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.