Synthesis, magnetic, spectral, and antimicrobial studies of Cu(II), Ni(II) Co(II), Fe(III), and UO2(II) complexes of a new Schiff base hydrazone derived from 7-chloro-4-hydrazinoquinoline

Article abstract of DOI:10.1016/j.saa.2006.02.017

A new hydrazone ligand, HL, was prepared by the reaction of 7-chloro-4-hydrazinoquinoline with o-hydroxybenzaldehyde. The ligand behaves as monoprotic bidentate. This was accounted for as the ligand contains a phenolic group and its hydrogen atom is reluctant to be replaced by a metal ion. The ligand reacted with Cu(II), Ni(II), Co(II), Fe(III), and UO₂(II) ions to yield mononuclear complexes. In the case of Fe(III) ion two complexes, mono- and binuclear complexes, were obtained in the absence and presence of LiOH, respectively. Also, mixed ligand complexes were obtained from the reaction of the metal cations Cu(II), Ni(II) and Fe(III) with the ligand (HL) and 8-hydroxyquinoline (8-OHqu) in the presence of LiOH, in the molar ratio 1:1:1:1. It is clear that 8-OHqu behaves as monoprotic bidentate ligand in such mixed ligand complexes. The ligand, HL, and its metal complexes were characterized by elemental analyses, IR, UV-vis, mass, and ¹H NMR spectra, as well as magnetic moment, conductance measurements, and thermal analyses. All complexes have octahedral configurations except Cu(II) complex which has an extra square-planar geometry, while Ni(II) mixed complex has also formed a tetrahedral configuration and UO₂(II) complex which formed a favorable pentagonal biprymidial geometry. Magnetic moment of the binuclear Fe(III) complex is quite low compared to calculated value for two iron ions complex and thus shows antiferromagnetic interactions between the two adjacent ferric ions. The HL and metal complexes were tested against one stain Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli), and fungi (Candida albicans). The tested compounds exhibited higher antibacterial acivities.

Full text of DOI:10.1016/j.saa.2006.02.017

Spectrochimica Acta Part A 66 (2007) 28–36
Synthesis, magnetic, spectral, and antimicrobial studies of Cu(II), Ni(II)
Co(II), Fe(III), and UO (II) complexes of a new Schiff base hydrazone
2
derived from 7-chloro-4-hydrazinoquinoline
∗
Mostafa El-Behery , Haifaa El-Twigry
Department of Chemistry, Education College for Girls, Scientific Departments, El-Montazah El-Gharby, Burydah, Qassim, KSA, Saudi Arabia
Received 12 November 2005; received in revised form 26 January 2006; accepted 13 February 2006
Abstract
A new hydrazone ligand, HL, was prepared by the reaction of 7-chloro-4-hydrazinoquinoline with o-hydroxybenzaldehyde. The ligand behaves
as monoprotic bidentate. This was accounted for as the ligand contains a phenolic group and its hydrogen atom is reluctant to be replaced by a
metal ion. The ligand reacted with Cu(II), Ni(II), Co(II), Fe(III), and UO (II) ions to yield mononuclear complexes. In the case of Fe(III) ion
2
two complexes, mono- and binuclear complexes, were obtained in the absence and presence of LiOH, respectively. Also, mixed ligand complexes
were obtained from the reaction of the metal cations Cu(II), Ni(II) and Fe(III) with the ligand (HL) and 8-hydroxyquinoline (8-OHqu) in the
presence of LiOH, in the molar ratio 1:1:1:1. It is clear that 8-OHqu behaves as monoprotic bidentate ligand in such mixed ligand complexes.
1
The ligand, HL, and its metal complexes were characterized by elemental analyses, IR, UV–vis, mass, and H NMR spectra, as well as magnetic
moment, conductance measurements, and thermal analyses. All complexes have octahedral configurations except Cu(II) complex which has an
extra square-planar geometry, while Ni(II) mixed complex has also formed a tetrahedral configuration and UO (II) complex which formed a
2
favorable pentagonal biprymidial geometry. Magnetic moment of the binuclear Fe(III) complex is quite low compared to calculated value for two
iron ions complex and thus shows antiferromagnetic interactions between the two adjacent ferric ions. The HL and metal complexes were tested
against one stain Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli), and fungi (Candida albicans). The
tested compounds exhibited higher antibacterial acivities.
©
2006 Elsevier B.V. All rights reserved.
Keywords: Schiff base ligand; Metal complexes; Antimicrobial; IR spectra; UV–vis spectra
1
. Introduction
logical applications [14–16]. Isonicotinic acid hydrazide (INH)
is a drug of proven therapeutic importance and is used as bacte-
rial ailments, e.g., tuberculosis [17]. Hydrazones derived from
condensation of isonicotinic acid hydrazide with pyridine alde-
hydes have been found to show better antitubercular activity than
INH [18,19]. Agarwal [18] investigated the coordinating ability
of INH-derivatives with metal ions.
In the present investigation we describe the synthesis, char-
acterization, and antimicrobial activitiy of transition metal com-
plexes of Schiff base hydrazone containing the quinoline moiety,
7-chloro-4-(o-hydroxybenzilidenehydrazo)quinoline (HL).
