Synthesis, structures, and antimicrobial activity of schiff base cobalt complexes [Co(HL1) 2(N 3) 2]H 2O and [CoL2 2]ClO 4

Article abstract of DOI:10.1080/15533174.2011.609510

The new Schiff bases 4-bromo-2-[(3-diethylaminopropylimino) methyl]phenol (HL¹) and 2-methoxy-6-[(2-phenylaminoethy limino) methyl]phenol (HL²) derived from 5-bromosalicylaldehyde with N,N-diethylpropane-1, 3-diamine and 3-methoxysal

Full text of DOI:10.1080/15533174.2011.609510

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Synthesis, Structures, and Antimicrobial Activity of
Schiff Base Cobalt Complexes [Co(HL1)2(N3)2]·H2O and
[CoL2 ]·ClO4
2
Ling-Wei Xue a , Yong-Jun Han a , Gan-Qing Zhao a & Yun-Xiao Feng a
a College of Chemistry and Chemical Engineering, Pingdingshan University, Pingdingshan,
Henan, P. R. China
Published online: 23 Mar 2012.
To cite this article: Ling-Wei Xue , Yong-Jun Han , Gan-Qing Zhao & Yun-Xiao Feng (2012): Synthesis, Structures, and
Antimicrobial Activity of Schiff Base Cobalt Complexes [Co(HL1)2(N3)2]·H2O and [CoL2 ]·ClO4 , Synthesis and Reactivity in
2
Inorganic, Metal-Organic, and Nano-Metal Chemistry, 42:2, 154-159
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 42:154–159, 2012
Copyright ꢀ Taylor & Francis Group, LLC
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ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2011.609510
Synthesis, Structures, and Antimicrobial Activity of Schiff
Base Cobalt Complexes [Co(HL1)2(N3)2]·H2O
and [CoL2 ]·ClO4
2
Ling-Wei Xue, Yong-Jun Han, Gan-Qing Zhao, and Yun-Xiao Feng
College of Chemistry and Chemical Engineering, Pingdingshan University, Pingdingshan, Henan,
P. R. China
The search in the Cambridge Crystallographic Database (ver-
sion 5.31 with addenda up to August 2010)[9] has revealed
that there are no complexes with the Schiff bases 4-bromo-
2-[(3-diethylaminopropylimino)methyl]phenol (HL1) and 2-
methoxy-6-[(2-phenylaminoethylimino)methyl]phenol (HL2;
Chart 1). In the present article, the preparation, characteriza-
tion and antimicrobial activity of two new cobalt complexes
with the Schiff bases are reported.
The new Schiff bases 4-bromo-2-[(3-diethylaminopropylimino)
methyl]phenol (HL1) and 2-methoxy-6-[(2-phenylaminoethy
limino) methyl]phenol (HL2) derived from 5-bromosalicylaldehyde
with N,N- diethylpropane -1,3- diamine and 3- methoxysalicylalde-
hyde with N-phenylethane-1,2-diamine, respectively, and their
cobalt complexes, [Co(HL1)2(N3)2]·H2O and [CoL2 ]·ClO4, have
2
been prepared and characterized by elemental analyses, infrared,
and single crystal X-ray crystallographic determination. The HL1
coordinates to the Co atom through the phenolic O and imino N
atoms with a zwitterionic form, while the HL2 coordinates to the
Co atom through the phenolic O, imino N, and amino N atoms with
a deprotonated form. Each Co atom in the complexes adopts an
octahedral coordination. The effect of the Schiff bases and the com-
plexes on the antimicrobial activity against Staphylococcus aureus,
Escherichia coli, and Candida albicans were studied.
H
N
N
OH
Br
N
N
O
OH
SCH. 1.
