Synthesis, structural characterization, and antibacterial activity of a Cu(II) complex, [Cu(CH3COO) (HL1)H2O]·H 2O

Article abstract of DOI:10.1080/15533174.2012.749911

A new copper(II) complex [Cu(CH₃COO)(HL)H₂O] ·H₂O, (where HL stands for 4-Nitro-2-[N-(2-{dimethylamino} ethyl-N′-methyl)aminomethyl]phenol), was synthesized and characterized by XRD, EPR, UV-Vis, and IR techniques. It crystallized in monoclinic system and P₂₁/c space group. The Cu(II) ion is coordinated by a tridendate HL ligand, an acetate anion, and a water molecule in a distorted square-pyramidal geometry. It is paramagnetic and has a potential antibacterial activity.

Full text of DOI:10.1080/15533174.2012.749911

This article was downloaded by: [University of Haifa Library]
On: 26 June 2013, At: 02:31
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Synthesis and Reactivity in Inorganic, Metal-Organic,
and Nano-Metal Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/lsrt20
Synthesis, Structural Characterization, and
Antibacterial Activity of a Cu(II) Complex, [Cu(CH3COO)
(HL1)H2O]·H2O
Bhagyaraju Bussa a , Late P. Sambasiva Rao a , S. Muthukamalam b , S. Ramachitra a , S.
Sudha Rani b & Toka Swu a
a Department of Chemistry , Pondicherry University , Kalapet , Puducherry , India
b Department of Biochemistry and Molecular Biology , Pondicherry University , Kalapet ,
Puducherry , India
Accepted author version posted online: 20 Feb 2013.Published online: 02 May 2013.
To cite this article: Bhagyaraju Bussa , Late P. Sambasiva Rao , S. Muthukamalam , S. Ramachitra , S. Sudha Rani & Toka Swu
(2013): Synthesis, Structural Characterization, and Antibacterial Activity of a Cu(II) Complex, [Cu(CH3COO) (HL1)H2O]·H2O,
Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:8, 1073-1077
To link to this article: http://dx.doi.org/10.1080/15533174.2012.749911
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to
anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation that the contents
will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should
be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims,
proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in
connection with or arising out of the use of this material.

