Water soluble organotin(IV) complexes with Girard-T reagent-based hydrazones: Synthesis, spectral characterization, and antibacterial activity

Article abstract of DOI:10.1080/00958972.2013.809424

Two ionic hydrazones, 3-methoxysalicylaldehyde and 4-hydroxysalicylaldehyde Girard-T hydrazinim chloride, (3-OMeH₂SalGT)Cl (1) and (4-OHH ₂SalGT)Cl (2), respectively, and five new water soluble diorganotin complexes R₂Sn((3-OMeSalGT)Cl [R = Ph (3), Me (4), Bu (5)], and R₂Sn(4-OHSalGT) Cl [R = Ph (6), Me (7)] have been synthesized. Spectroscopic data show that the ligand is deprotonated and coordinated to tin as a zwitterion using the imine nitrogen, and enolic and phenolic oxygens. The in vitro antibacterial activity of ligands and complexes has been evaluated against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. The ligands showed low activity while the organotin(IV) complexes exhibited remarkable inhibitory effects and with water solubility, these compounds have excellent potential to be used as drugs.

Full text of DOI:10.1080/00958972.2013.809424

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Water soluble organotin(IV) complexes with Girard-
T reagent-based hydrazones: Synthesis, spectral
characterization and antibacterial activity
TAHEREH SEDAGHAT a , ABBAS TARASSOLI a , ZEINAB ANSARI-ASL a & HOSSEIN MOTAMEDI b
a Department of Chemistry , College of Sciences, Shahid Chamran University , Ahvaz , Iran
b Department of Biology , College of Sciences, Shahid Chamran University , Ahvaz , Iran
Accepted author version posted online: 28 May 2013.
To cite this article: TAHEREH SEDAGHAT , ABBAS TARASSOLI , ZEINAB ANSARI-ASL & HOSSEIN MOTAMEDI (2013): Water soluble
organotin(IV) complexes with Girard-T reagent-based hydrazones: Synthesis, spectral characterization and antibacterial
activity, Journal of Coordination Chemistry, DOI:10.1080/00958972.2013.809424
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Water soluble organotin(IV) complexes with Girard-T reagent-based
hydrazones: Synthesis, spectral characterization and antibacterial activity
TAHEREH SEDAGHAT*†, ABBAS TARASSOLI†, ZEINAB ANSARI-ASL† and HOSSEIN MOTAMEDI‡
†Department of Chemistry, College of Sciences, Shahid Chamran University, Ahvaz, Iran
‡Department of Biology, College of Sciences, Shahid Chamran University, Ahvaz, Iran
Two ionic hydrazones, 3-methoxysalicylaldehyde and 4-hydroxysalicylaldehyde Girard-T
hydrazinim chloride, (3-OMeH2SalGT)Cl (1) and (4-OHH2SalGT)Cl (2), respectively, and five
new water soluble diorganotin complexes R2Sn((3-OMeSalGT)Cl [R = Ph (3), Me (4), Bu (5)]
and R2Sn(4-OHSalGT) Cl [R = Ph (6), Me (7)] have been synthesized. Spectroscopic data show
that the ligand is deprotonated and coordinated to tin as a zwitterion using the imine nitrogen,
and enolic and phenolic oxygens. The in vitro antibacterial activity of ligands and complexes has
been evaluated against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-
negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. The ligands showed low
activity while the organotin(IV) complexes exhibited remarkable inhibitory effects and with
water solubility have excellent potential to be used as drugs.
Keywords: Girard-T; Organotin; Water solubility; Antibacterial activity; Hydrazone
1. Introduction
Schiff bases and their metal complexes have industrial and biological applications [1-3]. In spite
of a large number of studies involving the synthesis and characterization of these compounds,
there are only a few investigations on ionic Schiff bases. Condensation of Girard’s reagents T
(trimethylammoniumacetohydrazide chloride), P (pyridiniumacetohydrazide chloride) and others
with ketones or aldehydes forming water-soluble ionic hydrazones represents an interesting
research subject. Although these Schiff bases are similar to semicarbazones and acid hydrazones,
only a few complexes of Girard reagent hydrazones with transition metals have been reported
[4-13]. To the best of our knowledge, no attempt has been made to synthesize organotin(IV)
complexes with Girard reagent-based ligands. Organotin(IV) complexes have chemical
properties, biological significance, industrial importance, and structural variety. Among the non-
platinum complexes exhibiting anticancer properties, organotin compounds have received
*Corresponding author. Email: tsedaghat@scu.ac.ir
1