Schiff bases play an important role in inorganic chemistry
as they easily form stable complexes with most transition metal
ions. The development in the field of bioinorganic chemistry
has increased the interest in Schiff base complexes, since it has
been recognized that many of these complexes may serve as
models for biologically important species [1–5]. The remark-
able biological activity of acid hydrazides R–CO–NH–NH2,
a class of Schiff base, their corresponding aroylhydrazones,
ꢀ
R CO NH N CH R , and the dependence of their mode of
chelation with transition metal ions present in the living sys-
tem have been of significant interest [6–12]. The coordination
compounds of aroylhydrazones have been reported to act as
enzyme inhibitors [13] and are useful due to their pharmaco-
2
. Experimental
2.1. Reagents and malerials
∗
CuCl ·2H O, NiCl ·H O, FeCl ·6H O, LiOH·H O, salicyl-
Corresponding author. Tel.: +966 507112969.
E-mail address: behery mostafa@hotmail.com (M. El-Behery).
2
2
2
2
3
2
2
aldehyde and hydrazine hydrate (100%), and 8-hydroxyqui-
1
386-1425/$ – see front matter © 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2006.02.017

M. El-Behery, H. El-Twigry / Spectrochimica Acta Part A 66 (2007) 28–36
29
noline were either BDH or Merck chemicals and were used
without further purification.
added to the metal salt (3 mmol), CuCl2·2H2O, NiCl2·6H2O, or
FeCl3·6H2O dissolved in the least amount of bidistilled water.
The reaction mixture was refluxed for 5 h with constant stirring
to ensure the complete formation of the metal complexes. The
precipitated solid complexes were filtered and washed several
times with 50% (v/v) methanol–water to remove any excess of
the unreacted starting materials. Finally, the complexes were
washed with diethyl ether and dried in a vacuum desiccator
over anhydrous CaCl2. The complexes obtained by this method
are [CuL(8-OHqu)]·H2O, [NiL(8-OHqu)]·3H2O, and [Fe(L)(8-
OHqu)(Cl)(H2O)]·2H2OwhicharesolubleinDMF, DMSO, and
ethanol and partially soluble in 1,4-dioxan.
2
2
.2. Synthesis of the organic ligand
.2.1. 4,7-Dichloroquinoline
It was provided as commercial sample from El-Nasr-
Company for pharmaceutical chemicals, Cairo, Egypt, and has
been purified in laboratory as follows. Under warming and con-
stant stirring, 10 g (10 mmol) of the sample was dissolved in
1
50 ml absolute ethanol. The solution was filtered while hot,
and then allowed to cool. After that white cottony crystals were
formed which were filtered and washed with 5–10 ml ethanol
◦
and then recrystallized from ethanol (70% yield, mp 82 C). The
2.5. Analytical and physical measurements
crystals were stored in brown container to avoid light, which may
affect it.
Electronic spectra were recorded for solution of the lig-
and, HL, in DMF, and for the metal complexes as Nujol Mull
on a Jasco UV–vis spectrophotometer model V-550 UV–vis.
The IR spectra were recorded using KBr discs on FT-IR 1650
2
.2.2. 7-Chloro-4-hydrazinoquinoline
To 10 g (5 mmol) of 4,7-dichloroquinoline dissolved in 20 ml
1
ethanol, 25 ml (50 mmol) hydrazine hydrate (100%) in 30 ml
absolute ethanol was added. The mixture was refluxed for 2 h.
After 1/2 h, a golden yellow precipitate started to precipitate.
After the refluxing time was reached, the mixture was allowed
to cool for 6 h. The golden yellow precipitate was filtered and
washed with 5 ml absolute ethanol and recrystallized from abso-
Perkin-Elmer Spectrometer. H NMR spectra were carried out
in DMF-d at room temperature using TMS as internal standard
6
on a Brucker 250 MHz spectrophotometer. Magnetic suscepti-
bilities of the complexes were measured by the Gouy method at
room temperature using a model MK1 Johnson Matthey. Alpha
Products, magnetic susceptibility balance. The effective mag-
◦
lute ethanol (80% yield, mp 223–224 C).
netic moments were calculated using the relation (μ = 2.828
eff
/2
(
χmT)1 B.M., where χm is the molar susceptibility corrected
2
.2.3. 7-Chloro-4-(o-hydroxybenzilidenehydrazo)quinoline
The ligand (HL) was synthesized as follows. 7-Chloro-
-hydrazinoquinoline, 2 g (1 mmol) was dissolved in 10 ml
using Pascal’s constants for diamagnetism of all atoms in the
compounds. The TG–DTA measurements were carried out on
a Shimadzu thermogravimetric analyzer in dry nitrogen atmo-
4
◦
absolute ethanol. To this solution salicylaldehyde, 13 ml
1.1 mmol), was added. The reaction mixture was refluxed for
h. After cooling, the formed yellow precipitate was collected,
sphere and a heating rate of 10 C/min using the TA-50 WS1
◦
(
2
program. Mass spectra were recorded at 70 eV and 300 C on an
MS 5988 Hewlett-Packard mass spectrometer. Conductivities
−3
filtered, and finally washed with 5–10 ml absolute ethanol and
purified by recrystallization from ethanol (80%, mp 235 C).
were measured in DMF solutions of the complexes (10 M)
using a model LBR, WTWD-812 Weilheim Conductivity meter
fitted with a model LTA100 cell. Analyses of the metals followed
decomposition of their complexes with concentrated nitric acid.
