A Variety of Ag-O Bonding Modes and Antimicrobial Activities of Light-Stable Coinage Metal Complexes with Carboxylate Ligands

Using light-stable dimeric silver(I) carboxylate precursors {[Ag(Hpyrrld)]_2}_n formed with chiral and racemic forms of 2-pyrrolidone-5-carboxylic acid (H_2pyrrld) ligand, six novel light-stable, triphenylphosphinesilver(I) complexes consisting of both a hard Lewis base (O atom) and a soft Lewis base (P atom) were prepared, i.e. [Ag_2(R-Hpyrrld)_2(H_2O)(PPh_3)_2]・H_2O 1,[Ag(R-Hpyrrld)(PPh_3)_2]_2 2, [Ag_2(S-Hpyrrld)_2(H_2O)(PPh_3)_2]・H_2O 3, [Ag(S-Hpyrrld)(PPh_3)_2]_2 4,{[Ag(R,S-Hpyrrld)(PPh_3)]_2}_n 5 and [Ag(R,S-Hpyrrld)(PPh_3)_2] 6. Their solid-state and solution structures were unequivocally characterized with elemental analysis, TG/DTA, FTIR, X-ray structure analysis, molecular weight measurements in EtOH with the vaporimetric method, solution (^1H, ^C, ^P) NMR and solid-state ^P CPMAS NMR spectroscopy. Two sets of enantiomeric complexes were isolated as (1 and 3) and (2 and 4). X-ray crystallography revealed that these complexes possessed different Ag-O bonding modes, depending on the number of PPh_3 ligands and the chirality of the Hpyrrld ligand. Complexes 1-6 behaved as a monomeric species in EtOH and CD_2Cl_2. Antimicrobial activites by silver(I) complexes in the water-suspension system against selected bacteria, yeast and molds were significantly correlated with the number of coordinating PPh_3 ligands per silver(I) atom in the complexes

Synthesis and structure of photodegradable 1-(4,5-dimethoxy-2,3-dinitrophenyl)-2-methylpropyl N-butylcarbamate

The reaction of 1-(4,5-dimethoxy-2,3-dinitrophenyl)-2-methylpropan-1-ol and butylisocyanate using dibutyltin dilaurate as a catalyst afforded 1-(4,5-dimethoxy-2,3-dinitrophenyl)-2-methylpropyl N-butylcarbamate, C17H25N3O8, which released butylamine upon photoirradiation. Single crystals of the title compound were grown in a 1:1 mixed solution of hexane and ethyl acetate. Two nitro groups and one methoxy group are twisted out of the plane of the aromatic ring in the novel photo-protecting group. Intermolecular hydrogen bonds are observed between N-butylcarbamate moieties parallel to the a axis

Syntheses, Structures, and Antimicrobial Activities of Remarkably Light-Stable and Water-Soluble Silver Complexes with Amino Acid Derivatives, Silver(I) <i>N</i>-Acetylmethioninates

Reaction of l- and dl-<i>N</i>-acetylmethionine (Hacmet) and Ag₂O in water at ambient temperature afforded the remarkably light-stable silver complexes {[Ag­(l-acmet)]}_<i>n</i> (<b>1</b>) and {[Ag₂(d-acmet)­(l-acmet)]}_<i>n</i> (<b>2</b>), respectively. The color of the solids and aqueous solutions of <b>1</b> and <b>2</b> did not change for more than 1 month under air without any shields. The light stability of these two silver­(I) complexes is much higher than that of silver­(I) methioninate {[Ag₂(d-met)­(l-met)]}_<i>n</i> (<b>3</b>) (Hmet = methionine), silver­(I) <i>S</i>-methyl-l-cysteinate {[Ag­(l-mecys)]}_<i>n</i> (<b>4</b>), and silver­(I) l-cysteinate {[Ag­(l-Hcys)]}_<i>n</i> (<b>5</b>). X-ray crystallography of <b>1</b> obtained by vapor diffusion revealed that ladder-like coordination polymers with two O- and two S-donor atoms were formed. The acetyl group of acmet^– prevents chelate formation of the ligand to the metal center, which is frequently observed in amino acid metal complexes, but allows for formation of hydrogen bonds between the ligands in the crystals of <b>1</b>. These two silver­(I) <i>N</i>-acetylmethioninates showed a wide spectrum of effective antimicrobial activities against Gram-negative bacteria (<i>Escherichia coli</i> and <i>Pseudomonas aeruginosa</i>) and yeasts (<i>Candida albicans</i> and <i>Saccharomyces cerevisiae</i>), the effectiveness of which was comparable to that of water-soluble Ag–O bonding complexes