Keywords antimicrobial, cobalt complex, crystal structure, Schiff
base, synthesis
INTRODUCTION
EXPERIMENTAL
Schiff bases are a kind of versatile ligands in coordina-
tion chemistry.[1–3] In recent years, metal complexes of Schiff
bases have attracted considerable attention due to their re-
markable biological activity, such as antifungal, antibacterial
and antitumor.[4–6] It has been shown that the Schiff base
complexes derived from salicylaldehyde and its derivatives
with primary amines, bearing the N2O, N2S, NO2, or NSO
donor sets, have interesting biological activity.[6–8] Further-
more, mono- and multinuclear complexes of cobalt in its
varied oxidation states have become a central theme of cur-
rent research because of their potentially useful properties
in the realm of relevant scientific and technological fields.
Material and Methods
5-Bromosalicylaldehyde, 3-methoxysalicylaldehyde, N,N-
diethylpropane-1,3-diamine, and N-phenylethane-1,2-diamine
were purchased from Fluka. Other reagents and solvents were
analytical grade and were used without further purification. El-
emental (C, H, and N) analyses were made on a PerkinElmer
Model 240B automatic analyzer. Cobalt analysis was carried out
by EDTA titration. Infrared (IR) spectra were recorded on an
IR-408 Shimadzu 568 spectrophotometer. X-ray diffraction was
carried out on a Bruker SMART 1000 CCD area diffractometer.
Preparation of HL1
The Schiff base ligand HL1 was prepared by the condensation
of equimolar quantities of 5-bromosalicylaldehyde (0.20 g, 1
mmol) with N,N-diethylpropane-1,3-diamine (0.13 g, 1 mmol)
in methanol (30 ml) at ambient temperature for 1 h. Then the
methanol was evaporated by distillation, yielding yellow oil
of the Schiff base, which was used for the preparation of the
complexes without purification. Elemental analysis found: C,
Received 17 February 2011; accepted 28 July 2011.
This research was supported by the National Sciences Foundation
of China (No. 20676057 and 20877036) and Top-class foundation of
Pingdingshan University (No. 2008010).
Address correspondence to Ling-Wei Xue, College of Chemistry
and Chemical Engineering, Pingdingshan University, Pingdingshan,
Henan 467000, P. R. China. E-mail: pdsuchemistry@163.com
154

SCHIFF BASE COBALT COMPLEXES
155
53.5; H, 6.7; N, 9.0%; C14H21BrN2O Anal. Calcd.: C, 53.7; H, RESULTS AND DISCUSSION
6.8; N, 8.9%.
Two new Schiff bases and their cobalt complexes have been
prepared. The Schiff bases prepared in this way are formed
in nearly quantitative yields and are of high purity. The reac-
tion involving the Schiff bases, Co(ClO4)2·6H2O, and sodium
azide in the molar ratio of 1:1:1 generates beautiful red colored
block-shaped single crystals of the complexes. The results of the
elemental analyses are in accord with the composition suggested
for the ligands and the complexes. The sodium azide was used
in the preparation of both complexes, however, it coordinates to
the Co atom of (1), but does not coordinate to the Co atom of
(2). This might be caused by the larger hindrance effect of the
Preparation of HL2
The Schiff base ligand HL2 was prepared by the condensation
of equimolar quantities of 3-methoxysalicylaldehyde (0.15 g, 1
mmol) with N-phenylethane-1,2-diamine (0.14 g, 1 mmol) in
methanol (30 ml) at ambient temperature for 1 h. Then the
methanol was evaporated by distillation, yielding yellow oil
of the Schiff base, which was used for the preparation of the
complexes without purification. Elemental analysis found: C,
71.2; H, 6.8; N, 10.2%; C16H18N2O2 Anal. Calcd.: C, 71.1; H,
6.7; N, 10.4%.
TABLE 1
Preparation of [Co(HL1)2(N3)2]·H2O (1)
Crystal and structure refinement data for (1) and (2)
The Schiff base HL1 (0.31 g, 1 mmol) was diluted by
methanol (20 ml), to which was added with stirring a methanol
solution (10 ml) of Co(ClO4)2·6H2O (0.36 g, 1 mmol) and an
aqueous solution (10 ml) of NaN3 (0.07 g, 1 mmol). The mixture
was stirred for 1 h at ambient temperature to give a red solution.
