Antimicrobial agents: Synthesis, spectral, thermal, and biological aspects of a polymeric Schiff base and its polymer metal(II) complexes

Article abstract of DOI:10.1080/00958972.2010.526207

Some new coordination polymers of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) obtained by the interaction of metal acetates with polymeric Schiff base containing formaldehyde and piperazine have been investigated. Structural and spectroscopic properties ha

Full text of DOI:10.1080/00958972.2010.526207

This article was downloaded by: [University of New Mexico]
On: 23 November 2014, At: 02:23
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Journal of Coordination Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/gcoo20
Antimicrobial agents: synthesis,
spectral, thermal, and biological
aspects of a polymeric Schiff base and
its polymer metal(II) complexes
Nahid Nishat a , Shamim Ahmad Khan a , Shadma Parveen a & Raza
Rasool a
a Materials Research Laboratory, Department of Chemistry , Jamia
Millia Islamia , New Delhi 110025, India
Published online: 02 Nov 2010.
To cite this article: Nahid Nishat , Shamim Ahmad Khan , Shadma Parveen & Raza Rasool (2010)
Antimicrobial agents: synthesis, spectral, thermal, and biological aspects of a polymeric Schiff base
and its polymer metal(II) complexes, Journal of Coordination Chemistry, 63:22, 3944-3955, DOI:
10.1080/00958972.2010.526207
To link to this article: http://dx.doi.org/10.1080/00958972.2010.526207
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

Journal of Coordination Chemistry
Vol. 63, No. 22, 20 November 2010, 3944–3955
Antimicrobial agents: synthesis, spectral, thermal, and
biological aspects of a polymeric Schiff base and its
polymer metal(II) complexes
NAHID NISHAT*, SHAMIM AHMAD KHAN,
SHADMA PARVEEN and RAZA RASOOL
Materials Research Laboratory, Department of Chemistry,
Jamia Millia Islamia, New Delhi 110025, India
(Received 28 February 2010; in final form 30 August 2010)
Some new coordination polymers of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) obtained by the
interaction of metal acetates with polymeric Schiff base containing formaldehyde and
piperazine have been investigated. Structural and spectroscopic properties have been studied
by elemental, spectral (FT-IR, 1H-NMR, and UV-Vis), and thermogravimetric analysis.
UV-Vis spectra and magnetic moments indicate that Mn(II), Co(II), and Ni(II) polymer metal
complexes are octahedral, while Cu(II) and Zn(II) polymer metal complexes are square planar
and tetrahedral, respectively. All compounds were screened for their antimicrobial activities
against Escherichia coli, Bacillus subtillis, Staphylococcus aureus, Pseudomonas aeruginosa,
Salmonella typhi, Candida albicans, Agelastes niger, and Microsporum canis using the Agar well
diffusion method with 100 mg mLꢀ1 of each compound.
Keywords: Polymeric Schiff base; Piperazine; Thermal decomposition; Antimicrobial activity
1. Introduction
The development of coordination polymers by linking transition metal ions with
polydentate ligands has been constantly growing [1–7]. Coordination polymers
(polymeric chelates) are defined as materials in which metal ions are linked together
with di- or polyfunctional ligands and known for their thermal stability [8, 9].
Important applications have been reported, such as their use as solar energy converters
[10] and the ability to remove SOx and NOx from the environment [11]. The choice of
the metal ions, the ligand design, the counter ions, and the solvents can have a
considerable effect on the final architecture of the coordination polymers and
particularly its dimensionality [12].
Preparation and study of coordination polymers containing biologically important
ligands are made easier because certain metal ions are active in many biological
processes; species of low molecular weight are sought that reproduce, as far as possible,
*Corresponding author. Email: nishat_nchem08@yahoo.com
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online ꢀ 2010 Taylor & Francis
DOI: 10.1080/00958972.2010.526207

