Silver(I) complexes of N,N′‐diarylformamidine ligands: Synthesis, crystal structures, and in vitro antibacterial studies

• Published in: Applied organometallic chemistry 2022-07, Vol.36 (7), p.n/a
• Main Authors: Bongoza, Unathi, Zamisa, Sizwe J., Munzeiwa, Wisdom A., Omondi, Bernard
• Format: Article
• Language: English
• Subjects: Anions; antimicrobial activity; Bacteria; Chemistry; Coordination; Crystal structure; crystal structures; Crystallography; E coli; Ligands; N,N'‐diarylformamidine; Physiochemistry; Silver nitrate; silver(I)
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.6726

Nine silver(I) N,N′‐diarylformamidine complexes of type [Ag (Ln)2X] (where X = NO3−, CF3COO−, and CF3SO3−, n = 1–5) were synthesised and characterised by physiochemical and spectroscopic techniques. Further confirmation for the formation of the complexes was provided by single‐crystal X‐ray crystallography. All complexes (but one) adopted linear geometry in which coordination was via two N atoms of two formamidine ligands with the anion (X) displaced from coordination sphere. In the structure of the exception, the anion is part of the coordination sphere and a T‐shaped geometry was adopted. The antimicrobial activity of the Ag(I) complexes were investigated against two Gram‐positive bacteria, that is, S. aureus ATCC 25923 and Methicillin‐resistant S. aureus ATCC 700699 (MRSA) and four Gram‐negative bacteria, that is, K. pneumoniae ATCC 31488, S. typhimurium ATCC 14026, P. aeruginosa ATCC 27853 and E. coli ATCC 25922 and they were evaluated based on ciprofloxacin and silver nitrate standards. The newly synthesised target complexes demonstrated promising antibacterial activity against Gram‐positive bacteria although less than the reference drug ciprofloxacin. The best active silver(I) complex contains a nitrate counter‐ion. N,N'‐diarylformamidine silver(I) complexes have been synthesized and characterized and they have exhibited potential antimicrobial activity against two gram‐positive bacteria, i.e. S. aureus and Methicillin‐resistant S. aureus (MRSA) and four gram‐negative bacteria, i.e. K. pneumoniae S. typhimurium, P. aeruginosa and E. coli.