Phenazine-based supramolecular photosensitizing assemblies:A“smart”selectivity control on catalytic activity of Pd(Ⅱ)nanoparticles

Photosensitizing supramolecular assemblies based on a phenazine derivative(PPA)have been developed,which show a strong affinity toward Pd2+ions to generate supramolecular ensemble PPA@Pd nanoparticles(NPs).The PPA@Pd NPs catalyse the Suzuki cross-coupled reaction under mild conditions(aerial conditions,mixed aqueous media,and visible light radiations).Although PPA@Pd NPs exhibit a strong affinity for arylboronic acid and could catalyse homocoupling of arylboronic acid,the preference of PPA assemblies for aryl halide directed the course of reactions toward the formation of cross-coupled products.The electron-rich PPA assemblies not only facilitate the oxidative addition step through photoinduced electron transfer to Pd^(2+)ions but also bring the reactants closer to the catalytic sites by selective interactions with aryl halides in the presence of arylboronic acid under visible light irradiation.The efficiency of PPA@Pd NPs to catalyse the Suzuki crosscoupled reaction has been demonstrated for the synthesis of unsymmetrically substituted terphenyl derivatives.

Entropically favoured through space charge transfer‘lighted’photosensitizing assemblies for‘metal free’regulated photooxidation of alcohols and aldehydes

Strong acceptor-weak acceptor system FN-TPy has been designed and synthesized,which undergoes solvent dependent self-assembly in mixed aqueous media to generate through space intermolecular charge transfer assemblies.The as-prepared entropically favoured assemblies of FN-TPy exhibit excellent photostability and photosensitizing properties in the assembled state to activate aerial oxygen for efficient generation of reactive oxygen species through Type-I and Type-II pathways.The FN-TPy exhibits excellent potential for regulated oxidation of alcohols and aldehydes under mild reaction conditions(visible light irradiation,aqueous media,room temperature)using aerial oxygen as the‘oxidant’.The present study demonstrates the potential of FN-TPy assemblies to catalyse controlled oxidation of benzyl alcohol to benzoic acid.