Polymeric Schiff base
3945
the structural properties and the reactivity of naturally occurring complexes of
these ions.
In the field of coordination polymers, polymer metal complexes of Schiff bases have
played a central role and have a curious history. Considerable interest attached with the
chemistry of Schiff bases derived from aldehydes, amine Schiff bases having oxygens,
nitrogens, and sulfurs has been reported and applications of Schiff bases and their metal
complexes in pharmacological and non-pharmacological fields have received increased
attention.
Schiff bases are an important class of ligands due to their synthetic flexibility and
sensitivity toward the central metal ion, structural similarities with natural biological
substances, and also the presence of imine (N¼CH–) which assists in elucidating the
mechanism of transformation and racemization in biological systems.
By incorporating metal ion into the polymeric backbone, the physical and chemical
properties are modified. Polymer metal complexes of Schiff base have been applied as
polymer catalysts [13, 14], metallomesogens [15], supramolecular metal complexes [16],
dendritic polymers [17], and in the construction of supramolecular systems [18].
Herein, we describe the synthesis of a polymeric Schiff base (PSB), which is capable
of being tetradentate and which should form linear polymer when allowed to react with
suitable metal ions like Mn(II), Co(II), Ni(II), Cu(II), and Zn(II). All the synthesized
polymeric compounds were characterized by using various spectral (IR, 1H-NMR, and
UV-Vis) and physico-chemical techniques. The elemental analysis, magnetic moment
measurements, thermal behavior, type of chelation of ligand, and the geometry of the
metal are discussed. In addition, the antimicrobial activities were determined using the
agar well diffusion method, where 100 mg mLꢀ1 concentration of each compound was
tested against these microbes. The PSB had varied antimicrobial as well as the thermal
properties, which were enhanced after chelation.
2. Experimental
2.1. Materials and strains
In this study, o-tolidine, 2-hydroxyacetophenone, formaldehyde (37% aqueous solu-
tion), acetic acid, sodium hydroxide, manganese(II) acetate tetrahydrate
Mn(CH3COO)2 Á 4H2O, cobalt(II) acetate tetrahydrate Co(CH3COO)2 Á 4H2O,
nickel(II) acetate tetrahydrate Ni(CH3COO)2 Á 4H2O, copper(II) acetate monohydrate
Cu(CH3COO)2 Á H2O, and zinc(II) acetate dihydrate Zn(CH3COO)2 Á 2H2O were used
without purification. Solvents such as acetone, methanol, ethanol, diethyl ether,
dimethylformamide (DMF), and dimethylsulfoxide (DMSO) were purified by standard
procedures before use. All microorganisms were provided by the Microbiological
Laboratory AMU.
2.2. Synthesis
2.2.1. Synthesis of monomeric Schiff base. Monomeric Schiff base was prepared by
a known procedure [19]. In a 250 mL round bottom flask, a solution of

3946
N. Nishat et al.
2-hydroxyacetophenone (0.02 mol) in ethanol (100 mL) was added dropwise to a
solution of o-tolidine (0.01 mol) in ethanol (50 mL). The reaction mixture was acidified
with concentrated hydrochloric acid (0.05 mol) then refluxed with constant stirring for
2 h and then the reaction mixture was allowed to stand for 30 min. Pale yellow
precipitate was obtained which was filtered and purified by washing repeatedly with
ethanol, distilled water, and acetone, then dried in a vacuum desiccator over calcium
chloride to remove the trapped solvent (ethanol); the monomeric Schiff base was
obtained in 65% yield and is soluble in DMF and DMSO at room temperature.
2.2.2. Synthesis of PSB. A mixture of monomeric Schiff base (0.01 mol) and
formaldehyde (0.02 mol) in a molar ratio of 1 : 2 was taken into a 250 mL three-
necked round bottom flask equipped with thermometer condenser and magnetic stirrer.
DMSO (ꢁ50 mL) was used as a solvent. In this reaction mixture, one or two drops of
40% aqueous NaOH were added and the temperature increased to 70–80ꢂC for 3 h with
continuous stirring. After that (0.01 mol) piperazine solution in 25 mL ethanol was
added to this system and stirred again for 1 h at 90–100ꢂC. The reaction progress was
monitored by thin-layer chromatography (TLC). The reaction mixture was cooled
and precipitated into 50/50 (v/v) water/acetone mixture. The solid brown product was
filtered, and reprecipitated from DMSO in ethanol, the brown solid product of PSB was
filtered and washed repeatedly with distilled water and acetone, and dried in a vacuum
oven to remove the trapped solvent (DMSO and ethanol), giving polymeric resin at
75% yield.
2.2.3. Synthesis of polymer metal complexes. All polymer metal complexes were
prepared by using equimolar ratio (1 : 1) of PSB and metal salts. The synthetic route for
preparation of polymer metal complex of Mn(II) is as follows: a hot solution of
manganese(II) acetate tetrahydrate (2.45 g, 0.01 mol in 10 mL DMF) was added to a
solution of PSB (5.31 g, 0.01 mol in 20 mL DMF). The mixture was refluxed at 80ꢂC for
3 h with constant stirring. It turned brown and was precipitated in distilled water.
Finally, the product was filtered, washed with distilled water, alcohol, and acetone and
dried in a vacuum desiccator on calcium chloride (yield 68%).
A similar procedure was adopted for the synthesis of other polymer metal complexes,
PSB–Co(II), PSB–Ni(II) PSB–Cu(II), and PSB–Zn(II), in yields between 71% and
78%. The products were soluble in DMF and DMSO and insoluble in other common
solvents. The synthetic route for the preparation of all polymer metal complexes has
been given in scheme 1.
2.3. Preparation of microbial culture
The microorganisms used in this study were provided by the culture collection of the
Microbiological Laboratory of AMU. Escherichia coli, Bacillus subtillis, Staphylococcus
aureus, Pseudomonas aeruginosa, Salmonella typhi, Candida albicans, Agelastes niger,
and Microsporum canis were used to investigate the bacteriological and antifungal
activities of the PSB and its polymer metal complexes. Bacterial strains were nourished
in nutrient broth (Difco) and yeast in malt extract broth (Difco) and incubated for 24
and 28 h, respectively.

