Synthesis, characterization, and antimicrobial activity of the ligand 3-methylpyrazole- 4-carboxaldehyde thiosemicarbazone and Its Pd(II) Complex

Article abstract of DOI:10.1080/10426507.2013.777726

The synthesis and characterization of a new palladium(II) complex [Pd(MePhPzTSC)2] and its corresponding ligand 3-methylpyrazole-4-carboxaldehyde thiosemicarbazone (MePhPzTSC) are described. The bidentate ligand is coordinated to Pd(II) through the azomethine nitrogen atoms and sulfur in the form of thiol by deprotonation of the NH-C = S. The antimicrobial activity of these new compounds was evaluated against gram-negative (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus and Bacillus thuringiensis) bacteria and two yeast strains (Candida albicans and Saccharomyces cerevisiae). Coordination of the ligand to the metallic ion showed improved antimicrobial activity compared to the free ligand. For the gram-positive bacteria the antimicrobial activity of the complex was higher than that of the positive control used. [Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the following free supplemental files: Additional figures and tables]

Full text of DOI:10.1080/10426507.2013.777726

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Synthesis, characterisation, and antimicrobial activity
of the ligand 3-methylpyrazole-4-carboxaldehyde
thiosemicarbazone and its Pd(II) complex
Lenka V. Tamayo a , Ana E. Burgos a & Pedro F. B. Brandão b
a Research Group on Coordination and Bioinorganic Chemistry, Department of Chemistry,
Faculty of Science , National University of Colombia , Av Cra 30 No. 45-03, Bogota , DC ,
Colombia
b Laboratory of Environmental and Applied Microbiology; Departamento de Química,
Facultad de Ciencias, Universidad Nacional de Colombia , Av. Cra 30 No. 45-03, Bogotá ,
D.C. , Colombia
Accepted author version posted online: 05 Apr 2013.
To cite this article: Phosphorus, Sulfur, and Silicon and the Related Elements (2013): Synthesis, characterisation, and
antimicrobial activity of the ligand 3-methylpyrazole-4-carboxaldehyde thiosemicarbazone and its Pd(II) complex, Phosphorus,
Sulfur, and Silicon and the Related Elements, DOI: 10.1080/10426507.2013.777726
To link to this article: http://dx.doi.org/10.1080/10426507.2013.777726
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Synthesis, characterisation, and antimicrobial activity of the ligand 3-
methylpyrazole-4-carboxaldehyde thiosemicarbazone and its Pd(II) complex
Lenka V. Tamayoa, Ana E. Burgosa,*, Pedro F. B. Brandãob
aResearch Group on Coordination and Bioinorganic Chemistry, bLaboratory of
Environmental and Applied Microbiology; Departamento de Química, Facultad de
Ciencias, Universidad Nacional de Colombia, Av. Cra 30 No. 45-03, Bogotá D.C.,
Colombia.
*corresponding author: aeburgosc@unal.edu.co
Suggested shortened title for running head:
Synthesis, characterisation, activity of Pd(II) complex
ACKNOWLEDGMENTS
The authors would like to thank the Dirección de Investigación Sede Bogotá (DIB,
Bogota Research Directorate) for funding this project (code number 201010016735)
and the Vicerrectoría de Investigación for financial support for the translation of this
manuscript through the “Convocatoria Nacional Fortalecimiento de la Visibilidad de
Producción Académica mediante el apoyo para traducción de estilo de artículos de
investigación 2011-2012”, both from the National University of Colombia. We also thank
Professor Milton Crosby, Faculty of Science in the Department of Pharmacy at the
National University of Colombia, for providing the strains used for the bioassays.
