Synthesis, characteristics, and antimicrobial activity of some complexes of Mn(II), Fe(III) Co(II), Ni(II), Cu(II), and Sb(III) containing bidentate Schiff base of SMDTC

Article abstract of DOI:10.1134/S1070363215030238

Abstract A novel series of transition metal complexes of Mn(II), Fe(III) Co(II), Ni(II), Cu(II), and Sb(III) containing the bidentate Schiff base derived from condensation of S-methyldithiocarbazate and cinnamaldehyde were synthesized and characterized by

Full text of DOI:10.1134/S1070363215030238

ISSN 1070-3632, Russian Journal of General Chemistry, 2015, Vol. 85, No. 3, pp. 667–672. © Pleiades Publishing, Ltd., 2015.
Synthesis, Characteristics, and Antimicrobial Activity
of Some Complexes of Mn(II), Fe(III) Co(II), Ni(II), Cu(II),
and Sb(III) Containing Bidentate Schiff Base of SMDTC1
Md. Kudrat-E-Zahan, M. S. Islam, and Md. Abul Bashar
Inorganic Research Laboratory, Department of Chemistry, University of Rajshahi,
Rajshahi-6205, Bangladesh
e-mail: kudrat.chem@ru.ac.bd
Received November 6, 2014
Abstract—A novel series of transition metal complexes of Mn(II), Fe(III) Co(II), Ni(II), Cu(II), and Sb(III)
containing the bidentate Schiff base derived from condensation of S-methyldithiocarbazate and
cinnamaldehyde were synthesized and characterized by IR, 1H NMR, UV-Vis, and some physical
measurements. IR spectral studies indicated the binding sites of the Schiff base ligand with the metal ions.
Molar conductance data and magnetic susceptibility measurements indicated monomeric and neutral nature of
the complexes. The complexes demonstrated moderate to strong antimicrobial activity.
Keywords: transition metal complex, SMDTC, antimicrobial activity, Schiff base
DOI: 10.1134/S1070363215030238
INTRODUCTION
complexes of different structures and properties, and
(3) the complexes are potentially biologically active.
The classical synthesis of Schiff bases [1] is a
primary amine condensation with a carbonyl compound
[2] under specific conditions. Cinnamaldehyde is the
main component of bark extract of cinnamon [3]. It is
active against a range of forborne pathogens bacteria
[4]. Nontoxic doses of cinnamaldehyde and its
derivatives have been reported to potentiate the cell-
inactivating effect of cis- diaminodichloroplatinum(II)
in human NHIK 3025 cells culture [5]. Nowadays, the
increasing microbial resistance to antibiotics in use
necessitates the search for new compounds with
potential effects against pathogenic bacteria. The nitro
group and halogen containing Schiff bases de-
monstrated such activities as antimicrobial, antitumor
[6] and antifungal [7].
Previously, we had synthesized few complexes of
such type and studied their antimicrobial activity
[19–22]. In this paper we present synthesis of a Schiff
base formed by condensation of cinnamaldehyde with
S-methyldithiocarbazate, its complexation with Mn(II),
Fe(III), Co(II), Ni(II), Cu(II), and Sb(III) and anti-
microbial activity of the complexes.
EXPERIMENTAL
Reagents and chemicals. All the reagents used
were of analytical or chemical grade purity. Solvents
were purified and dried according to the standard
procedures.
Physical measurements. Melting points of all
metal complexes were measured by an electro thermal
melting point apparatus model no. AZ6512. The
SHERWOOD SCIENTIFIC Magnetic Susceptibility
Balance was used for the present study. Infrared
spectra (KBr) were recorded in a SIMADZU FTIR-
8400 (Japan) spectrophotometer in the range 4000–
400 cm–1.
The Schiff bases, namely dithiocarbazate
NH2NHCS2 (DTC) substituted derivatives, have been
synthesized and studied over recent decades [8–18] for
the following major reasons: (1) they provide
interesting series of ligands whose properties can be
modified by introducing organic substituents, thereby
causing a variation in the ultimate donor properties,
(2) the interaction of such donors with metal ions give
Procedure. SMDTC was prepared in accordance
1 The text was submitted by the authors in English.
with the method of Akbar Ali [23].
667

