Benzil/triethylamine: a photo-reducing system for Cu(2+)

ABSTRACT: We have investigated the photo-induced reduction of Cu(2+)–Cu(0) using benzil/triethylamine mixtures. The formation of elemental Cu is indicated by the appearance of its characteristic plasmon absorption peaks at 515 nm and 620 nm. Importantly, the nature of the counterion of the Cu(2+) salt affects the reduction process. In the presence of Cl(−), the reduction proceeds faster than with SO(4)(2-). Photo-induced electron transfer between excited benzil and triethylamine leads to the benzil radical anion, which acts as the reducing agent for Cu(2+) and generates Cu(0). GRAPHICAL ABSTRACT: [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00706-017-2085-7) contains supplementary material, which is available to authorized users.