range for data collection (°)
Reflections collected
Independent reflections
3566
No. of reflections [I > 2
No. of parameters
r
(I)]
2994
251
0.0299/0.0885
1.036
0.238, ꢁ0.153
3.1.4. 1H and 13C NMR studies. 1H and 13C NMR spectra of the ligand
(L) (Figs. S3 and S4) and its Cu(II)-complex (Figs. S5 and S6), were
recorded in DMSO-d6 at 500 and 125 MHz respectively. The assign-
ment of protons and carbons was made with the help of 2D NMR
Final R indices R/wR
Goodness of fit on F2
Largest difference peak and hole (e Åꢁ3
)

G.Y.S.K. Swamy et al. / Polyhedron 49 (2013) 145–150
147
Fig. 1. Structural representation and atom-numbering scheme. Thermal ellipsoids are drawn at the 30% probability level.
via deprotonation. Similarly, a resonance peak occurs at 5.66 ppm
corresponds to C(2)H in the ligand (L), disappeared in the Cu(II)–
complex. This may be due to the dehydrogenation in the DHPM
ring as confirmed by XRD study. The region at 6.7–7.8 ppm corre-
sponds to hydrogens of the aromatic rings. In the spectrum of the
Cu(II)–complex, the peaks were broadened in this region and
shifted down field, attributed to increased conjugation on coordi-
nation [22].
Table 2
Selected geometric parameters [Å, °] by X-ray diffraction and theoretical calculations.
Exp.
Cal.
Exp.
Cal.
89.84
89.87
C1–N1
C1–O1
C2–N1
C2–N2
C3–N2
C9–N2
Cu1–N1
Cu1–Cl1
Cu1–O1
1.407 (2)
1.234 (2)
1.331 (2)
1.381 (2)
1.424 (2)
1.496 (2)
2.025 (1)
2.323 (5)
2.740 (3)
1.402
1.222
1.309
1.370
1.408
1.478
1.992
2.312
2.865
N1–Cu1–Cl1 90.87 (4)
O1–Cu1– Cl1 88.70 (5)
C1–N1–C2
C1–N1–Cu1
C2–N1–Cu1
C2–N2–C3
C2–N2–C9
C3–N2–C9
122.20 (14) 122.49
107.38 (10) 111.58
130.31 (11) 125.93
119.98 (14) 119.57
120.94 (14) 120.62
118.32 (14) 119.76
3.2. Description of the crystal structure
Fig. 1 shows an ORTEP drawing of the title molecule with atomic
numbering scheme which was drawn at 30% probability level using
C17–C2–N1–C1
C17–C2–N2–C3
N2–C9–C10–C11 177.83 (14) 178.70
176.17 (15) 179.72
175.40 (15) 179.81
PLATON. Selected bond distances and angles are given in Table 2.
The complex (I) consists of mononuclear units with copper (II)
ions coordinating in a bis-bidentate fashion. A perspective view
is shown in Fig. 1. The copper (II) ion is located on the inversion
center (Wyckoff position, 4b) and has an octahedral coordination
environment. Two imine nitrogens (N1 and N1a, a = ꢁx, 1 ꢁ y,
1 ꢁ z) from two different pyrimidine rings cis coordinate to the
Cu atom in the equatorial plane with Cu–N distance of 2.025
(1) Å, while two carbonyl oxygens (O1 and O1a) occupy the other
cis sites in the equatorial plane with Cu–O bonds of 2.740 (3) Å.
The axial sites are occupied by two chlorine atoms (Cl1 and Cl1a)
with Cu–Cl distances of 2.323 (1) Å to complete six coordination.
The long distances of Cu–O bonds compare to other four coordina-
tion bonds indicate the existence of the Jahn–Teller elongation ef-
fect. The bite angle of the chelating ligand is 78.9 (4)°.
Table 3
Hydrogen bonding geometry [Å, °].
D–H. . .A
D–H
H. . .A
D. . .A
D–H. . .A
C14–H14. . .O1i
C21–H21. . .Cl1ii
0.93
0.93
2.81
2.97
3.701
3.830
161.40 (2)
153.79 (2)
Symmetry code: (i) ꢁx + ½, ꢁy + ½, z ꢁ ½; (ii) x, yꢁ1, z.
(HSQC, HMBC DQFCOSY, TOCSY and NOESY). The 1H and 13C NMR
spectral data of the ligand and the complex along with the assign-
ments are given in Table 4. The 1H NMR spectrum of the ligand (L)
exhibits one doublet at 8.54 ppm, corresponding to the amine,
N(1)H (D2O exchangeable), not observed in the Cu(II)–complex
1H NMR spectrum. The absence of the N(1)H resonance peak con-
firms the involvement of N(1)H in coordination with the metal ion
The DHPM ring in the pure ligand adopts a sofa conformation
[9] due to the effect of conjugation, where as in the present com-
plex, the ring is almost planar (an average deviation of 0.0089 Å
from the least squares plane) though it has some effect of conjuga-
tion (the formal single bonds N1–C2 and N2–C2 have partial

148
G.Y.S.K. Swamy et al. / Polyhedron 49 (2013) 145–150
Table 4
1H and 13C NMR chemical shift data of the ligand (L) and its Cu(II)–complex (in ppm).