Red block-shaped single crystals suitable for X-ray diffraction
were formed by slow evaporation of the solution in air for about
a week. Yield: 37%. Elemental analysis found: C, 42.6; H, 5.6;
N, 17.9; Co, 7.7%; C28H44Br2CoN10O3 Anal. Calcd.: C, 42.7;
H, 5.6; N, 17.8; Co, 7.5%.
(1)
(2)
Empirical formula C28H44Br2CoN10O3 C32H34ClCoN4O8
Color; habit
Formula weight
Temperature (K)
Block, red
787.5
298(2)
Block, red
697.0
298(2)
Crystal size (mm) 0.20 × 0.20 × 0.17 0.27 × 0.25 ×
0.23
Radiation (λ, Å)
Crystal system
Space group
Unit cell dimensions
Mo Kα (0.71073)
Monoclinic
P21/c
Mo Kα (0.71073)
Triclinic
P-1
Preparation of [CoL2 ]·ClO4 (2)
2
The Schiff base HL2 (0.27 g, 1 mmol) was diluted by
methanol (20 ml), to which was added with stirring a methanol
solution (10 ml) of Co(ClO4)2·6H2O (0.36 g, 1 mmol) and an
aqueous solution (10 ml) of NaN3 (0.07 g, 1 mmol). The mixture
was stirred for 1 h at ambient temperature to give a red solution.
Red block-shaped single crystals suitable for X-ray diffraction
were formed by slow evaporation of the solution in air for 5
d. Yield: 45%. Elemental analysis found: C, 54.9; H, 5.0; N,
8.1; Co, 8.6%, C32H34ClCoN4O8 Calcd: C, 55.1; H, 4.9; N, 8.0;
Co, 8.5%.
a (Å)
b (Å)
c (Å)
α (◦)
β (◦)
γ (◦)
V (Å3)
Z
12.679(2)
9.269(1)
28.627(4)
90
101.913(2)
90
3291.8(7)
4
1.589
10.869(1)
11.375(1)
14.370(1)
99.874(1)
111.284(1)
103.512(1)
1543.9(1)
2
Density (g cm−3
Absorption
)
1.499
0.702
2.996
coefficient
X-Ray Diffraction
(mm−1
)
Data were collected from selected crystals mounted on glass
fibers. The data for the two complexes were processed with
SAINT[10] and corrected for absorption using SADABS.[11]
Semi-empirical absorption corrections were applied with
ψ-scans.[12] The structures were solved by direct methods using
the program SHELXS-97, and were refined by full-matrix
least-squares techniques on F2 using anisotropic displacement
parameters.[13] H2 and H4A atoms in (2) were located from
a difference Fourier map and refined isotropically, with N–H
distances restrained to 0.90(1) Å. The remaining hydrogen
atoms were placed at the calculated positions. Idealized H
atoms were refined with isotropic displacement parameters set
to 1.2 (1.5 for O and methyl C atoms) times the equivalent
isotropic U values of the parent atoms. The crystallographic
data for the complexes are listed in Table 1.
θ range for data
2.64–27.00
1.59–27.00
collection (◦)
Index ranges (h, k, –16, 15; –11, 11;
l)
–13, 13; –14, 10;
–17, 18
9263
–36, 36
26640
Reflections
collected
Independent
reflections
Data/parameters
Final R indices [I > 0.0783
2σ(I)]
R indices (all data) 0.1406
Goodness-of-fit on 0.970
F2
7144
6476
3005/404
5461/423
0.0375
0.0879
1.026

156
L.-W. XUE ET AL.
TABLE 2
N,N-diethyl groups in (1) than that of the phenyl groups in (2).
It is notable that the oxidation numbers of the Co atoms are +2
for (1) and +3 for (2). The air-stable Schiff bases and the cobalt
complexes are soluble in DMF, methanol, ethanol, chloroform,
and acetonitrile.
