Unusual mixed-valence CuII/CuI coordination polymer based on 2,5-bis(pyridine-2-yl)-1,3,4-thiadiazole and thiocyanate: Synthesis, structural characterization and antimicrobial in vitro activity assessment

Abstract The unusual mixed valence CuII/CuI coordination polymer based on 2,5-bis(pyridine-2-yl)-1,3,4-thiadiazole [CuI3CuIIL2(SCN)5]n has been prepared by reaction between the thiadiazole ligand (L), CuCl2·2H2O and KSCN in H2O/CH3CN solution. The title complex has been characterized using single-crystal X-ray diffraction, and spectroscopic measurements, as well as Hirshfeld surface analysis. TGA analysis and magnetic measurements were also performed. The polymeric complex crystallizes in monoclinic symmetry and C2/c space group with three independent copper crystallographic sites, trigonal and tetrahedral for CuI and octahedral for CuII. The thermal analysis reveals that this complex is thermally stable up to 200 °C. Magnetic measurements carried out on [CuI3CuIIL2(SCN)5]n complex indicate a paramagnetic behaviour. While this new polymer exhibited a noticeable activity against the phytopathogenic bacteria Agrobacterium tumefaciens , no significant activity was recorded against Pseudomonas syringae pv. syringae and Pseudomonas syringae pv. tobacco nor against the phytopathogenic fungi Verticillium dahlia and Fusarium oxysporum fsp. melonis.