Synthesis, characterization, and antimicrobial activity of complexes of Cu(II), Ni(II), Zn(II), Pb(II), Co(II), Mn(II), and U(VI) containing bidentate Schiff base of [S-methyl-3-(4-methoxybenzylidine)dithiocarbazate]

Article abstract of DOI:10.1134/S1070363215040350

Abstract A novel bidentate Schiff base containing NS donor sequences was synthesized by condensing S-methyldithiocarbazate (SMDTC) with p-anisaldehyde. A series of complexes of the ligand with Cu(II), Ni(II), Zn(II), Pb(II), Co(II), Mn(II) and U(VI) were

Full text of DOI:10.1134/S1070363215040350

ISSN 1070-3632, Russian Journal of General Chemistry, 2015, Vol. 85, No. 4, pp. 979–983. © Pleiades Publishing, Ltd., 2015.
Synthesis, Characterization, and Antimicrobial Activity
of Complexes of Cu(II), Ni(II), Zn(II), Pb(II), Co(II), Mn(II),
and U(VI) Containing Bidentate Schiff Base
of [S-Methyl-3-(4-methoxybenzylidine)dithiocarbazate]1
Md. Kudrat-E-Zahan and M. S. Islam
Inorganic Research Laboratory, Department of Chemistry, University of Rajshahi, Rajshahi-6205, Bangladesh
e-mail: kudrat.chem@ru.ac.bd
Received October 16, 2014
Abstract—A novel bidentate Schiff base containing NS donor sequences was synthesized by condensing S-
methyldithiocarbazate (SMDTC) with p-anisaldehyde. A series of complexes of the ligand with Cu(II), Ni(II),
Zn(II), Pb(II), Co(II), Mn(II) and U(VI) were studied and characterized by various physico-chemical methods.
Cu(II), Ni(II) and Zn(II), Pb(II) complexes were four-coordinate with square plannar and tetrahedral geometry
respectively. Co(II), Mn(II), and U(VI) complexes were six-coordinate with octahedral geometry. Antimicrobial
activity of the prepared complexes was tested as resistance to antimicrobial agents in a wide variety of
nosocomial and community-acquired pathogens. The highest antimicrobial activity was detected for the
complex Co(II) against candida species.
Keywords: transition metal complex, SMDTC, antimicrobial activity, Schiff base
DOI: 10.1134/S1070363215040350
INTRODUCTION
tive of the current study was synthesis of the new
Schiff base ligand [S-methyl-3-(4-methoxybenzyl-
idine)dithiocarbazate] by condensation of p-anisal-
dehyde with S-methyldithiocarbazate followed by testing
antimicrobial activity of its metal complexes with
Cu(II), Ni(II), Zn(II), Pb(II), Co(II), Mn(II), and U(VI).
The Schiff base ligands are produced by the
condensation of a primary amine and an active
carbonyl group and contain the azomethine group
(−CH=N− or >C=N−:). Schiff bases can act as mono-,
di-, tri-, or tetradentate ligands depending on the
number of coordinating atoms present in the molecule
and form generally five or six membered chelate rings
with a metal ion. Among many Schiff bases
dithiocarbazate (NH2NHCS2) and its substituted
derivatives have been studied as ligands for long time
[1–5]. The compounds have received considerable
attention due to the following reasons: (1) They
provide an interesting series of ligands whose
properties can be significantly modified by introducing
different organic substituents that impart a variety of
donor properties. (2) Interaction of such donors with
metal ions gives complexes of different geometries and
features. (3) The complexes are potentially biolo-
gically active [6–9].
EXPERIMENTAL
All reagents and chemicals were reagent grade and
used as supplied.
Physical measurements. Melting points or decom-
position temperature of all synthesized metal com-
plexes were measured by an electro thermal melting
Scheme 1.
S
.