considerable attention. They may show no cross-resistance and possess less or different toxicity
than platinum drugs. Many organotin(IV) compounds have been synthesized and tested for their
antitumor activities [14-18]. In many cases in vitro activity of these compounds was not retained
under in vivo conditions, frequently from lack of water solubility of these molecules. Solubility
in water dominates the in vivo testing of compounds with promising in vitro properties [19, 20].
As a part of our studies on organotin(IV) complexes [21-25], and to design organotin(IV)
complexes with improved water solubility, herein we report synthesis, characterization and
antibacterial activity of two Girard-T hydrazones, (3-OMeH2SalGT)Cl and (4-OHH2SalGT)Cl,
derived from condensation of Girard’s T reagent with 3-methoxysalicylaldehyde and
4-hydroxysalicylaldehyde, respectively, and their diorganotin(IV) complexes.
2. Experimental
2.1. Materials and methods
All starting materials were purchased from Merck while diphenyltin dichloride and Girard-T
reagent were supplied from Alfa Aesar and Acros Company, respectively; all were used as
received. All solvents were of reagent grade and used without purification. IR spectra were
obtained using a FT BOMEM MB102 spectrophotometer. 1H and 119Sn{1H} NMR spectra were
recorded with a Bruker 400 MHz Avance Ultrashield spectrometer using TMS and SnMe4, as
references, respectively.
2.2. Synthesis of (3-OMeH2SalGT)Cl (1)
3-Methoxysalicylaldehyde (0.760 g, 5 mmol) in absolute methanol (5 mL) was added slowly to a
solution of Girard-T (0.835 g, 5 mmol) in absolute methanol (7 mL) with constant stirring. The
resulting solution was refluxed for 60 min at 80 °C. A white precipitate formed after evaporating
the solvent at room temperature. The resulting product was collected, washed with ethanol
followed by diethyl ether and dried over CaCl2.
Yield: 0.869 g (60%); m.p. 110-115 °C; Anal. Calc. for C13H20ClN3O3 (%): C, 51.74; H,
6.68; N, 13.92. Found: C, 51.50; H, 6.74; N, 13.46. FT-IR (KBr, cm-1): 3450-3420 br, ν(OH);
3160, ν(NH); 3020, 2930, ν(CH); 1692, ν(C=O); 1612, ν(C=N). 1H NMR (DMSO-d6): δ = 13.3
(s, br, NH), 12.06 (s, OHenolic), 10.43, 9.38 (s, OHphenolic), 8.65, 8.46 (s, HC=N), 7.36-6.81
(aromatic protons), 4.81, 4.45 (s, CH2), 3.82, 3.80 (s, OCH3), 3.34, 3.31 (s, NCH3).
2

