DESIGN, SYNTHESIS, AND PHARMACOLOGICAL EVALUATION OF SOME NOVEL BIS-THIAZOLE DERIVATIVES

 Objective: A series of substituted 5,2-bis-thiazoles derivatives were synthesized by Hantzsch reaction and evaluated in vitro for antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. Methods: 2-(4-(benzyloxy)phenyl)-4-methylthiazole-5-carbothioamide were synthesized and allowed to react with various α-haloketones to give 5,2-bis-thiazoles, i.e., 2-(4-(benzyloxy)phenyl)-4-methyl-5-(4-substituted thiazol-2-yl)thiazole derivatives in excellent yield. The synthesized compounds were characterized by spectroscopic methods as well as elemental analyses. They were screened for their antimicrobial activity using the agar diffusion method.Result: Literature survey reveals that the synthesis of 2-(4-(benzyloxy)phenyl)-4-methyl-5-(4-substituted thiazol-2-yl)thiazole, i.e., (5,2-Bis-thiazoles) derivatives (10a-e) was not reported. The entire compound exhibited mild to moderate antimicrobial activity.Conclusion: The antimicrobial results revealed that the synthesized derivatives have significant antimicrobial properties, and further, structure– activity relationship studies may develop more potent and less toxic molecule

Synthesis, spectral, thermal, potentiometric and antimicrobial studies of transition metal complexes of tridentate ligand

A series of metal complexes of Cu(II), Ni(II), Co(II), Fe(III) and Mn(II) have been synthesized with newly synthesized biologically active tridentate ligand. The ligand was synthesized by condensation of dehydroacetic acid (3-acetyl-6-methyl-(2H) pyran-2,4(3H)-dione or DHA), o-phenylene diamine and fluoro benzaldehyde and characterized by elemental analysis, molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, 1H-NMR, UV–Vis spectroscopy and mass spectra. From the analytical data, the stoichiometry of the complexes was found to be 1:2 (metal:ligand) with octahedral geometry. The molar conductance values suggest the non-electrolyte nature of metal complexes. The IR spectral data suggest that the ligand behaves as a dibasic tridentate ligand with ONN donor atoms sequence towards central metal ion. Thermal behaviour (TG/DTA) and kinetic parameters calculated by the Coats–Redfern and Horowitz–Metzger method suggest more ordered activated state in complex formation. To investigate the relationship between stability constants of metal complexes and antimicrobial activity, the dissociation constants of Schiff bases and stability constants of their binary metal complexes have been determined potentiometrically in THF–water (60:40%) solution at 25 ± 1 °C and at 0.1 M NaClO4 ionic strength. The potentiometric study suggests 1:1 and 1:2 complexation. Antibacterial and antifungal activities in vitro were performed against Staphylococcus aureus, Escherichia coli and Aspergillus niger, Trichoderma, respectively. The stability constants of the metal complexes were calculated by the Irving–Rosotti method. A relation between the stability constant and antimicrobial activity of complexes has been discussed. It is observed that the activity enhances upon complexation and the order of antifungal activity is in accordance with stability order of metal ions