668
MD. KUDRAT-E-ZAHAN et al.
Scheme 1.
S
HC=CH−CHO
HC=CH−CH=N−NH−C
SCH3
S
+
H2N−NH−C
SCH3
Schiff base (NS)
Preparation of the cinnamaldehyde Schiff base of
SMDTC. To the solution of SMDTC (0.122 mol) in
hot absolute ethanol (35 mL) a solution of the
equimolar amount of cinnamaldehyde in hot absolute
ethanol (20 mL) was added and the mixture was heated
for 20 min. Upon cooling down the orange precipitate
was formed. It was separated and dried in vacuo over
anhydrous CaCl2 (Scheme 1).
where M = Mn(II), Ni(II), Cu(II); M' = Sb(III), Fe(III);
M" = Co(II), NS = Cinnamaldehyde Schiff base of
SMDTC.
RESULTS AND DISCUSSION
Physical properties and molar conductance.
Physical properties of the complexes are listed in
Table 1. The analytical data were in good agreement
with the proposed empirical formula of the complexes.
The conductance values of the complexes revealed that
those were non electrolytes [24].
General method for preparation of the
complexes of cinnamaldehyde Schiff base of
SMDTC. 1 mmol of either hydrated salt [Mn(NO3)2·
6H2O], [Cucl2·6H2O], [Ni(NO3)2·6H2O], [CoCl2·
6H2O], [Sb(NO3)3·3H2O], or [Fe(NO3)3·9H2O] was
dissolved in absolute ethanol (15 mL). The Schiff base
(NS) (2 mmol) solution in hot absolute ethanol
(50 mL) was added to a salt solution. The mixture was
refluxed for 30 min and then cooled down. The
precipitate was filtered off, washed with hot ethanol
and dried in vacuo over anhydrous CaCl2.
IR spectra. IR spectra of SMDTC contained all
characteristic bands that had been reported earlier [25].
IR spectra of Schiff base did not contain ν(S–H) bands
(ca 2570 cm–1) indicating that in the solid state it
existed in the thioketo form. However, in solutions
both thione and thiol tautomeric forms were possible.
According to IR spectra in alkaline media the
ligand was deprotonated (loss of the proton =NH) in
favor of formation of the C=N bond (Fig. 1).
M(NO3)2·nH2O + NS → [M(II)(NS)2],
M'(NO3)3·nH2O + NS → [M'(II)(NS) 2(NO3)(H2O)],
M"Cl2·nH2O + NS → [M"(II)(NS) 2(H2O)2],
Based on comparison of IR spectra of free SMDTC
and the corresponding complexes the former can have
three modes of coordination.
Table 1. Analytical data and physical properties of the complexes
Melting point or
Molar
Complexes
Color
decomposition
temperature(± 5°C)
Yield, %
conductance,
μ
eff , B.M.
Ω–1 cm2 mol–1
SMDTC
[NS]
White
81
171
210
196
223
261
190
191
75
70
65
68
70
68
58
60
9.90
8.39
5.96
10.15
3.50
6.56
7.83
2.42
–
Orange
–
[Mn(II)(NS)2]
Greenish
Black
Dia
5.94
3.94
Dia
1.86
Dia
[Fe(III)(NS)2(NO3)(H2O)]
[Co(II)(NS)2(H2O)2]
[Ni(II)(NS)2]
Reddish
Greenish brown
Reddish
Cream
[Cu(II)(NS)2]
[Sb(III)(NS)2(NO3)(H2O)]
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 3 2015