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Synthesis, characterisation, and antimicrobial activity of the ligand 3-
methylpyrazole-4-carboxaldehyde thiosemicarbazone and its Pd(II) complex
ABSTRACT
N
H2N
NH2
S
N
N
N
HN
N
S
N
Pd
S
N
MeOH, reflux
N
N
PdCl2
+
N
NH2
N
The synthesis and characterisation of a new palladium(II) complex [Pd(MePhPzTSC)2]
and its corresponding ligand 3-methylpyrazole-4-carboxaldehyde thiosemicarbazone
(MePhPzTSC) are described. The bidentate ligand is coordinated to Pd(II) through the
azomethine nitrogen atoms and sulfur in the form of thiol by deprotonation of the NH-
C=S. The antimicrobial activity of these new compounds was evaluated against gram-
negative (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) and
gram-positive (Staphylococcus aureus and Bacillus thuringiensis) bacteria and two
yeast strains (Candida albicans and Saccharomyces cerevisiae). Coordination of the
ligand to the metallic ion showed improved antimicrobial activity compared to the free
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ligand. For the gram-positive bacteria the antimicrobial activity of the complex was
higher than that of the positive control used.
KEYWORDS
Thiosemicarbazone, palladium complexes, antimicrobial activity.
[Supplementary materials are available for this article. Go to the publisher’s online
edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following
free supplemental files: Additional tables and figures.]
<AQ> Editorial work on your manuscript has created a file of supplemental materials
that will be available on-line only.</AQ>
INTRODUCTION
Thiosemicarbazones complexed with transition metals are of great chemical and
biological interest because they exhibit diverse pharmacological actions, including
antibacterial, antifungal, antitumor, antiviral, and antimalarial effects, among others.1,2,3
It is also important to note that the pyrazole nucleus and its derivatives exhibit a wide
range of biological activities, such as analgesic, anti-inflammatory, antipyretic,
antibacterial, antifungal, and hypoglycaemic activities.4,5
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Additionally, many Pd(II) complexes with ligands that have nitrogen and sulphur donor
atoms, such as thiosemicarbazones, exhibit biological activity.6 These findings have
motivated the study of these types of compounds. This paper reports the synthesis and
characterisation of a new pyrazolyl-thiosemicarbazone ligand and its Pd(II) complex
(Figure 1). These compounds were characterised by spectroscopic techniques (infrared,
FTIR and mono and two-dimensional nuclear magnetic resonance, NMR) and fast atom
bombardment (FAB) mass spectrometry for the Pd(II) complex. The antimicrobial
activity of the synthesised compounds was evaluated against gram-positive and gram-
negative bacteria and two yeast strains.
[Insert Figure 1]
RESULTS AND DISCUSSION
MePhPzTSC Ligand
The ligand, 3-methylpyrazole-4-carboxaldehyde thiosemicarbazone (MePhPzTSC), was
prepared from the condensation reaction between 3-methyl-1-phenylpyrazole-4-
carboxaldehyde and thiosemicarbazide. The characteristic spectral bands of the product
and the disappearance of the carbonyl band of the pyrazole precursor were observed in
the IR spectrum (Figure S 1 Supplemental Materials). These observations confirmed the
formation of the thiosemicarbazone compound. An absorption band was observed at
1209 cm-1 corresponding to the (C=S) elongation bound to the nitrogen atom, and
another band was observed at 1097 cm-1 corresponding to the (C=S) elongation. In the
3000 to 4000 cm-1 region, the spectrum registered two bands at 3424 and 3248 cm-1
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that corresponded to the symmetric and asymmetric elongations, respectively, of the
(NH2) group. The band at 3144 cm-1 was assigned to the (NH) of the hydrazine group;
a strong band observed at 1595 cm-1 was assigned to the (C=N) bond of the
azomethine group, and a band at 1551 cm-1 corresponded to the (C=N)pz of the
pyrazole ring. The absence of a band between 2600 and 2800 cm-1, corresponding to
