Synthesis and characterization of water-soluble silver(I) complexes with L-histidine (H(2)his) and (S)-(-)-2-pyrrolidone-5-carboxylic acid (H(2)pyrrld) showing a wide spectrum of effective antibacterial and antifungal activities. Crystal structures of chiral helical polymers [Ag(Hhis)](n) and {[Ag(Hpyrrld)](2)}(n) in the solid state

Two water-soluble, silver(I) complexes showing a wide spectrum of effective antibacterial and antifungal activities, i.e., {[Ag(Hhis)].0.2EtOH}(2) (1; H(2)his =L-histidine) and [Ag(Hpyrrld)](2) (3; H(2)pyrrld = (S)-(-)-2-pyrr olidone-5-carboxylic acid) were prepared. In aqueous solution 1 and 3 were present as dimers, whereas in the solid state they were polymers. Crystalli zation of 1 by slow evaporation and/or vapor diffusion gave water-insoluble crystals of [Ag(Hhis)](n) (2) showing modest antimicrobial activities. The complex 1 in the solid state is a polymer formed by intermolecular hydroge n-bonding interactions between dimeric [Ag(Hhis)](2) cores, while 2 is a di fferent polymer without a core complex. X-ray crystallography revealed that 2 was a left-handed helical polymer consisting of a bent, 2-coordinate sil ver(I) atom bonding to the N-amino atom of one Hhis(-) ligand and the N-pi atom of a different Hhis- ligand. Of particular note is the fact that O-car boxyl atoms do not participate in the coordination. X-ray crystallography a lso revealed that 3 was a left-handed helical polymer formed by self-assemb ly of dimeric [Ag-(Hpyrrld)](2) cores with an intramolecular metal(I)-metal (I) interaction (Ag-Ag distance, 2.9022(7) Angstrom). The FTIR and the soli d-state C-13 and N-15 NMR spectra showed that the dimeric core of 1 was for med through Ag-N bonds, while that of 3 was formed through Ag-O bonds. The molecular ions of 1 and 3 were detected by the positive-ion electrospray io nization (ESI) mass spectrometry. For 1-3, characterization by elemental an alysis, TG/DTA, PT-IR, and variable-temperature solid-state C-13 NMR and ro om-temperature N-15 NMR measurements was performed, and for 1 and 3, that b y solution molecular weight measurements and solution (Ag-109,H-1, and C-13 ) NMR spectroscopies was also carried out. The antibacterial and antifungal activities of 1 and 3 were remarkable and comparable to those of the previ ous silver(I)-N-heterocycle complexes.