NH2−NH−C
H2N−NH−C
NH2NH2 H2O + KOH
S−K+
S
S
Previously, we have reported few complexes and
their antimicrobial activity [10–14]. The major object-
H2N−NH−C
+ CH3I
S−K+
SCH3
1 The text was submitted by the authors in English.
SMDTC
979

980
KUDRAT-E-ZAHAN, ISLAM
SH
Scheme 2.
S
HC N N
C
CH=N−NH−C
S
SCH3
SCH3
CHO
CH=N−NH−C
SCH3
S
H2N−NH−C
+
SCH3
OCH3
OCH3
Fig. 1. Tautomeric forms of the Schiff base.
OCH3
OCH3
point apparatus model no. AZ6512. The SHERWOOD
SCIENTIFIC Magnetic Susceptibility Balance was
used for the present investigation. Infrared spectra as
KBr disc were recorded by a SIMADZU FTIR-8400
(Japan) spectrophotometer in the range 4000–400 cm–1.
UV-Vis spectra were recorded on SHIMUDZU
Spectrophotometer.
6H2O], [CoCl2·6H2O], [MnSO4·7H2O], or [Pb(NO3)2·
6H2O], was dissolved in absolute ethanol (15 mL) and
added to the above synthesized Schiff base (2 mmol)
solution in hot absolute ethanol (50 mL). The mixture
was refluxed for 30 min and then cooled down. The
precipitate was filtered off and washed with hot
ethanol and dried in vacuo over anhydrous CaCl2.
Metal salt of UO2(NO3)2·7H2O (1 mmol) was dis-
solved in ethanol (20 mL). The synthesized Schiff base
(2 mmol) in hot absolute ethanol (40 mL) was added to
the salt solution. The mixture was refluxed for 30 min
and then cooled down. The corresponding product
crystallized upon 30 days of storage at room tem-
perature. The crystalline product was separated,
washed with ethanol and dried in vacuo over an-
hydrous CaCl2.
Synthesis. The ligand S-methyldithiocarbazate
(SMDTC) was synthesized according to the previously
reported method [2] (Scheme 1).
Synthesis of p-anisaldehyde Schiff base of
SMDTC: [S-methyl-3-(4-methoxybenzylidine)dithio-
carbazate] (NS). To a solution of SMDTC (0.2 mol) in
hot absolute ethanol (35 mL) was added the equimolar
amount of p-anisaldehyde in hot absolute ethanol
(20 mL). The mixture was heated for 20 min and then
cooled down to give white precipitate. It was separated
and dried in vacuo over anhydrous CaCl2. mp 165°C
(Scheme 2).
M(NO3)2·nH2O + NS → [M(II)(NS)2]; M"Cl2·nH2O + NS
→ [M"(II)(NS)2(H2O)2],
UO2(NO3)2·nH2O + NS → [U(VI)(NS)3],
General method for synthesis of metal
complexes of the Schiff base. 1 mmol of one of metal
salts, [Cu(NO3)2·3H2O], [Ni(NO3)2·6H2O], [Zn(NO3)2·
where M = Cu(II), Ni(II), Zn(II), Pb(II); M" = Co(II),
Mn(II); NS = [S-methyl-3-(4-ethoxybenzylidine)di-
thiocarbazate].
Table 1. Analytical and physical data of the complexes
mp/decomp. temperature
Molar conductance,
Compounds
SMDTC
Color
White
μeff, B.M.
(± 5°C)
Ω–1 cm2 mol–1
81
10.80
4.50
3.25
2.30
5.72
–
[NS]
White
165
–
[Cu(II)(NS)2]
[Ni(II)(NS)2]
[Zn(II)(NS)2]
Brown
265
1.94
2.97
Dia
Golden brown
Light yellow
188
205
[Co(II)(NS)2(H2O) 2]
[Mn(II)(NS)2(H2O)2]
[Pb(II))(NS)2]
Reddish black
Chocolate
220
276
223
95
3.54
8.25
5.05
3.45
3.94
3.94
2.79
Dia
Off white
U(VI)(NS)3]
Golden brown
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 4 2015

SYNTHESIS, CHARACTERIZATION, AND ANTIMICROBIAL ACTIVITY
H2O
981
H3CO
CH
SCH3
C
H3CO
HC
N
SCH3
S
S
C
N
N
C
N
N
S
M2+
M2+
C
N
N
N
S
H3CS
CH
OCH3
CH
OCH3
SCH3
H2O
Fig. 3. Octahedral geometry of M2+(II) complex, M2+
Co(II), Mn(II).