(SH), confirmed that the ligand exists as a thione tautomer in the solid state.4, 7
1
The H NMR spectrum of the MePhPzTSC ligand (Figure S 2) showed eight signals
corresponding to the expected protons for the proposed structure. The NH2 group
protons appeared at different chemical shifts because there is no free rotation around
the C-N bond, due to its double-bond character.4,8 The 13C NMR spectrum (Figure S 3)
displayed the nine expected signals for the synthesised compound, a signal at 13.2 ppm
corresponded to the methyl group, and another signal at 117.3 ppm (Cq) represented
the C-4 carbon of the pyrazole ring. The signals corresponding to the aromatic ring
appeared at 117.9, 126.2, and 129.5 ppm for Co, Cp, and Cm, respectively. The chemical
shift at 128.3 ppm represented the C-5 carbon on the pyrazole ring, and the signal at
135.8 ppm corresponded to the azomethine group carbon (CH=N). Three signals were
detected in the lower range: one at 139.0 ppm (Cq) corresponding to the Ci of the
aromatic ring and another signal at 148.7 ppm (Cq) corresponding to the C-3 of the
pyrazole ring. These two signals have lower electron densities caused by the inductive
effect of the N-1 nitrogen atom for Ci and of the surplus N-2 π-character of the pyrazole
for the C-3. The last signal was observed at 177.3 ppm (Cq) and corresponded to the
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carbon thiocarbonyl group (C=S). A distortionless enhancement by polarisation transfer
(DEPT) 135 experiment identified the quaternary carbons in the structure (C-3 and C-4
on the pyrazole ring, Ci on the aromatic ring, and the carbon from the C=S bond), and
the bi-dimensional NMR experiments (heteronuclear single quantum correlation
spectroscopy (HSQC, Figure S 4) and heteronuclear multiple-bond correlation
spectroscopy (HMBC) confirmed the proposed structure.
[Pd(MePhPzTSC)2] Complex
The IR spectrum of the [Pd(MePhPzTSC)2] complex (Figure S 5) did not contain the
band at 3143 cm-1 that corresponds to the (N-H) elongation of the hydrazine group on
the free ligand, most likely because the group was deprotonated. The presence of a
new band with low intensity at 1156 cm-1 was attributed to the (N-N) elongation,
suggesting deprotonation of the hydrazine (N-H) group. The emergence of new bands
at 400 cm-1 and 441 cm-1 corresponding to (Pd-S) and (Pd-N), respectively, indicated
that the Pd(II) cation was coordinated to these donor atoms.7,9,10 However, no bands
were observed in the 305-335 cm-1 region, which is attributed to a (Pd-Cl) bond,10
suggesting that the chloride ligand is not in the coordination sphere. Coordination of the
ligand (MePhPzTSC) through its nitrogen and sulphur atoms to the metal ion was
confirmed because the bands from the C=N bond of the azomethine group and the C=S
bond were shifted compared to those observed in the spectrum of the
[Pd(MePhPzTSC)2] complex.
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1
When comparing the chemical shifts in the H NMR spectrum (Table 1) of the free
ligand with the complex [Pd(MePhPzTSC)2] in [DMSO-d6] (Figure S 6), the
corresponding proton from the NH-C=S group was observed to be absent, suggesting
enolisation of the ligand and not supporting the proposed structure of the ligand in the
tautomeric thione form. This result was also corroborated by the high-field shift of the
amino group protons that overlap with the signal corresponding to Hp. This shift
suggests a change in the electron density to this portion of the molecule (-CSNH2) due
to a change from a thione to a thiol in the thiocarbonyl group. The downfield shift of the
azomethine proton displayed a  = 0.07 ppm compared to that of the free ligand,
suggesting the group has a lower spectroscopic electron density and is coordinated to
the metal through the nitrogen atom.
(Table 1 goes here)
13
Assignments of the signals in the C NMR spectrum are based on the chemical shifts
and intensity patterns and coordination induced shift (CIS) of carbon signals in the
complex, in comparison to those of the free ligand,  =  (complex) -  (free ligand).
