Silver(i) complexes of 9-anthracenecarboxylic acid and imidazoles: synthesis, structure and antimicrobial activity

Abstract

[Ag₂(9-aca)₂] (1) (9-acaH = 9-anthracenecarboxylic acid) reacts with a series of imidazoles to give [Ag(imidH)_2.3(CH₃CN)_0.7](9-aca) (3), [Ag₆(imidH)₄(9-aca)₆(MeOH)₂] (4), {[Ag(1-Me-imid)₂]₂[Ag₄(9-aca)₆]} (5), {[Ag(1-Bu-imid)₂]₂[Ag₄(9-aca)₆]} (6) and [Ag(apim)](9-aca)·H₂O (7) (imidH = imidazole; 1-Me-imid = 1-methylimidazole; 1-Bu-imid = 1-butylimidazole; apim = 1-(3-aminopropyl)imidazole). The mononuclear complex 3, hexanuclear 4–6, and polymeric 7, were all characterised using X-ray crystallography. While many of the complexes possess excellent in vitro antifungal and antibacterial activities they are, unanimously, more effective against fungal cells. The insect, Galleria mellonella, can survive high doses of the Ag(I) complexes administered in vivo, and a number of the complexes offer significant protection to larvae infected with a lethal dose of pathogenic Candida albicans cells.