Synthesis, structure and antimicrobial activities of meso silver(I) histidinate [Ag2(D-his)(L-his)]n (Hhis = histidine) showing different self-assembly from those of chiral silver(I) histidinates

An achiral coordination polymer, [Ag2(D-his)(L-his)]n, DL-1 (Hhis = histidine), was prepared by slow diffusion of two aqueous solutions of chiral complexes, {[Ag(D-his)]2}n (D-2) and {[Ag(L-his)]2}n (L-2).1Note: From the viewpoint of pKa, the abbreviation of histidine is changed from H2his [8,9] to Hhis. Abbreviation of silver histidinates: L-2 and D-2 are water-soluble complexes of L-his and D-his, respectively, L-3 and D-3 are the corresponding water-insoluble complexes, and DL-1 is the water-insoluble meso complex. crystal structure of DL-1 consists of a linkage of meso-form dimer units through two kinds of Ag⋯Ag contacts. Crystals of the achiral silver(I) histidinate complex DL-1 exhibited different self-assembly from those of chiral helical polymers (D-3 and L-3). The formation of DL-1 from the two aqueous solutions indicated that ligand exchange around silver(I) atoms took place in water. The antimicrobial activities of DL-1 against selected bacteria, yeasts and molds were evaluated by minimum inhibitory concentration (MIC).