Syntheses, structure, Hirshfeld analysis and antimicrobial activity of four new Co(II) complexes with s-triazine-based pincer ligand

Abstract

The [Co(BPMT)(H2O)2Cl]Cl; (1), [Co(BPMT)(H2O)3](ClO4)2·H2O; (2), [Co(BPMT)(NO3)2]; (3) and [Co(BPMT)(H2O)3](NO3)2·H2O; (4) pincer complexes of 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine, (BPMT) ligand were synthesized by self-assembly technique in methanol as solvent. In all complexes, the BPMT acting as a tridentate N-donor pincer ligand. The Co(II) is hexa-coordinated in complexes 1, 2 and 4 with distorted octahedral coordination geometry while 3 has a rare hepta-coordinated Co(II) comprised a CoN3O4 coordination sphere with two bidentate nitrate ions as ligand. In 1, the most important contacts are the Cl…H (16.5%) and O…H (9.8%) interactions. For complexes 2–4, the O…H and C…O (anion-π stacking) contacts are the most important. The percentages of O…H contacts are 40.2, 39.2–37.2 and 36.4% in complexes 2–4, respectively while the percentages of C…O (anion-π stacking) contacts are 2.8, 3.2–3.7 and 2.5%, respectively. The natural charge populations of the cobalt central metal ion (Co(II)) are decreased to 0.891, 0.948, 0.950–0.953 and 0.951 e due to the interactions with the ligand groups coordinating it. The antimicrobial activity of complexes 1–3 were evaluated and compared with some commercial antibiotics. Complex 1 has better antimicrobial activity against all microbes compared to complexes 2 and 3. Also, 1 and 2 performed better than Amoxicillin, Tetracycline and Ampicillin antibiotics against E. coli and C. albicans.