Benzimidazole derivatives play an important role in medicinal field with many biological and pharmacological activities. Therefore the synthesis of hydrazones containing benzimidazole and their organotin(IV) complexes are the potential area of research. In this work we have synthesized and characterized two hydrazones bearing benzimidazole, H2La and H2Lb, by condensation of 4-(1H-benzimidazole-2-yl)benzoic acid hydrazide with 5-bromo-salicylaldehyde and 2-hydroxynaphthaldehyde, respectively. The new organotin(IV) complexes, SnPh2La, SnMe2La, SnPh2Lb, SnMe2Lb, have been synthesized by reaction of the corresponding ligand with SnR2Cl2 (R= Ph, Me) in presence of triethylamine. The hydrazones and their complexes have been investigated by IR, 1H NMR and 119Sn NMR spectroscopy. In all complexes hydrazine acts as a tridentate dianionic ligand and coordinates via the imine nitrogen and phenolic and enolic oxygen atoms. On the basis of 119Sn NMR, coordination number of tin is five in solution The in vitro anticancer activity of ligands and complexes has been determine against Caco-2 cells by MTT method. It has been observed that the complexes were found to be more effective than ligand. The DNA cleavage activity of all compounds has been studied by agarose gel electrophoresis method.

Due to the importance of hydrazonic schiff base complexes and their potential antibacterial activities, in this research work, new hydrazonic ligand (H2L) was prepared by condensation of 3-hydroxy-2-naphthonic acid hydrazide with 2,4-dihydroxy benzaldehyde. It was characterized by 1HNMR, IR, and UV-Vis spectroscopy. Then, the new ternary complexes [NiL(Imd)], [NiL(MeImd)], [NiL(2,2-Bpy)], [PdL(Imd)], [PdL(MeImd)], [NiL(4,4-Bpy)], [ZnL(MeImd)], [ZnL(4,4-Bpy)], [ZnL(2,2-Bpy)] have been synthesized by reaction of the hydrazonic ligand with Ni(CH3COO)2.2H2O , Zn((CH3COO)2.4H2O and PdCl2 in the presence of 2,2-Bipyridine, 4,4-bipyridine, Imidazole or 2-MethylImidazole as auxiliary ligand. These complexes have been investigated by elemental analysis, IR, UV-Vis, 1HNMR spectroscopy. Thermal behavior of the complexes was investigated by thermogravimetry analysis. On the basis of these data, in all complexes hydrazone acts as a tridentate dianionic ligand and coordinates via enolate oxygen, azomethine nitrogen and phenolic oxygen atoms. Coordination sphere of complexes was completed by co-ligand. The in vitro antibacterial activity of ligand and its complexes has been evaluated against two Gram-positive (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and compared with the standard antibacterial drugs.

In view of biological and structural importance of organotin(IV) complexes with Schiff bases, in this research work Schiff bases H2L1.HCl, H2L2.HCl and H2L3.HCl were prepared from the reaction of 2-aminophenol, 2-amino-4-cholorophenol and 2-amino-4-methylphenol with pyridoxal hydrochloride respectively. Then the new organotin(IV) complexes, SnMe2L1, SnMe2L2, SnBu2L2 and SnMe2L3 have been synthesized by reaction of SnR2Cl2 (R= Me, Bu) with corresponding Schiff bases in the presence of triethylamine. The new compounds were characterized by elemental analysis, IR, 1HNMR, 13CNMR and 119SnNMR spectroscopies. The structure of SnMe2L1, SnBu2L2 and SnMe2L3 have been also confirmed by X-ray crystallography. On the basis of these data in all complexes Schiff bases are completely deprotonated and coordinated to tin(IV) as dianionic tridentate ONO ligand via imine nitrogen and two phenolic oxygens. The geometry around the tin atom in SnBu2L2 is distorted square pyramidal with butyl group in apical position. The structure of SnMe3L3 and SnMe3L1 is distorted square pyramid that imine nitrogen occupies the apical position but the sixth coordination site is occupied by phenolic oxygen atom of neighboring molecule and a dimer was formed. The in vitro antibacterial activity of the ligands and synthesized complexes has been evaluated against Gram-negative (Escherichia coli and Pseudomonas aeruginosa ) and Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacteria and compared with standard drugs. The DNA cleavage activity of all compounds has been studied by agarose gel electrophoresis method.

