An effective green molecular reactor for photocatalytic aerobic oxidation of sulfide under natural sunlight

Abstract

Expanding the light absorption range is of great significance for photocatalysts to improve the solar light utilization and photocatalytic efficiency. In this work, we reported a novel zirconium-based metal–organic framework (Zr-MOF) with a formula of {[Zr₆O₈(H₂O)₈(Cl-PDI-TA)₂]_0.5·11DMF·12H₂O}_n, (Zr-PDI-2, Cl-PDI-TA = N,N′-di(3′,3″,5′,5″-tetrakis(4-carboxyphenyl))-1,2,6,7-tetrachloroperylene-3,4,9,10-tetracarboxylic acid diimide, and DMF = N,N-dimethylformamide) with scu topology constructed from 4-connected ligands and 8-connected [Zr₆O₈(H₂O)₈]⁸⁺ clusters, showcasing 1D rhombic channels along the c-axis, by regulating the modulator in the synthesis of Zr-PDI-1 with csq topology reported in our previous work. Particularly, the C–C bond length around the amide group in Zr-PDI-2 was found to be apparently longer than that in Zr-PDI-1 and most other PDI-based compounds. Such a unique structure induced Zr-PDI-2 to feasibly generate carbon-centered radicals and thus endowed Zr-PDI-2 with much stronger light absorption in the near infrared region (600–880 nm), making it a promising photocatalyst candidate under natural sunlight. Further photocatalytic experiments demonstrated the high efficiency of Zr-PDI-2 as the photocatalyst for the aerobic oxidation of sulfides to sulfoxides under the irradiation of a white LED or even ambient natural sunlight, and mechanistic studies confirmed the vital role of O₂˙⁻ and ¹O₂ in the reaction process.