Polymeric Schiff base
3947
OH
CH
2
H
NH
2
N
+
2
O
H C
3
CH
3
o-tolidine
2-hydroxy acetophenone
3
HCl
HO
OH
N
2
O
H C
2
+
N
Formaldehyde
CH
H C
CH
3
3
CH3
OH
3
o
NaOH
–
70 80 C
Monomeric Schiff base
H C OH
2
HO CH
2
HO
+
NH
HN
N
N
Piperazine
H C
CH
3
CH
CH
N
3
3
3
CH
2
CH
2
N
HO
OH
CH
N
N
H C
CH
3
CH
3
3
3
Metal acetate
Metal acetate
H
C
O
H
C
O
2
2
CH
CH
N
CH
CH
N
3
3
3
3
H
C
H C
3
3
X
H C
N
H C
N
3
3
M
M'
X
O
O
CH
N
CH
2
2
N
N
N
Where M = Mn(II), Co(II), and Ni(II),
X=H O
M„=Cu(II) and Zn(II)
2
Scheme 1. Synthetic route for the preparation of PSB and its polymer metal complexes.
According to the agar well diffusion method bacteria were incubated in Muller
Hinton agar (Difco) and yeast in Saburoud dextrose agar (Difco). The PSB and its
polymer metal complexes (100 mg mLꢀ1) were dissolved in DMSO. A circular well was
made at the center of each Petri dish with a sterilized steel borer. Then, 0.1 mL of each

3948
N. Nishat et al.
test solution was added to the well and incubated at 37ꢂC for 24 h; yeast samples
were incubated at 30ꢂC for 72 h. The experiment was repeated three times
simultaneously under the same conditions for each compound and the mean value
obtained from the three wells was used to calculate the zone of growth inhibition of
each sample. DMSO was used for positive control. The resulting inhibition zones on the
dish were measured in millimeters and compared with Kanamycine as a standard drug
for antibacterial activity and Miconazole for antifungal activity. The data are given
in tables 5 and 6.
2.4. Measurements
The elemental analyses of metal coordination polymers were carried out on a Perkin
Elmer Model-2400 elemental analysis [IIT, Roorkee]. The metal contents were
determined by complexometric titration against EDTA after decomposing with
concentrated nitric acid. The FT-IR spectra were recorded (4000–400 cmꢀ1) on
a Perkin Elmer infrared spectrophotometer model 621 using KBr pellets. The UV-Vis
spectra were carried out on a Perkin Elmer Lambda EZ-201 spectrophotometer using
DMSO. Proton and carbon-13 nuclear magnetic resonance spectra were recorded on a
Jeol GSX 300 MHz FX-1000 FT NMR spectrometer using DMSO as a solvent and
tetramethylsilane (TMS) as an internal standard. Thermal behaviors (thermogravi-
metric analysis (TGA)) of all the synthesized polymeric compounds were determinedꢀo1n
a TA analyzer 2000 in nitrogen atmosphere at a heating rate of 20ꢂC and 10ꢂC min
.
The solubility of the polymer was tested in various solvents at room temperature.
Antimicrobial activities of all the polymeric compounds were determined against
various selected microorganisms from the Microbiological Laboratory of AMU.
3. Results and discussion
Analytical data of the PSB and its polymer metal complexes and some physical
properties are given in table 1. The PSB was prepared in two steps by polycondensation.
In the first step monomeric Schiff base was prepared by the reaction of 2-
hydroxyacetophenone with o-tolidine in 2 : 1 molar ratio. In the second step monomeric
Schiff base was polymerized with formaldehyde and piperazine in 1 : 2 : 1 molar ratio.
The PSB was soluble in DMF and DMSO and insoluble in common organic solvents
and water. The polymer metal complexes were obtained by the reaction of PSB with
metal acetates in DMSO in 1 : 1 molar ratio. The polymer metal complexes were
insoluble in common organic solvents but soluble in DMSO and DMF. The polymer
metal complexes were colored and obtained in good yield. The high thermal stability,
metal to PSB ratio (1 : 1), and insolubility of the polymer metal complexes in common
organic solvents suggest their polymeric nature [20]. The insolubility of the polymer
metal complexes in common organic solvents does not permit the determination of
molecular weight, but indicates the polymeric nature. Elemental analyses, physical
properties, and IR data provide good evidence that the compounds are polymeric in
nature [21]. The elemental analyses (table 1) show that PSB to metal ratio in all the
polymer metal complexes was 1 : 1 and in agreement with the calculated values.

