Thermal behaviour of some novel biologically active complexes with a triazolopyrimidine pharmacophore

A new derivative 5-phenyl-7-methyl-1,2,4-triazolo[1,5-a]pyrimidine (pmtp) was synthesised by [1 + 1] condensation of benzoylacetone and 3-amino-4H-1,2,4-triazole. Single crystal X-ray diffraction revealed that the pmtp crystallises in monoclinic system, P21/n spatial group. In order to modulate the biological activity, new species M(pmtp)Cl2·nH2O (M: Co, n = 2; M: Ni, n = 3; M: Cu, n = 1; M: Zn, n = 0) were synthesised by one-pot method. Chemical analysis, molar conductivities, IR, UV–Vis-NIR and EPR spectroscopy, as well as magnetic data recorded at room temperature provided useful information concerning the molecular formula, stereochemistry and ligand coordination mode. The modifications at heating and also the thermodynamic effects that accompany them were investigated by thermal analysis. The nature of the gaseous products formed in each step was evidenced by simultaneous TG/DSC/EGA measurements. Processes as water and chloride elimination, fragmentation and oxidative degradation of the triazolopyrimidine derivative were observed during the thermal studies. The final residue was the most stable metallic oxide as X-ray powder diffraction indicates. Zinc (II) and copper (II) complexes exhibited the most significant antimicrobial activity against a wide spectrum of Gram-positive and Gram-negative bacterial strains, both reference and clinical resistant ones, in planktonic and biofilm state. The minimal biofilm eradication values were two to four times lower than the minimal inhibitory concentrations demonstrating the potential of the obtained complexes to act as anti-pathogenic agents.