2.3. Synthesis of (4-OHH2SalGT)Cl (2)
Girard-T (0.835 g, 5 mmol) in methanol (7 mL) was added to a solution of 4-hydroxy
salicylaldehyde (0.690 g, 5 mmol) in methanol (5 mL) and stirred for 30 min. During this time a
white precipitate gradually formed, was collected, washed with ethanol followed by diethyl ether
and dried over CaCl2.
Yield: 1.338 g (93%); m.p. 250 °C; Anal. Calc. for C12H18ClN3O3 (%): C, 50.09; H, 6.31;
N, 14.60. Found: C, 50.33; H, 6.15; N, 14.84. FT-IR (KBr, cm-1): 3250-3150 br, ν(OH); 3113,
ν(NH); 3012, 2905, ν(CH); 1693, ν(C=O); 1618, ν(C=N). 1H NMR (DMSO-d6): δ = 12.70 (s, br,
NH), 11.73 (s, OHenolic), 10.97, 10.08, 9.97 (s, OHphenolic), 8.42, 8.25 (s, HC=N), 7.54, 7.37 (d,
H6, J = 9.0 Hz), 6.41-6.31 (m, H3,5), 4.73, 4.31 (s, CH2), 3.30, 3.28 (s, NCH3).
2.4. Synthesis of Ph2Sn((3-OMeSalGT)Cl (3)
Triethylamine (0.28 mL, 2 mmol) was added to a stirring solution of (3-OMeH2SalGT)Cl
(0.289 g, 1 mmol) in absolute methanol (7 mL). Then a solution of Ph2SnCl2 (0.340 g, 1 mmol)
in methanol (3 mL) was added. This solution was refluxed for 120 min at 80 °C. During this
time, a yellow precipitate gradually formed. The product was filtered, washed with cool ethanol
and dried in vacuum on CaCl2. Yield: 0.3 g (52%); m.p. 250 °C; Anal. Calc. for
C25H28N3O3ClSn (%): C, 52.43; H, 4.94; N, 7.34. Found: C, 52.54; H, 4.64; N, 7.29. FT-IR
1
(KBr, cm-1): 1612, 1605, ν(C=N); 1212, ν(C-O); 548, ν(Sn-O); 461, ν(Sn-N). H NMR
3
(DMSO-d6): δ = 8.65 [s, 1H, CH=N, J(119Sn-1H) = 40.0 Hz], 7.56 [dd, 4H, Ho in SnPh2, 3JHH
=
7.4, JHH = 1.8, J(119Sn-1H) = 86.7 Hz], 7.31-7.36 (m, 6H, Hm,p in SnPh2), 7.00-7.06 (m, 2H,
4
3
H4,6), 6.68 (dd, 1H, H5, J = 7.9, 7.9 Hz), 4.17 (s, 2H, CH2), 3.77 (s, 3H, OCH3), 3.12 (s, 9H,
13
N-CH3). C NMR (DMSO-d6): δ = 53.08 (NCH3), 55.91 (OCH3), 65.76 (C9), 115.65 (C1),
116.29 (C4), 117.33 (C5), 126.39 (C6), 127.94 [Cmeta in SnPh2, 3J(119Sn-13C) = 60.6 Hz], 128.26
2
[Cpara in SnPh2], 134.20 [Cortho in SnPh2, J(119Sn-13C) = 60.0 Hz], 136.39 [Cipso in SnPh2)],
150.08 (C7), 151.30 (C2), 159.31 (C3), 164.12 (C8). 119Sn{1H} NMR (DMSO-d6): δ = -443.2.
2.5. Synthesis of Me2Sn((3-OMeSalGT)Cl (4)
(3-OMeH2SalGT)Cl (0.289 g, 1 mmol) was dissolved in MeOH (7 mL) in presence of NEt3
(0.28 mL, 2 mmol). This solution was stirred for 30 min and then Me2SnCl2 (0.220 g, 1 mmol) in
3