Coordinate bond distances (Å) and angles (◦) for (1) and (2)
(1)
Co1-O1
Co1-N1
1.877(5)
1.949(6)
1.957(7)
178.0(2)
88.1(2)
91.7(2)
88.8(3)
90.5(3)
91.8(3)
92.1(3)
177.3(3)
Co1-O2
Co1-N3
Co1-N8
O2-Co1-N3
O2-Co1-N1
N3-Co1-N1
O1-Co1-N5
N1-Co1-N5
O1-Co1-N8
N1-Co1-N8
1.866(5)
1.949(6)
1.971(7)
93.5(2)
86.7(2)
177.9(3)
92.3(3)
87.4(3)
87.0(3)
89.9(3)
Co1-N5
IR Spectra
O2-Co1-O1
O1-Co1-N3
O1-Co1-N1
O2-Co1-N5
N3-Co1-N5
O2-Co1-N8
N3-Co1-N8
N5-Co1-N8
(2)
Complexes (1) and (2) exhibit similar IR absorption. Both
complexes exhibit strong and sharp bands at 1627 and 1633
cm−1, respectively, which can be assigned to the C N stretch-
ing frequency of the coordinated Schiff base ligands.[14,15] The
shift of these bands toward lower frequencies compared to those
of the free Schiff bases indicates the coordination of the imino
N atoms to the metal centers. For the complexes, the phenolic
C–O stretching is obtained at about 1273 cm−1. The sharp bands
in both spectra of the complexes at 3272 and 3253 cm−1 can
be attributed to the N–H vibrations. The bands at about 2935
cm−1 can be correlated to the alkyl C–H bond stretching. Several
weak peaks observed in the range 3180–3000 cm−1 are likely
to be due to the aromatic stretches. For (1), a very strong single
sharp band is obtained at 2037 cm−1 characteristic of the azide
ligands,[16] whereas complex (2) exhibits a very strong splitted
band centered at 1091 cm−1 for the perchlorate anion. The bands
in the region 560–410 cm−1 are assigned to the Co-N and Co-O
vibrations.[17]
Co1-O1
Co1-N1
Co1-N3
1.868(1)
1.906(2)
1.904(2)
90.7(1)
92.8(1)
84.8(1)
87.7(1)
84.2(1)
178.2(1)
95.8(1)
91.5(1)
Co1-O2
Co1-N2
Co1-N4
O1-Co1-N3
O1-Co1-N1
N3-Co1-N1
O2-Co1-N4
N1-Co1-N4
O2-Co1-N2
N1-Co1-N2
1.893(1)
2.046(2)
2.032(2)
85.7(1)
94.4(1)
177.6(1)
176.6(1)
98.3(1)
90.2(1)
84.2(1)
O1-Co1-O2
O2-Co1-N3
O2-Co1-N1
O1-Co1-N4
N3-Co1-N4
O1-Co1-N2
N3-Co1-N2
N4-Co1-N2
Crystal Structure Description of Complex (1)
The molecular structure of complex (1) is in Figure 1. Se-
lected bond distances and angles are listed in Table 2.
The complex contains a mononuclear cobalt(II) complex
moiety and a water molecule. The Co atom has an octahedral ge-
ometry and coordinated by two zwitterionic Schiff base ligands
HL1 and two azide groups. The Schiff bases act as bidentate
ligands and coordinate to the Co atom through the phenolic O
and imino N atoms. The azide groups are monodentate ligands
and coordinate to the Co atom through the terminal N atoms.
For the octahedral coordination, the three trans angles are in the
range 177.3(3)–178.0(2)◦, and the other angles are in the range
86.7(2)–93.5(2)◦, indicating a slightly distorted octahedral ge-
ometry. The distances of the Co–O and Co–N bonds are compa-
rable to the values observed in other cobalt(II) complexes with
Schiff bases.[18,19] In the crystal structure, the molecules are con-
nected by intermolecular hydrogen bonds O–H···N, N–H···O,
and N–H···N, forming 2D layered structure along the ab plane,
as shown by Figure 2. The corresponding hydrogen bonding
parameters are listed in Table 3.
Crystal Structure Description of Complex (2)
The molecular structure of the complex (2) is in Figure 3.
Selected bond distances and angles are listed in Table 2.