Synthesis and structural investigation of hydrazones, as a kind of Schiff bases, and
their metal complexes have attracted great and growing interest due to their
coordinative properties and versatile applications. They have been well known to be
biologically important and found to have therapeutic activity. At first, H2L1 was
synthesized from the reaction of furan-2-carbohydrazide and benzoylacetone. Bisacylhydrazones (H4L2 and H4L3) have been also prepared by reacting of
benzoylacetone, with adipic dihydrazide acid and succinic dihydrazide acid,
respectively. The synthesized ligands were characterized by elemental analysis, FT-IR
and 1HNMR spectroscopy. The structures of H2L1 and H4L3 have been also
investigated by X-ray crystallography. Then, the new mononuclear and binuclear
organotin(IV) complexes, [R2SnL1] (R = Me, R = Ph), [R2Sn] 2L2 and [R2Sn]2L3 have
been synthesized via reacting of the related hydrazone and dihydrazone ligand with
R2SnCl2(R= Me or Ph) ,respectively, in alcoholic solvents, in the presence of
triethylamine. The synthesized compounds were chercterized by elemental analysis,
Ft-IR, 1H NMR, 13C NMR and 119Sn NMR spectroscopy. The structures of Me2SnL1
and [Me2Sn]2L2 have been also confirmed by X-ray crystallography. On the basis of
evidence obtained from X-ray crystallography and other analysis, hydrazone and
dihydrazone exist exclusively in cyclic form in both solid phase and solution. These
ligands undergo a ring opening reaction on complexation with tin, during which they
are doubly deprotonated and coordinated to this metal through imine and enolic
oxygens as tridentate ligands. Coordiation number of tin in Me2SnL1 is five and the
geometry is between square-pyramidal and trigonal-bipyramidal. [Me2Sn]2L2 is
binuclear and the coordination number of tin is five in solution. The geometry around
tin atom is between square-pyramidal and trigonal-bipyramidal.
The in vitro antibacterial activity of ligands and its complexes have been evaluated
against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gramnegative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Ph2SnL1 and
(Me2Sn)2L3 complex exhibited good activities along with the standard antibacterial
drugs. The DNA cleavage activity of all compounds has been studied by agarose gel
electrophoresis method.

In this research work hydrazones, H2L1 and H2L2, were prepared by condensation of benzhydrazide with 2,4-dihydroxyacetophenone and 2,4-dihydroxybenzaldehyde, respectively. Then the new ternary complexes, [CuL1Phen], [CuL1bipy].EtOH, [ZnL1Phen].0.5.H2O, [NiL1Phen].H2O, [NiL1Imd]. EtOH, [CuL2Imd]. H2O, [CuL2 bipy.H2O] and [NiL2 bipy].H2O have been synthesized by reaction of corresponding metal(II) acetate salt with H2L1 and H2L2 in presence of heterocyclic bases, such as phenanthroline, bipyridine or imidazole, as auxiliary ligands. All the compounds were investigated by elemental analysis , FT-IR, UV-Vis or 1H NMR spectroscopy. The structure of H2L1 was also determined by X-ray crystallography. The thermal behavior of complexes was studied by thermogravimetry. On the basis of these data, in all the complexes hydrazone acts as a tridentate dianionic ligand and coordinates via imine nitrogen and phenolic and enolic oxygens. Coordination sphere of complexes are completed by heterocyclic base. The in vitro antibacterial activity of ligands and complexes has been evaluated against Gram-positive (Bacillus sabtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and compared with standard drugs.

