Polythiophene-encapsulated bimetallic Au-Fe₃O₄ nano-hybrid materials: A potential tandem photocatalytic system for nondirected C(sp²)–H activation for the synthesis of quinoline carboxylates

Abstract

Hetero-oligophenylene derivative 3 appended with thiophene moieties has been designed and synthesized which undergoes aggregation to form J-type fluorescent aggregates in in H₂O/THF (7/3) media. These aggregates served as reactors for the preparation of bimetallic Au-Fe₃O₄ NPs. During the reduction process, aggregates of derivative 3 were oxidized to the polythiophene species 4. Interestingly, the polythiophene species 4, having a fibrous morphology, served as a shape- and morphology-directed template for assembly of bimetallic Au-Fe₃O₄ NPs in a flower-like arrangement. Furthermore, polythiophene-encapsulated bimetallic 4:Au-Fe₃O₄ nanohybrid materials served as an efficient and recyclable catalytic system for C(sp²)–H bond activation of unprotected electron-rich anilines for the construction of synthetically versatile quinoline carboxylates via C–H activation, carbonylation, and subsequent annulation under mild and eco-friendly conditions (aqueous media, room temperature, visible-light irradiation, and aerial conditions).