A series of methylated imidazolium salts with varying substituents on the 4 and 5 positions of the imidazole ring were synthesized. These salts were reacted with silver acetate to afford their corresponding silver N-heterocyclic carbene (NHC) complexes. These complexes were then evaluated for their stability in water as well as for their antimicrobial efficacy against a variety of bacterial strains associated with cystic fibrosis and chronic lung infections.

A class of Ag(I) N-heterocyclic carbene silver complexes, 1–3, derived from 4,5-dichloro-1H-imidazole has been evaluated for their anticancer activity against the human cancer cell lines OVCAR-3 (ovarian), MB157 (breast), and Hela (cervical). Silver complexes 1–3 are active against the ovarian and breast cancer cell lines. A preliminary in vivo study shows 1 to be active against ovarian cancer in mice. The results obtained in these studies warrant further investigation of these compounds in vivo.

A π-conjugated polymer with 2,5-bis(benzoxazol-2′-yl)benzene-1,4-diol fluorene units is synthesized by using a Suzuki-Miyaura coupling reaction (M w ) 1.3 × 10 4 ; PDI ) 1.8). The polymer exhibits UV-vis absorption, λ max ≈ 421 nm, and fluorescence, λ max ≈ 616 nm. The observed large Stokes shift (∼200 nm) is attributed to an excited-state intramolecular proton-transfer process. The addition of anionic species (hydroxide, fluoride, and acetate) causes the absorption λ max to be red-shifted to 510-540 nm and the fluorescence quantum efficiency to be increased by a factor of ∼20. Through the study of a model compound, the structure of the anion complex is determined to be deprotonated monoanion, as evidenced from the Benesi-Hildebrand plot and electron-spray mass spectrometry. On the basis of a large spectral response in absorption and significant fluorescence enhancement, the material could be useful for dualchannel detection of anions.

Due to the properties of silver as an antimicrobial, our research group has synthesized many different silver carbene complexes. Two new silver N-heterocyclic carbene complexes derived from 4,5-dichloroimidazole and theobromine bearing methyl benzoate substituents were synthesized by in situ carbene formation using silver acetate as the base in the reaction. The new compounds were fully characterized by several methods including NMR spectroscopy and X-ray crystallography. Preliminary antimicrobial efficacy studies against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli were conducted. The results of this study demonstrated antimicrobial efficacy of the two complexes comparable to silver nitrate, showing their potential for use in the treatment of bacterial infections.