Synthesis, structures, and antimicrobial activity of solvated and desolvated polymeric copper(II) complexes derived from {[1-(2-hydroxyphenyl) methylidene]amino}acetic acid

Article abstract of DOI:10.1080/15533174.2012.750670

A solvated and a desolvated polymeric copper(II) complexes, [(CuL) ₂]_n ·nxMeOH (H₂L = {[1-(2-hydroxyphenyl) methylidene]amino}acetic acid), have been prepared and characterized by elemental analysis and infrared spectrosco

Full text of DOI:10.1080/15533174.2012.750670

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Synthesis, Structures, and Antimicrobial
Activity of Solvated and Desolvated Polymeric
Copper(II) Complexes Derived from {[1-(2-
Hydroxyphenyl)methylidene]amino}acetic Acid
Chuan-Gao Zhu a
a Department of Chemistry and Chemical Engineering , Huainan Normal University ,
Huainan , P. R. China
Accepted author version posted online: 28 Feb 2013.Published online: 04 Apr 2013.
To cite this article: Chuan-Gao Zhu (2013): Synthesis, Structures, and Antimicrobial Activity of Solvated and Desolvated
Polymeric Copper(II) Complexes Derived from {[1-(2-Hydroxyphenyl)methylidene]amino}acetic Acid, Synthesis and Reactivity
in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:7, 886-891
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:886–891, 2013
Copyright ꢀ Taylor & Francis Group, LLC
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ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.750670
Synthesis, Structures, and Antimicrobial Activity of Solvated
and Desolvated Polymeric Copper(II) Complexes Derived
from {[1-(2-Hydroxyphenyl)methylidene]amino}acetic Acid
Chuan-Gao Zhu
Department of Chemistry and Chemical Engineering, Huainan Normal University, Huainan, P. R. China
are a kind of interesting primary amines for the preparation
of Schiff bases, we report in this paper the synthesis, crystal
structures, and antimicrobial activity of solvated and desolvated
polymeric copper(II) complexes, [(CuL1)2]n·nxMeOH (H2L =
{[1-(2-hydroxyphenyl)methylidene]amino}acetic acid).
A solvated and a desolvated polymeric copper(II) com-
plexes, [(CuL)2]n·nxMeOH (H2L
=
{[1-(2-hydroxyphenyl)
methylidene]amino}acetic acid), have been prepared and char-
acterized by elemental analysis and infrared spectroscopy. The
methanol molecules located in the cavities of the solvated complex
can be slowly escaped when exposed in air for three months, gener-
ating the desolvated complex. The structures of the complexes have
been determined by X-ray crystallography. The coordination ge-
ometry around the Cu atoms in the complexes are square pyramid.
The antimicrobial activity of the complex was studied.
EXPERIMENTAL
Materials and Methods
All the starting materials and organic solvents for synthesis
were of analytical grade as purchased commercially and puri-
fied by standard methods prior to use. Infrared spectra were
recorded on a Nicolet 55XC Fourier transform spectropho-
tometer (Huainan Normal University, China) using KBr pel-
lets (4000–400 cm–1). Elemental analysis was carried out on a
Perkin-Elmer model 240 analyzer (Huainan Normal University,
China).
Supplemental materials are available for this article. Go to the
publisher’s online edition of Synthesis and Reactivity in Inorganic,
Metal-Organic, and Nano-Metal Chemistry to view the supplemen-
tal file.
Keywords copper complex, crystal structure, polymeric complex,
Schiff base, synthesis
Caution: Although no problems were encountered in this
work, perchlorate salts are potentially explosive. This should be
prepared in small quantities and handled with care.
INTRODUCTION
Schiff bases and their complexes have received much atten-
tion for the medicinal and pharmaceutical applications, espe-
cially for their antibacterial, antifungal, and antitumor activi-
ties.[1–8] A number of studies indicated that the coordination
of the Schiff bases to the metal atoms can increase the biologi-
cal properties.[9,10] Copper complexes derived from symmetrical
and nonsymmetrical Schiff bases have received considerable at-
tention in the past few decades due to their structural richness,
electrochemical properties as well as a potential model for a
number of important biological systems.[4,11–13] Besides, sev-
eral N-salicylidene aminoalkanato complexes have been shown
to exhibit antimicrobial, anti-inflammatory, and antipyretic ac-
tivities.[14,15] Study on the structures and antimicrobial activities
of new copper complexes with Schiff bases may help us to
search for novel antimicrobial agents. Considering amino acids
Preparation of the Schiff Base H2L
Glycine (0.075 g, 1.0 mmol) in 10 mL of water containing
KOH (0.056 g, 1.0 mmol) was added to a solution of salicy-
laldehyde (0.122 g, 1 mmol) in 15 mL of methanol. The yellow
solution was stirred for 1 h and kept at room temperature. The
Schiff base solution was used without further purification.
Preparation of the Solvated Complex
Methanolic solution of the Schiff base ligand (1.0 mmol)
was added dropwise to a methanolic solution (20 mL) of copper
perchlorate (0.370 g, 1.0 mmol) with stirring for 1 h to give
blue solution, which was left undisturbed at room temperature
to slow evaporation of the solvent. Blue crystals of the complex
suitable for X-ray diffraction were obtained after a few days.
The crystals were isolated by filtration, and were washed with
cold methanol and air-dried. Yield: 56%. IR data (cm–1, KBr
pellets): 3455 (w), 1646 (s), 1615 (s), 1457 (w), 1353 (m), 1203
(w), 754 (w). Anal. Calcd. for C9H7CuNO3·0.24CH3OH: C,
44.7; H, 3.2; N, 5.6. Found: C, 44.5; H, 3.3; N, 5.6.
Received 23 July 2012; accepted 14 November 2012.
This project was supported by Huainan Normal University.
Address correspondence to Chuan-Gao Zhu, Department of Chem-
istry and Chemical Engineering, Huainan Normal University, Huainan
232001, P. R. China. E-mail: zhuchuangao@yahoo.com.cn
886

