FACILE SYNTHESIS, SPECTRAL STUDIES, DFT CALCULATIONS AND BIOLOGICAL ACTIVITIES OF NOVEL NI (II), CU (II), AND PD (II) COMPLEXES OF THIADIAZOLE ANALOGS

Abstract

Objective: A facile synthesis of some novel Schiff base derivatives of 2-substituted-5-amino-thiadiazoles along with their Ni (II), Cu (II), and Pd (II) complexes were achieved by sonication and the conventional method. In addition to establish the structure by DFT studies and to explore antimicrobial and anticancer activities of these novel compounds.Methods: The precursor 2-substituted-5-amino-thiadiazoles (T1-T3), target ligands and their metal complexes were synthesized by ultra-sonication and conventional means. The isolated products were thoroughly characterized by physical and spectroscopic techniques including 1H-NMR, [13]C-NMR and IR spectroscopy. All characterized compounds were screened for antimicrobial activities using well diffusion method, and MTT assay was performed for cytotoxicity.Results: All novel compounds were synthesized by a green route i.e. ultra sonication and a noticeable improvement in yield with shorter reaction time than the conventional method were observed. The octahedral geometry was proposed for Ni (II)/Cu (II) complexes whereas square planar for Pd (II) complexes on the basis of the spectral techniques which were supported by DFT analysis by Gaussian03. On the analysis of antimicrobial activities, the compound T7 and T10 showed maximum antibacterial and antifungal activities respectively. However, compounds T25, T37, T31 found to be a potential cytotoxic compound with IC50 value 0.469, 0.865 and 1.131 μM respectively.Conclusion: Analysis of synthetic protocol, it could be concluded that ultra-sonication is the better method to synthesize these potential biological active moiety. On the whole Cu (II) and Ni (II) complexes showed promising activity towards all microorganisms while Pd (II) complex emerged an excellent moiety in carcinoma cell line.