Molecular design of dye-TiO2 assemblies for green light-induced photocatalytic selective aerobic oxidation of amines

Dye-semiconductor assemblies are very versatile visible light photocatalysts in terms of tunability by tweaking either dye molecules or semiconductor materials. Here, we adopted a strategy of molecular inverse design of alizarin red S (ARS) to identify the blueprint underlying the superior photocatalytic activity of ARS-TiO2 assembly. We discovered that the substituted -OH groups of anthraquinone provide visible light absorption and binding sites. Importantly, the molecular features of 1,2-dihydroxyanthraquinone (1,2-DHA) contributes mostly to the unique photocatalytic activity after binding with TiO2 with broad visible light absorption which can be maintained at high concentration of amines. Moreover, the electron-withdrawing effect of -SO3 Na+ groups increase the acidities of substituted -OH groups, leading to stronger binding and subsequent higher activity. Ultimately, in situ formed 1,2-DHA-TiO2 assembly can be a powerful photocatalyst for green light-induced selective oxidation of amines into imines with aerial O-2. This work makes evident the promise of molecular design in tailoring dye-semiconductor assemblies for visible light-induced photocatalytic selective chemical transformations. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

Through molecular inverse design, researchers have revealed the underlying mechanism of the superior photocatalytic activity of alizarin red S-TiO2 assembly, showing that the substituted -OH groups provide visible light absorption and binding sites, 1,2-DHA plays a major role in photocatalytic activity, and the -SO3 Na+ groups increase the binding strength. The study indicates that this dye-semiconductor assembly can be used for green light-induced selective oxidation reactions.