Synthesis and characterization of water-soluble silver(I) complexes with L-histidine (H2his) and (S)-(-)-2-pyrrolidone-5-carboxylic acid (H2pyrrld) 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; H2his = L-histidine) and [Ag(Hpyrrld)]2 (3; H2pyrrld = (S)-(-)-2-pyrrolidone-5-carboxylic acid) were prepared. In aqueous solution 1 and 3 were present as dimers, whereas in the solid state they were polymers. Crystallization 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 hydrogen-bonding interactions between dimeric [Ag(Hhis)]2 cores, while 2 is a different polymer without a core complex. X-ray crystallography revealed that 2 was a left-handed helical polymer consisting of a bent, 2-coordinate silver(I) atom bonding to the Namino atom of one Hhis- ligand and the N pi atom of a different Hhis- ligand. Of particular note is the fact that Ocarboxyl atoms do not participate in the coordination. X-ray crystallography also revealed that 3 was a left-handed helical polymer formed by self-assembly of dimeric [Ag(Hpyrrld)]2 cores with an intramolecular metal(I)-metal(I) interaction (Ag-Ag distance, 2.9022(7) A). The FT-IR and the solid-state 13C and 15N NMR spectra showed that the dimeric core of 1 was formed 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 ionization (ESI) mass spectrometry. For 1-3, characterization by elemental analysis, TG/DTA, FT-IR, and variable-temperature solid-state 13C NMR and room-temperature 15N NMR measurements was performed, and for 1 and 3, that by solution molecular weight measurements and solution (109Ag, 1H, and 13C) NMR spectroscopies was also carried out. The antibacterial and antifungal activities of 1 and 3 were remarkable and comparable to those of the previous silver(I)-N-heterocycle complexes.
Nomiya
K
K
Department of Materials Science, Faculty of Science, Kanagawa University, Hiratsuka, Kanagawa 259-1293, Japan. nomiya@chem.kanagawa-u.ac.jp
Takahashi
S
S
Noguchi
R
R
Nemoto
S
S
Takayama
T
T
Oda
M
M
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects; D018360:Crystallography, X-Ray; D006639:Histidine / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D011761:Pyrrolidonecarboxylic Acid / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D015003:Yeasts / Q000187:drug effects
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D011108:Polymers; D012834:Silver; D006639:Histidine; D011761:Pyrrolidonecarboxylic Acid