The complex contains one [CoL2 ]+ cation and one
2
perchlorate anion. The hexa-coordinated cobalt(III) center is
bonded to two tridentate Schiff base ligands L2 in an octahedral
geometry. Each Schiff base ligand offers deprotonated phenolic
O, imino N, and amino N atoms as the coordination sites
FIG. 1. Perspective view of complex (1) with 30% probability thermal
ellipsoids.

SCHIFF BASE COBALT COMPLEXES
157
FIG. 3. Perspective view of complex (2) with 30% probability thermal ellip-
soids.
FIG. 2. Molecular packing of complex (1), viewed along the b axis.
providing a CoN4O2 chromophore. The fact that Co–Namino
bonds are longer than Co–Nimino bonds is quite evident from
the difference in hybridization states (sp2 for imino N and sp3
for amino N). For the octahedral coordination, the three trans
angles are in the range 176.6(1)–178.2(1)◦, and the other angles
are in the range 84.2(1)–98.3(1)◦, indicating a slightly distorted
octahedral geometry. The distances of the Co–O and Co–N
bonds are consistent with corresponding values of analogous
CoN4O2 chromophores.[20,21] The perchlorate anion plays a
significant role in hydrogen bonding interactions leading to the
formation of 1D chain along the c axis, as shown by Figure 4.
The corresponding hydrogen bonding parameters are listed in
Table 3.
TABLE 3
Hydrogen bonding parameters for (1) and (2)
d(D–H) d(H···A) d(D···A) ꢀ(D–H···A)
D–H···A
(1)
(Å)
(Å)
(Å)
(◦)
O3–H3A···N4a 0.85
O3–H3B···N5 0.85
N4–H4A···O3b 0.91
2.30
2.40
2.13
2.98(1)
2.98(1)
2.98(1)
137
126
154
169 (8)
158 (7)
N2–H2···N8c
N2–H2···N9c
(2)
0.90(1)
0.90(1)
2.05(2) 2.94(1)
2.63(4) 3.48(1)
N4–H4A···O6 0.90(3)
2.00(3) 2.87(1)
2.65(2) 3.41(1)
2.52(2) 3.24(1)
163 (3)
142 (3)
137 (3)
N2–H2···O6
0.90(3)
0.90(3)
N2–H2···O8d
Symmetry transformations used to generate equivalent atoms: (a)
1 – x, 1/2 + y, 1/2 – z; (b) 1 – x, –1/2 + y, 1/2 – z; (c) 2 – x, 1/2 + y,
1/2 – z; (d) 2 – x, 2 – y, 1 – z.
FIG. 4. Molecular packing of complex (2), viewed along the b axis.

158
L.-W. XUE ET AL.
TABLE 4
SUPPLEMENTARY MATERIALS
Minimum inhibitory concentration values (µg/mL) for the
The crystallographic data of the structures described in this
paper were deposited with the Cambridge Crystallographic Data
Centre as supplementary publication no. CCDC- 812229 for
(1) and 763167 for (2). Copies of these data are available free
of charge from http://www.ccdc.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.
antimicrobial activities of the tested compounds
Staphylococcus Escherichia
Candida
albicans
aureus
coli
HL1
512
128
16
512
256
64
> 1024
> 1024
512
HL2
(1)
(2)
2
16
256
Tetracycline
0.32
2.12
> 1024
REFERENCES
1. Borisova, N.E.; Reshetova, M.D.; Ustynyuk, Y.A. Metal-free methods in
the synthesis of macrocyclic Schiff bases. Chem. Rev. 2007, 107, 46–79.
2. Adhikary, C.; Sen, R.; Bocelli, G.; Cantoni, A.; Solzi, M.; Chaudhuri,
S.; Koner, S. Tridentate (NNO) Schiff-base copper(II) complex: synthesis,
crystal structure, and magnetic study. J. Coord. Chem. 2009, 62, 3573–3582.
3. Zhang, C.-X.; Cui, C.-X.; Lu, M.; Yu, L.; Zhan, Y.-X. In situ synthesis,
characterization and crystal structure of a novel cobalt(III) complex with
tridentate Schiff base. Synth. React. Inorg. Met.-Org. Nano-Met. Chem.
