Metal complexes of phenylpiperazine-based dithiocarbamate ligands. Synthesis, characterization, spectroscopic, thermal, and antimicrobial activity studies

Article abstract of DOI:10.1081/SIM-120020326

Potassium salts of phenylpiperazine (Phpzdtc), fluorophenylpiperazine (F-Phpzdtc) and nitrophenylpiperazine (N-Phpzdtc) dithiocarbamates and their manganese(II), iron(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes have been synthesized and characterized by elemental analyses, IR, UV-VIS, magnetic moment measurements and thermal analysis techniques. On the basis of experimental data, the dithiocarbamates (dtcs) have been observed to coordinate to the metal ions via both sulphur atoms of the -NCS₂ group forming metal complexes with a metal to ligand ratio of 1:2. The thermal reactivity and antimicrobia activity of the ligands and their metal complexes were also studied. The decomposition of the metal complexes resulted in the formation of the corresponding metal thiocyanates or cyanates as stable intermediates. Phpzdtc was found to be microbiologically more active than its nitro and fluoro derivatives and biological activity of the dtc ligands either remained unaltered or decreased on complexation with metal ions.

Full text of DOI:10.1081/SIM-120020326

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Metal Complexes of Phenylpiperazine‐Based
Dithiocarbamate Ligands. Synthesis, Characterization,
Spectroscopic, Thermal, and Antimicrobial Activity
Studies
Veysel T. Yilmaz a , Turan K. Yazıcılar a , Hasan Cesur a , Resit Ozkanca b & Fatma Z. Maras b
a Department of Chemistry , Faculty of Arts and Sciences , Ondokuz Mayis University , 55139
Kurupelit, Samsun, Turkey
b Department of Biology , Faculty of Arts and Sciences , Ondokuz Mayis University , 55139
Kurupelit, Samsun, Turkey
Published online: 15 Feb 2007.
To cite this article: Veysel T. Yilmaz , Turan K. Yazıcılar , Hasan Cesur , Resit Ozkanca & Fatma Z. Maras (2003) Metal
Complexes of Phenylpiperazine‐Based Dithiocarbamate Ligands. Synthesis, Characterization, Spectroscopic, Thermal, and
Antimicrobial Activity Studies, Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 33:4, 589-605, DOI:
10.1081/SIM-120020326
To link to this article: http://dx.doi.org/10.1081/SIM-120020326
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SYNTHESIS AND REACTIVITY IN INORGANIC AND METAL-ORGANIC CHEMISTRY
Vol. 33, No. 4, pp. 589–605, 2003
Metal Complexes of Phenylpiperazine-Based
Dithiocarbamate Ligands. Synthesis,
Characterization, Spectroscopic, Thermal,
and Antimicrobial Activity Studies
1
1
Veysel T. Yilmaz,1, Turan K. Yazıcılar, Hasan Cesur,
*
Resit Ozkanca,2 and Fatma Z. Maras2
1Department of Chemistry, and 2Department of Biology, Faculty of Arts
and Sciences, Ondokuz Mayis University, Samsun, Turkey
ABSTRACT
Potassium salts of phenylpiperazine (Phpzdtc), fluorophenylpiperazine
(F-Phpzdtc) and nitrophenylpiperazine (N-Phpzdtc) dithiocarbamates
and their manganese(II), iron(II), cobalt(II), nickel(II), copper(II) and
zinc(II) complexes have been synthesized and characterized by elemental
analyses, IR, UV-VIS, magnetic moment measurements and thermal
analysis techniques. On the basis of experimental data, the dithiocarba-
mates (dtcs) have been observed to coordinate to the metal ions via both
sulphur atoms of the –NCS2 group forming metal complexes with a metal
*
Correspondence: Veysel T. Yilmaz, Department of Chemistry, Faculty of Arts
and Sciences, Ondokuz Mayis University, 55139 Kurupelit, Samsun, Turkey;
E-mail: vtyilmaz@omu.edu.tr.
589
DOI: 10.1081/SIM-120020326
0094-5714 (Print); 1532-2440 (Online)
www.dekker.com
Copyright D 2003 by Marcel Dekker, Inc.