Polymeric Schiff base
3949
Table 1. Analytical and physical data of polymeric ligand (PSB) and its polymer metal complexes.
Calculated (found) (%)
Polymeric compounds
Color (yield %)
C
H
N
M
PSB
Dark yellow (75)
Brown (68)
77.38
(78.02)
66.76
(67.10)
66.35
(66.70)
66.37
(66.50)
69.71
6.85
(7.03)
6.22
(6.55)
6.18
(6.41)
6.18
(6.23)
5.85
10.02
(10.55)
8.65
(9.00)
8.59
(8.68)
8.60
(8.79)
9.03
–
–
PSB–Mn(II)
PSB–Co(II)
PSB–Ni(II)
PSB–Cu(II)
PSB–Zn(II)
8.48
(8.75)
9.04
(9.29)
9.00
(9.21)
10.24
(10.44)
10.51
(10.65)
Light brown (74)
Light green (71)
Light brown (72)
Yellow (78)
(69.92)
69.50
(69.70)
(5.99)
5.83
(6.01)
(9.20)
9.00
(9.25)
The structure of PSB and its metal complexes was also confirmed by IR, proton NMR,
UV-Vis, and magnetic susceptibility measurements.
3.1. FT-IR spectra
In order to study the bonding of PSB to the metal, the IR spectrum of PSB was
compared with spectra of the corresponding polymer metal complexes (table 2). In the
spectra of PSB, a strong band at 1650 cmꢀ1 is attributed to C¼N (azomethine). On
coordination, due to shift of lone pair density toward the metal, this band is expected to
shift to lower frequency indicating coordination of azomethine nitrogen to metal [21].
IR spectra of PSB exhibit a broad band at 3400–3250 cmꢀ1 due to phenolic –OH [22].
The phenolic –OH stretch disappears in spectra of polymer metal complexes indicating
that the ligand coordinates with metal through oxygen of Ar–OH. The ꢀC–H out-of-
plane bending vibration of the aromatic system is at 775–740 cmꢀ1 and the C–N band
appears at 1020 cmꢀ1. A comparison between IR spectra of PSB and PSB–M(II) also
show that a band, characteristic of ꢀ(C–O) at 1310 cmꢀ1, is shifted to 1350–1330 cmꢀ1
,
due to C–O–M bond formation [23]. Bands at 2920–2850 cmꢀ1 are assigned to CH2
asymmetric and symmetric stretching vibrations. The PSB showed a band at 1534 cmꢀ1
for ꢀC¼C of aromatic rings while its polymer metal complexes shift to 1555–1540 cmꢀ1
.
In addition to these, all polymer metal complexes show two new bands at 537–520 and
470–430 cmꢀ1 due to formation of M–O and M–N bonds [24, 25] further confirming the
formation of coordination polymer. Spectra of the polymer metal complexes of Mn(II),
Co(II), and Ni(II) exhibited a broad band (3350–3200 cmꢀ1) suggesting the presence of
water [26, 27]. This band is not found in spectra of polymer complexes of Cu(II) and
Zn(II) which is also supported by electronic spectra andTGA.
3.2. 1H-NMR spectra
1H-NMR spectra of PSB and its Zn(II) complex are shown in ‘‘Supplementary
material’’. The aromatic protons show multiple resonance signals between 6.92 and

