Ag(I)N bond-containing compound showing wide spectra in effective antimicrobial activities: Polymeric silver(I) imidazolate

A neutral, Ag(I)-N bonding compound, polymeric silver(I)-imidazolate [Ag(imd)]n (1) consisting of Ag+: imd = 1:1 (Himd = imidazole, C3H4N2), showed wide spectra in effective antimicrobial activities against bacteria, yeast and mold. Of particular note are the activities against a wide range of mold. This polymeric solid does not crystallize and is sparingly soluble in all solvents. The monomeric, cationic, water-soluble Ag(I)-N bonding complex, [Ag(Himd)2](NO3) (2), has also shown wide spectra of effective antimicrobial activities. These activities observed here were significantly different from those of the recently prepared oligomeric Ag(I)-S bonding complexes; the latter have shown narrow spectra. It is proposed that the Ag(I)-N bonding is one of the key factors showing the wide spectra of antimicrobial activities and the potential targets for inhibition of bacteria and yeast by these Ag(I) complexes are proteins, but not nucleic acids. The physico-chemical properties of (1), in comparison with those of (2), with various measurements (FT-IR, Laser Raman scattering spectroscopy, ESCA and solid 13C CP-MAS NMR spectroscopies) are described.