The resultant solution was diluted with distilled water and fil-
tered to remove the precipitated ligand. The solution was then
neutralized with aqueous ammonia solution and the metal ions
titrated with EDTA. Analysis of the uranyl complex was carried
out at the Central Laboratory for Environmental Quality Mon-
itoring, CLQM, Kalubia, Cairo, Egypt. The complex was first
dried and grinded followed by digestion by nitric–HF digestion
mixture using Milestone Microwave Digester Model MLS 1200
Mega. The digestible uranium metal was analyzed using Perkin-
Elmer ICP OES, Model Optima-3000 coupled with an Ultra
Sonic Nebulizer, USN. Microanalyses of carbon, hydrogen,
nitrogen, and chlorine were carried out at the Micro Analytical
Center, Cairo University, Giza, Egypt.
◦
2
.3. Synthesis of the metal complexes
A solution of metal salt dissolved in ethanol was added grad-
ually to a stirred ethanolic solution of the ligand, HL, in the
molarratio1:1. Thereactionmixturewasfurtherstirredfor2–4 h
to ensure the complete precipitation of the formed complexes.
The precipitated solid complexes were filtered, washed several
times with 50% (v/v) ethanol–water to remove any excess of
the unreacted starting materials. Finally, the complexes were
washed with diethyl ether and dried in vacuum desiccators over
anhydrous CaCl2. The reaction of uranyl salt was carried out in
methanol as it dissolved better in this solvent. The preparations
described were repeated in the presence of LiOH, as deprotonat-
ing agent in the molar ratio 1:1:1 (M:HL:LiOH) and its addition
is a must in order to obtain such preparation with good yield of
Ni(II), and binuclear iron complexes.
2.6. Pharmacology
2
.4. Synthesis of mixed ligand complexes
The in vitro evaluation of antimicrobial activity was carried
out at Saudi Pharmaceutical Industries and Medical Appliance
Corporation. The purpose of the screening program is to pro-
vide antimicrobial activity and bacteriostatic and fungistatic
A mixture of 0.126 g (3 mmol) LiOH, H2O, 0.898 g (3 mmol)
HL, and 0.44 g (3 mmol) of 8-OHqu in 60 ml methanol was

3
0
M. El-Behery, H. El-Twigry / Spectrochimica Acta Part A 66 (2007) 28–36
Table 2
1
H NMR data of the ligand HL in DMF-d6
Chemical shift, δTMS (ppm)
Assignmenta
1
1
4.5
.2
1.7
[s, 1H] (1)
[s, 1H] (2)
[s, 1H] (3)
6
7.9–8.3
[m, 9H, Ar–H, and quinoline–H]
a
s, singlet and m, multiplet.
efficiencies of the investigated metal complexes. The prepared
compounds were tested against one strain of Gram posi-
tive bacteria (Staphylococcus aureu), Gram negative bacteria
(Escherichia coli), and fungi (Candida albicans) to provide the
minimum inhibitory concentration (MIC’s) for each complex.
Bacteriostatic and fungistatic efficiency is the lowest concentra-
tion of solution to inhibit the growth of a test organism.
3. Results and discussion
3.1. The organic ligand, HL
Elemental analyses (Table 1) of the ligand reflected that the
1
ligand has molecular formula given. The H NMR spectrum
(Table 2) of the ligand in deuterated dimethylformamide showed
two signals at δ = 14.5 and 11.7 ppm for the proton of the pheno-
lic OH and the NH groups, respectively. A signal is also observed
at δ = 6.62 ppm for the HC N– group [20] (Table 2). Addition of
D2O to the previous solution results in diminishing the signals
due to the protons of phenolic OH and HN–N groups.
TheIRspectrumoftheligand(Table3)showsastrongbandat
−
1
3
530 cm assigned to νOH of the phenolic group. The stretch-
−1
ing vibration of NH group appears as weak bands at 3300 cm
.
The spectrum shows also vibrational bands at 1605, 1600, and
−
1
1
140 and 1130 cm assigned for νs and νas of the C N and
N–N groups, respectively. The deformation vibration, δ, of the
−
1
phenolic OH group appears at 1278 cm . The vibrational band
−
1
observed at 2570 cm could be assigned for the intramolecular
hydrogen bonding.
The UV–vis spectrum (Table 4) recorded for the ethanolic
solution of the ligand showed absorption bands at 48,076 and
−
1
*
4
4,642 cm assigned for ␲–␲ transitions within the aromatic
−1
and quinoline rings. The band observed at 36,231 cm would
be due to the n–␲ transition of the C N group. The absorption
bandsat26,176and24,752 cm areassignedforCTtransitions.
The band at 24,752 cm encroaches on the visible region [21]
and impacts the ligand and its colour.
*
−
1
−
1

M. El-Behery, H. El-Twigry / Spectrochimica Acta Part A 66 (2007) 28–36
31
Table 3
Characteristic IR bands (cm 1) of HL and its corresponding metal complexes
−
Compound, M.F. (M.Wt.)