3950
N. Nishat et al.
Table 2. IR spectral bands and their assignments for polymeric ligand (PSB) and its polymer metal
complexes.
Assignments
Compounds
Ar–OH/H2O
CH (asym–sym)
ꢀC¼N
ꢀC¼C
ꢀC–O
ꢀM–O
ꢀM–N
PSB
3400–3250
3350–3200
3350–3200
3350–3200
–
2920–2850
2920–2850
2920–2850
2920–2850
2920–2850
2920–2850
1650
1635
1629
1622
1630
1640
1534
1540
1550
1555
1550
1554
1310
1350
1346
1330
1350
1339
–
–
PSB–Mn(II)
PSB–Co(II)
PSB–Ni(II)
PSB–Cu(II)
PSB–Zn(II)
525
537
520
530
520
463
449
470
430
435
–
8.1 ppm [28]. The methyl proton attached to the carbonyl carbon of acetophenone was
observed at 2.02 ppm. Resonance at 4.87 ppm is due to the proton of phenolic–OH and
resonances at 2.74–2.88 ppm indicate the presence of –CH2–CH2– of piperazine
1
and a resonance at 1.70 is due to proton of benzylic methylene. The H-NMR spectra
reveal that the piperazine moieties are attached to the Schiff base with methylene
groups of formaldehyde. In the 1H-NMR spectra of Zn(II) polymer complex, the signal
for the protons of phenolic–OH disappear suggesting formation of Ar–O–M and
a significant shifting in all the peaks was observed confirming formation of
polymer metal complexes. The peak of benzylic methylene proton was at 2.08 ppm.
Aromatic protons became broad due to the intermolecular interaction towards
the metal ion.
3.3. Electronic spectra and magnetic properties
The electronic spectra and magnetic properties of polymer metal complexes of PSB
were recorded at room temperature using DMSO-d6 as a solvent; transitions with their
assignment are given in table 3. The electronic spectrum of PSB–Mn(II) exhibited bands
4
4
at 13,465, 18,574, and 22,445 cmꢀ1 due to T1g(G) 6A1g(F), T2g(G) 6A1g(F), and
4A1g(G) 6A1g transitions, respectively, and suggest octahedral environment around
Mn(II) [29]. The magnetic moment of PSB-Mn(II) was 5.83 BM Ligand field
parameters 10 Dq, B and ꢁ are 5020, 837, and 0.87 cmꢀ1, respectively. The magnetic
moment value of PSB-Co(II) was 3.95 BM [30, 31] and it shows three bands at 16,584,
4
4
23,310, and 29,412 cmꢀ1 due to T2g(F) 4T1g(F), A2g(F) 4T1g(F) and
4T1g(P) 4T1g(F) transitions. The value of 10 Dq, B and ꢁ are 8650, 1081, and
0.97 cmꢀ1. All these observations suggest an octahedral environment for Co(II). PSB-
Ni(II) showed three bands at 16,583, 25,510, and 29,762 cmꢀ1 due to 3T2g(F) 3A2g(F),
3
3T1g(F) 3A2g(F), and T1g(P) 3A2g(F), respectively, with ligand field parameters
10 Dq, B, and ꢁ as 13,600, 850, and 0.79 cmꢀ1, respectively. The ꢂeff value 2.79 BM is in
the range expected for the spin only value for two unpaired electrons in an octahedral or
distorted octahedral geometry [32]. Electronic spectra of the copper(II) complex show
broad bands centered at 25,000 and 16,556 cmꢀ1, which may be due to square planar
configuration [33, 34]; the magnetic moment value of PSB–Cu(II) at 1.70 BM is in
accord with square planar geometry.