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:1073–1077, 2013
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.749911
Synthesis, Structural Characterization, and Antibacterial
Activity of a Cu(II) Complex, [Cu(CH3COO)
(HL1)H2O]·H2O
Bhagyaraju Bussa,1 Late P. Sambasiva Rao,1 S. Muthukamalam,2 S. Ramachitra,1
S. Sudha Rani,2 and Toka Swu1
1Department of Chemistry, Pondicherry University, Kalapet, Puducherry, India
2Department of Biochemistry and Molecular Biology, Pondicherry University, Kalapet,
Puducherry, India
termine the g-tensor parameters (g and g ). Keeping all these
ꢁ
⊥
in mind, we have successfully synthesized a new mononuclear
copper(II) complex from polydentate ligand derived from Man-
nich base reaction. It was characterized by using single crystal
XRD, EPR, UV-Vis, and IR. Also, we herein report the antibac-
terial activity of this complex.
A new copper(II) complex [Cu(CH3COO)(HL)H2O]·H2O,
(where HL stands for 4-Nitro-2-[N-(2-{dimethylamino}ethyl-Nꢀ-
methyl)aminomethyl]phenol), was synthesized and characterized
by XRD, EPR, UV-Vis, and IR techniques. It crystallized in mono-
clinic system and P21/c space group. The Cu(II) ion is coordinated
by a tridendate HL ligand, an acetate anion, and a water molecule
in a distorted square-pyramidal geometry. It is paramagnetic and
has a potential antibacterial activity.
EXPERIMENTAL
Keywords anti-bacterial, copper(II) complex, EPR, IR, UV-VIS,
Chemicals and General Methods
XRD
All the chemicals for the synthesis of ligand as well as cop-
per complex were purchased from Sigma-Aldrich (Bangalore,
India) and were used without further purification. UV-Vis spec-
tra was measured on a Shimadzu UV-2450 PC spectrophotome-
ter (Tokyo, Japan) at room temperature. Infrared (IR) spectra
were recorded on a Nicolet iS10 instrument using KBr pellets
(Thermo Scientific, India). The single-crystal X-ray structure
was performed on an Oxford Diffraction Xcalibur Diffractome-
ter (Virginia) equipped with graphite monochromatic Mo-Ka
radiation (λ = 0.71073Å) at 296 K. The antibacterial activity
of the Cu(II) complex was assessed by well diffusion method.
Electron paramagnetic resonance (EPR) spectra were recorded
with a JEOL TES100 EPR spectrometer (Tokyo, Japan). Low
temperature measurements were recorded at the liquid N2 tem-
perature (77 K) using ES-UCD3X insertion type Dewar.
INTRODUCTION
Among the trace transition metals, copper is found in nu-
merous proteins and enzymes. The presence of Cu(II) ion in
enzymes and proteins ligated with O,N-coordinating ligands as
mimetic systems has a great interest.[1] The structure and mag-
netic properties of these metalloproteins are well studied.[2,3]
The metal carboxylate complexes are the models of metallo-
proteins.[4,5] The ligands containing carboxylate group have
a greater biological relevance.[6] The carboxylate group that
bridges between two metal ions forms a wide variety of polynu-
clear complexes.[7–10] Analysis of Cu(II) compounds with EPR
spectroscopy technique is immense interest because of its high
sensitivity and accessibility to measure the samples in different
physical states (i.e., solids and liquids [crystal, polycrystalline,
and frozen solution]). The EPR spectra of the Cu(II) complex
gives hyperfine lines (65Cu I = 3/2) through which one can de-
Synthesis
Synthesis of 4-Nitro-2-[N-(2-{dimethylamino}ethyl-Nꢂ-
methyl)aminomethyl]phenol (abbreviated as HL1)
4-Nitrophenol (5.29 g, 0.038 mol) in ethanol (150 mL)
was mixed with N,N,Nꢂ-trimethylethylenediamine (3.882 g,
0.038 mol) under stirring and cooled in ice. Formaldehyde
(9 mL, 35%, 0.114 mol) was added dropwise with constant
stirring. The mixture was stirred at room temperature (28◦C)
for 24 h and then refluxed for 8 h. The solvent was removed
under vacuo and the resulting oily product was neutralized with
Received 4 October 2012; accepted 11 November 2012.
Bhagyaraju Bussa acknowledges the financial support from the
DST-New Delhi of India.
Address correspondence to Toka Swu, Department of Chemistry,
Pondicherry University, Kalapet Puducherry-605014, India. E-mail:
tokaswu.che@pondiuni.edu.in
1073