=
Fig. 2. Square planar geometry of the M2+(II) complex,
M2+ = Cu(II), Ni(II).
RESULTS AND DISCUSSION
upon complexation (Table 2). The Schiff base coor-
dinated to the metal via the thiolate sulfur (Fig. 1) and
β-nitrogen atoms which was evident from the IR
spectrum demonstrating bands at ca 480 cm–1 and ca
531 cm–1 attributed to ν(M–S) and ν(M–N) stretching
vibrations respectively. In case of complexes [Co(NS)2·
(H2O)2] and [Mn(II)(NS)2(H2O)2] the bands in the
region 3250–3467 cm–1 indicated presence of coor-
dinated water molecules.
Physical properties of the complexes. Analytical
data were in good agreement with the proposed
empirical formula of the complexes (Table 1).
According to conductance data the complexes were
non electrolytes [15].
IR spectra. The (C=N) stretching vibrations of the
free Schiff base (ca 1604 cm–1) shifted to 1565 cm–1
Table 2. IR data of the compounds
ν, cm–1
Compounds
NH2
N–H
C=S
C=N
–
C–S
–
M–S
–
M–N
–
OH
SMDTC
3309–3182 3415
1045
–
[NS]
–
–
–
–
–
–
–
–
3110
1043
1604
1564
1572
1565
1580
1567
1598
1571
876
825
823
803
829
828
834
838
–
–
–
[Cu(II)(NS)2]
[Ni(II)(NS)2]
[Zn(II)(NS)2]
[Co(II)(NS)2(H2O)2]
[Pb(II)(NS)2]
[Mn(II)(NS)2(H2O)2]
U(VI)(NS)3]
–
–
–
–
–
–
–
–
–
–
–
–
–
–
480
406
472
465
445
472
486
531
538
535
530
524
518
694
–
–
–
3466–3250
–
3467–3280
–
Table 3. Electronic spectra of the complexes
Complexes
[Cu(II)(NS)2]
λmax, nm
280
312
320
235
310
384
230
320
470
412
–
–
–
[Ni(II)(NS)2]
355
–
[Zn(II)(NS)2]
–
[Mn(II)(NS)2(H2O)]2]
[Co(II)(NS)2(H2O)]2]
[Pb(II))(NS)2]
380
420
–
505
540
–
–
–
–
U(VI)(NS)3]
290
520
610
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 4 2015

982
KUDRAT-E-ZAHAN, ISLAM
H3CO
S
CH3
SCH3
H
C
C
C
N
N
S
S
N
N
N
6+
M2+
H3C
S
C
S M
C
OCH3
S
H3CO
CH N
N
CH
N
OCH3
H
N
C
S
C
H3CO
N
CH3
H
SH
C
SCH3
Fig. 4. Tetrahedral geometry of the M2+(II) complex, M2+
Zn(II), Pb(II).
=
Fig. 5. Octahedral geometry of M6+(VI) complex, M6+ = U(VI).
Magnetic moment and electronic spectra. Mag-
netic susceptibility measurement (Table 1) indicated
that the complex [Cu(II)(NS)2] was paramagnetic and
its magnetic moment (1.94 B.M.) corresponded to one
unpaired electron. UV-Vis spectrum of the complex
demonstrated d–d bands at 470 and 320 nm (Table 3),
arising from the 2B1g→ 2A1g and 2B1g→ 2E1g transitions,
respectively, characteristic to a square planar structure
[17] (Fig. 2). The intense band at 280 nm was
presumably caused by charge transfer.