methanol (3 mL) was added. The solution was refluxed for 180 min at 80 °C. A yellow
precipitate formed after evaporating the solvent at room temperature. This product was collected,
washed with cool ethanol and dried in vacuum on CaCl2. Yield: 0.4 g (89%); m.p 198 °C; Anal.
Calc. for C15H24N3O3ClSn (%): C, 40.17; H, 5.39; N, 9.37. Found: C, 40.29; H, 5.89; N, 9.00,
FT-IR (KBr, cm-1): 1619, 1605, ν(C=N); 1214, ν(C-O); 546, ν(Sn-O); 417, ν(Sn-N); 610,
νas(Sn-C); 585, νs(Sn-C). 1H NMR (DMSO-d6): δ = 8.58 [s, 1H, CH=N, 3J(119Sn-1H) = 22.0 Hz],
6.94-6.97 (m, 2H, H4,6), 6.61 (dd, 1H, H5 , J = 7.8, 7.8 Hz), 4.1 (s, 2H, CH2), 3.71 (s, 3H, OCH3),
2
13
3.22 (s, 9H, N-CH3), 0.68 [s, 6H, Sn-CH3, J(119Sn-1H) = 96.4 Hz]. C NMR (DMSO-d6): δ =
10.57 [SnCH3, 1J(119Sn-13C) = 876.6 Hz], 53.25 (NCH3), 55.40 (OCH3), 65.53 (C9), 115.30 (C1),
115.70 (C4), 116.83 (C5), 126.05 (C6), 151.08 (C7), 156.24 (C2), 160.47 (C3), 164.70 (C8).
119Sn{1H} NMR (DMSO-d6); δ = -272.9.
2.6. Synthesis of Bu2Sn((3-OMeSalGT)Cl (5)
This complex was synthesized as described for 4 from Bu2SnCl2 (0.304 g, 1 mmol). Yield:
0.43 g (82%); m.p. 140 °C; Anal. Calc. for C21H36N3O3ClSn (%): C, 47.35; H, 6.81; N, 7.88.
Found: C, 48.00; H, 6.38; N, 7.85. FT-IR (KBr, cm-1): 1622, 1601, ν(C=N); 540, ν(Sn-O); 423,
1
ν(Sn-N). H NMR (DMSO-d6): δ = 8.61 [s, 1H, CH=N], 6.58-6.94 [m, 2H, H4,6], 6.55 [dd, 1H,
H5, J = 7.8, 7.8 Hz], 4.13 (s, 2H, CH2), 3.71 (s, 3H, OCH3), 3.24 (s, 9H, N-CH3), 0.74 (t, J =
8 Hz, 6H, Hδ), 1.31-1.34 (m, 4H, Hγ), 1.35-1.43 (m, 8H, Hα,β). 13C NMR (DMSO-d6): 13.51 (Cδ
3
2
in SnBu2), 25.65 [Cγ in SnBu2, J(119Sn-13C) = 126.1 Hz], 26.87 (Cβ in SnBu2, J(119Sn-13C) =
34.4 Hz), 29.21 (Cα in SnBu2), 53.16 (NCH3), 55.50 (OCH3), 65.33 (C9), 115.03 (C1), 115.89
(C4), 116.68 (C5), 126.18 (C6), 150.98 (C7), 157.22 (C2), 161.04 (C3), 165.20 (C8).
119Sn{1H} NMR (DMSO-d6): δ = -303.5.
2.7. Synthesis of Ph2Sn((4-OHSalGT)Cl (6)
Complex 6 was synthesized as described for 3 from (4-OHH2SalGT)Cl (0.287 g, 1 mmol). Yield:
0.34 g (61%); m.p. 272-274 °C (dec.); Anal. Calc. for C24H26N3O3ClSn (%): C, 51.60; H, 4.69;
N, 7.52. Found: C, 51.53; H, 4.96; N, 8.04, FT-IR (KBr, cm-1): 1623, 1600, ν(C=N); 558,
1
ν(Sn-O); 450, ν(Sn-N). H NMR (DMSO-d6); δ = 8.54 [s, 1H, CH=N], 7.55-7.57 [m, 4H, Ho in
3
SnPh2, J(119Sn-1H) = 85.7 Hz], 7.34-7.36 (m, 6H, Hm,p in SnPh2), 7.26 (d, 1H, H6, J = 9.1 Hz),
6.24-6.35 (m, 2H, H3,5), 4.16 (s, 2H, CH2), 3.16 (s, 9H, N-CH3). 13C NMR (DMSO-d6): δ =
4