SYNTHESIS, CHARACTERISTICS, AND ANTIMICROBIAL ACTIVITY
SCH3
669
H2N−NH−C
KOH
or metal ion
S
S−K+
SCH3
S
H2N−NH−C
H2N−N=C
I
SCH3
SCH3
S−
SCH3
H2N−N=C
M
H2N−NH−C
M
S
II
III
Fig. 1. Reaction of SMDTC with KOH/metal ion.
Fig. 2. Modes of coordination of SMDTC.
In neutral media condensation of SMDTC with
cinnamaldehyde gave the isomeric Schiff base (NS) in
high yield. The Schiff base existed in tautomeric forms
through the loss of thiol protons (Fig. 3). IR spectrum
of the Schiff base contained the strong band at
3113 cm–1 which was attributed to the secondary
amine of free ligands. The thione group is relatively
unstable in the monomeric form and tends to turn to
the more stable thiol form by enethiolization in a
solution. The absence of S–H bands at ca 2570 cm–1
indicated that in the solid state the base existed
primarily in the thione form. Disappearance of N–H
bands in the spectra of metal complexes indicated
deprotonation and consequent coordination with the
thiolate anions. The Schiff base spectra contained
strong bands at ca 1579 cm–1 assigned to the C=N
bond of the free ligand. In the metal complexes the
band was shifted towards lower frequencies due to the
lower C=N bond order and formation of the metal–
nitrogen bond. The C=S band (1037 cm–1) observed in
spectra of the free ligand was not registered in the
spectra of complexes, thus supporting the thiolate
bonding with metal ions.
In neutral media condensation of SMDTC with
cinnamaldehyde gave the isomeric Schiff base (NS) in
high yield. The Schiff base existst in tautomeric forms
(Fig. 3) and acted as anionic bidentate ligand that
coordinated by the thiol sulfur and the azomethine
nitrogen.
The C=N bond stretching vibration in the free NS
Schiff base was registered at 1579 cm–1, which upon
complexation, shifted towards lower frequency region
(ca 1478 cm–1) supporting coordination with the
nitrogen atom. The free Schiff base band (1037 cm–1)
was not registered in the spectra of metal complexes
indicating coordination with the thiolate anion.
In IR spectra of the complex [Co(NS)2(H2O)2] the
band at 3250–3300 cm–1 indicated the presence of the
coordinated water. The ionized NO3 group of complexes
[Sb(NS)2(NO3)(H2O)] and [Fe(III)(NS)2(NO3)(H2O)] was
registered at 1458 and 1296 cm–1.
Magnetic moment and electronic spectra. The
magnetic susceptibility measurements (Table 1) the
paramagnetic character of the complex [Cu(II)(NS)2].
The greenish brown paramagnetic copper complex had
the magnetic moment 1.86 B.M. (one unpaired
electron). UV-Vis spectrum of the complex contained
(a)
S
CH=CH−CH=N−NH−C
SCH3
2
2
d-d bands at 640 and 420 nm (2B1g → A1g and B1g →
2E1g transitions respectively), characteristic for a
square planar stereostructure. The intensive band at
310 nm was attributed to the charge transfer.
(b)
SH
CH=CH−CH=N−N−C
SCH3
The magnetic susceptibility measurements (Table 1)
indicated that the complexes [Ni(II)(NS)2] and
[Mn(II)(NS)2] were diamagnetic. The diamagnetic
nature of complex indicated a singlet ground state
characteristic for square planar Ni(II) and Mn(II).
Fig. 3. Tautomeric forms of Schiff base (a) thione form and
(b) thiol form.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 3 2015

670
MD. KUDRAT-E-ZAHAN et al.
H2
O
H5C6−HC=CH−CH
SCH3
C
SCH2C6H5
C6H5−HC=HC−HC
N
C
N
S
S
N
N
S
S
C
N
M2+
M2+
N
N
C
N
CH−CH=CH−C6H5
CH−CH=CH−C6H5
SCH3
C6H5H2CS
O
H2
Fig. 4. Square planar structure of the complex. M2+
=
Fig. 5. Octahedral structure of M(II) complex. M2+ = Co(II).
Mn(II), Ni(II), and Cu(II)
1
1
Three bands of the transitions A1g → A2g (314 and
340 nm), 1A1g → 1B1g (358 and 420 nm) and 1A1g → 1Eg
(416 and 530 nm) were observed in the spectra of a
square-planar Ni(II) complex.
(4H, H2O), 5.15 d (J = 12 Hz, 2H, –CH), 5.05 d (J =
8 Hz, 2H, –CH), 4.10 d.d (J = 12 Hz, 8 Hz, 2H, –CH),
2.76 s (6H, SCH3).
The –OH signals were registered at low field
probably due to formation of the intramolecular
hydrogen bond.
The complex [Co(II)(NS)2(H2O)2] had magnetic
moment about 3.94 B.M. (Table 1) that indicated its
octahedral structure. The electronic spectra of the
complex contained three bands at 380, 420 and 550 nm
assigned to the transitions 4T1g → 4T2g(ν1), 4T1g → 4A2g(ν2),
Structure of the complexes. On the basis of ex-
perimental and literature data the following structures
of the complexes are considered (Figs. 4–6).
4T1g → T2g(F)(ν3). UV-Vis spectrum of the complex
4
[Sb(III)(NS)2(NO3)(H2O)] exhibited the band at 320 nm
assigned to the charge transfer transition. The complex
was diamagnetic and had octahedral structure.
Antibacterial activity of the metal complexes.
Complexes of Zn(II) and Cd(II) with tridentate ONS
donor Schiff base ligands were synthesized and
biological activity was studied by Gunthkal et al. [26].
Wang et al. [27] have synthesized and studied the
biological activity of Cu(II), Co(II), and Ni(II)
complexes with thiosemicarbazones. Complexes of
Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) with 3-amino-
phenol-N-benzylidine Schiff base ligand were
synthesized and their antibacterial activity was studied
The magnetic moment of Fe(III) (5.96 B.M.)
indicated that the complex [Fe(III)(NS)2(NO3)(H2O)]
was paramagnetic with five unpaired electrons and
hence, had octahedral structure with sp3d2
hybridization. The electronic spectra of the complex
contained four bands at 536, 480, 410, and 390 nm
assigned to the transitions [6A1g → 4T1g(G); 6A1g → 4T2g(G);
6A1g → 4Eg(G);6A1g → 4A1g(G)], respectively.
H2
O
The above observations indicated that the com-
plexes [Cu(II)(NS)2], [Ni(II)(NS)2], and [Mn(II)(NS)2]
had square planar structure with two ligands. The
complexes [Co(II)(NS)2(H2O)2], Sb(II)(NS)2(NO3)(H2O)],
and [Fe(III)(NS)2(NO3)(H2O)] had octahedral structure.
SCH3
C6H5−HC=HC−HC
N
N
S
S
C
M3+
1H NMR spectra. Complex [Cu(II)(NS)2]. 7.67–
7.64 d.d (J = 8.2 Hz, 4H, Ar-H), 7.20–7.06 m (6H,
Ar-H), 5.13 d (J = 12 Hz, 2H, –CH), 4.93 d (J = 8 Hz,
2H, –CH), 4.48 d.d (J = 12, 8 Hz, 2H, –CH), 2.65 s
(6H, SCH3).
C
N
N
CH−CH=CH−C6H5
H3CS
N
O3
Fig. 6. Octahedral structure of the complex. M3+ = Fe(III)
Complex [Co(II)(NS)2(H2O)2]. 7.99–7.61 d.d (J =
8.2 Hz, 4H, Ar-H), 7.59–7.43 m (6H, Ar-H), 7.27 s
and Sb(III).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 3 2015