The 13C NMR spectrum of the [Pd(MePhPzTSC)2] complex (Figure S 7, Table 2)
displayed a signal at 172.2 ppm, which corresponds to the thiocarbonyl group, and
when compared to the same signal from the free ligand (177.3 ppm), the high-field shift
with a difference of 5.1 ppm () suggests a change from a thione to a thiol functional
group.11 This shift confirms that the sulphur atom in the thiol form of the ligand is
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coordinated to the Pd(II) cation.4,12 In addition, the signal corresponding to the carbon
atom in the azomethine group in the Pd(II) complex was observed at 144.2 ppm. This
chemical shift is downfield compared to the signal of the free ligand with a difference of
8.4 ppm (). This shift suggests that the nitrogen on the azomethine group has a lower
electron density, thereby confirming coordination of the nitrogen atom’s free electron
pair to the metal.4
(Table 2 goes here)
The positive ion FAB mass spectrum for the [Pd(MePhPzTSC)2] complex (Figure S 8),
showed two m/z peaks at 622.9272 and 644.9314 that correspond to M+ and [M-H +
Na]+, respectively. This complex, [Pd(MePhPzTSC)2], was prepared in a 1:1 ligand-
metal molar ratio, however the complex obtained presented a 2:1 ligand-metal molar
ratio. This is indicated by the FAB mass spectrum, as the peak of major abundance was
observed at a m/z 622.9272, confirming the molecular mass of the compound.
1
13
Considering this mass relation and the results obtained by H y C NMR spectra the
purity and proposed structure of the Pd(II) complex was corroborated.
Antimicrobial activity assays
The MePhPzTSC ligand, PdCl2 and the [Pd(MePhPzTSC)2] complex did not exhibit
antifungal activity in the range of concentrations tested, and the metal precursor did not
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exhibit antimicrobial activity in the range tested for any of the organisms (Table S 1
Supplemental Materials).
For the antibacterial activity assays, the pyrazolyl-thiosemicarbazone ligand,
MePhPzTSC, only registered growth inhibition for B. thuringiensis with a minimum
inhibitory concentration of 965 M (Table S1) and with an inhibition halo of 6 mm (Table
S2).
The [Pd(MePhPzTSC)2] complex registered activity for both gram-positive bacteria
examined (Tables S 1 and S 2). A minimum inhibitory concentration (MIC) of 322 M
was observed for S. aureus with an inhibition halo of 14 mm; the results suggest that
the antimicrobial activity occurs due to synergy between the metal and the ligand
because individually they showed no effect (Table S2). This behaviour can be explained
by the Overtone's concept of cell permeability13,14 and Tweedy's chelation theory.15
According to the Overtone’s concept, the lipid membrane surrounding the cell only
favours the passage of lipid-soluble materials; therefore, the lipid is an important factor
that controls antimicrobial activity. According to Tweedy’s theory, the polarity of the
Pd(II) cation is reduced by the overlap of the ligand orbitals and the partial exchange of
the metal ion’s positive charge to the donor atoms of the ligand, thereby increasing π-
electron delocalisation on the chelate ring and improving the lipophilicity of the complex.
This increased lipophilicity promotes penetration of the complex through the lipid
membranes and blocks the metal-binding sites on the enzymes of the microorganisms.
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This effect possibly disturbs the process of cell respiration and therefore blocks the
synthesis of the proteins that limit the organism’s growth.15 For B. thuringiensis, the
[Pd(MePhPzTSC)2] complex registered a MIC of 483 M (Table S 1 Supplemental
Materials) and an inhibition halo of 8 mm (Table S 2). As observed with S. aureus, an
increase in the antibacterial activity of the complex compared to that of the free ligand
was observed with B. thuringiensis (Table S 2). Again this shows the synergetic effect
that the ligand and the metal show when assembled as the Pd(II) complex. One could
expect a higher antimicrobial activity effect by the complex compared to the free ligand,
since the complex contains two ligand molecules in its structure. However, the
coordination between the ligand and the metal introduces different chemical
characteristics to the novel Pd(II) complex which not necessarily have additive
antimicrobial activity of the free ligand.