590
Yilmaz et al.
to ligand ratio of 1:2. The thermal reactivity and antimicrobial activity of
the ligands and their metal complexes were also studied. The
decomposition of the metal complexes resulted in the formation of the
corresponding metal thiocyanates or cyanates as stable intermediates.
Phpzdtc was found to be microbiologically more active than its nitro and
fluoro derivatives and biological activity of the dtc ligands either
remained unaltered or decreased on complexation with metal ions.
Key Words: Phenylpiperazine dithiocarbamate; Fluorophenylpipe-
razine dithiocarbamate; Nitrophenylpiperazine dithiocarbamate; Anti-
microbial activity; Thermal analysis.
INTRODUCTION
The coordination of dithiocarbamates (dtcs) to metals has been known
for many years. Dtc ligands readily form chelates with all transition metal
ions through its two donor sulfur atoms.[1] Furthermore, in some cases, the
bidentate anion also acts as a bridge between two transition metal centers.[2]
Their sodium salts were found to be good extracting agents for most
transition metals.[3] Some salts of dtc derivatives exhibit interesting biolo-
gical effects including anti-alkylation,[4,5] anti-HIV properties[6] and anti-
tumor activity against leucemic cells.[7] They are also used for cadmium
intoxication.[8] Large quantities of water-soluble dtc complexes are used in
agriculture as fungicides[9] and also tested in various medical applications.[10]
In recent years, the study of transition metal complexes of substituted
dtc complexes has been a subject of considerable interest because of their
structural, magnetic, electrochemical and thermal properties. Studies on dtc
compounds and their metal complexes were reviewed by Coucouvanis.[11,12]
In this paper, we report the synthesis, characterization, spectral, thermal, and
antimicrobial properties of new phenylpiperazine (Phpzdtc), fluoro-
phenylpiperazine (F-Phpzdtc) and nitrophenylpiperazine (N-Phpzdtc) dithio-
carbamates and their manganese(II), iron(II), cobalt(II), nickel(II), copper(II)
and zinc(II) complexes. This work may also help to understand the inhibi-
tory effect of the dtc compounds for medical and agricultural applications.
EXPERIMENTAL
Reagents and Instruments
All chemicals were purchased commercially and used without further
purification. Electronic spectra were measured using a Unicam UV2

Complexes of Phenylpiperazine Derivatives
591
spectrophotometer in DMSO in the 200–800 nm range. IR spectra were
recorded on a Mattson FTIR spectrophotometer as KBr pellets. Room
temperature magnetic susceptibility measurements were carried out on a
Sherwood Scientific MXI model Gouy magnetic balance. C, H and N
analyses were carried out at the TUBITAK Marmara Research Centre
(Gebze). The simultaneous TG, DTG and DTA curves were obtained using
a Rigaku TG8110 thermal analyzer combined with a TAS100 thermogravi-
metric analyzer. The experiments were carried out in a dynamic nitrogen
atmosphere with a flow rate of 80 mL min–1 in the temperature range 20–
1000 °C, using platinum crucibles. Sample sizes of 5–10 mg and a heating
rate of 10 °C min–1 were used. Sintered a-alumina was used as the ref-
erence material.
Synthesis of the Ligands and Metal Complexes
The potassium salts of the phenylpiperazine based dtc ligands were
prepared by direct reaction between phenylpiperazine, fluorophenylpiper-
azine and nitrophenylpiperazine and CS2 in the presence of KOH in a
water-ice bath at about 0 °C. The resulting precipitates were washed with
diethyl ether for several times and dried in air. The metal complexes were
obtained by direct reaction of the respective dtc potassium salt with the
metal nitrates. The polycrystalline solids were filtered by suction, washed
with H2O, diethyl ether, and dried in air.
Antimicrobial Activity Screening
As a preliminary screening for antimicrobial activity, compounds were
tested against standard strains of gram ( ꢀ ) Escherichia coli W3110,
Salmonella tyhimurium LT2, Pseudomonas aeruginosa ATCC 27853, gram
( + ) Bascillus pumilus, Staphylococcus aureus ATCC 43300, a yeast Can-
dida albicans ATCC 10231 and a mould Aspergillus niger. Antimicro-
bial studies were performed according to both broth dilution and agar
diffusion methods. For broth dilution studies, starter cultures were grown
overnight on nutrient broth (Merck) at 37 °C in an incubator (GLF,
Germany) for 18 hours, and then transferred to the test tubes initially
containing approximately 3 ꢁ 105 bacteria. Nutrient broth containing tubes
then were supplemented with phenylpiperazine-, fluorophenylpiperazine-
and nitrophenylpiperazine dithiocarbamates and their metal complexes for
measuring the antimicrobial activity. MIC (Minimal Inhibitory Concentra-
tion) assays were performed in nutrient broth medium 1:10 dilutions and
further dilutions in order to find suitable MIC values. The MIC was