2009, 39, 136–138.
4. Liu, Z.-C.; Wang, B.-D.; Yang, Z.-Y.; Li, Y.; Qin, D.-D.; Li, T.-R. Syn-
thesis, crystal structure, DNA interaction and antioxidant activities of two
novel water-soluble Cu2+ complexes derivated from 2-oxo-quinoline-3-
carbaldehyde Schiff-bases. Eur. J. Med. Chem. 2009, 44, 4477–4484.
5. Qin, D.-D.; Yang, Z.-Y.; Qi, G.-F.; Li, T.-R. Crystal structure and biological
activities of water-soluble nickel(II) and copper(II) complexes of a Schiff-
base derived from paeonol. Transition Met. Chem. 2009, 34, 499–505.
6. Yu, Y.-Y.; Xian, H.-D.; Liu, J.-F.; Zhao, G.-L. Synthesis, characterization,
crystalstructureandantibacterialactivitiesoftransition metal(II)complexes
of the Schiff base 2-[(4-methylphenylimino)methyl]-6-methoxyphenol.
Molecules, 2009, 14, 1747–1754.
Antimicrobial Activity
Qualitative determination of antimicrobial activity was done
using the disk diffusion method.[22,23] The results are summa-
rized in Table 4. A comparative study of minimum inhibitory
concentration values of the Schiff bases and the two complexes
indicate that the cobalt complexes have better activity than
the free Schiff bases. Generally, this is caused by the greater
lipophilic nature of the complexes than the ligand. Such in-
creased activity of the metal chelates can be explained on the
basis of chelating theory.[24] On chelating, the polarity of the
metal atoms will be reduced to a greater extent due to the over-
lap of the ligand orbital and partial sharing of positive charge
of the metal atoms with donor atoms. Further, it increases the
delocalization of p-electrons over the whole chelate ring and
enhances the lipophilicity of the complexes. This increased
lipophilicity enhances the penetration of the complexes into
lipid membrane and blocks the metal binding sites on enzymes
of micro-organisms.
7. Yuan, C.X.; Lu, L.P.; Gao, X.L.; Wu, Y.B.; Guo, M.L.; Li, Y.; Fu, X.Q.;
Zhu, M.L. Ternary oxovanadium(IV) complexes of ONO-donor Schiff base
and polypyridyl derivatives as protein tyrosine phosphatase inhibitors: syn-
thesis, characterization, and biological activities. J. Bio. Inorg. Chem. 2009,
14, 841–851.
From Table 4, it is obvious that the cobalt complexes show
greater antimicrobial and antifungi activities against Staphylo-
coccus aureus, Escherichia coli, and Candida albicans when
compared with the Schiff bases. The structures of the tested
compounds seem to be the principal factor influencing the an-
timicrobial activity. The activity of (2) is stronger than (1). For
Staphylococcus aureus and Escherichia coli, even though the
activities of the cobalt complexes are stronger than those of the
Schiff bases, it is still much less than the control drug Tetracy-
cline. But for Candida albicans, both complexes show stronger
activity than the Schiff bases and Tetracycline.
8. Sonmez, M.; Celebi, M.; Berber, I. Synthesis, spectroscopic and biologi-
cal studies on the new symmetric Schiff base derived from 2,6-diformyl-
4-methylphenol with N-aminopyrimidine. Eur. J. Med. Chem. 2010, 45,
1935–1940.
9. Allen, F.H. The Cambridge Structural Database: a quarter of a million
crystal structures and rising. Acta Crystallogr. 2002, B58, 380–388.
10. Bruker. SMART and SAINT. Area Detector Control and Integration Soft-
ware; Bruker Analytical X-ray Instruments: Madison, WI, 1997.
11. Sheldrick, G.M. SADABS. Program for Empirical Absorption Correction of
Area Detector Data; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
12. North, A.C.T.; Phillips, D.C.; Mathews, F.S. A semi-empirical method of
absorption correction. Acta Crystallogr. 1968, A24, 351–359.