SYNTHESIS, CHARACTERISTICS, AND ANTIMICROBIAL ACTIVITY
671
Table 2. In vitro antibacterial activities of the complexes and Kanamycine (K-30)
Diameter of zone inhibition, mma
Gram
staining
Bacteria
Bacillus subtilis
Positive
Positive
Positive
4
7
7
8
12
6
4
12
9
25
24
26
25
20
21
22
24
Staphlococcus aureus
Bacillus megatherium
6
9
5
Streptococcus-β-haemolyticus Positive
19
15
15
4
10
2
11
12
15
16
17
9
Escherichia coli
Shigella dysenteriae
Shigella sonnei
Shigella shiga
Negative
Negative
Negative
Negative
7
14
3
14
17
13
5
16
a (SMDTC) = S-methyldithiocarbazate, (NS) = Cinnamaldehyde Schiff base of SMDTC.
Table 3. Antifungal activities of the complexes and standard Fluconazole
Diameter of zone of inhibition, mma
Fungal Status
Aspergillus Candidus
Penicillium Marneffei
Candida Albicans
Aspergilius niger
17
11
14
14
7
15
16
4
17
9
10
13
11
6
20
18
17
17
9
11
a (SMDTC) = S-methyldithiocarbazate, (NS) = Cinnamaldehyde Schiff base of SMDTC.
by Patil and co-workers [28]. The susceptibility of
microorganism to antimicrobial agents can be deter-
mined in vitro by a number of methods. The disc
diffusion technique is widely acceptable for pre-
liminary investigations of compounds.
The accumulated data revealed that the complexes
were of higher microbial toxicity than free metal ions
or ligands. The Co(II), Ni(II), Mn(II), and Fe(III) metal
Schiff bases complexes (Table 2) demonstrated
moderate to strong activity against both Gram positive
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 3 2015