In view of the importance and potential applications of thiosemicarbazones and their complexes, this research work describes the synthesis, spectral and structural studies and antibacterial activity of a thiosemicarbazone and thirteen new complexes. The pyridoxal thiosemicarbazone (H3L+Cl-) has been synthesized by condensation of the N(4)-phenythiosemicarbazide and 3-hydroxy-5-(hydroxymethyl)-2-methyl-4-pyridinecarbaldehyde. Then the new complexes [Zn(OAC)(H2O)HL].H2O, [Cu(Cl)HL].H2O, [Ni(OAC)(H2O)HL].H2O, [Zn(Imd)(Cl)HL].H2O, [Cu(Imd)(Cl)HL], [Ni(Imd)(Cl)HL] , [Zn(Phen)HL]Cl.2H2O, [Cu(Phen)(Cl)HL].H2O, [Ni(Phen)(Cl)HL].2H2O, [Zn(bpy)(Cl)HL].2H2O, [Cu(bpy)HL]Cl.2EtOH, [Ni(bpy)(Cl)HL].H2O and [Ni(PPh3)(Cl)(H2O)HL].2H2O, have been synthesized by reaction of the ligand with Zn(II), Cu(II) and Ni(II) acetate salts and also with Ni(pph3)2Cl2 in presence or in absence of heterocyclic bases, imidazole, bipyridine and phenanthroline as auxiliary ligands. All compounds have been characterized by FT-IR, UV-Vis, 1H NMR, thermal and elemental analysis spectroscopy. The structures of [Zn(OAC)(H2O)HL].H2O, [Cu(Cl)HL].H2O, [Zn(Imd)(Cl)HL].H2O, [Zn(Phen)HL]Cl.2H2O and [Cu(bpy)HL]Cl.2EtOH have been also confirmed by X-ray crystallography. In all the complexes thiosemicarbazone is doubly protonated and as a tridentate ligand and coordinates via phenolic oxygen, the azomethine nitrogen and thiolate sulfur atoms. The metal coordination geometry for [Zn(OAC)(H2O)HL].H2O, [Zn(Imd)(Cl)HL].H2O and [Cu(bpy)HL]Cl.2EtOH is described as distorted square pyramid, for [Cu(Cl)HL].H2O as square planar and for [Zn(Phen)HL]Cl.2H2O is between square-pyramidal and trigonal-bipyramidal. The crystal lattices are stabilized by intermolecular hydrogen bands. The in vitro antibacterial activity of ligand and its complexes has been evaluated against two Gram-positive (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative bacteria (Escherichia coli and Pseudmonas aeruginosa). All compounds exhibited good activities along with the standard antibacterial drugs.

 In view of biological and structural importance of organotin(IV) complexes with Schiff bases, in this research work Schiff bases H2L1, H2L2, H2L3 and H2L4 were prepared from reaction of 3-amino-2-naphthol with 5-bromo-2-hydroxybenzaldehyde, 2-hydroxy-3-methoxybenzaldehyde, 2-hydroxynaphthaldehyde and 2,4-dihydroxybenzaldehyde, respectively. Then the new organotin(IV) complexes, SnPh2L1, SnPh2L2, SnPh2L3, SnBu2L1, SnBu2L2, SnBu2L3 and SnBu2L4 have been synthesized by reaction of SnR2Cl2 (R = Ph and Bu) with corresponding schiff bases in the presence of triethylamine. The new compounds were characterized by elemental analysis and IR, 1HNMR and 119SnNMR spectroscopy. On the basis of these data in all complexes Schiff base is completely deprotonated and coordinated to tin(IV) as dianionic tridentate ONO ligand via imine nitrogen and two phenolic oxygens. Coordination number of tin is five. The In vitro antibacterial activity of ligands and synthesized complexes along with dimethyl derivatives has been evaluated against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and compared with standard drugs. Some complexes exhibit more activity than the parent ligands and SnPh2L2 show a remarkable inhibitory effect against S. aureus.