Conjugated π-Linker Engineering of Covalent Metal-Organic Frameworks for Enhanced Photocatalysis

Abstract

Covalent metal-organic frameworks (CMOFs) combining the chemistry of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have demonstrated promising potential as reticular photocatalysts, owing to their tunable structures, high surface areas, and efficient light absorption, which provide enhanced charge separation and improved catalytic activity. Herein, we report three imine-linked CMOFs constructed by Cu(I) cyclic trinuclear units (CTUs) and organic linkers with tunable conjugated functional groups, such as benzene (JNM-61), naphthalene (JNM-62), or anthracene (JNM-63), via dynamic covalent chemistry. Due to the incorporation of conjugated linkers, the obtained CMOFs exhibited good photocatalytic activity for the cross-dehydrocoupling reaction of N-phenyl-tetrahydroisoquinoline with alkynes. Interestingly, the variation of linker conjugation strongly influences the light absorption, charge separation and reactive oxygen species (ROS) generation of the materials, resulting in significantly controlled photocatalytic efficiency. Notably, JNM-63 with anthracene linkers showed more efficient photocatalytic performance than JNM-61 containing benzene units and JNM-62 containing naphthalene moieties, suggesting the extended conjugation enhanced the oxygen activation and electron transfer during the photocatalytic process. This work presents a simple yet effect approach to optimizing reticular photocatalysts via dynamic covalent chemistry.

Keywords

Metal-organic frameworks / Covalent organic frameworks / Dynamic covalent chemistry / Photocatalysis / Linker engineering

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