The results for antimicrobial activity showed that the synthesised compounds have
lower inhibition halos than the antibiotic positive controls (Table S 2). However,
considering the concentrations used for the antimicrobial controls in the biological
assays, it can be seen that the synthesised Pd(II) complex has a high growth inhibitory
effect on the Gram-positive bacteria evaluated. For example, for S. aureus a
concentration of 322 M of the [Pd(MePhPzTSC)2] complex originated a 14 mm zone of
inhibition, while for the same bacteria the positive antimicrobial control used
(cephalothin) showed a 34 mm zone of inhibition but at a 310 times higher
concentration (100’000 M). The same situation is observed for B. thuringiensis with an
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inhibition zone of 8 mm for the complex at 483 M concentration, while the control
showed a 14 mm inhibition zone but at a 207 times the concentration (100’000 M) of
the positive inhibition control cephalothin. It is interesting to notice that the free ligand, at
the concentration used (965 M), had only effect against B. thuringiensis and that this
inhibition was also higher (>100 times) than the positive antimicrobial control used.
These antimicrobial assays show an interesting potential of the newly synthesised
[Pd(MePhPzTSC)2] complex to be used as an antimicrobial compound directed
specifically to Gram-positive bacteria..Nevertheless, further studies should be carried
out to confirm the antimicrobial ability of the complex against other Gram-positive
bacteria. This complex should also be used in biological assays to observe its effect
against parasitic organisms and tumor cells, since similar Pd(II) compounds have
shown promising effects against these type of cells.1,2,16
EXPERIMENTAL
Determination of the synthesised compounds’ melting points was performed with a Melt-
Temp II melting point meter (Laboratory Devices). The IR spectra were captured from
4000 to 250 cm-1 using an FTIR-8400/8900 (Shimadzu) and a Nicolet iS10
Spectrometer (Thermo Fisher Scientific). The samples were prepared in KBr tablets.
1
The H and 13C NMR and two-dimensional spectra were determined on a 400 MHz
Bruker UltrashieldTM NMR spectrophotometer using DMSO-d6 as the deuterated
solvent. The high-resolution mass spectrum with an EBE configuration was captured on
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an AUTOSPEC-Q spectrometer. Positive ion FAB was used as the ionisation technique,
and thioglycerol was the ionisation matrix.
The following organisms were used for the antimicrobial assays: i) gram-positive
bacteria: Staphylococcus aureus ATCC 29213 and Bacillus thuringiensis sp., ii) gram-
negative bacteria: Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 700603,
and Pseudomonas aeruginosa sp., and iii) yeast strains: Candida albicans ATCC 10231
and Saccharomyces cerevisiae ATCC 38626.
Synthesis of the MePhPzTSC Ligand
The ligand, MePhPzTSC, was prepared by combining a 1:1 molar ratio of 3-methyl-1-
phenylpyrazole-4-carboxaldehyde (1 g, 5 mmol) and thiosemicarbazide (0.49 g, 5
mmol) in ethanol (20 mL) and refluxed for 4 h. Several drops of acetic acid were added
to the mixture as a catalyst. The white precipitate was filtered and washed three times
with ethanol to remove traces of the aldehyde precursor and was dried with anhydrous
calcium chloride. A 72% percent yield was obtained. The ligand is stable at room
temperature (19±1 °C) and is soluble in DMSO.
MePhPzTSC: Mp 200-204 ºC, yield 72%. IR (KBr)/cm-1 3423-3247 (NH2 asym and
sym), 3143 (NH hydrazine), 1590 (C=N azomethine), 1551 (C=N pyrazole), 1209
(NHC=S), 1096 (C=S). 1H NMR (DMSO-d6)  2.38 (s, 3H, CH3), 7.29 (t, 1H, J=7.5 Hz,
Hp), 7.46-7.50 (t, 3H, H-NH2, y, Hm), 7.78 (d, 2H, J=8.03Hz, Ho), 8.07 (s, 1H, CH=N),
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13
8.17 (brs, 1H, H-NH2), 8.85 (s, 1H, H-5pz), 11.33 ppm (s, 1H, NH-C=S). C NMR
(DMSO-d6)  13.2 (CH3), 117.3 (C-4 pz), 117.9 (Co), 126.2 (Cp), 128.3 (C-5 pz), 129.5
(Cm), 135.8 (CH=N), 139.0 (Ci), 148.7 (C-3 pz), 177.3 (C=S).
