Metal-free photocatalysis at charged aqueous interfaces: boosting the photocatalytic oxidative coupling of arylamines to azoaromatics under ambient conditions

Abstract

Azoaromatics are an important class of functional organic molecules. Herein, we formulated a sustainable metal-free photocatalytic oxidative coupling of arylamines to azoaromatics at the charged aqueous interfaces (CAIs) of micelles with excellent yields (up to 100%) and selectivity (100%) under ambient air atmosphere. The micellar surface acts as an efficient scaffold to host both Eosin Y (EY) as the photocatalyst (PC) and arylamines as substrates for a non-diffusive photoinduced electron transfer (PET) with a time constant of 0.3 ps. The present approach shows fast kinetics (4 h) and a broad substrate scope with only 0.6 mol% of PC. Our present approach outperforms all the previously reported catalytic methodologies. This remarkable boosting of the catalytic efficacy arises mainly due to the non-diffusive PET and modulation of redox potentials at the CAI. Being the most sustainable and first report on the aqueous phase synthesis of azo compounds, this work opens newer opportunities in the synthesis of azoaromatics.