13. Sheldrick, G.M. SHELXL-97. Program for the Refinement of Crystal Struc-
tures; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
14. Garg, R.; Fahmi, N.; Singh, R.V. Synthetic, Spectral, and antimicrobial
aspects of biologically relevant coordination compounds of dioxomolybde-
num(VI) and oxovanadium(V). Russ. J. Coord. Chem. 2008, 34, 198–203.
15. Patil, S.A.; Naik, V.H.; Kulkarni, A.D.; Badami, P.S. DNA cleavage, antimi-
crobial, spectroscopic and fluorescence studies of Co(II), Ni(II) and Cu(II)
complexes with SNO donor coumarin Schiff bases. Spectrochim. Acta Part
A 2010, 75, 347–354.
CONCLUSION
The new Schiff bases The new Schiff bases 4-bromo-2-[(3-
diethylaminopropylimino)methyl]phenol and 2-methoxy-6-[(2-
phenylaminoethylimino)methyl]phenol and their cobalt com-
plexes were prepared and characterized. The crystal structures
of both complexes were confirmed by X-ray single crystal struc-
ture determination. The antimicrobial test shows that both com-
plexes have potential activity against Staphylococcus aureus,
Escherichia coli, and Candida albicans.
16. Sen, S.; Mitra, S.; Luneau, D.; El Fallah, M.S.; Ribas, J. Synthesis,
crystal structure and magnetic properties of two new manganese Schiff
base complexes [Mn2(L1)2(NCS)2] and [Mn(L2)(N3)(H2O)] [{L1H =
C
13H10N2O2}; {L2H2
= C19H22N2O4}]. Polyhedron 2006, 25,
2737–2744.

SCHIFF BASE COBALT COMPLEXES
159
17. Chandra, S.; Kumar, U. Spectral and magnetic studies on manganese(II),
cobalt(II) and nickel(II) complexes with Schiff bases. Spectrochim. Acta
Part A 2005, 61, 219–224.
21. Li, S.-Y.; You, Z.-L.; Chen, B.; Lin, Y.-S.; Xiong, Z.-D.; Zhu, H.-L.
trans-Bis{1-[3-(cyclohexylamino)propyliminomethyl]-2-naphtholato-
κ3O,N,Nꢁ}cobalt(III) perchlorate. Acta Crystallogr. 2004, E60,
m999–1001.
18. De, R.L.; Samanta, K.; Maiti, K.; Keller, E. Metal specific variable binding
modes in Schiff base complexes—facile synthesis and crystal structure 22. Barry, A. Proceduresand theoreticalconsiderationsfortesting antimicrobial
of anionic bis-N-(2-oxyethyl-5-bromosalicylal-diminato) cobalt(III). Inorg.
Chim. Acta 2001, 316, 113–116.
agents in agar media. In Antibiotics in Laboratory Medicine, 5th Edn.,
Lorian, V. (ed.); Williams and Wilkins: Baltimore, MD, 1991, p. 1–16.
23. Rosu, T.; Negoiu, M.; Pasculescu, S.; Pahontu, E.; Poirier, D.; Gulea, A.
Metal-based biologically active agents: Synthesis, characterization, antibac-
terial and antileukemia activity evaluation of Cu(II), V(IV) and Ni(II) com-
plexes with antipyrine-derived compounds. Eur. J. Med. Chem. 2010, 45,
774–781.
19. Li, Y.; Wu, Q.; Lecren, L.; Clerac, R. Synthesis, structure and magnetism
of new polynuclear transition metal aggregates assembled with Schiff-base
ligand and anionic N-donor ligands. J. Mol. Struct. 2008, 890, 339–345.
20. Thakurta, S.; Butcher, R.J.; Pilet, G.; Mitra, S. Synthesis of octahedral
cobalt(III) complexes with mono- and di-condensed Schiff base ligands: a
template-directed approach for the isolation of a rare kind of mixed-ligand
complex. J. Mol. Struct. 2009, 929, 112–119.
24. Searl, J.W.; Smith, R.C.; Wyard, S. Electron spin resonance absorption for
polycrystalline substances. J. Proc. Phys. Soc. 1961, 78, 1174–1176.