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Yilmaz et al.
expressed as the lowest compound concentration that inhibited bacterial
growth in 24 hours. Viable bacterial counts were determined by the
standard plate counting method. Agar diffusion experiments were based on
the obtained MIC values by dilution methods. The following test conditions
were applied. All the compounds (ligands and their complexes) were
dissolved in dimethylsulfoxide (DMSO, Merck). Nutrient agar (Acumedia)
plates were prepared and dried at 35–36 °C for about 30 min in an
incubator. Test strains were spread on the solid nutrient agar surface by
using a sterile glass rod. Spread inoculum was a 3.5 ꢁ 105 colony forming
unit/mL–1 (0.5 McFarland standard). At the same time, absorbent paper
discs were placed on an agar surface (10 mm for compounds and 6 mm for
antibiotics) and impregnated with known concentrations, determined
previously by MIC tests. Tetracyclin antibiotics (Bioanalyse) were also
used for prokaryote microorganisms and nystatin (BDH) for eucaryotes
(Aspergillus niger and Candida albicans) as positive control. Blank tests
showed that DMSO in the preparation of the test solutions does not affect
the test organisms. They were inverted and allowed to incubate at 37 °C.
The inhibition zone around the disc was calculated as zone diameter in
millimeters. All tests were repeated tree times and average data were taken
as the final result.
RESULTS AND DISCUSSION
Synthesis
The structural formulae of the ligands are shown in Figure 1. Analy-
tical data and some physico-chemical properties of the prepared compounds
are listed in Table 1, and the proposed formulae are in agreement with the
elemental analyses. The metal to ligand ratio is 1:2 for all metal complexes.
All the compounds are air-stable and were obtained in high yield. The
metal complexes are insoluble in water, but sparingly soluble in ethanol,
benzene, dioxan, DMSO, acetone, chloroform and CCl4. All attempts to
prepare single crystals of the compounds in various solvents failed. The
Figure 1. Structures of the dtc ligands.

Complexes of Phenylpiperazine Derivatives
593

594
Yilmaz et al.

Complexes of Phenylpiperazine Derivatives
595

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Yilmaz et al.
relatively high melting or decomposition points suggest that the metal
complexes may be dimeric or polymeric.
Spectral and Magnetic Characteristics
Table 2 summarizes the most significant IR bands of the prepared
compounds. The bands in the range 1410–1525 cm–1 are attributed to the
n(CN) stretching vibration of the thioureide group of the ligands,[13] they
shifted to higher frequency in the spectra of the metal complexes. The
absorption of the NCS2 groups in the ligands occurs between 1150–1110
cm–1 and shifts to higher frequency by about 10–45 cm–1 in the complexes.
The n(CS) stretching bands are located prominently in the range 1000–
1040 cm–1 in the ligands and their metal complexes and are considered to
be indicative of dtc acting as a bidentate ligand.[14] The same observations
were reported for amino acid dtcs,[13] dipropyldtc[15] and dtc complexes
with piperidine or pyrrolidine.[16]
Electronic spectra of the dtc ligands show two strong absorption bands
in the UV region (Table 2). These bands may be due to n ! p* and p !p*
transitions. In all the metal complexes, bands below 300 nm are attributed
to the intra-ligand transitions. The intense bands in the range 325–436 nm
in the spectra of complexes are ascribed to charge transfer processes,[13]
probably from ligand to metal, mainly associated with the N–C= S and
S–C =S and nitro groups, since the zinc(II) complexes of Phpzdtc and F-
Phpzdtc do not show these transitions. The absorption bands at higher
wave lengths are due to d–d transitions.
Magnetic moment measurements showed that the nickel(II) complexes
are diamagnetic, while the manganese(II), iron(II), cobalt(II) and copper(II)
complexes are paramagnetic (Table 2). The room temperature magnetic
moment values are consistent with a square-planar coordination for the
nickel(II) complex and an octahedral coordination for manganese(II),
iron(II), cobalt(II) and copper(II) complexes. In most cases, the effective
magnetic moments are found to be significantly lower than the spin-only
values. This observation indicates the presence of a strong antiferromag-
netic interaction in the complexes due to bridging of the metals by the dtc
ligands through the sulphur atoms.
Single crystal X-ray analyses of the copper(II) and cadmium(II) com-
plexes of the dialkyl substituted dtcs show that the neutral dtc complexes
exhibit dimeric structures achieved by long secondary M-S interac-
tions.[14,15] On the basis of the observed elemental analyses, spectral and
magnetic data, the structures of the metal complexes may be suggested as
illustrated in Figure 2.