HLa, C16H12N3OCl (297.5)
ν(C N)
ν(N H)
ν(N–N)
ν(M–N)
ν(M–O)
ν(OH), H2O
Other bands
1605 s
3300 w
1140 s
–
–
3530 (νOH–phenolic)
1600 ν(C N)as, 1130
ν(N–N)as, 1278 (δ
OH–phenolic)
[
Cu(L)2]·H2O,
1595 s
3214 w, br
1136 s
420 w
540 m
3380 (lattice water)
3380 (lattice water)
C32H24N6O3Cl2 Cu
(
674.5)
[Cu(L)(8-OHqu)]·H2O,
C25H19N4O3Cl Cu (522)
[Ni(L)2(OH2)2]·3H2O,
C32H32N6O7Cl2 Ni (742)
[Ni(L)(8-OHqu)]·3H2O,
C25H23N4O5Cl Ni (553.5)
[Fe(L)2(OH2)2]·NO3·2H2O,
C32H30N7O9Cl2 Fe (783)
[Fe2(L)4(Cl)2]·3H2O,
1597 m
1597 s
1598 m
1594 s
1597 s
3200 s
1137 w
1125 w
1136 s
1137 s
1134 s
425 w
410 w
445 w
465 w
460 w
520 m
515 m
520 w
520 m
540 w
3215 w
3210 w
3214 w, br
3211 w
3380 (lattice water), 3495
(coordinated water)
3375 (lattice water)
3385 (lattice water), 3490
(coordinated water)
3390 (lattice water)
1385 s, 835 s, 710 m (νNO3)
C64H50N12O7Cl6 Fe2
(
1423)
[
Fe(L)(8-
1597 s
3218 w
1138 w
460 w
515 w
3380 (lattice water), 3495
(coordinated water)
OHqu(Cl)(H2O)]·2H2O,
C25H23N4O6Cl2 Fe (602)
Co(L)2(OH2)2]·3H2O,
C32H30N6O8Cl Co (706.5)
UO2(L)2(OH2)]·2H2O,
C32H28N6O7Cl2 U (917)
[
[
1597 m
1595 s
3222 w
3214 w
1145 s
1140 s
465 w
465 w
540 m
530 m
3390 (lattice water), 3490
(coordinated water)
3390 (lattice water), 3495
(coordinated water)
906 s (νU(VI)O2)
s: strong, w: weak, m: medium, and br: broad.
The mass spectrum oftheligand(Fig. 1)showedits molecular
ion at m/e 297 which coincides with formula weight. Metastable
ion(s) is not observed. Scheme 1 represents the proposed frag-
mentation pattern of the ligand.
The pH-metric measurement for 3 × 10 M of 75% (v/v)
ethanol–water solution of the ligand indicated that only one pro-
ton dissociates together with the value of pKa (10.63) suggesting
that the ligand behaves as a weak monoprotic acid. The value
of pKa reveals that the proton dissociated from the phenolic OH
group rather than from the N-proton of the hydrazino moiety
which may dissociated at higher pH region.
ligand and its coordination mode could be represented as shown
in Fig. 2.
3.2. Metal complexes
−
3
Table 1 shows the elemental analyses and molecular for-
mula of the complexes obtained from the reaction of the Schiff
base hydrazone ligand, HL, with the transition metal ions,
Cu(II), Ni(II), Co(II), UO2(II), and Fe(III), in the molar ratio
1:1 (M:L). The reactions were carried out in presence and in
absence of LiOH as deprotonating agent. In all cases, except
for Fe(III) ion, only one product obtained indicating that the
presence of LiOH does not affect the formation of the com-
plexes. The exception is Fe(III) ion, where two complexes were
Elemental analyses and IR spectra of ligand and its metal
complexes under investigation (Tables 1 and 3) showed that the
HL coordinated with the metal ions as monoprotic bidentate
Table 4
Magnetic moment, molar conductance, and electronic spectral data (cm 1) for HL and its metal complexes
−
*
*
a
−1
)
Compound, M.F. (M.Wt.)
μeff (B.M.)
␲ → ␲ , n → ␲ , and charge transfer
d → d transitions (cm
a
−1
)
transitions (cm
HL, C16H12N3OCl (297.5)
diab
1.75
1.80
2.85
3.02
5.40
5.65
7.25
5.08
48067, 44642, 36231, 26176, 24752
36765, 28612, 22396
36630, 28129, 22446
37037, 28653, 22371
37037, 28653, 22371
35906, 28248, 25707, 21459
35971, 27701, 25252, 20230
35971, 27701, 25252, 20230
37037, 28449, 22421
–
[
[
[
[
[
[
[
[
[
Cu(L)2]·H2O, C32H24N6O3Cl2 Cu (674.5)
15520
15850
16220
14599, 15058
14050
Cu(L)(8-OHqu)]·H2O, C25H19N4O3Cl Cu (522)
Ni(L)2(OH2)2]·3H2O, C32H32N6O7Cl2 Ni (742)
Ni(L)(8-OHqu)]·3H2O, C25H23N4O5Cl Ni (553.5)
Fe(L)2(OH2)2]·NO3·2H2O, C32H30N7O9Cl2 Fe (783)
a
Fe(L)(8-OHqu(Cl)(H2O)]·2H2O , C25H23N4O6Cl2 Fe (602)
14050
a
Fe2(L)4(Cl)2]·3H2O , C64H50N12O7Cl6 Fe2 (1423)
14331, 13850
18.480, 15390
–
Co(L)2(OH2)2]·3H2O, C32H30N6O8Cl Co (706.5)
UO2(L)2(OH2)]·2H2O, C32H28N6O7Cl2 U (917)
b
dia
37147, 27956, 22371
a
As Nujol mull.
b
dia, diamagnetic.

3
2
M. El-Behery, H. El-Twigry / Spectrochimica Acta Part A 66 (2007) 28–36
Fig. 2. Mode of coordination sites of the ligand HL.
