Water-Soluble NNN-Type Pincer Ligand and Its Platinum, Copper, and Cobalt Complexes: Synthesis, Characterization,...

This study successfully synthesized and characterized a novel bis-(pyridylimino)-isoindole ligand, 4-(((1Z,3Z)-1,3-bis-((4-methylpyridin-2-yl)-imino)-isoindolin-5-yl)-oxy)-5-(1,2-dihydroxyethyl)-tetrahydro-furan-2,3-diol and its platinum-(II), copper-(II), and cobalt-(II) complexes. Many biological properties of these compounds (1b-4b) such as antioxidant, DNA cleavage, antimicrobial, microbial cell viability inhibition, biofilm inhibition, and antidiabetic activity were also investigated. Compounds 2b, 3b, and 4b exhibited 100% free radical scavenging activity equivalent to Trolox and ascorbic acid used as standards at a 200 mg/L concentration. All compounds showed powerful DNA nuclease activity at 50 mg/L concentrations. The most efficient MIC values of 1b, 2b, 3b, and 4b were obtained as 8, 4, 4, and 2 mg/L against S. aureus. The most resistant microorganism was determined as C. tropicalis. After photodynamic antimicrobial therapy, the antimicrobial activities of the compounds increased by 2 or 4 times. Inhibition of microbial cell viability and biofilm was obtained at almost 100% for all compounds at 10 mg/L concentrations. In addition, at a 250 mg/L concentration, 2b, 3b, and 4b exhibited 29.55, 38.73, and 47.96% antidiabetic activities, respectively. Furthermore, this investigation quantifies the affinity of four distinct molecules (1b-4b) toward specific sites on DNA by assessing hydrogen bond lengths and computing binding energies. It was observed that all four molecules establish hydrogen bonds with DNA residues within the major groove. The span of the hydrogen bond distances for the compounds is reported to be between 1.77 and 2.12 Å.