Complexes of Phenylpiperazine Derivatives
597
Figure 2. Proposed structures of the metal complexes. The manganese(II), iron(II),
cobalt(II), copper(II) and zinc(II) complexes adopt structure (A).
Thermal Decomposition Behavior
The thermal behavior of the dtc ligands and their metal complexes
has been followed up to 1000 °C. Thermoanalytical data including mass
losses, temperature ranges and peak temperatures of the ligands and
metal complexes are given in Table 3. KPhpzdtcꢂH2O, decomposes in
two steps. The first step, between 55 and 135 °C, corresponds to the
dehydration of the compound. After dehydration, it melts at 285 °C and
degradation of the organic part of the ligand takes place in the second
decomposition stage in the range 287–775 °C, giving a final decompo-
sition product of KSCN as identified by IR spectra and mass loss cal-
culations. The manganese(II) complex melts at 179 °C. The endothermic
decomposition of the Phpzdtc part of the complex takes place in the
temperature range 182–352 °C with three DTG peaks. Mass loss cal-
culations correspond to formation of Mn(SCN)2, which decomposes at
higher temperatures to give MnS at 800 °C. The iron(II), cobalt(II),
nickel(II), copper(II) and zinc(II) complexes with the Phpzdtc ligand ex-
hibit the similar decomposition behavior. These complexes show two
main decomposition stages, and the first stage is due to degradation of
the ligand to give the stable intermediates Fe(SCN)2, Co(SCN)2, Ni(CN)2,
Cu(CN)2, and Zn(CN)2 at around 330 °C. The decomposition of these
intermediates occurs at the second stage between 300–800 °C. The ex-
perimental mass losses of the compounds are in very good agreement
with the calculated values.
KN-Phpzdtc is anhydrous and is stable up to 250 °C, following a
plateau in the TG curve, and begins to decompose exothermically above
this temperature. It is violently explosive at 275 °C under nitrogen at-
mosphere, leaving an empty crucible at 282 °C. The explosive behavior of
this compound is mainly due to the presence of the nitro group. In most

598
Yilmaz et al.
Table 3. Thermal decomposition data for the compounds.
Temp.
range
(°C)
DTG peak
temp.
(°C)a
Mass loss
(%)
t.g.
Compound
(Calcd.)
KPhpzdtcꢂH2O
55–135
287–775
102( + )
298( + ),
313( + )
188( + ),
215( ꢀ ),
302( + )
500( + )
233( + ),
267( + )
400( ꢀ )
291( + )
700( + )
333( + )
510( + )
238( + ),
277( + )
570( + )
326( + )
510( + )
275( ꢀ )
45( + )
6.1
60.4
6.1
60.9
[Mn(Phpzdtc)2]
182–352
66.9
67.7
368–800
220–300
20.8
66.6
21.9
67.6
[Fe(Phpzdtc)2]
310–630
190–350
350–950
300–360
360–900
200–310
15.7
67.1
15.7
75.5
10.5
75.5
15.8
67.2
15.8
79.2
9.8
[Co(Phpzdtc)2]
[Ni(Phpzdtc)2]
[Cu(Phpzdtc)2]
78.5
320–900
300–382
392–805
250–282
25–75
10.7
73.1
9.3
9.7
78.3
9.6
–
[Zn(Phpzdtc)2]
KN-Phpzdtc
[Mn(N-Phpzdtc)2]ꢂH2O
–
3.0
2.8
83.5
165–1000
218( ꢀ ),
250( ꢀ )
195( ꢀ ),
223( ꢀ ),
281( ꢀ )
59( + )
83.5
[Fe(N-Phpzdtc)2]
155–1000
78.4
85.8
[Co(N-Phpzdtc)2]ꢂ2H2O
25–120
240–900
232–850
204–1000
263–1000
56–150
5.8
79.1
84.6
89.2
86.6
5.7
6.3
79.9
90.6
89.9
89.6
5.6
275( ꢀ )
323( ꢀ )
270( ꢀ )
330( ꢀ )
95( + )
[Ni(N-Phpzdtc)2]
[Cu(N-Phpzdtc)2]
[Zn(N-Phpzdtc)2]
KF-Phpzdtcꢂ1.5H2O
150–265
300–750
140–380
192( + )
330( + )
182( + ),
324( + )
460( + )
209( + )
299( + )
480( + )
2.9
2.8
60.5
74.6
61.4
79.8
[Mn(F-Phpzdtc)2]
[Fe(F-Phpzdtc)2]
380–600
160–330
8.5
70.4
9.0
69.6
330–650
15.4
14.8