3.3. The IR spectra of the metal complexes
The IR spectra (Table 3) of the metal complexes showed that
the band due to phenolic OH group that appeared in the spectrum
−
1
of the ligand at 3530 cm has disappeared in the spectra of the
complexes, which may be due to the displacement of its proton
by the metal ion in accordance with the pH-metric and dissoci-
ation constant of the ligand. Moreover, the spectra showed that
the vibrations of –C N group were shifted to a lower frequency
due to the coordination of the nitrogen atom of the azomethine
group. As a result, the Schiff base hydrazone ligand, HL, coor-
dinates in all complexes as monoprotic bidentate ON ligand via
the oxygen atom of the phenolic OH and the nitrogen atom of the
azomethine groups [22]. Similar results were obtained from the
IR spectra of the mixed 8-hydroxyquinoline complexes (Table 3)
in which the frequency of the C8–OH group does not appear due
to the replacement of the proton of the OH by the metal ion, and
the lowering in the frequency of the azomethine group due to
◦
Fig. 1. Mass spectrum of HL recorded at 300 C and 70 eV.
obtained in the presence and absence of LiOH. This could be
attributed to the aggregate tendency of Fe(III) ion. The table
represents, also, the obtained mixed ligand complexes from the
reaction mixture of Cu(II), Ni(II), and Fe(III) with HL and
8
(
-OHqu in the presence of LiOH in the molar ratio 1:1:1:1
M:HL:8-OHqu:LiOH).
Scheme 1. Proposed mass fragmentation pattern of HL.

M. El-Behery, H. El-Twigry / Spectrochimica Acta Part A 66 (2007) 28–36
33
Fig. 3. Proposedstructuresofsquare-planargeometryof[Cu(L)(8-OHqu)]com-
plex.
the coordination of the nitrogen atom of the quinoline moiety
with the metal ions [22]. In all spectra, new bands appeared, for
−
1
all types of the complexes, at 515–540 and 410–465 cm , that
would be assigned to νM–O and νM–N, respectively.
3
.4. Magnetic moments and electronic spectra of the metal
complexes
The electronic spectra and magnetic moment of the metal
complexes are listed in Table 4. Generally, in all spectra of metal
complexes, the absorption bands due to ␲–␲ and n–␲ transi-
Fig. 4. Proposed octahedral structures of [M(L)2(OH2)2], where M = Cu, Ni,
Co, and Fe.
*
*
tions that are observed in the spectrum of the free ligand higher
−
1
than 22,300 cm have shifted to lower frequencies due to the
coordination of the ligand with metal ions.
(μeff = 3.02 B.M.) which is in harmony with the reported
[24] value, μeff = 3.07 B.M., for the tetrahedral complex
NiCl2(PPh3)2.
The spectra of [Cu(L)2]·H2O and [Cu(L)(8-OHqu)]·H2O
−
1
complexes showed absorption bands at 15,520–15,850 cm
The electronic spectra of [Fe(L)2(OH2)2]·NO3·2H2O and
2
2
which could be attributed to the A1g → B1g transitions charac-
terized by Cu(II) ion in a square-planar geometry [23–25]. The
square-planar geometry [23–25] of Cu(II) ion in both complexes
Fig. 3) is confirmed by the measured magnetic moments values,
.75 and 1.80 B.M., respectively. The square-planar geometry is
[Fe(L)(8-OHqu)(Cl)(H2O)]·2H2O complexes showed bands
−
1
at 13,230–14,050 and 19,830–20,680 cm
assigned for
6
4
6
4
A1g → T2g(G) and A1(G) → T1(G) transitions. These
(
1
results together with measured magnetic moments for both com-
plexes 5.40 and 5.65 B.M., respectively, are compatible with
those reported for octahedral geometry around Fe(III) ions [29].
On the other hand, the electronic spectrum of
[Fe2(L)4(Cl)2]·3H2O showed broad bands at 14,331 and
achieved by the coordination of two molecules of HL or through
one molecule of HL [Cu(L)2]·H2O and one molecule of 8-OHqu
in the mixed ligand complex [Cu(L)(8-OHqu)]·H2O.
−
1
The electronic spectrum of the [Ni(L)2(OH2)2]·3H2O com-
13,850 cm . The former band may be due to the spin for-
−
1
6
4
plex showed broad absorption band at 16,220 cm which may
bidden transition A1g → T2g(G), which may gain intensity
as a result of the vibronic mechanism in the octahedral field
around ferric ion (Fig. 5). The second band may be attributed to
3
3
be assigned to A1g(F) → T2g(F), while the absorption due
3
3
to A2g(F) → T1g(P) (Table 4) is overlapped with the ligand
absorption bands. This indicates that the Ni(II) ion coordinated
to N2O2 sites in an octahedral geometry (Fig. 4). The Ni(II) ion
completes its six-coordination sphere by two water molecules.
6
4
A1 → T1(G) transitions [29]. In addition, a third absorption
−1
band with a high intensity observed at 25,252 cm is assigned
for charge transfer transition. The magnetic moment of complex
is 7.25 B.M. This value is quite low compared to the calculated
magnetic moment value for binuclear ion complex.
3
3
The third transition due to A2g(F) → T1g(P) would be out of
scale of the used spectrophotometer [26]. The magnetic moment
of the complex is 2.85 B.M. which agrees with the presence of
Ni(II) ion in octahedral geometry [27,28].
