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Indexed by:期刊论文

Date of Publication:2018-11-21

Journal:NEW JOURNAL OF CHEMISTRY

Included Journals:SCIE

Volume:42

Issue:22

Page Number:18448-18457

ISSN No.:1144-0546

Abstract:Pharmaceutically meaningful conversions like photocatalytic sulfonylation call for the precise control of the photoelectronic properties of photocatalysts. A ligand engineering strategy of inserting different numbers of thiophenes into the scaffold of triphenylamine (TPA)-based ligands was developed to improve the visible light absorption, enhance the oxidation potentials of the ground states, and decrease the reduction potentials of the excited states, providing a powerful tool for continuous modulation of the photoelectronic properties of metal-organic framework (MOF)-based heterogeneous photocatalysts. The ligand inserted with two thiophenes was found to possess a well-balanced photoelectronic performance, endowing the corresponding MOF Zn-BCTA with good visible light-harvesting ability and a moderate excited-state reduction potential with minimal over-potential for the photoinduced generation of sulfonyl radicals while avoiding the competitive over-reduction of the sulfonyl moieties. The breaking of the C-3-symmetry of the TPA-based ligand forged a distorted coordination geometry of the Zn4O nodes of the MOF to provide potential active sites to facilitate the fixation and activation of alpha, beta-unsaturated carbonyl substrates, and the two-fold interpenetrated frameworks further enhanced the spatial proximity between the encapsulated substrate and the photoredox-active centre. The synergy of the well-tuned photoelectronic properties of Zn-BCTA and the spatial confinement effect within the pores benefited the tandem sulfonylation-cyclisation of unsaturated alkenes in an efficient and diastereoselective mode for the construction of bio-interesting sulphoyl isoquinolinediones/oxindoles.