Polymeric Schiff base
3951

3952
N. Nishat et al.
Table 4. Thermal properties of PSB and its metal complexes.
Weight left (%) at the indicated temperature (ꢂC)
Characteristic weight
left (%) at 800ꢂC
Compounds
100
200
300
400
500
600
700
PSB
90
92
95
92
98
94
72
76
83
88
95
90
65
70
72
75
82
77
50
61
59
69
70
68
43
56
47
57
63
58
30
46
36
49
51
47
23
30
27
33
37
32
5
10
13
18
25
19
PSB–Mn(II)
PSB–Co(II)
PSB–Ni(II)
PSB–Cu(II)
PSB–Zn(II)
The above discussion very strongly indicates octahedral geometry around the Mn(II),
Co(II), and Ni(II), requiring two coordination sites by H2O making the octahedral
environment.
3.4. Thermogravimetric analysis
Thermal decompositions of PSB and its polymer metal complexes are depicted in
‘‘Supplementary material’’; data are given in table 4. All the compounds were highly
heat resistant and they do not decompose easily, even at high temperature. No sharp
weight loss was observed in the TGA curves of the polymer metal complexes, consistent
with their polymeric nature. The thermograms show two step decomposition with the
first, faster than the second step. This may be due to the non-coordinated part of the
ligand decomposing first, while the coordinated part decomposes later [35]. In Mn(II),
Co(II), and Ni(II) polymer metal complexes, the curve showed 8–15% weight loss
corresponding to two water molecules up to 150ꢂC. The presence of water in these
polymer metal complexes was also supported by IR studies. In the case of Cu(II) and
Zn(II) polymers, this weight loss corresponds to lost solvent or absorbed water up to
150ꢂC. For thePSB, a steady and regular loss of weight was observed, and at 300ꢂC the
weight loss was about 35%. The temperature of maximum rate of decomposition for
the ligand was 700ꢂC and almost the entire ligand was lost by 800ꢂC, whereas the
polymer metal complexes lost only 75–90%. This suggests that all the polymer metal
complexes have higher thermal stability than the PSB due to chelation. Another factor
responsible for increased thermal stability of the polymer metal complexes is increase in
molecular weight due to joining of two different polymer chains. The thermal stability
of the polymeric compounds was in the order Cu(II) 4 Zn(II) 4 Ni(II) 4
Co(II) 4 Mn(II) 4 PSB. The greater stability of Cu(II) polymer metal complex
compared with other polymer metal complexes is in agreement with the spectrochemical
series, according to which Cu(II) polymer metal complex is always more stable than
other polymer metal complexes.
3.5. Antimicrobial activity
PSB and its metal complexes exhibited varying degrees of inhibitory effects on the
growth of the bacterial and fungal strains. These results, given in tables 5 and 6, show
that the newly synthesized PSB and its manganese(II), cobalt(II), nickel(II), copper(II),

Polymeric Schiff base
3953
Table 5. Antibacterial activities of polymeric ligand and its polymer metal complexes.
Zones diameter showing complete growth inhibitiona (mm)
Compound
E. coli
P. aeruginosa
B. subtillis
S. aureus
S. typhi
PSB
10 ꢃ 1
11 ꢃ 1
12 ꢃ 2
10 ꢃ 1
14 ꢃ 2
12 ꢃ 2
20 ꢃ 1
12 ꢃ 1
12 ꢃ 1
10 ꢃ 1
12 ꢃ 1
13 ꢃ 1
11 ꢃ 2
18 ꢃ 1
11 ꢃ 2
12 ꢃ 1
11 ꢃ 1
12 ꢃ 2
14 ꢃ 1
11 ꢃ 3
18 ꢃ 2
11 ꢃ 1
13 ꢃ 3
10 ꢃ 1
10 ꢃ 2
15 ꢃ 1
12 ꢃ 1
20 ꢃ 1
10 ꢃ 1
11 ꢃ 1
11 ꢃ 1
13 ꢃ 1
13 ꢃ 1
12 ꢃ 2
18 ꢃ 1
PSB-Mn(II)
PSB-Co(II)
PSB-Ni(II)
PSB-Cu(II)
PSB-Zn(II)
Kanamycineb
a14–15 mm: significant activity and 7–13 mm: moderate activity.
bStandard drug.
Table 6. Antifungal activity of PSB and its metal complexes.
Zones diameter showing complete growth inhibitiona (mm)
Compound
C. albicans
M. canis
A. niger
PSB
13 ꢃ 1
18 ꢃ 1
17 ꢃ 1
20 ꢃ 2
21 ꢃ 1
19 ꢃ 1
20 ꢃ 1
15 ꢃ 2
14 ꢃ 3
19 ꢃ 1
21 ꢃ 3
22 ꢃ 2
20 ꢃ 1
25 ꢃ 1
16 ꢃ 2
18 ꢃ 1
16 ꢃ 1
19 ꢃ 1
22 ꢃ 1
19 ꢃ 3
25 ꢃ 2
PSB–Mn(II)
PSB–Co(II)
PSB–Ni(II)
PSB–Cu(II)
PSB–Zn(II)
Miconazoleb
a14–22 mm: significant activity and 7–13 mm: moderate activity.
bStandard drug.
and zinc(II) complexes possess good biological activity. The compounds were screened
for their antibacterial activity against E. coli, B. subtillis, S. aureus, P. aeruginosa, and
S. typhi and for their antifungal activity against C. albicans, A. niger, and M. canis. All
complexes show moderate to high biocidal action as compared to the ligand, but the
activity was less than that of standard drugs while more significant antifungal activity
was observed against most strains. The results as described by Nishat et al. [36] show
comparatively high activities, while the microbial action of Kumaraguru et al. [37] was
in correlation with our results. A marked enhancement of activity was exhibited in all
the polymer metal complexes against all the bacterial/fungal strains. It was evident from
the data that the antimicrobial activity of all the polymeric compounds was increased
on coordination.
This enhancement in the activity can be rationalized on the basis of their structures
possessing an additional C¼N bond and chelation. It has also been observed [38–41]
that solubility, conductivity, and dipole moment are influenced by the presence of metal
ions and could be significant factors responsible for increasing the hydrophobic
character and liposolubility of the molecule, hence enhancing biological activity. The
results of antifungal and antibacterial screening indicate that polymer complexes of
Cu(II) show more activity than the other polymer metal complexes, perhaps from
higher stability. Cu(II) has stronger interaction with N and O donors by which
lipophilic nature is increased.