Ligand (L)
Cu(II)–complex
8.54, (d, J = 3.8 Hz, 1H, N(1)H)
–
7.68 (127.8), (dd, J = 1.6, 7.6 Hz, 1H, C(7)H)
7.38 (133.9) (m, 1H, C(5)H)
8.17 (127.4), (d, J = 7.5 Hz, 1H, C(7)H)
7.97 (117.0), (d, J = 8.5 Hz, 1H, C(4)H)
7.92 (133.7), (t, J = 7.5 Hz, 1H, C(6)H)
7.61 (125.9), (t, J = 7.0 Hz, 1H, C(5)H)
7.29 (128.4), (m, 2H, C(18)H–C(19)H)
7.24 (127.5), (m, 2H, C(21)H–C(22)H)
7.17 (128.2), (m, 3H, C(13)H, C(13)H, C(15)H)
6.76 (128.4), (d, J = 7.5 Hz, 2H, C(12)H, C(16)H)
–
7.27 (128.2), (m, 2H, C(15)H–C(17)H)
7.22 (128.6), (m, 3H, C(12)H,C(14)H, C(16)H)
7.18 (126.3), (d, J = 8.5 Hz, 2H, C(18)H, C(19)H)
7.11 (128.8), (d, J = 7.6 Hz, 2H, C(21)H–C(22)H)
6.90 (112.6), (d, J = 8.4 Hz, 1H, C(4)H)
6.72 (116.9), (d, J = 8.4 Hz, 1H, C(6)H)
5.66 (70.6), (d, J = 3.8 Hz, 1H, C(2)H)
3.67 (50.0), (m, 1H, C(9)H)
3.28 (50.0), (m, 1H, C(90)H)
2.86 (32.7), (m, 1H, C(10)H)
2.72 (32.7), (m, 1H, C(100)H)
4.40 (50.0), (m, 2H, C(9)H, C(90)H)
2.90 (33.2), (m, 2H, C(10)H, C(100)H)
2.40 (20.7), (s, 3H, C(23)H3)
2.23 (20.7), (s, 3H, C(23)H3)
double bond character and are shorter than the typical Csp2–N
bond distance (1.426 Å)) [23]. One of the reasons for the planarity
of the DHPM ring may be due to the ligand–metal complexation
through the atoms N1 and O1 of the DHPM ring. In other words,
the strain in the ligand (DHPM ring) is very much restricted to min-
imum due to ligand–metal complexation. Further, on complexa-
tion of the ligand to the metal atom, some dehydrogenation has
been observed (Sp3 becomes Sp2 (atom C2)) in the DHPM ring. Aro-
maticity may be the driving force for it.
It has been reported that, more the planarity of the DHPM ring
higher the pharmacological activity of the molecule [5]. In the
present structure, we have observed that the structure–activity
correlation was supported by two important points. The first one,
DHPM ring planarity and the second one is ligand–metal complex-
ation. It is important to note that, on complexation with the metal,
the planarity of the DHPM ring increased drastically (average devi-
ation of the atoms N1, N2, C1–C3, C8 from the l.s. plane is 0.0089 Å
as compared to the ligand, 0.105 Å) which in turn increased mod-
erately, the antibacterial activity (Table 5). As stated by several
researchers [24–27] the metal chelates exhibit more inhibitory ef-
fects than the parent ligands due to the increasing lipophilic char-
acter of the metal chelate which in turn responsible for their
enhanced potent antibacterial activity.
The phenethyl group in the molecule has a fully extended con-
formation with respect to the central pyrimidine ring (Table 2). The
sum of the bond angles around the atoms N1 (359.9°) and N2
(359.2°) indicate the pyramidal configuration. It is interesting to
note that, the p-tolyl group is positioned equatorially at C2
(average torsion angle of C1–N1–C2–C17 & C3–N2–C2–C17 is
175.79(15)°), while in the ligand it is oriented axially (89.4(2)°).
Table 5
Antibacterial activity of the quinazolinone ligand and its Cu(II)–complex.
Compound
BS
(MIC
mL)
SA
g/ (MIC
mL)
SE
g/ (MIC
mL)
EC
g/ (MIC
mL)
PA
g/ (MIC
mL)
KE
g/ (MIC
mL)
l
l
l
l
l
lg/
Ligand
Cu-complex
Penicillin
150
150
1.562
150
75
1.562
6.25
150
150
3.125
3.125
150
150
12.5
6.25
150
18.75
12.5
150
150
6.25
Streptomycin 6.25
1.562
3.125
BS = B. subtilis; SA = S. aureus; SE = S. epidermidis; EC = E. coli; PA = P. aeruginosa;
KP = K. pneumoniae.