53.12 (NCH3), 65.87 (C9), 106.45 (C1), 106.97 (C6), 110.44 (C5), 128.05 [Cmeta in SnPh2),
2
3J(119Sn-13C) = 90.1 Hz], 128.46 [Cpara in SnPh2)], 134.20 [Cortho in SnPh2), J(119Sn-13C) =
57.3 Hz], 148.90 [Cipso in SnPh2)], 136.91 (C3), 159.01 (C7), 162.76 (C2), 164.26 (C4), 168.73
(C8). 119Sn{1H} NMR (DMSO-d6): δ = -433.9.
2.8. Synthesis of Me2Sn((4-OHSalGT)Cl (7)
Complex 7 was synthesized as described for 4 from (4-OHH2SalGT)Cl (0.287 g, 1 mmol). Yield:
0.31 g (80%); m.p. 237 °C; Anal. Calc. for C14H22N3O3ClSn (%): C, 38.69; H, 5.10; N, 9.67.
Found: C, 38.49; H, 4.78; N, 9.76. FT-IR (KBr, cm-1): 1605, ν(C=N); 621, νas(Sn-C); 552,
1
νs(Sn-C); 552, ν(Sn-O); 429, ν(Sn-N). H NMR (DMSO-d6): δ = 8.52 [s, 1H, CH=N,
3J(119Sn-1H) = 35.1 Hz], 7.20 (d, 1H, H6, J = 8.7 Hz), 6.21 [dd, 1H, H5, J = 8.6, 2.2 Hz], 6.05 (d,
1H, H3, J = 2.2 Hz), 4.01 (s, 2H, CH2), 3.17 (s, 9H, N-CH3), 0.67 [s, 6H, Sn-CH3, 2J(119Sn-1H) =
1
88.3 Hz]. 13C NMR (DMSO-d6): δ = 7.42 [SnCH3, J(119Sn-13C) = 811.4 Hz], 53.23 (NCH3),
65.61 (C9), 105.86 (C1), 106.91 (C6), 109.94 (C5), 136.76 (C3), 160.91 (C7), 163.22 (C2),
164.68 (C4), 168.25 (C8). 119Sn{1H} NMR (DMSO-d6): δ = -223.4.
2.9. Antibacterial tests
The in vitro antibacterial activities of ligands and their corresponding organotin(IV) complexes
were investigated against standard strains of two Gram-positive (Bacillus subtilis ATCC 12711
and Staphylococcus aureus ATCC 6538) and two Gram-negative (Escherichia coli ATCC 11303
and Pseudomonas aeruginosa ATCC 27853) bacteria. In order to compare the results,
Vancomycin (30 mg/disc), Streptomycin (10 mg/disc), penicillin (10 mg/disc), Nalidixic acid
(30 mg/disc) and Gentamicin (10 mg/disc) were used as standard antibacterial drugs.
Determination of the antibacterial activity was carried out by paper-disc diffusion method. The
solutions from 3 and 6 in DMSO and 1, 2, 4, 5 and 7 in H2O were prepared at 5, 10, 20 and
40 mg/mL concentration. Muller Hinton broth was used for preparing basal media for the
bioassay of the organisms. A lawn culture from 0.5 MacFarland suspension of each strain was
prepared on Muller Hinton agar. Blank paper discs (6.4 mm diameter) were saturated with a
solution of test compounds (40 μL) and placed on the surface of the agar plates. On one paper
disc only DMSO was poured as a control. The plates were incubated at 37 °C for 24 h. The
inhibition zone diameters around each disc were measured in mm.
5