3954
N. Nishat et al.
4. Conclusion
Newly developed polymer metal complexes were prepared in good yield and
characterized by various instrumental techniques. All the polymeric compounds were
soluble in DMF and DMSO, but insoluble in common organic solvents, allowing the
possibility of use as solvent resistant coating materials. The attachment of metal ion
in the polymeric backbone enhances thermal as well as antimicrobial activity. Due to
stability at high temperatures, they can be used for medical and biomaterial
applications requiring thermal sterilization. Owing to effective toxic behaviors, PSB–
Cu(II) may be used as antifungal and antifouling coating for various projects.
Acknowledgments
One of the co-authors, Miss Shadma Parveen, acknowledges the Council of Scientific
and Industrial Research (CSIR, New Delhi, India) for granting Senior Research
Fellowship (SRF) vide grant No. 9/466(0097)2K8-EMR-I.
References
[1] S.R. Batten, R. Robson. Angew. Chem. Int. Ed., 37, 1460 (1998).
[2] O.M. Yaghi, M. O’Keeffe, N. Ockwig, H.K. Chae, M. Eddaoudi, J. Kim. Nature, 423, 705 (2003).
[3] S. Kitagawa, R. Kitaura, S.I. Noro. Angew. Chem. Int. Ed., 43, 2334 (2004).
[4] S. Kitagawa, K. Uemura. Chem. Soc. Rev., 34, 109 (2005).
[5] H.W. Raoesky, M. Andruh. Coord. Chem. Rev., 91, 236 (2003).
[6] C. Janiak. J. Chem. Soc., Dalton Trans., 2781 (2003).
[7] N.H. Patel, K.N. Patel, M.N. Patel. Synth. React. Inorg. Met.-Org. Chem., 32, 1879 (2002).
[8] A. Bajpai, S. Rai, U.D.N. Bajpai. Polym. J. (Tokyo), 29, 44 (1997); Chem. Abstr., 127, 126137 (1997).
[9] K. Tokaji, I. Tomita. Endo T Macromol., 30, 7386 (1997).
[10] D.H. Grayson, J.M. Kelly. Chem. Abstr., 99, 178958 (1983).
[11] N. Toshima, Kogya Zairyo., 39, 45 (1991); Chem. Abstr., 115, 238558F (1991).
[12] A.N. Khlobystov, A.J. Blake, N.R. Champness, D.A. Lemenovskii, A.G. Majouga, N.V. Zyk,
M. Schroder. Coord. Chem. Rev., 222, 155 (2001).
¨
[13] M. Kimura, H. Shirai. In Functional Monomers and Polymers. K. Takemoto, R.M. Ottenbrite, M.
Kamachi (Eds). Chap. 2, p. 552, Marcel Dekker Inc., New York (1997).
[14] E.A. Bekturov, S.E. Kudaibergenov. Catalysis of Polymers, p. 180, Huttig-Werf, Heidelberg (1996).
[15] D.W. Bruce. In Inorganic Materials, D.W. Bruce, D. O’Hare (Eds), p. 405, John Wiley and Sons,
Chichester (1992).
[16] J.P. Sauvage (Ed.). In Perspectives in Supramolecular Chemistry: Transition Metals in Supramolecular
Chemistry. Vol. 5. John Wiley & Sons. Chichester (1999).
[17] G. Denti, S. Campagna, V. Balzani. In Mesomolecules: from Molecules to Materials, G.D. Mendenhall,
A. Greenberg, J.F. Liebman (Eds), p. 69, Chapman & Hall, New York (1995).
[18] I. Haiduc, F.T. Edelmann. Supramolecular Organometallic Chemistry, Wiley-VCH, Weinheim (1999).
[19] D.K. Dwivedi, R.K. Shukla, B.K. Shukla. Acta Cienc Indica Chem., 17c, 383 (1991); Chem Abstr., 117,
142241n (1992).
[20] V.V. Korshak, S.V. Vinogradova, V.A. Artemova. Vysokomolekul Soidien., 2, 492 (1960); Chem. Abstr.,
55, 3404c (1961).
[21] R.K. Agarwal, H. Agarwal, I. Chakraborti. Synth. React. Inorg. Met.-Org. Chem., 25, 679 (1999).
[22] K. Nakanishi. Infrared Absorption Spectroscopy, 2nd Edn, Nakado, Japan (1964).
[23] D.M. Boghaei, M. Lashanizadegan. J. Sci. I. R. Iran, 11, 301 (2004).
[24] E.M. Jouad, A. Riou, M. Allain, M.A. Khan, G.M. Bouet. Polyhedron, 20, 67 (2001).
[25] G.G. Mohamed, N.E.A. El-Gamed, E.A. Nour El-Dien. Synth. React. Inorg. Met.-Org. Chem., 31, 347
(2001).