Magnetic susceptibility measurements (Table 1)
and three bands corresponding to the transitions 1A1g →
1
1
1A2g (312 nm), A1g →1B1g (355 nm) and A1g
→
Table 4. In vitro antibacterial activities of the compounds and Kanamycine (K-30)
Diameter of inhibition zone (mm)
[Cu(II)(NS)2] [Ni(II)(NS)2] [U(VI)(NS)3] [Co(II)(NS)2(H2O)2] K-30
Gram
staining
Bacteria
100 mg/disc
100 mg/disc
100 mg/disc
100 mg/disc
mg/disc
Bacillus subtilis
Positive
Positive
Positive
25
17
23
26
13
22
25
16
20
16
7
8
17
8
25
24
26
25
20
21
22
24
Staptococcus aureus
Bacillus megaterium
18
23
26
24
8
22
17
25
24
6
Streptococcus-β-haemolyticus Positive
25
18
26
17
14
Escherichia coli
Shigella dysenteriae
Shigella sonnei
Shigella shiga
Negative
Negative
Negative
Negative
7
12
17
Table 5. Antifungal activity of the complexes and standard Fluconazole
Diameter of inhibition zone (mm)
Fungal status
[Cu(II)(NS)2] 100
mg/disc
[Ni(II)(NS)2]
100 mg/disc
[U(VI)(NS)3] [Co(II)(NS)2(H2O)2]
Fluconazole F-50
mg/disc
100 mg/disc
100 mg/disc
Aspergillus
11
15
14
14
13
15
15
7
12
8
9
14
16
9
17
20
19
20
Penicillium
Candida species
Aspergilius niger
13
11
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 4 2015

SYNTHESIS, CHARACTERIZATION, AND ANTIMICROBIAL ACTIVITY
1Eg (412 nm) recorded in the electronic spectra (Table 3)
983
REFERENCES
indicated the square-planar structure of Ni(II) complex
[17] (Fig. 2). Spectra of the complex [Zn(II)(NS)2]
demonstrated the absorption band at 320 nm assigned
to charge transfer transitions (Table 3).
1. Tarafder, M.T.H., Manaf, A.A., Saravanan, N., Wong, Y.W,
Saravana, K., Umar-Tsafe, N., and Karen, A.C.,
Transition Metal Chemistry, 2000, vol. 25, pp. 295–298.
2. Akbar Ali, M., Livingstone, S. E., and Philips, D.J.,
According to magnetic moment (Table 1) and
electronic spectra bands, 310, 420 and 540 nm (Table 3),
assigned to the transitions 4T1g→4T2g(ν1), 4T1g→4A2g(ν2),
4T1g→4T2g(F)(ν3) respectively, the complex [Co(II)(NS)2·
(H2O)2] had octahedral structure [17] (Fig. 3). The
octahedral complex [Mn(II)(NS)2(H2O)]2] demon-
strated similar characteristics (Tables 1 and 3). The
absorption band at 384 nm of the complex [Pb(II)(NS)2]
was assigned to charge transfer transitions (Table 3).
The magnetic susceptibility data indicated its distorted
tetrahedral geometry (Fig. 4). The octahedral structure
of U(VI) complex is shown in Fig. 5.
1H NMR spectra. 1H NMR spectrum of [Zn(II)(NS)2]
complex was typical for all synthesized complexes and
demonstrated the following signals (ppm): 7.57–7.54 d
(J = 8.4 Hz, 4H, Ar-H), 7.03–7.00 d (J = 8.4 Hz, 4H,
Ar-H), 4.84 s (6H, –OCH3), 3.86 s (2H, –CH), 2.73 s
(6H, –SCH3).
Inorg. Chim. Acta, 1973, no. 7, pp. 179-–186.
3. Akbar Ali, M., Livingstone, S. E., and Philips, D.J.,
Inorg. Chim. Acta, 1973, no. 7, pp. 531–537.
4. Akbar Ali , M., Tarafder, M.T.H., Jalil miah, M.A., and
Bose, R.N., J. Inorg. Nucl. Chem., 1981, vol. 43,
pp. 3151–3157.