Octahedral, tetrahedral and square-planar cobalt(II) com-
plexes show magnetic moment [30] between 4.7 and 5.2, 4.2
and 4.8, and 2.2 and 2.9 B.M., respectively. The μeff value mea-
sured for the present [Co(L)2(OH2)2]·3H2O complex (Table 4)
is 5.08 B.M. which is fairly close to those reported [30] for
the unpaired electrons for Co(II) ion in an octahedral environ-
ment (Fig. 4). The electronic spectrum of the complex showed
On the other hand, the spectrum of [Ni(L)(8-OHqu)]·3H2O
−
1
complex showed absorption bands at 14,599 and 15,058 cm
arising from the 3T1(F) → A2(F) transitions characterized
3
by Ni(II) ion in a tetrahedral environment which agrees
with the electron spectrum of [NiCl4]2 . The tetrahedral
−
−1
geometry is confirmed by the measured magnetic moment
two d–d transitions in the range 15,250–15,390 cm
and

3
4
M. El-Behery, H. El-Twigry / Spectrochimica Acta Part A 66 (2007) 28–36
Fig. 6. Tentative structure of [UO2(L)2(OH2)] complex.
Fig. 5. Proposed structures of bridged octahedral geometry of [Fe2(L)4(Cl)2]
complex.
complexes, except two, are non-conducting and the measured
−
1
2
−1
molar conductance ranged from 2.0 to 3.6 ꢀ cm mol indi-
cating their neutrality and the divalent metal cations replaced the
phenolicproton. Theexceptionsare[Fe(L)2(OH2)2]·NO3·2H2O
and [Fe2(L)4(Cl)2]·3H2O complexes which showed molar
−
1
4
4
1
8,410–18,480 cm due to the transitions T1g(F) → A2g(F)
4 4
and T1g(F) → A2g(P), respectively, indicating an octahedral
4
4
configuration around Co(II). The T2g(F) → T1g(F) transition
−1
(
9510 cm ) would be observed in near IR region [31]. This
−
1
2
−1
conductance of 80.0 and 59.0 ꢀ cm mol , respectively,
indicating their electrolytic nature as 1:1 electrolyte for the
former complex while the electrolytic nature of the second
complex may be due to the replacement of the coordi-
nated chloride ions by solvent molecules, a phenomenon
usually encountered in complexes containing chloride ions
33].
.6. 1H NMR spectrum of the uranyl complex
The uranyl complex was selected as it is diamagnetic. Its H
region is out of scale of our spectrophotometer.
The electronic spectra of the diamagnetic uranyl complex,
[
UO2(L)2(OH2)]·2H2O (Fig. 6), show two bands, in addition
−
1
to the ligand bands. The first band is observed at 22,500 cm
corresponding to charge transfer from equatorial donor atoms
of the ligand to the uranyl ion. The second band is observed at
9,040 cm due to electronic transitions from apical oxygen
atom to the f-orbitals of the uranyl atom characteristic of the
uranyl moiety [32].
[
−1
1
3
1
3
.5. Molar conductance of the metal complexes
The conductance measurements, recorded for 10 3 M solu-
NMR spectra in DMF and after deuteration are discussed. The
spectrum of the complex differs from that of the free ligand in
the following aspects:
−
tions of the metal complexes in DMF, are listed in Table 1. All
Table 5
Thermal analyses data for some metal complexes of HL
Compound, M.F. (M.Wt.)
Dissociation stages
Temperature
range in TG ( C)
Weight loss found
(calculated) (%)
Decomposition assignment
1 mol lattice H2O
◦
[
Cu(L)2]·H2O,
Stage I
41–98
2.46 (2.67)
C32H24N6O3Cl2 Cu
(
674.5)
Stage II
Stage III
Stage IV
233.5–383.9
385.8–645.0
646.0–795.4
41.95 (41.79)
15.35 (15.36)
14.86 (11.7)
C7H5N and C9H7N2Cl
C6H5N and C9H7NCl
Formation of CuO
a
[
Ni(L)2(OH2)2]·3H2O ,
Stage I
37–89
7.51 (7.27)
3 mol lattice H2O
C32H32N6O7Cl2 Ni
(
742)
Stage II
Stage III
Stage IV
Stage V
129.3–243.5
244.6–290.9
292.9–538.9
539.9–796.8
28.70 (28.90)
27.97 (27.77)
23.98 (24.06)
12.98 (10.10)
2 mol coord. H2O, C9H7N2Cl
2 C6H5N
C9H7N2Cl
Formation of NiO
[
Fe(L)2(OH2)2]·NO3·2H2O,
Stage I
34.4–98
4.43 (4.60)
2 mol lattice H2O
C32H30N7O9Cl2 Fe
(
783)
Stage II
Stage III
Stage IV
Stage V
195.4–250.4
251.5–489.9
491.9–643.9
644.9–795.7
25.56 (2.59)
13.13 (13.71)
22.90 (22.76)
23.97 (20.86)
2 mol coord. H2O, C6H5N, NO3
C6H5N
2 mol C9H7N2Cl
Formation of Fe2O3
a
Complex [Co(L)2(OH2)2]·3H2O exhibited the same decomposition pattern.