1074
B. BUSSA ET AL.
FIG. 1. The synthetic route of ligand.
saturated sodium carbonate and extracted with chloroform (4 × of 8 mm diameter were made. These wells were filled with the
50 mL), the organic layers were combined and dried over test compounds at a concentration if 900 μg/30 μL methanol.
anhydrous magnesium sulfate followed by filtration afforded The antibacterial activity of the monomeric Cu(II) complex was
a yellow semisolid product. This was purified by column chro- compared with that of standard antibiotic streptomycin at a con-
matography on silica gel (CHCl3/MeOH). A yellow solid was centration 900 μg/30 μL methanol/well. Methanol was used as
obtained (Yield: 87%). The synthetic route is shown in Figure 1.
TABLE 1
Crystal data and structure refinement
Synthesis of [Cu(HL1)(CH3COO)(H2O)] H2O
The methanolic solution of copper(II) acetate (10 mL,
0.1 mmol) was added dropwise to a methanolic solution of HL1
(50 mL, 0.1 mmol) with constant stirring and was refluxed for
4 h. The final clear dark green solution was allowed to stand at
room temperature for several days. Green Plate shaped crystals
suitable for single-crystal X-ray diffraction analysis. The yield
was (68.3%) based on ligand.
Empirical formula C14H25N3O7Cu
Formula weight
410.92
Temperature/K
296
Crystal system
monoclinic
Space group
P21/c
a/Å
20.3222(11)
b/Å
7.7896(3)
11.9849(5)
90.00
106.111(5)
90.00
1822.73(15)
4
1.497
1.238
860.0
0.4 × 0.2 × 0.08
5.64 to 49.98◦
−20 ≤ h ≤ 24, −9 ≤ k ≤ 9,
−13 ≤ l ≤ 14
8711
X-Ray Crystallography
c/Å
A suitable single crystal of title compound was selected and
mounted on a Xcalibur, Eos diffractometer (Europe, UK). Using
Olex2,[11] the structure was solved with the ShelXS[12] struc-
ture solution program by Direct Methods. Refinements were
performed using the ShelXL[13] refinement package using least-
squares minimization. All of the non-hydrogen atoms were re-
fined with anisotropic thermal parameters. The hydrogen atoms
bonded to carbon atoms were placed in calculated positions with
a C–H bond distance of 0.93 Å. Table 1 lists crystallographic
details.
α/◦
β/◦
γ /◦
Volume/Å3
Z
ρcalcmg/mm3
m/mm−1
F(000)
Crystal size/mm3
2ꢀ range for data collection
Index ranges
Antibacterial Activity by Well Diffusion Method
The antibacterial activity was carried out by well diffusion
method as described by Tagg and McGiven.[14] Bacillus sub-
tilis, which is a gram-positive bacterium, and Pseudomonas
fluorescens, which is a gram-negative bacterium, were used in
this study. Overnight grown bacterial culture was mixed with
molten nutrient agar at 55◦C and poured into the petriplates
under sterile conditions. After solidification, wells were made
in the plate using sterile cork borer. In each plate, three wells
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
3205[R(int) = 0.0518]
3205/0/234
1.011
Final R indexes [I ≥ 2σ (I)]
R1 = 0.0485, wR2 = 0.0917
Final R indexes [all data]
R1 = 0.0817, wR2 = 0.1045
Largest diff. peak/hole / e Å−3 0.36/−0.32

