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

Abstract

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.

Silver Organometallics that are Highly Potent Thioredoxin and Glutathione Reductase Inhibitors: Exploring the Correlations of Solution Chemistry with the Strong Antibacterial Effects

“…In contrast to the promising results with the Gram-negative strains, a poor antibacterial activity against the two Gram-positive strains was determined for all silver complexes. Such observations are in line with previous reports, where Gram-positive bacteria have been shown to be less sensitive toward silver salts and their complexes. ,,, …”

“…Such observations are in line with previous reports, where Gram-positive bacteria have been shown to be less sensitive toward silver salts and their complexes. 11 , 26 , 51 , 52 …”

“…Such observations are in line with previous reports, where Gram-positive bacteria have been shown to be less sensitive toward silver salts and their complexes. 11,26,51,52 Effect of Growth Media on the Antibacterial Activity. The importance of the culture medium used in antibacterial assays has been pointed out for antibiotics and in particular for silver.…”

Dicyanoargentate(I)‐based complexes induced in vivo tumor inhibition by activating apoptosis‐related pathways

“…[17][18][19][20] Although silver compounds such as silver zinc sulfadiazine cream and silver diammine fluoride both approved by the FDA have already been in use as anti-microbial and carrier agents, respectively, three Ag complex, epidermal growth factor with silver sulfadiazine cream (phase II-III trials, NCT01553708), silver nanoparticles (NCT04894409), and colloidal silver (NCT04978025) are testified to qualify for clinical trials, respectively, against burns and COVID-19. [21] X-Ray single-crystal analyses of Ag(I) complexes show that these can be synthesized as both mono [22][23][24] and bimetallic. [25,26] This versatility of the Ag(I) complexes allow them directly to participate in many biological processes, including enzyme activation.…”

“…X‐Ray single‐crystal analyses of Ag(I) complexes show that these can be synthesized as both mono [ 22–24 ] and bimetallic. [ 25,26 ] This versatility of the Ag(I) complexes allow them directly to participate in many biological processes, including enzyme activation.…”