Polymeric Schiff base
3955
[26] K. Nakamoto. Infrared Spectra of Inorganic and Coordination Compounds, Wiley Interscience, New York
(1975).
[27] G.C. Percy. J. Inorg. Nucl. Chem., 37, 2071 (1975).
[28] W. Radecka-Paryzek, E. Jankowska. Inorg. Chim. Acta, 134, 179 (1987).
[29] F. Cotton, G. Wilkinson, C. Murillo, M. Bochmann. Advanced Inorganic Chemistry, 6th Edn, Wiley-
Interscience, New York (1999).
[30] N. Nishat, S. Parveen, S. Dhyani Asma, T. Ahamad. J. Appl. Polym. Sci., 113, 1671 (2009).
[31] T. Ahamad, V. Kumar, S. Parveen, N. Nishat. Appl. Organomet. Chem., 21, 1013 (2007).
[32] N. Nishat, M.M. Haq, T. Ahamad, V. Kumar. J. Coord. Chem., 60, 85 (2007).
[33] I. Y|lmaz, A. C¸ ukuroval|. Transition Met. Chem., 28, 399 (2003).
[34] H. Irvg, R.J.P. Williams. J. Chem. Soc., 3192 (1953).
[35] S.M. Roy, H.D. Juneja, K.N. Munshi. J. Therm. Anal. Calorim., 65, 197 (2001).
[36] N. Nishat, S. Parveen, S. Dhyani Asma. J. Coord. Chem., 62, 1091 (2009).
[37] N. Kumaraguru, K. Santhakumar. J. Coord. Chem., 62, 3500 (2009).
[38] Z.H. Chohan, A. Munawar, C.T. Supuran. Met. Based Drugs, 8, 137 (2001).
[39] Z.H. Chohan, C.T. Supuran. Main Group Met. Chem., 24, 399 (2001).
[40] Z.H. Chohan, H. Pervez, A. Rauf, C.T. Supuran. Met. Based Drugs, 8, 287 (2002).
[41] M.U. Hassan, Z.H. Chohan, C.T. Supuran. Main Group Met. Chem., 25, 291 (2002).