Fig. 2. Crystal packing in the unit cell viewed down the [010] axis.

G.Y.S.K. Swamy et al. / Polyhedron 49 (2013) 145–150
149
Fig. 3. A superposition of the molecular conformations of the title molecule (I) and its optimized structure (II). The overlay was made by making a least-squares fit through
DHPM ring of (I). The r.m.s. deviation with respect to the conformation of (I) (red in the electronic version of the journal) is 0.091 (Io – blue) (color online).
No classical hydrogen bonds were found in the structure
(Fig. 2). The crystal lattice is stabilized by C–H. . .O and van der
Waals interactions. The structure contains a number of intermolec-
ular C–H. . .X contacts with H. . .X being well within the van der
Waals radii (those with C–H. . .X angle above 100° are listed in Ta-
ble 3). The intermolecular contacts may be regarded as weak non-
classical C–H. . .O hydrogen bonds, but their contribution to the
overall lattice energy must be very small.
3.3. Optimised geometry
DFT calculations were performed using the crystallographic
structure parameters of the Cu(II)–complex as a starting point.
The DFT method was applied at the B3LYP hybrid exchange corre-
lation function level [28,29] using the 6–31G(d,p) basis set [30] as
implemented in GAUSSIAN03 [31]. The combination of hybrid ex-
change functional and correlation functional known as B3LYP has
been widely used for several metal complexes [32–34]. The opti-
Scheme 1.
mized geometric parameters for some selected bond lengths and
angles are given in Table 2 and represent the molecule in the
making a least-squares fit through the DHPM ring of the title mol-
gas-phase like orientation. The DFT calculations predict the aver-
ecule (see scheme 1).
age C–N bond length to be 1.393 Å, which is slightly less than
the experimentally obtained value 1.406 Å. The calculated Cu1–
3.4. PXRD measurement
O1 bond length is 2.865 Å, while the experimental value is slightly
less (2.740 Å). Similarly, there is a variation of 0.32–4.4° in the
bond angles around the atoms N1 and N2 between the calculated
and experimental values (Table 2). In addition, the orientation of
the p-tolyl group with respect to DHPM ring (experimental av. tor-
sion angles of C17–C2–N1–C1 and C17–C2–N2–C3 175.79 (15)°) is
also slightly effected (cal. value 179.77°). These discrepancies be-
tween the calculated and the crystallographically determined val-
ues may be accounted for by solid-state packing effects in the
crystal structure of the title molecule, which are not included in
the gas-phase DFT structure optimization. A superposition of the
molecular conformation of both the geometries (experimental
and theoretical) is shown in the Fig. 3. The overlay was made by
The simulated and experimental PXRD patterns of Cu(II)–com-
plex (Fig. S7) are in agreement with each other. It was found a
few additional peaks and some differences in the intensities be-
tween the peaks of the patterns. This may be attributed to a very
minor quantity of an impurity phase and the effect of preferred ori-
entation of the powder sample.
3.5. Thermal studies
The thermogravimetric (TG) curve (Fig. S8), of the title
compound exhibits a two step of weight loss from 30 to 800 °C.

150
G.Y.S.K. Swamy et al. / Polyhedron 49 (2013) 145–150
The initial weight loss of 8.72% (calc.: 8.69%) in the temperature
range 100–250 °C is due to the loss of two chlorides in the mole-
cule. The next weight loss of 84.4% (calc.: 84.1%), in the range
250–550 °C is due to loss of two ligands. A plateau is obtained after
heating the complex above 550 °C up to 800 °C, which corresponds
to the final residuals and the formation of stable CuO.
http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: +44 1223 336 033; or e-mail: depos-
it@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.2012.10.002.
3.6. Antimicrobial screening
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Both the ligand and the copper(II)–complex were subjected to
antimicrobial screening. The results show that the complex exhibit
more inhibitory effects than the parent ligand. The activity of the
ligand and the metal complex was tested against some pathogenic
test organism including Gram-positive (B. subtilis, S. aureus and S.
epidermidis), Gram-negative (E.coli, P. aeruginosa and K. pneumo-
niae) by the micro dilution (DMSO as solvent) method. One can
see from the results of the antibacterial screening (Table 5), that
the ligand has hardly any activity against the tested bacteria.
Where as the copper complex inhibits the growth of S. aureus
and P. aeruginosa even at low concentration (18 lg/mL). Further,
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against some test organism (A. niger, S. cerevisiae, C. rugosa and C.
albicans). The results show neither the ligand nor the complex
has any activity.
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Acknowledgements
The authors are thankful to Dr. U. S. N. Murthy, Head, Biology
Dept. IICT for antimicrobial data, Dr. N. Jagadeesh Babu, X-ray Crys-
tallography center, IICT for the theoretical calculations and Dr. J. S.
Yadav, Director, IICT, Hyderabad for his kind encouragement.
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Appendix A. Supplementary data
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CCDC 812390 contains the supplementary crystallographic data
for the title molecule. These data can be obtained free of charge via