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Anisaldehyde-4-phenyl-thiosemicarbazone (HL) complexes of Ni(II), Cu(II) and Pd(II) have been synthesized. Conductivity measurements, spectroscopic (FTIR, UV-visible, ESI(+) mass, 13 C and 1 H NMR, ESR), cyclic voltammetry study and thermal analyses were used to propose their molecular formulations. Ni(II), Cu(II) and Pd(II) complexes show room temperature magnetic moments of 3.07, 1.59 and 0.00 BM, respectively. The ligand and the metal complexes have been screened in vitro for antibacterial activity against the bacterial strains viz. P. vulgaris, S. aureus, E. coli, S. aeruginosa, B. subtillis and S. epidemidis and for antifungal activity against the fungal strains viz. A. niger, F. Oxosporum ciceri, F. oxosporum NCIM1281 and R. solani. The ligand, Cu(II) and Pd(II) complexes have been tested for antitubercular activity against Mycobacterium tuberculosis H37RV strain and for anticancer activity against three human cancer lines. The Cu(II) complex was found to be most potent against M. tuberculosis H37RV strain and showed its MIC as 10 µM. The ligand and Cu(II) complex exhibited quite good growth inhibitory activity against most of the tested bacterial and fungal strains.

The catalytic activity of three N,S‐donor ligands, viz L1 [2‐(4‐methoxybenzylidene)‐N‐phenylhydrazinecarbothioamide], L2 [2,2′‐(1,2‐diphenylethane‐1,2‐diylidene)bis(hydrazinecarbothioamide)] and L3 [2‐(4‐methoxybenzylidene)hydrazinecarbothioamide] has been reported for N‐arylation of imidazoles with arylboronic acids in ethanol at room temperature. The method was found to be applicable in N‐arylation for a wide range of electronically diverse arylboronic acids with imidazoles having modest to excellent isolated yields. The in situ generated copper(II) complex of the ligand namely, 2‐(4‐methoxybenzylidene)‐N‐phenylhydrazinecarbothioamide (L1) was found to be highly efficient homogeneous catalyst for N‐arylation reaction.

INTRODUCTIONDerivatives of thiosemicarbazones are unique N,S-donors because of their mixed hard-soft character, variable binding modes, flexibility, selectivity and sensitivity towards the central metal atom [1]. These ligands have gained significant attention because of structural similarities with natural biological substances due to the presence of imine group (-N=CH-) which imparts biological activity including antifungal, antibacterial, anti-inflammatory, antiviral, anticonvulsant, antidepressant, anticancer along with good anti-HIV activity and as a result received wide applications in pharmacology and nuclear medicine [2][3][4][5][6]. These ligands can also act as analytical reagents for determining, fixing and entrapping heavy metal ions [7,8]. The transition metal incorporation into thiosemicarbazones leads to an enhancement in their pharmacological activities [9] and the subsequent synergistic effects involving both metal and the thiosemicarbazone leads to the improvement of their biological activities and decreases the cytotoxicity of both the metal ions and ligands [10]. They bind to the transition metal center in a neutral or anionic form. It has been reported that the substituent at the carbon atom of the imine group (-HC=N) can affect the bonding to the metal halides, which determines the formation of mono-, di-and poly-nuclear complexes. Various transition metals such as organotin(IV), iron(II), copper(II), zinc(II), nickel(II), palladium, platinum, ruthenium, etc. have been incorporated into thiosemicarbazones and their applications have been studied [11][12][13][14][15]. Palladium(II) derivatives were found to be more preferred for cancer treatment because of their structural analogy with Pt(II) complexes and some complexes show The complexes were found to be diamagnetic, four coordinated mononuclear neutral molecules with square planar or distorted square planar geometry.