Synthesis, Structure and Biological Evaluations of Zn(II) Pincer Complexes Based on S-Triazine Type Chelator

Abstract

2,4-bis (3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (BPMT) pincer ligand was used to synthesize the new [Zn(BPMT)(NCS)(2)] (1) and [Zn(BPMT)(Br)(2)] (2) complexes by a reaction with Zn(NO3)(2)center dot 6H(2)O in the presence of either KSCN or KBr, respectively. The structure of complex 1 has been exclusively confirmed using single crystal X-ray diffraction. In this neutral heteroleptic complex, the BPMT is a pincer chelate coordinating the Zn(II) ion via three interactions with the two pyrazole moieties and the s-triazine core. Hence, BPMT is a tridentate NNN-chelate. The coordination environment of Zn(II) is completed by two strong interactions with two terminal SCN- ions via the N-atom. Hence, the Zn(II) is penta-coordinated with a distorted square pyramidal coordination geometry. Hirshfeld analysis indicated the predominance of H horizontal ellipsis H, H horizontal ellipsis C and N horizontal ellipsis H intermolecular interactions. Additionally, the S horizontal ellipsis H, S horizontal ellipsis C and S horizontal ellipsis N contacts are the most significant. The free ligand has no or weak antimicrobial, antioxidant and anticancer activities while the studied Zn(II) complexes showed interesting biological activity. Complex 1 has excellent antibacterial activity against B. subtilis (2.4 mu g/mL) and P. vulgaris (4.8 mu g/mL) compared to Gentamycin (4.8 mu g/mL). Additionally, complex 1 (78.09 +/- 4.23 mu g/mL) has better antioxidant activity than 2 (365.60 +/- 20.89 mu g/mL). In addition, complex 1 (43.86 +/- 3.12 mu g/mL) and 2 (30.23 +/- 1.26 mu g/mL) have 8 and 12 times the anticancer activity of the free BPMT ligand (372.79 +/- 13.64 mu g/mL).