POLYMERIC COPPER(II) COMPLEXES
887
TABLE 1
Crystal data for the solvated and desolvated complexes
Compound
Solvated complex
Desolvated complex
Chemical formula
Fw
C9.12H7.48CuNO3.12
244.5
C9H7CuNO3
240.7
T (K)
298(2)
298(2)
Crystal shape/color
Crystal size (mm3)
Crystal system
Space group
block/blue
0.11 × 0.09 × 0.07
Hexagonal
R – 3
block/blue
0.20 × 0.20 × 0.18
Hexagonal
R – 3
a (Å)
b (Å)
c (Å)
V (Å3)
26.956(6)
26.956(6)
6.965(2)
4382.9(18)
18
1.663
2.222
2206
1.51/27.48
–34/33, –34/32, –9/8
2209 (Rint = 0.0200)
1500
0.7922/0.8600
2209/13/133
1.053
26.985(1)
26.985(1)
6.946(1)
4380.4(3)
18
1.642
3.028
2178
5.68/72.33
–33/31, –33/32, –6/8
1924 (Rint = 0.1210)
1863
0.5826/0.6117
1924/0/127
1.176
Z
Dc (g/cm3)
μ (MoKα) (cm–1)
F(000)
θ range (◦)
Index ranges (h, k, l)
Independent reflections
Observed reflections [I ≥ 2σ(I)]
T(min)/T(max)
Data/restraints/parameters
Goodness of fit on F2
R1, wR2 [I ≥ 2σ(I)]a
R1, wR2 (all data)a
0.0624, 0.1656
0.0998, 0.1836
0.0394, 0.1191
0.0411, 0.1207
ꢀ
ꢀ
ꢀ
ꢀ
2 2
2 2 1/2
aR1 = ||Fo| – |Fc||/ |Fo|, wR2 = [ w(Fo2 – Fc ) / w(Fo ) ]
.
RESULTS AND DISCUSSION
Preparation of the Desolvated Complex
The complexes were readily prepared by the reaction of
salicylaldehyde, glycine, and copper perchlorate in methanol.
We have tried to use copper nitrate and copper acetate to pre-
pare the complex, and the same structures were obtained. The
freshly prepared complex containing 0.24 portion of disordered
methanol molecules. When the crystals of the complex were
exposed in air for three months, the methanol molecules in the
cavity can be completely escaped. The results can be proved
by the elemental analyses, IR spectra, and single-crystal X-ray
diffraction. In the IR spectra of the none solvated complex, there
is no typical broad and weak absorption centered at 3455 cm–1,
which indicates the absence of the methanol molecules. In order
to avoid the existence of methanol molecules, we have tried to
use high purity ethanol as the solvent to prepare the complex.
Fortunately, none solvated structure can also be obtained.
The desolvated complex was obtained by the exposition of
the solvated complex in air for three months. IR data (cm–1,
KBr pellets): 1645 (s), 1615 (s), 1456 (w), 1351 (m), 1203 (w),
754 (w). Anal. Calcd. for C9H7CuNO3: C, 44.9; H, 2.9; N, 5.8.
Found: C, 44.8; H, 3.0; N, 5.7.
X-Ray Crystallography
X-ray diffraction data for the solvated and desolvated com-
plexes were collected on Bruker SMART 1000 CCD area de-
tector diffractometer (Xuzhou Normal University, China) and
Oxford diffraction Xcalibur Sapphire3 diffractometer (Shanghai
Maritime University, China), using graphite monochromatized
Mo Kα and Cu Kα radiations, respectively. The crystal data, data
collection, and refinement parameters for the two compounds
are presented in Table 1. Selected bond lengths and angles are
summarized in Table 2. The structures of the complexes were
solved by direct methods using the program SHELXS-97.[15]
Refinements were done by the full-matrix least-squares on F2
using SHELXL-97.[16] Non-hydrogen atoms were refined with
anisotropic displacement parameters. Hydrogen atoms were
placed in geometrically idealized positions and constrained to
ride on their parent atoms.
Infrared Spectroscopy
In the infrared spectrum of the complex, the weak and broad
band centered at 3455 (w) cm–1 is assigned to the O–H vibrations
of the methanol molecules. The intense band at 1615 cm–1 for the
complex is assigned to the azomethine groups, ν(C N).[17] The
νas(COO–) is assigned to the strong band at 1646 cm–1 whereas
the νs(COO–) is attributed to the 1353 cm– band. The separation

