Thermal behaviour of some biologically active species based on complexes with a triazolopyrimidine pharmacophore

A series of complexes of type M(pmtp)(CH 3 COO) 2 ·nH 2 O (( 1 ) M: Co, n = 4.5; ( 2 ) M: Ni, n = 3.5; ( 3 ) M: Cu, n = 0.5; ( 4 ) M: Zn, n = 0; pmtp: 5-phenyl-7-methyl-1,2,4-triazolo[1,5- a ]pyrimidine) were synthesised by one-pot condensation. The complexes were characterized by elemental analysis, ESI–MS, IR, UV–Vis-NIR, EPR spectra, magnetic susceptibility at room temperature as well as thermogravimetric analysis. The modifications in the IR spectra of complexes are in accordance with the condensation process and indicate the triazolopyrimidine coordination as unidentate. The electronic and EPR spectra together with magnetic moments indicate an octahedral stereochemistry for paramagnetic ions, except for Cu(II) with a square pyramidal geometry. Processes such as water elimination, acetate into carbonate transformation, as well as oxidative degradation of the triazolopyrimidine derivative were evidenced during thermal decomposition. The complexes exhibited an improved antimicrobial activity in comparison with the ligand, on both planktonic and biofilm-embedded microbial cells. The best antimicrobial activity in both susceptible and resistant strains was obtained for complex ( 3 ) followed by complex ( 1) , which can be related to both oxidation state and stereochemical versatility. At high concentrations, the Cu(II) complex exhibits both cytotoxicity on HT 29 tumour cell line and anti-inflammatory activity.