Synthesis of the [Pd(MePhPzTSC)2] Complex
The complex, [Pd(MePhPzTSC)2] (Graphical Abstract), was prepared in a 1:1 metal-
ligand molar ratio by adding a hot solution of MePhPzTSC (50 mg, 0.19 mmol) and
methanol (10 mL) to a refluxing solution of PdCl2 (35 mg, 0.20 mmol) in methanol (10
mL). The mixture was refluxed for 24 h. Fifty-four milligrams of an orange solid were
obtained and washed several times with methanol to remove excess Pd. The solid was
dried with anhydrous calcium chloride, and the percent yield of the synthesised complex
was 45%. The complex is stable at room temperature (19±1 °C) and is soluble in
DMSO.
[Pd(MePhPzTSC)2]: Decomposition temperature 208 ºC, yield 45%. IR (KBr)/cm-1 3446-
3308 (NH2 asym and sym), 1619 (C=N azomethine), 1536 (C=N pyrazole), 1156 (N-N),
863 (C-S), 400 (Pd-S), 441 (Pd-N). Mass (m/z) 622.9272 (M+ 100%), 644.9312 ([M-H +
1
Na]+ 23%). H NMR (DMSO-d6)  2.35 (s, 3H, CH3), 7.34-7.44 (t, 3H, NH2, y, Hp), 7.52
(t, 2H, J=7.58 Hz, Hm), 7.85 (d, 2H, J=7.57Hz, Ho), 8.14 (s, 1H, CH=N), 9.23 (s, 1H, H-5
13
pz). C NMR (DMSO-d6)  11.9 (CH3), 114.2 (C-4 pz), 119.1 (Co), 130.0(Cm), 127.4
(Cp), 132.7 (C-5 pz), 139.1 (Ci), 144.2 (CH=N), 152.2 (C-3 pz), 172.2 (C-S).
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Antimicrobial activity assays
The antibacterial activity was analysed by the disk diffusion method in a Petri dish using
TSA medium (Trypticase Soy Agar, Scharlau) for bacteria and PDA (Potato Dextrose
Agar, Scharlau) for yeasts. The minimum inhibitory concentration (MIC in mcg/mL or
ppm) of the studied compounds was estimated using the methodology of Bauer et al.17
The compounds (20 L each), in concentrations ranging between 50 and 500 ppm (282-
2820 M for PdCl2, 193-1930 M for MePhPzTSC, and 80-803 M for
[Pd(MePhPzTSC)2]), were dissolved in DMSO, and placed in 7 mm-diameter wells,
where the microorganisms under evaluation were grown (~108 UFC/mL) in their
respective culture media. The microbial cultures were incubated at 35 °C for 24 h for the
bacterial strains and at 20 °C for 72 h for the yeast strains. DMSO was used to prepare
the compounds and as the negative control for all of the growth inhibition assays.
Cephalothin (40 mg/mL) was used as the positive control for all bacterial strains, except
ciprofloxacin (0.3%), which was used for P. aeruginosa. Clotrimazole (1%) was used as
the positive control for the yeasts. The susceptibility of the microorganisms to each of
the tested compounds was determined by observing the formation of an inhibition zone
around each well on agar, which was measured in millimetres.
CONCLUSIONS
A new pyrazolyl-thiosemicarbazone ligand, MePhPzTSC, and its respective complex
with Pd(II), [Pd(MePhPzTSC)2], were synthesised and characterised. The ligand is a
bidentate chelator and coordinated to the metal through the nitrogen and sulfur atoms in
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its thiol form. The results obtained by various spectroscopic techniques confirmed the
proposed structure of each compound. The synthesised compounds showed
antimicrobial activity only against the gram-positive bacteria evaluated and this activity
was higher than that of the antibiotic controls. Compared to the free ligand, the metal
complex showed a better antimicrobial activity.
