Controlling the Photofunctionality of a Polyanionic Heteroleptic Copper(I) Photosensitizer for CO 2 Reduction Using Its Ion-pair Formation with Polycationic Ammonium in Aqueous Media.

A water-soluble trianionic heteroleptic copper(I) photosensitizer having four sulfonate groups (CuPS 3- ) was found to afford the 1 : 2 ion-pair adduct with dicationic alkylammonium (hexamethonium) cations (HM 2+ ) in aqueous media, leading to exhibit excellent photophysical and photocatalytic performances owing to the substantial suppression of water-derived non-radiative decay of the photoexcited state.