A comparative study of Cd(II) complexes with pyridyl-based 1,3- selen/thiazolyl-hydrazones

In order to obtain biologically active compounds with (1,3-selenazol/thiazol-2-yl)hydrazine ligands, new cadmium(II) complexes [Cd(HLSe1)2](ClO4)2 (1–Se) and [Cd(HLS1)2](ClO4)2 (1–S) were synthesized and characterized (Figure 1). X-ray structural analysis revealed that both complexes crystallize in a monoclinic C2/c space group. Coordination number of Cd(II) is sixth in both cases and the ligands are coordinated in neutral form via NNN donor atoms set: pyridine and azomethine nitrogen atoms and nitrogen atom from selenazole or thiazole ring. For analysis of intermolecular interactions Hirshfield surfaces and 2D pseudosymmetric fingerprint plots were constructed. Crystal packings of both complexes are based on classical and non-classical hydrogen interactions. The thermal stability of the Cd(II) complex was analyzed. Based on the analysis of data obtained from spectrophotometric titration, the number of species present in the solution, the stoichiometry, and the stability of the formed Cd(II) complexes were determined. The obtained values of the cumulative stability constant indicate significant stability of the investigated compounds. The antimicrobial and antioxidant activity of the desired complexes and corresponding ligands were determined. Complex 1–S exhibited 40 times better activity against the strains P. aeruginosa, B. subtilis, and C. sporogenes compared to the control antibiotic.