Cu(II) COMPLEX, [Cu(CH3COO) (HL1)H2O]·H2O
1075
solvent control. The plates were incubated at 37◦C for 24 h.
The inhibition was measured in millimeter using antibiotic zone
scale (HiMedia, Mumbai)
TABLE 2
Selected bond lengths (Å) and bond angles (◦) of the complex
Atom Atom Length/Å Atom Atom Atom
Angle/◦
Cu1
Cu1
Cu1
Cu1
Cu1
O3
O5
N1
N2
O4
1.926 (3)
1.967 (3)
2.054 (3)
2.040 (3)
2.310 (3)
O3
O3
O3
O5
O5
N1
N2
O3
O5
N2
Cu1
Cu1
Cu1
Cu1
Cu1
Cu1
Cu1
Cu1
Cu1
Cu1
O5
N2
O4
N1
O4
O4
N1
88.10 (11)
92.72 (12)
99.82 (11)
89.62 (12)
95.69 (10)
91.21 (11)
86.17 (13)
RESULTS AND DISCUSSION
Spectroscopic Characterization
Ligand: IR: 1454 (Aromatic); 1370 (N-CH2); 2920–2800 cm
(C H aliphatic); 3400–3500 (OH). 1317, (N-CH3).
Complex: The peak observed at 1445 cm–1 is the character-
istic for the stretching vibrations of the aromatic skeleton. The
peak at 1339 cm–1 is assigned to the N-CH3 stretching frequency
and the one at the region 2938–2816 cm–1 C H to aliphatic
stretching frequency. The O-H stretching frequency is occurred
N1 168.90 (12)
N2 162.25 (11)
O4 101.63 (11)
at 1290 cm–1 The Cu-OH2 stretching frequency is occurred at
.
Symmetry code: (i) −x, 1/2 + y, 1/2−z.
3480 cm–1 Cu-N stretching frequency is occurred at 451 cm–1,
.
which confirmed the participation of the nitrogen atom in the
complex formation. The binding of acetate to metal complex
give a characteristic IR absorption at 1599 cm–1, which is at-
tributable to the antisymmetric νas(COO) stretching frequency.
Electronic spectrum of the complex contains four bands in the
region 683, 376, 289, and 235 nm. The calculated absorbance
values are 14641, 26595, 34602, and 42553 cm–1. The absorp-
tion bands at 289 and 235 nm are attributed to intraligand
charge transfer transition and 376 nm is assigned to phenoxo
to copper LMCT.[15] A broad band around 683 nm indicates d-d
transition.
from the ideal square plane is evidenced by the smaller bond an-
gles of N(1)-Cu(1)-N(2) {86.18◦}, O(3)-Cu(1)-O(5) {88.09◦},
and N(1)-Cu(1)-O(5) {89.61◦} as compared to larger bond an-
gles of N(2)-Cu(1)-O(3) {92.73◦}. The aqua molecule is in the
apical position (distance of Cu(1)-O(4) = 2.31 Å). Similar to
the great majority of real square-pyramidal structure,[16] in the
present system also the XRD crystal structure reveals that the
Cu(II) ion is slightly displaced out of the basal plane toward the
apical ligand.
Donor-acceptor distances indicate hydrogen bonds among
coordinated and non-coordinated water molecules {O(4)-O(7),
2.810 Å} and also between the oxygen atoms of lattice water
and HL1 ligand {O(7)-O(3), 2.930 Å and O(7)-O(2), 2.885 Å}.
Lattice water molecules are bridging the three moeties leading to
the formation of two-dimensional network (Figure 3). When the
crystal packing is viewed along b direction (Figure 4), it appears
that there are π-π interactions; however, the centroid-centroid
distance measurement (6.425 Å) reveals that the π-π interac-
Description of the Crystal Structure
The structure was solved, achieving a final R value of 4.85%;
an ORTEP view is given in Figure 2. Selected bond distances
and angles are shown in Table 2. The Cu(II) ion is pentaco-
ordinated with a square pyramidal geometry. The base of the
pyramid is formed by the tridentate HL1 and monodentate ac-
etate anions. Although the distances Cu(1)-N(1), Cu(1)- N(2),
Cu(1)-O(3), and Cu-O(5) span only 0.127 Å (Table 2), distortion
FIG. 2. ORTEP structure of the title compound viewed along c direction with
atom numbering scheme (50% displacement ellipsoids) (color figure available
online).
FIG. 3. The 2D network of the title compound bridged by water molecule
through hydrogen bonding (color figure available online).

1076
B. BUSSA ET AL.
FIG. 6. EPR spectrum of complex in methanol at liquid N2 temperature ν =
9.03128 GHz.
signal exhibits a characteristic line shape for powder sample
containing a paramagnetic ion without any hyperfine splitting.
Due to dipolar-dipolar interaction, the spectrum shows only one
broad line giso = 2.12. The frozen solution spectrum of complex
shown in Figure 6 gives the signature spectrum for an axially
2
2
symmetric complex with a dx −y ground state (g > g
>
ꢁ
⊥
2.0). The hyperfine lines are not resolved at perpendicular com-
ponent. It is possible to infer that the trend for the location of
2
2
magnetic electron (in dx −y orbital) continues due to g
>
ꢁ
ꢁ
g
⊥
> 2. An analysis of the frozen state spectrum gives g =
2.28, g = 2.05, and A = 15.76 mT. On the whole, these
⊥
ꢁ
observations suggest a distorted square-pyramidal geometry.
Antibacterial Activity
FIG. 4. Crystal packing viewed along b direction with centroid-centroid and
In Pseudomonas fluorescens plate the acetate monomer
showed a zone of inhibition 23 mm as compared with strep-
tomycin 23 mm. Interestingly, the antibacterial activity of title
Cu(II) complex was more pronounced against Bacillus subtilis
plate with a zone of inhibition of 30 mm as compared with that
of 23 mm against streptomycin.[17–19] Methanol alone did not
show any inhibition.
C
H···π distances (Å) (color figure available online).
tions are very unlikely. The presence of C H···π interaction is
evident from the distance measurement (3.639 Å).
The EPR spectrum of the title complex recorded at room
temperature in polycrystalline form is shown in Figure 5. The
CONCLUSION
We have successfully synthesized a new mononuclear cop-
per(II) complex having a slight distorted square-pyramidal
structure as observed by XRD data. As revealed by EPR studies,
it is paramagnetic in nature. Although the antibacterial activ-
ity of this complex against Pseudomonas fluorescens was only
equivalent to that of standard streptomycin, it was found to be
more pronounced against Bacillus subtilis.
SUPPLEMENTARY MATERIALS
Crystallographic information of the complex has been de-
posited with the Cambridge Crystallographic Data Centre,
CCDC no. 867608. These data can be obtained free of charge
from the Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data–request/cif.
FIG. 5. Powder EPR spectrum of complex at ν = 9.20481 GHz.