3. Results and discussion
3.1. Synthesis
Condensation of the Girard’s
T
reagent [(NH2-NH-C(=O)-CH2N(CH3)3]Cl with
3-methoxysalicylaldehyde and 4-hydroxysalicylaldehyde gives the corresponding hydrazones as
ammonium quaternary salts, (3-OMeH2SalGT)Cl (1) and (4-OHH2SalGT)Cl (2), respectively.
Owing to the existence of ketoamide (NH-C=O) in these compounds two tautomers, keto-amine
and enol-imine, are possible. The synthetic pathway and tautomeric forms of 1 and 2 are shown
in figure 1. According to the literature [10, 12], in the solid state such compounds are in keto-
amine form (I) and associated with the organic cation through a short hydrogen bond with
chloride. Organotin(IV) complexes 3-7 were prepared by reaction of R2SnCl2 (R = Ph, Me or
Bu) with the corresponding hydrazone in methanol in the presence of NEt3 as a base. The ligands
and complexes are stable in air, soluble in DMSO and DMF, less soluble in EtOH and CHCl3
and insoluble in Et2O. Compounds 3 and 6 are moderately soluble and the others are readily
soluble in water. The ligands and complexes were characterized by elemental analysis and IR
and NMR spectroscopy. Attempts to grow single crystals suitable for X-ray crystallography were
abortive.
3.2. Spectroscopic studies
IR spectra of ligands NH and C=O stretches indicate tautomeric form I in the solid state. In IR
spectra of the complexes disappearance of ν(O-H) and ν(N-H) shows deprotonation of ligand and
subsequent coordination to tin. The strong and sharp band assigned to ν(C=O) in the ligand at
1692 cm-1 is absent in spectra of complexes supporting ligand coordination in the enol form. The
ν(C=N) at 1612-1618 cm-1 in the spectra of ligands shifts to lower frequency indicating
coordination of azomethine nitrogen. The appearance of new bands in the IR spectra of
complexes at 417-461 and 558-540 cm-1 assigned to ν(Sn–N) and ν(Sn–O), respectively,
supports bonding of nitrogen and oxygen to tin [26].
1
In H NMR spectra of free Schiff bases two groups of signals were observed from
presence of tautomeric forms I and II in solution. The ratio of the integrals of the signals
provides a reliable measure of ketonic to enolic forms in solution as 55:45 for 1 and 60:40 for 2.
1
In H NMR spectra of complexes the absence of signals for two acidic hydrogens suggests
6

deprotonation and coordination of phenolic and enolic oxygens. The signal attributable to imine
proton of the free ligands is accompanied by satellites in complexes due to 3J(119Sn-H) coupling,
1
an indication that the imine nitrogen is coordinated to tin(IV). The H NMR spectrum of
dimethyl complexes shows a singlet at low frequency for SnMe2 accompanied by satellites
because of 119Sn-1H coupling. Substitution of this coupling constant in the Lockhart–Manders
equation [27] gives the values 155.8 and 142.4° for the Me-Sn-Me angle in 4 and 7, respectively,
in DMSO.
The 119Sn{1H} NMR spectra of all complexes show one sharp singlet at lower frequency
than SnPh2Cl2 (-32 ppm), SnBu2Cl2 (+122 ppm) and SnMe2Cl2 (+137 ppm). 119Sn NMR
chemical shift is strongly dependent on the coordination number of tin, and an increase in
coordination number produces a large upfield shift. On the basis of the chemical shift ranges
proposed empirically for organotin(IV) derivatives [28-32], the coordination number of tin is six
for all complexes.
3.3. Antibacterial studies
The in vitro antibacterial activities of the Schiff bases and their organotin(IV) complexes were
evaluated along with five standard antibacterial drugs, viz, Vancomycin, Streptomycin,
penicillin, Nalidixic acid and Gentamycin. The microorganisms used in this work include
Bacillus sabtilis and Staphylococcus aureus (as Gram-positive bacteria) and Escherichia coli and
Pseudomonas aeruginosa (as Gram-negative bacteria). The results are presented in table 1.
Comparing the biological activity of the Schiff bases, organotin(IV) complexes and standard
drugs, reveals that the organotin complexes have activity against all bacteria under investigation
and show more inhibition than the parent ligands. Enhanced antibacterial activity of the ligand
on complexation may be due to electron delocalization over the whole chelate ring increasing the
lipophilic character which favors permeation of the complexes through the lipid layer of the cell
membrane [33-36] and also because of the intrinsic biological activity of organotin. Bacteria of
the genus Pseudomonas are a resistant microorganism that many standard drugs have no activity
against [37, 38]. Therefore it is interesting that P. aeruginosa was remarkably inhibited by all
complexes. In most cases toxicity towards S. aureus (as Gram-positive bacteria) is more than
Gram(-) strains. The reason is the difference in the structures of cell walls. The walls of Gram(-)
cells are more complex than those of Gram(+) cells. Lipopolysaccharides form an outer lipid
7

