A Novel Na(I) Coordination Complex with s-Triazine Pincer Ligand : Synthesis, X-ray Structure, Hirshfeld Analysis, and Antimicrobial Activity

Abstract

The pincer ligand 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (bpmt) was used to synthesize the novel [Na(bpmt)2][AuCl4] complex through the self-assembly method. In this complex, the Na(I) ion is hexa-coordinated with two tridentate N-pincer ligands (bpmt). The two bpmt ligand units are meridionally coordinated to Na(I) via one short Na-N(s-triazine) and two slightly longer Na-N(pyrazole) bonds, resulting in a distorted octahedral geometry around the Na(I) ion. In the coordinated bpmt ligand, the s-triazine core is not found to be coplanar with the two pyrazole moieties. Additionally, the two bpmt units are strongly twisted from one another by 64.94°. Based on Hirshfeld investigations, the H···H (53.4%) interactions have a significant role in controlling the supramolecular arrangement of the [Na(bpmt)2][AuCl4] complex. In addition, the Cl···H (12.2%), C···H (11.5%), N···H (9.3%), and O···H (4.9%) interactions are significant. Antimicrobial investigations revealed that the [Na(bpmt)2][AuCl4] complex has promising antibacterial and antifungal activities. The [Na(bpmt)2][AuCl4] complex showed enhanced antibacterial activity for the majority of the studied gram-positive and gram-negative bacteria compared to the free bpmt (MIC = 62.5–125 µg/mL vs. MIC = 62.5–500 µg/mL, respectively) and Amoxicillin (MIC > 500 µg/mL) as a positive control. Additionally, the [Na(bpmt)2][AuCl4] complex had better antifungal efficacy (MIC = 125 µg/mL) against C. albicans compared to bpmt (MIC = 500 µg/mL).