888
C.-G. ZHU
between νas(COO–) and νs(COO–) bands is consistent with a
TABLE 2
Selected bond lengths (Å) and angles (◦) for the solvated and
desolvated complexes
bidentate coordination of the carboxylate group.[18]
Structure Description of the Complexes
Solvated complex
The molecular structure of the complexes is shown in
Figure 1. The solvated complex is made up by [(CuL)2]n frame-
work and disordered methanol molecules. The asymmetric unit
of the complex contains a centrosymmetric dinuclear copper
complex which is the same as the desolvated complex, and 0.24
disordered methanol molecule. The methanol molecules located
in the cavities of the complex can be slowly escapted when ex-
posed in air. The Cu. . .Cu distances are 3.014(1) and 3.018(1)
Å, respectively, in the solvated and desolvated complexes. The
Cu atom is in a square pyramidal coordination, with two phe-
nolate O, one imine N, and one carboxylate O atom from two
Schiff base ligands defining the basal plane, and with another
carboxylate O atom occupying the apical position. The Cu atom
deviates from the basal plane defined by the four donor atoms
by 0.180(2) Å. It is obvious that the apical bond is longer than
the basal bonds. Slight distortion from ideal square pyramidal
geometry is also indicated by the deviation of the bond angles
in the basal plane, varying from 83.8(2) to 102.8(2)◦ for the
cissoid angles, and from 162.0(2) to 174.9(2)◦ for the transoid
angles. Angular distortions in the basal plane are caused by the
Cu1-N1
1.920 (5) Cu1-O1
1.936 (4) Cu1-O1i
2.255 (4)
83.8 (2) N1-Cu1-O1
174.9 (2) N1-Cu1-O1i
101.8 (2) O1-Cu1-O1i
102.8 (2) O2-Cu1-O3ii
91.0 (2) O1i-Cu1-O3ii
1.946 (4)
1.988 (4)
Cu1-O2
Cu1-O3ii
N1-Cu1-O2
O2-Cu1-O1
O2-Cu1-O1i
N1-Cu1-O3ii
O1-Cu1-O3ii
Desolvated complex
Cu1-N1
93.1 (2)
162.0 (2)
80.0 (2)
93.6 (2)
93.9 (2)
1.928 (2) Cu1-O1
1.935 (2) Cu1-O1i
2.257 (2)
84.0 (1) N1-Cu1-O1
174.9 (1) N1-Cu1-O1i
101.6 (1) O1-Cu1-O1i
102.6 (1) O2-Cu1-O3ii
90.4 (1) O1i-Cu1-O3ii
1.951 (2)
1.992 (2)
Cu1-O2
Cu1-O3ii
N1-Cu1-O2
O2-Cu1-O1
O2-Cu1-O1i
N1-Cu1-O3ii
O1-Cu1-O3ii
92.9 (1)
162.0 (1)
80.1 (1)
94.2 (1)
94.1 (1)
Symmetry transformation used to generate the equivalent atoms: i):
1 – x + y, 1 − x, 2 + z; ii) 1/3 – x, 5/3 – y, 2/3 – z.
FIG. 1. Molecular structure of the complex with 30% probability thermal ellipsoids. Disordered methanol molecules are omitted.

POLYMERIC COPPER(II) COMPLEXES
889
FIG. 2. Molecular packing of the solvated complex, viewed along the c axis. Disordered methanol molecules are located at the cavities of the 3D framework.
FIG. 3. Molecular packing of the desolvated complex, viewed along the c axis.

890
C.-G. ZHU
TABLE 3
Minimum inhibitory concentration values (μg/mL) of the antimicrobial activity of the complex
Bacillus
subtilis
Staphylococcus
aureus
Pseudomonas
fluorescence
Escherichia
Compound
coli
Complex
Penicillin
0.8
1.4
6.2
2.0
>25.0
>100
>12.5
>100
five and six-membered chelate rings. The Cu–N and Cu–O bond plexes for this article. These data can be obtained free of charge
distances in the solvated and desolvated complexes are compa- at http://www.ccdc.cam.ac.uk/conts/retrieving.html or from the
rable to each other, and also similar to those observed in similar Cambridge Crystallographic Data Center, 12 Union Road,
copper(II) complexes with Schiff bases.[19–21]
In the crystal structures of the complexes, the dinuclear cop- deposit@ccdc.cam.ac.uk.
per(II) complex moieties are bridged through the carboxylate O
Cambridge CB2 1EZ, UK; Fax: +44-1223-336-033; E-mail:
atoms of the Schiff base ligands, forming a 3D channel frame-
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