Complexes of Phenylpiperazine Derivatives
Table 3. Continued.
599
Temp.
range
(°C)
DTG peak
temp.
(°C)a
Mass loss
(%)
t.g.
Compound
(Calcd.)
[Co(F-Phpzdtc)2]ꢂ2H2O
25–110
190–350
350–900
310–385
385–1000
258–375
50( + )
290( + )
560( + )
360( + )
510( + )
274( + ),
284( + ),
291( + )
600( + )
323( + )
530( + )
6.1
65.5
14.5
79.3
9.2
6.0
65.1
14.3
80.6
9.1
[Ni(F-Phpzdtc)2]
[Cu(F-Phpzdtc)2]
79.4
79.9
375–1000
310–390
390–100
9.3
79.8
9.4
9.1
79.6
9.0
[Zn(F-Phpzdtc)2]
a( + ) = endothermic process; ( ꢀ ) = exothermic process.
cases, the metal complexes of Phpzdtc are also extremely explosive, which
makes the mass loss calculations difficult by affecting the shape of the
thermal curves. Therefore, there are significant differences between cal-
culated and found mass loss values.
KF-Phpzdtcꢂ1.5H2O dehydrates in the temperature range 56–150 °C
and melts at 295 °C. The endothermic degradation of the F-Phpzdtc moiety
takes place in a single stage between 300 and 700 °C to form KSCN. The
metal complexes of the F-Phpzdtc ligand also show similar decomposition
patterns. All the complexes, except the cobalt(II) complex, decompose
endothermically in two stages. The first stage corresponds the degradation
of the dtc ligand to give stable intermediates, which also decomposes at the
second stage at higher temperatures.
The present thermoanalytical data showed that under nitrogen, the
decomposition of the dtcs and their metal complexes gives the corres-
ponding metal thiocyanates or cyanates as stable intermediates and metal
sulfides or metals as the end products. IR spectroscopy was used for the
identification of the metal thiocyanates or cyanates by the n(CN) vibration
frequency around 2053 and 2080 cm–1, respectively.[17] The decompositions
of the thiocyanates or cyanates proceed at a slow rate at higher tem-
peratures. The literature suggests that metal thiocyanates are common
products in the thermal decomposition of dtcs,[18] although this conclusion
does not apply as a general rule at some cyclic dtcs.[13,16,19]

600
Yilmaz et al.

Complexes of Phenylpiperazine Derivatives
601

602
Yilmaz et al.
Antimicrobial Activity
Phenylpiperazine-, fluorophenylpiperazine- and nitrophenylpiperazine
dithiocarbamates and their metal complexes have been screened for anti-
microbial activities against three gram-negatives namely E. coli, S. typhi-
murium, P. aeruginosa and two gram-positives namely S. aureus, B. pumilus
and a yeast C. albicans, a mold A. niger using the agar disc diffusion method.
Table 4 lists the zone of inhibitions and effective concentrations used (MICs).
The dtc ligands and their metal complexes showed different anti-
microbial activities against test strains. For example, KPhpzdtcꢂH2O was
active against 6 test organisms with the exception of E. coli, while it showed
a remarkable inhibition on B. pumilus, C. albicans and A. niger. The modest
inactivation was detected for P. aeruginosa, S. typhimurium and S. aureus.
[Mn(Phpzdtc)2] exhibited modest activity on test bacteria and also fungies.
In contrast, this complex was not able to inhibit the growth of E. coli cells.
[Fe(Phpzdtc)2] showed modest activity against B. pumilus, S. aureus, C.
albicans and A. niger. However, a similar effect was not observed against
gram ( ꢀ ) test bacteria. [Ni(Phpzdtc)2] was detected as effective against S.
typhimurium, B. pumilus, S. aureus, C. albicans and A. niger. The highest
antimicrobial activity among the group of these organisms was observed
against C. albicans. [Zn(Phpzdtc)2] only inhibited the growth of B. pumilus,
C. albicans and A. niger, and it was ineffective against gram ( ꢀ ) bacterial
strains, whereas [Cu(Phpzdtc)2] was capable of inhibiting all test organisms.
KN-Phpzdtc was found to be active against gram ( +) test organisms but
not against gram ( ꢀ ) E. coli, S. typhimurium and P. aeruginosa and fungi.
This is probably due to the outer membrane layer of these bacteria, which did
not allow this compound to enter the cell. [Fe(F-Phpzdtc)2] showed weak
antimicrobial activity that only inhibited the growth of S. typhimurium and B.
pumilus, while [Co(N-Phpzdtc)2]ꢂ2H2O had inhibition only against S.
typhimurium. Among the compounds with Phpzdtc, [Cu(N-Phpzdtc)2] showed
an effective antimicrobial activity to all test strains, which was similar to
[Cu(Phpzdtc)2]. [Ni(N-Phpzdtc)2] was capable of inhibiting growth of gram
(+), gram ( ꢀ ) and fungi. It can be seen from Table 4 that the widest inhibition
zones were observed for [Ni(N-Phpzdtc)2] against P. aeruginosa, S.
typhimurium and C. albicans. Among the metal complexes of the N-Phpzdtc
ligand, [Zn(F-Phpzdtc)2] showed the highest antifungal activity against A.
niger, but it had no effect on P. aureginosa, S. typhimurium and B. pumilus.
KF-Phpzdtcꢂ1.5H2O, [Co(F-Phpzdtc)2]ꢂ2H2O and [Ni(F-Phpzdtc)2]
exhibited antibacterial activity against all bacterial test organisms. KF-
Phpzdtcꢂ1.5H2O especially had the strongest effect on C. albicans and A.
niger. [Mn(F-Phpzdtc)2] and [Fe(F-Phpzdtc)2] did not inhibit growth of S.
aureus. On the other hand, [Cu(F-Phpzdtc)2] was found to be important in