M. El-Behery, H. El-Twigry / Spectrochimica Acta Part A 66 (2007) 28–36
35
Table 6
Results of antimicrobial activity of some tested complexes
Compound Concentration
Microorganism
(%)
Staphylococcus aureus
Escherichia coli (ATCC
8739, MIC 25%)
Candida albicans (ATCC
10231, MIC 25%)
a
b
(ATCC 6538, MIC 25%)
7
-Chloro-4-(o-
1c
hydroxybenzilidenehydrazo)quinoline,
HL
2
5
00
5
0
Positive
Positive
Negative
Positive
Positive
Positive
Positive
Positive
Positive
1
[
Ni(L)2(OH2)2]·3H2O
1
Positive
Negative
Negative
Negative
Positive
Negative
Negative
Negative
Positive
Negative
Negative
Negative
2
5
5
0
1
1
1
00
[
Fe(L)2(OH2)2]·NO3·2H2O
1
Positive
Negative
Negative
Negative
Positive
Negative
Negative
Negative
Positive
Negative
Negative
Negative
2
5
5
0
00
7
-Chloro-4-hydrazinoquinoline
1c
25
Negative
Negative
Negative
Positive
Negative
Negative
Negative
Negative
Negative
50
00
[
Co(L)2(OH2)2]·3H2O
UO2(L)2(OH2)]·2H2O
1
Positive
Negative
Negative
Negative
Positive
Negative
Negative
Positive
Positive
Negative
Negative
Negative
2
5
5
0
1
00
[
25
Negative
Negative
Negative
Negative
Negative
Positive
Negative
Negative
Negative
50
1
00
Key to symbols—Active and inhibit the growth of the stain: negative; inactive: positive.
a
Number of stain in the American collection.
MIC is the lowest concentration of the product material solution to inhibit the growth of the microorganism.
Not tested in this concentration.
b
c
1
. The disappearance of the signal due to the phenolic OH group
removal of coordinated water in this stage. The third to fifth
stages represented the loss of the rest of the organic moiety and
the formation of metal oxides.
is attributed to its involvement in coordinating the uranyl
cation, while the signal due to the NH group was broad and
appeared at δ = 12.4 ppm compared to that of the ligand which
appeared at δ = 11.7 ppm, i.e. shifted to low-field.
. The signals due to the aramaic ring showed fine structure
and appear as four separate signals at δ = 6.53, 6.67, 7.14,
and 7.6 ppm.
3.8. Antimicrobial activity and minimum inhibitory
2
concentration
The test was performed according to the method reported
previously [34]. 0.02 g of each complex was dissolved in 100 ml
dimethylsulfoxide, DMSO, to produce 0.02% solutions. To a
series of culture tubes, in which each tube contains sterile 5 ml
double strength solution of Soyabean Casein Digest Medium
(Tryptic Soy Broth), 5 ml of the 0.02% DMS solution was added
to each tube and mixed. To determine the bacteriostatic effi-
ciency of the S. aureu and E. coli organisms, 1 ml of a 1:10
diluted solution of Tryptic Soy Broth (TSB) was added to each
culture tube. A 1:10 diluted solution of Tryptic Soy Broth was
prepared by pipetting 1 ml of bacterial cultures incubated at
3
. A new signal for coordinated water appeared at δ = 3.4 ppm.
3
.7. Thermal analyses
The TG–DTA results of the solid complexes, [Cu(L)2]·H2O,
[
Ni(L)2(OH2)2]·3H2O, and [Fe(L)2(OH2)2]·NO3·2H2O, are
listed in Table 5. The results show good agreement with the for-
mulae suggested from the analytical data (Table 1). A general
decomposition pattern was concluded in which the complexes
decomposed in four stages. Besides the four stages, complexes,
which have coordinated water, exhibited additional stage to be
decomposed in five stages (Table 5). Complexes with lattice
◦
37 C for 24 h into 9 ml of sterile Tryptic Soy Broth. For the
test of the fungistatical efficiency, 0.1 ml of undiluted sample
◦
◦
water become anhydrous at 41–98 C. The second stage is the
loss of the coordinated water molecules at 130–250 C and in
incubated for 72 h at 37 C TSB cultivation of C. albicans was
◦
◦
used. All inoculated culture tubes were incubated at 30–35 C
some cases loss of part of the organic ligand accompanying the
for 18–24 h. After that, the “MIC” level was assessed visually.

3
6
M. El-Behery, H. El-Twigry / Spectrochimica Acta Part A 66 (2007) 28–36
MIC was recorded as the first clear tubes after turbidity, starting
with the blank broth. In other words, the highest dilution of the
antiseptic/disinfectant preventing growth is taken as the “MIC”
of the test organism [34].
[2] C. Jayabalakrishnan, K. Natarajan, Synth. React. Inorg. Met. Org. Chem.
1 (2001) 983.
3
[
3] T. Jeeworth, H.L.K. Wah, M.G. Bhowon, D. Ghoorhoo, K. Babooram,
Synth. React. Inorg. Met. Org. Chem. 30 (2000) 1023.
[
4] N. Dharmaraj, P. Viswanalhamurthi, K. Natarajan, Transition Met. Chem.
The tests were carried out for concentrations of 1, 25, 50, and
26 (2001) 105.
1
00% DMSO solutions of the compounds. The inhibition zones
[5] C.H. Colins, P.M. Lyne, Microhiul Methods, University Park Press, Balti-
more, 1970, p. 422.
caused by the various compounds on the microorganisms were
examined. The results of the preliminary screening test are listed
in Table 6. From the data obtained in Table 4, it is clear that
[6] L. Savanini, L. Chiasserini, A. Gaeta, C. Pellerano, Biorganic and Medical
Chemistry 10 (2002) 2193.