Supplemental Materials
Biological Activities
Table S 1: Minimum inhibitory concentration of PdCl2, MePhPzTSC, and the
[Pd(MePhPzTSC)2] complex in the examined microorganisms
Minimum inhibitory concentration (M) of the compound
Microorganism
E. coli
MePhPzTSC
> 1930
> 1930
> 1930
> 1930
965
[Pd(MePhPzTSC)2]
PdCl2
> 803
> 803
> 803
322
> 2820
> 2820
> 2820
> 2820
> 2820
> 2820
> 2820
K. pneumoniea
P. aeruginosa
S. aureus
B. thuringiensis
C. albicans
S. cerevisiae
483
> 1930
> 1930
> 803
> 803
Table S 2: Diameter of the antimicrobial inhibition halo for PdCl2, MePhPzTSC, the
[Pd(MePhPzTSC)2] complex, and the antibiotic control in the examined microorganisms
Inhibition halo (mm) over the growth of
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Bacteria
Yeasts
Compound
EC
0
KP
0
PA
0
SA
0
BT
6
CA
0
SC
0
MePhPzTSC
[Pd(MePhPzTSC)2]
PdCl2
0
0
0
14
0
8
0
0
0
0
0
0
0
0
Control antibiotic
20
10
40
34
14
25
30
EC, Escherichia coli; KP, Klebsiella pneumoniae; PA, Pseudomonas aeruginosa; SA,
Staphylococcus aureus; BT, Bacillus thuringiensis; CA, Candida albicans; SC, Saccharomyces
cerevisiae.
Figure S 1: IR spectrum of MePhPzTSC Ligand
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Figure S 2: 1H NMR spectrum of the MePhPzTSC ligand
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3
Figure S 3: 13C NMR spectrum of the MePhPzTSC ligand
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Figure S 4: HSQC Spectrum of MePhPzTSC ligand
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Figure S 5: IR spectrum of [Pd(MePhPzTSC)2]
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Figure S 6: 1H NMR spectrum of [Pd(MePhPzTSC)2]
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Figure S 7: 13C NMR spectrum of the [Pd(MePhPzTSC)2]
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Figure S 8: Positive ion FAB mass spectrum for the [Pd(MePhPzTSC)2]
REFERENCES
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1
Table 1. Chemical shift of H NMR (ppm) for MePhPzTSC ligand and [Pd(MePhPzTSC)2]
complex
δ (ppm)
Free ligand
(MePhPzTS
C)
δ (ppm)
Complex
[Pd(MePhPzT
SC)2]
Assign
ment
-(CH3)
2.38
2.35
CH=N
H-5
8.07
8.85
8.14
9.23
Ho
7.78
7.85
Hm
Hp
NH-C=S
7.46-7.50
7.29
11.33
7.52
7.34-7.44
11.33
8.17; 7.46-
7.50
N-H2
7.34-7.44
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13
Table 2. Chemical shift of C NMR (ppm) for MePhPzTSC ligand and [Pd(MePhPzTSC)2]
complex
δ (ppm)
Free ligand
(MePhPzTSC)
δ (ppm)
Complex
[Pd(MePhPzTSC)2]
δ =
δ (complex-free ligand)
(ppm)
Assignment
-CH3
C-3 pz
C-4 pz
C-5pz
CH=N
C=S
Ci
13.2
11.9
1.3
3.5
3.1
4.4
8.4
5.1
0.1
1.2
0.5
1.2
148.7
117.3
128.3
135.8
177.3
139.0
117.9
129.5
126.2
152.2
114.2
132.7
144.2
172.2
139.1
119.1
130.0
127.4
Co
Cm
Cp
Figure 1
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N
H2N
NH2
HN
N
N
N
S
N
N
S
Pd
S
N
MeOH, reflux
N
N
PdCl2
+
N
NH2
N
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