N-doped ZnO as an efficient photocatalyst for thiocyanation of indoles and phenols under visible-light

Abstract

In this study, nitrogen-doped ZnO nanorods (N–ZnO NRs) were synthesized via a very simple hydrothermal process, fully characterized, and this photocatalyst was successfully exploited in thiocyanation reactions of indoles and phenols at room temperature under visible light irradiation. Two important classes of aromatic compounds indoles, and phenols using N–ZnO NRs as photocatalyst treated with ammonium thiocyanate as thiocyanation agent formed the corresponding thiocyano compounds in good yields. Nitrogen is one of the most appropriate p-type dopants that is nontoxic, similar to the atomic radius to oxygen, and lower electronegativity and ionization energy than the O atom. Therefore, the N doping converts ZnO into the p-type ZnO semiconductor structure. This potent, simple, and versatile protocol afforded thiocyanation reactions of indole and phenols under visible light. The reactions proceeded through a radical pathway by applying air molecular oxygen as a low cost and environmentally friendly terminal oxidant. The proposed mechanism based on control experiments was thoroughly described. Graphic abstract: [Figure not available: see fulltext.]