Semiconductor photocatalysis: quantised CdS-catalysed photoformation of 1-benzyl-1,4-dihydronicotinamide (BNAH) from 1-benzylnicotinamide (BNA+)

Abstract

Freshly pepared CdS suspensions (CdS-0) consisting of quantised particles and their loose aggregates catalyse the photoreduction of 1-benzylnicotinamide (BNA⁺) in water under visible-light irradiation using triethylamine (TEA) as a sacrificial electron donor. Isomeric dimers of (BNA)₂ are also found as one-electron reduction products from BNA⁺, whereas the photocatalysis of commercially available CdS powder (Aldrich, CdS-Ald) leads only to the formation of the dimers. The formation of cadmium metal (Cd⁰) on the lattice is indispensable for the photoformation of BNAH, suggesting that the eventual two-electron reduction on irradiation of CdS-0 with TEA in water, should proceed through hydrogen atom transfer from Cd⁰—H formed on the lattice of CdS-0.