Complexes of Phenylpiperazine Derivatives
603
selective and effective inhibition against P. aeruginosa and C. albicans and
the rest of the test strains was affected moderately by [Cu(F-Phpzdtc)2],
whereas [Zn(F-Phpzdtc)2] seemed to be less effective among these metal
complexes and showed the slightest inhibition on B. pumilus.
When the antimicrobiological effect of ligands and their metal com-
plexes on test strains was categorized on the basis of cell wall structure,
there seemed some differences. For instance, as given in Table 4, KF-
Phpzdtcꢂ1.5ꢂH2O [Co(F-Phpzdtc)2]ꢂ2H2O, [Ni(N-Phpzdtc)2], [Cu(Phpzdtc)2]
and [Cu(N-Phpzdtc)2] inhibited all test microorganisms including gram ( +),
gram ( ꢀ ) and fungi. [Co(N-Phpzdtc)2]ꢂ2H2O affected only gram ( ꢀ ) E. coli
and S. typhimurium cells. However, while [Zn(F-Phpzdtc)2], [Fe(Phpzdtc)2]
and KN-Phpzdtc were active against gram ( + ) and fungi, they did not cause
any inhibition on growth of gram ( ꢀ ) bacteria. On the other hand, among
used ligands and metal complexes, [Mn(N-Phpzdtc)2]ꢂH2O and [Co(N-
Phpzdtc)2]ꢂ2H2O were not found to be effective on fungi. [Ni(Phpzdtc)2] and
[Zn(Phpzdtc)2] showed a selective inhibition on gram( +) bacteria with the
exception of S. aureus. In general, the growth of fungi was inhibited by
KPhpzdtcꢂH2O and its manganese(II), iron(II), cobalt(II), nickel(II) and
copper(II) complexes, KF-Phpzdtcꢂ1.5H2O and their metal complexes, KN-
Phpzdtc, [Cu(N-Phpzdtc)2] and [Ni(N-Phpzdtc)2].
In conclusion, the rate of antimicrobial activities of ligands and metal
complexes on microorganisms partly depends on the dtc chemical complex
used. Here, we found that the phenylpiperazine-based dtc ligands have the
strongest effect on fungi and also remarkable effects on bacteria and
KPhpzdtcꢂH2O was found to be more active than its nitro and fluoro deri-
vatives. In contrast to a review on dtc pesticides by Malik and Faubel,[20]
it was observed that some of the metal complexes reduce the inhibitory
effect of dithiocarbamates. Therefore, it may be concluded that this field
needs further work to clarify the effect of dtcs and their metal complexes
on microorganisms.
ACKNOWLEDGMENTS
This work was supported by the Research Fund of Ondokuz Mayis
University, Samsun, Turkey.
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Received: June 10, 2002
Accepted: December17, 2002
Referee I: F. Hepp
Referee II: V. Duffy