672
MD. KUDRAT-E-ZAHAN et al.
Jasinski, J.P., and Jasinski, J.M., Polyhedron, 1997,
vol. 16, pp. 2749–2754.
and Gram negative bacteria compared to standard
Kanamycine.
14. Ali, M.A., Dey, K.K., Uddin, M.N., Smith, F.E.,
Butcher, R.J., Jasinski, J.P., and Jasinski, J.M.,
Polyhedron, 1996, vol. 15, no. 19, pp. 3331–3339.
Antifungal activity of the metal complexes. The
zone of inhibition indicated that all complexes of
Co(II), Ni(II), Mn(II), and Fe(III) (Table 3) demonstrated
significant activity towards all the fungi tested.
15. Ali, M.A. and Tarafder, M.T.H., J. Inorg. Nucl. Chem.,
1977, 39(10), pp. 1785–1791.
16. Hossain, M.E., Alam, M.N., Begum, J., Ali, M.A.,
Uddin, M.N., Smith, F.E., and Hynes, R.C., Inorg.
Chim. Acta, 1996, vol. 249(2), pp. 207–213.
REFERENCES
1. Schiff H., Justus Liebigs Ann Chem, 1864, vol. 131(1),
17. Tarafder, M.T.H. and Ali, M.A., Can. J. Chem., 1978,
pp. 118–119.
vol. 56, pp. 2000–2002.
2. Bell, S.S.C, Conklin, G.L., and Childress, S.J, J. Am.
Chem. Soc., 1963, vol. 85, pp. 2868–2869.
3. Holley, R.A. and Patel D., Food Microbiology, 2005,
vol. 22, pp. 273–292.
4. Amalaradjou, M.A.R. et al., Food Microbiology, 2010,
vol. 27, pp. 841–844.
5. Dornish, J.M., Pettersen, E.O., and Oftebro, R., Cancer
Res., 1989, vol. 49, pp. 3917–3921.
18. Tarafder, M.T.H., Miah, M.A.J., Bose, R.N., and
Ali, M.A., J. Inorg. Nucl. Chem., 1981, vol. 43,
pp. 3151–3157.
19. Kudrat-E-Zahan, Md., Yuzo Nishida, and Hiroshi
Sakiyama., Inorg. Chim. Acta, 2010, vol. 363(1),
pp. 168–172.
20. Abdul Alim Al-Bari, M., Faruk Hossen, M., Alam
Khan, Kudrat-E-Zahan, M., Ashik Mossadik, M.,
Choudhury M Zakaria, and Anwar Ul Islam, M., J. Appl.
Sci. Res., 2007, vol. 3(11), pp. 1279–1287.
6. Chaudhari, T.D. and Subnis, S.S., Bull. Haskine Inst.,
1986, vol. 4, pp. 85–88.
7. Raman, N., Kulandaisamy, A., Shunmugasundaram, A.,
and Jeyasubramaniam, K., Transition Met. Chem., 2001,
vol. 26, pp. 131–135.
8. Ali, M.A., Ibrahim, N.E., Butcher, R.J., Jasinski, J.P.,
Jasinski, J.M., and Bryan, J.C., Polyhedron, 1998,
vol. 17, pp. 1803–1809.
21. Saidul Islam, M., Farhana Aktar, Roushown Ali, Abdul
Kader, Kudrat-E-zahan, Md., and Abdur Rahim Khan, M.,
Oriental J. Chem., 2003, vol. 19(2), pp. 343–350.
22. Kudrat-E-Zahan, Md. and Hiroshi Sakiyama, Asian J.
Res. Chem., 2013, vol. 6(11), pp. 1072–1074
23. Akbar Ali, M., Livingstone, S.E., and Philips, D.J.,
Inorg. Chim. Acta., 1973, vol. 7, pp. 179–186.
24. Geary, W.J., Coord. Chem. Rev., 1971, vol. 7, pp. 81–
9. Ali, M.A., Haroon, C.M., Uddin, M.N., Majumder, S.M.,
Tarafder, M.T.H., and Khair, M.A., Transition Met.
Chem., 1992, vol. 17(2), pp. 133–136.
122.
10. Ali, M.A., Hossain, S.M.G., Majumder, S.M.M.H.,
Uddin, M.N., and Tarafder, M.T.H., Polyhedron, 1987,
vol. 6, pp. 1653–1656.
25. Das, M. and Livingstone, S.E., Inorg. Chim. Acta.,
1976, vol. 19, pp. 5–10
11. Ali, M.A., Intan-Safinar, I., Mackeen, M.M., El-
Sharkawy, S.H., Takahata, K., Kanzaki, H., and
Kawazu, K., Nat. Prod. Sci., 1998, vol. 4, pp. 180–184.
26. Gunthkal, M.S., Timmanagoud, R.G., and Sangamesh, A.P.,
Oriental J. Chem., 2000, vol. 16(1), pp. 151–155.
27. Wang, X., Zhaq, Q., Wang, D., and Xi, Y., Zhongguo
Yaoke Daxue Xuebao., 1997, vol. 28(3), pp. 180–182.
12. Ali, M.A. and Livingstone, S.E., Coord. Chem. Rev.,
1974, vol. 13, nos. 1–2, pp. 101–132
13. Ali, M.A., Majumder, S.M.M.H., Butcher, R.J.,
28. Dharmaraj, N. and Viswanathamurthi, P., Transition
Met. Chem., 2001, vol. 26, nos. 1–2, pp. 105–109.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 3 2015