Cu(II) COMPLEX, [Cu(CH3COO) (HL1)H2O]·H2O
1077
REFERENCES
11. Dolomanov, O.V.; Bourhis, L.J.; Gildea, R.J.; Howard, J.A.K.; Puschmann,
H. OLEX2: a complete structure solution, refinement and analysis program.
J. Appl. Cryst. 2009, 42, 339–341.
12. Sheldrick, G.M. SHELXS-97, Program for Crystal Structures Solution;
University of Go¨ttingen, Germany, 1997.
1. Lee, D.H.; Hatcher, L.Q.; Vance, M.A.; Sarangi, R.; Milligan, A.E.; Hed-
man, B.; Solomon, E.I.; Karlin, K.D. Inorg. Chem. 2007, 46, 6056–
6068.
2. Kahn, O. Adv. Inorg. Chem. 1995, 43, 179.
13. Sheldrick, G.M. SHELXL. Acta Cryst. A 2008, 64, 112–122.
14. Tagg, J.R.; McGiven, A.R. Assay system of bacteriocins. J. Appl. Microbiol.
1971, 21, 943–948.
15. Penfield, K.W.; Gewirth, A.A.; Solomon, E.J. J. Am. Chem. Soc. 1985, 107,
4519.
16. Hoskins, B.S.; Whillans, F.D. Coord. Chem. Rev. 1973, 9, 365–388.
17. Tagg, J.R.; Dajani, A.S.; Wannamaker, L.W. Bacteriocins of gram positive
bacteria. Bacteriol. Rev. 1976, 40, 722–756.
18. Shingalapur, R.V.; Hosamani, K.M.; Keri, R.S. Eur. J. Med. Chem. 2009,
44, 4244–4248.
3. Kahn, O. Molecular Magnetism; VCH, Weinheim, Germany, 1993.
4. Wieghardt, K. Angew. Chem. Int. Ed. Engl. 1989, 28, 1153.
5. Que, L.; True, A. Prog. Inorg. Chem. 1990, 38, 97.
6. Rardin, R. L; Tolman, W.B.; Lippard, S.J. New J. Chem. 1991, 417.
7. Doedens, R.J. Prog. Inorg. Chem. 1976, 21, 209.
8. Rettig, S.J.; Thompson, R.C.; Trotter, J.; Xia, S. Inorg. Chem. 1999, 38,
1360.
9. Tangoulis, V.; Psomas, G.; Dendrinou-Samara, C.; Raptopoulou, C.P.;
Terzis, A.; Kessissoglou, D.P. Inorg. Chem. 1996, 35, 7655.
10. Colacio, E.; Dom´ınguez-Vera, J.M.; Ghazi, M.; Kiveka¨s, R.; Klinga, M.;
Moreno, J.M. Eur. J. Inorg. Chem. 1999, 441.
19. Sharma, D.; Narasimhan, B.; Kumar, P.; Judge, V.; Narang, R.; De Clercq,
E.; Balzarini, J. Eur. J. Med. Chem. 2009, 44, 2347–2353.