No abstract

The electroreduction of polychloromethanes and polychloroethanes has been studied by means of cyclic voltammetry (CV) and preparative electrolysis experiments in acetonitrile (ACN), dimethylformamide (DMF) and their admixtures with water. Silver has been used as cathode material, on account of our extended experience on its well established electrocatalytic activity toward reductive dehalogenation reactions of organic compounds. Polychloromethanes and -ethanes are common chlorinated solvents pertaining to the large family of volatile organic halides (VOH), whose high toxicity, or even carcinogenicity, demands careful treatment of contaminated soils, drinking waters and gaseous emissions. The results confirm the electrocatalytic role of silver and suggest a general route for the development of appropriate degradation processes.

A comparative study between two novel, highly water soluble, ruthenium(II) polypyridyl complexes, [Ru(phen)2L′] and [Ru(phen)2Cu(II)L′] (L and L‐CuII), containing the polyaazamacrocyclic unit 4,4′‐(2,5,8,11,14‐pentaaza[15])‐2,2′‐bipyridilophane (L′), is herein reported. L and L‐CuII interact with calf‐thymus DNA and efficiently cleave DNA plasmid when light‐activated. They also possess great penetration abilities and photo‐induced biological activities, evaluated on an A375 human melanoma cell line, with L‐CuII being the most effective. Our study highlights the key role of the Fenton active CuII center within the macrocycle framework, that would play a synergistic role with light activation in the formation of cytotoxic ROS species. Based on these results, an optimal design of RuII polypyridyl systems featuring specific CuII‐chelating polyamine units could represent a suitable strategy for the development of novel and effective photosensitizers in photodynamic therapy.

Novel cationic liposomes containing the photo-activatable drug methylene blue (MB) strongly enhance the antibacterial activity of MB towards Gram-negative bacteria and improve biofilm penetration.

5-Nitroimidazole (5NIMH), chosen as a molecular model of nitroimidazole derivatives, which represent a broadspectrum class of antimicrobials, was incorporated into the ruthenium complexes [Ru(tpy)(phen)(5NIM)]PF 6 (1) and [Ru(tpy)(dmp)(5NIM)]PF 6 (2) (tpy = terpyridine, phen = phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline). Besides the uncommon metal coordination of 5-nitroimidazole in its imidazolate form (5NIM), the different architectures of the spectator ligands (phen and dmp) were exploited to tune the "mode of action" of the resulting complexes, passing from a photostable compound where the redox properties of 5NIMH are preserved (1) to one suitable for the nitroimidazole phototriggered release (2) and whose antibacterial activity against B. subtilis, chosen as cellular model, is effectively improved upon light exposure. This study may provide a fundamental knowledge on the use of Ru(II)−polypyridyl complexes to incorporate and/or photorelease biologically relevant nitroimidazole derivatives in the design of a novel class of antimicrobials.