[7] E. Ochiai, Bioinorganic Chemistry, Allyn and Bacon, Boston,
7
-chloro-4-hydrazinoquinoline was found to be highly active
against all organisms and in all concentrations while 7-chloro-4-
o-hydroxybenzilidenehydrazo)quinolene exhibited its activity
1
977.
[8] J.A. Anten, D. Nicholis, J.M. Markpoulos, O. Markopoulou, Polyhedron 6
1987) 1074.
(
(
[
9] I.A. Tossadis, C.A. Bolos, P.N. Aslanidis, G.A. Katsoulos, Inorg. Chim.
Acta 133 (1987) 275.
at its 100% concentration for only S. aureu and does not affect
the other tested stained organisms in all of its concentration.
Remarkable result is that the complexes, [Ni(L)2(OH2)2]·3H2O,
[
[
10] A. Maiti, S. Ghosh, Indian J. Chem. 28A (1989) 980.
11] R.C. Aggarwal, N.K. Singh, R.P. Singh, Inorg. Chim. Acta 29 (1981) 2794.
[12] J.C. Craliz, J.C. Rub, D. Willis, J. Edger, Nature 34 (1955) 176.
13] J.R. Dilworth, Coord. Chem. Rev. 21 (1976) 29.
14] J.R. Merchant, D.S. Clothia, J. Med. Chem. 13 (1970) 335.
15] N.S. Biradar, B.R. Havinale, Inorg. Chim. Acta 17 (1976) 157.
16] H.N. Fox, Science 116 (1952) 129.
[
Co(L)2(OH2)2]·3H2O, and [Fe(L)2(OH2)2]·NO3·2H2O, were
[
[
[
[
[
found to have high activity against all stains in all of their
concentrations except their 1% concentration. On the other
hand, [UO2(L)2(OH2)]·2H2O was found to have higher activity
against stains Staphylococcus aureus and C. albicans in its 25,
17] S. Kakimoto, K. Yashamoto, Pharm. Bull. 4 (1956) 4.
5
0, and 100% concentrations, while for E. coli, its activity was
[18] R.K. Agarwal, R.K. Sarin, Polyhedron 12 (1993) 241.
[
[
19] G. Durgaprasad, C.C. Patel, Indian J. Chem. 11A (1973) 1300.
20] R.M. Silverstein, G.C. Bassler, C. Morill, Spectrometric Identification of
Organic Compound, fourth ed., John Wiley, New York, 1981.
21] K. Ueno, A.E. Martell, J. Chem. Phys. 61 (1957) 257.
22] C. Dreti, G. Tosi, Aust. J. Chem. 29 (1996) 543.
exhibited for 25 and 50% concentrations. The tested compounds
showed an inhibitory activity of 25%.
[
[
[
4
. Conclusion
23] B.N. Figgs, J. Lewis, Prog. Inorg. Chem. 37 (1964) 67.
The results of this investigation support the suggested struc-
[24] B.N. Figgs, Introduction to Ligand Field, Wiley, New York, 1966, pp. 203;
A.B.P. Lever, Inorganic Electronic Spectroscopy, second ed., Elsevier,
Amsterdam, 1984.
turesofthemetalcomplexes. IncaseofCu(II), Ni(II), Co(II), and
UO2(II) cations, only mononuclear complexes were obtained
in presence and absence of LiOH indicating that the presence
of LiOH does not affect the formation of such complexes.
On the other hand, two Fe(III) complexes, mono- and binu-
clear, were obtained in the absence and presence of LiOH,
respectively, during their preparation as mentioned in Section
[
[
25] A. Symal, K.S. Kale, Indian J. Chem., Sect. A 16 (1978) 46.
26] J.C. Bailar, H.H. Emeleus, R. Nyholm, A.F. Trotman-Dickenson (Eds.),
Comprehensive Inorganic Chemistry, vol. 3, Pergamon Press, Oxford,
1975, pp. 1088.
[
[
[
27] M.M. Patel, R. Manvalan, J. Macromol. Sci. Chem. 19 (1973)
951.
28] A.S. Aswar, R.G. Mahale, P.R. Kakde, S.Q. Bhadange, J. Indian Chem.
Soc. 75 (1998) 395.
29] K. Dey, J. Indian Chem. Soc. 48 (1971) 641.
2
. All metal cations, Cu(II), Ni(II), Co(II), and Fe(III), were
octahedral, while Cu(II) and Ni(II) cations in mixed ligand com-
plexes proved an extra square-planar and tetrahedral geometries,
respectively. Binuclear complexes of Fe(III) have octahedral
structure in which the two Fe(III) cations are bridged by two
chlorine atoms.
[30] G. Dyer, D.W. Meek, J. Am. Chem. Soc. 81 (1967) 3983.
[
[
[
31] F.A. Cotton, G. Wilkinson, Advanced Inorganic Chemistry, third ed., Inter
Science Publishers, New York, 1972, pp. 538.
32] A. Lal, K. Sigh, N. Siva, S. Adhikari, S. Yadav, Synth. React. Inorg. Met.
Org. Chem. 26 (1996) 321.
33] M.E. Balewin, J. Chem. Soc. 3123 (1961);
References
S.J. Gruber, C.M. Harris, E. Sinn, J. Inorg. Nucl. Chem. 30 (1968)
1805.
[
1] Z.H. Chohan, S.K.A. Sheazi, Synth. React. Inorg. Met. Org. Chem. 29
1999) 105.
[34] H. William, V. Stephen, Theory and Application of Microbiological Assay,
Academic Press, San Diego, 1989, p. 320.
(