5. Tarafder, M.T.H., .Saravanan, N., Karen, A.C., Manaf, A.A.,
Transition Metal Chemistry, 2001, vol. 26 (6), pp. 613–
618.
6. Akbar Ali, M. and Tarafder, M.T.H.,. J. Inorg. Nucl.
Chem., 1977, vol. 39, pp. 1785–1791.
7. Akbar Ali, M., Hossain, G., Mazumder, S.M.M.H.,
Nazimuddin, M., and Tarafder, M.T.H., Polyhedron,
1987, no. 6, pp. 1653–1656.
8. Hazari, S.K.S., Palit, D., Dey, B.K., and Mazumder, J.L.,
Chittagong University Studies, Part 2, 1996, vol. 20(1),
p. 53.
9. Akbar Ali, M., Chowdhury, D.A., and Nazimuddin, M.,
Polyhedron, 1984, vol. 3(5), pp. 595–598.
Antibacterial activity of the complexes.
Complexes of Zn(II) and Cd(II) with tridentate ONS
donor Schiff base ligands had been synthesized and
their biological activity tested by Gunthkal et al [18].
Wang and co-authors [19] had 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-
aminophenol-N-benzylidine Schiff base ligand had
been synthesized and tested for antibacterial activity
by Patil and co-workers [20].
10. Kudrat-E-Zahan, Md., Nishida, Y., and Sakiyama, H.,
Inorg. Chim. Acta., 2010, vol. 363(1), pp. 168–172.
11. Abdul Alim Al-Bari, M., Faruk Hossen, M., Khan, A.,
Kudrat-E-Zahan, Md., Ashik Mossadik, M., Zakaria, C.M.,
and Anwar Ul Islam, M., J. Appl. Sci. Res., 2007,
vol. 3(11), pp. 1279–1287.
12. Saidul Islam, M., Aktar, F., Roushown Ali, Kader, A.,
Kudrat-E-zahan, Md., and Abdur Rahim Khan, M.,
Orient. J. Chem., 2003, vol. 19(2), pp. 343–350.
13. Kudrat-E-Zahan, Md. and Sakiyama, H.,. Asian J. Res.
Chem., 2014, no. 7(13), pp. 278–280.
Accumulated in the current study data revealed that
the complexes had higher microbial toxicity than free
metal ions or ligands. Co(II), Ni(II), Cu(II), and U(VI)
Schiff bases complexes (Table 4) demonstrated
moderate to strong activity against both Gram positive
and Gram negative bacteria compared to standard
Kanamycine.
14. Kudrat-E-Zahan, Md. and Sakiyama, H.,. Asian J. Res.
Chem., 2013, no. 6(11), pp. 1072–1074.
15. Geary, W.J., Coord. Chem. Rev., 1971, no. 7(1), pp. 81–
122.
16. Das, M. and Livingstone, S.E.,. Inorg. Chim. Acta,
1976, no. 19, pp. 5–10.
17. Figgis, B.N., Introduction to Ligand Fields, New York:
Interscience, 1967, pp. 3, 316.
18. Gunthkal, M.S., Timmanagoud, R.G., and Sangamesh, A.P.,
Orient. J. Chem., 2000, vol. 16(1), pp. 151–155.
19. Wang, X., Zhaq, Q., Wang, D., and Xi, Y., Zhongguo
Yaoke Daxue Xuebao, 1997, vol. 28(3), pp. 180–182.
20. Dharmaraj, N., Viswanathamurthi, P., and Natarajan, K.,
Transition Met. Chem., 2001, vol. 26, nos. 1–2,
pp. 105–109
Antifungal activity of the complexes. Antifungal
activity of the complexes and standard fluconazole (F-
50 mg/mL)) were determined in the concentration of
100 mg/mL against four pathogenic fungi (Table 5).
The complexes of Co(II), Ni((II), Cu(II), and U(VI)
demonstrated significant activity towards all fungi
tested with the highest determined for the complex of
Co(II) against Candida species.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 4 2015