membrane and contribute to the complex antigenic specificity of Gram(-) cells. The antibacterial
activities of compounds are due to either killing the bacteria or inhibiting multiplication of them
by blocking their active sites. A mechanism postulated for action of antibacterial compounds is
deactivation of various cellular enzymes or denaturation of one or more proteins of the cell
[39-42]. Lipophilicity is an important factor making the drug more soluble in lipids which
facilitate microorganism membrane crossing. Solubility in water is important for activity in vivo.
In view of the remarkable biological activities of synthesized complexes with solubility in both
water and organic solvents, these compounds have excellent potential as drugs.
4. Conclusion
On the basis of the above discussion and with due regard to the structure of transition metal
complexes with similar ligands [4, 10, 12], the aforesaid Schiff bases were coordinated as twice-
deprotonated using ONO donors. Therefore the complexes are six-coordinate and neutral
(figure 2). The synthesized organotin complexes are remarkable in inhibiting Gram-positive
(Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and
Pseudomonas aeruginosa) bacterial species. These new complexes are the first examples of
organotin compounds with Girard reagent-based ligands. In view of the solubility of these
complexes in both water and organic solvents, they are good candidates for cytotoxicity studies
and solubility in water dominates the in vivo testing of compounds with promising in vitro
properties. This research opens new avenues to study water soluble organotin(IV) complexes
with potential biological activities. This project is currently under study in our laboratory.
Acknowledgement
Support of this work by Shahid Chamran University, Ahvaz, Iran is gratefully acknowledged.
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10

Table 1. Antibacterial activity data of ligands and their organotin(IV) complexes.
Inhibition zone (mm)
Conc.
Compound
(mg/mL)
E. Coli
P. aeruginosa S. aureus B. subtilis
5
7
7
8
13
17
17
20
8
9
14
16
7
9
10
12
1
2
3
4
5
6
7
10
20
40
16
5
7
7
9
15
15
18
20
8
8
10
15
7
7
7
9
10
20
40
16
5
23
23
24
24
12
14
17
19
n.c.
n.c.
n.c.
n.c.
29
33
34
34
10
20
40
5
22
24
25
27
14
18
24
24
19
23
24
26
30
30
30
31
10
20
40
5
10
16
18
20
14
20
24
27
7
8
12
14
17
23
23
31
10
20
40
5
8
9
7
7
9
19
21
25
30
10
20
40
14
19
25
11
19
24
11
5
22
24
27
28
13
16
18
19
n.c.
n.c.
n.c.
n.c.
28
32
33
38
10
20
40
Vancomycin
Streptomycin
Penicillin
19
16
12
25
20
n.a.
n.a.
n.a.
n.a.
20
17
12
19
12
16
24
22
13
23
21
Nalidixic acid
Gentamicin
n.a. = no activity; n.c. = no check
11

X
H3C
O
HO
Y
H3C
N
NH2
+
N
H
O
H3C
Cl
H
X
X
3
HO
Y
HO
Y
2
1
H3C
4
H3C
OH
O
H3C
H3C
N
N
N
N
5
8
N
N
9
6
H3C
7
Cl
H3C
H
Cl
(3-OMeH2SalGT)Cl (1): X = OMe, Y = H
(4-OHH2SalGT)Cl (2): X = H, Y = OH
(I)
(II)
Figure 1. Synthetic pathway and tautomeric forms of ligands.
12

X
Cl
N
R
R
O
Y
Sn
H3C
O
H3C
N
N
H3C
(3) R = Ph, X = OMe, Y = H
(4) R = Me, X = OMe, Y = H
(5) R = Bu, X = OMe, Y = H
(6) R = Ph, X = H, Y = OH
(7) R = Me, X = H, Y = OH
Figure 2. Suggested structures for 3-7.
13