Imine-linked donor–acceptor metal–organic frameworks for an efficient photocatalytic oxidative coupling reaction

Abstract

Donor–acceptor metal–organic frameworks (D–A MOFs) are promising platforms for photocatalytic organic transformation and energy conversion due to their controllable chemical structures and tunable energy band gaps. Herein, we report two imine-linked D–A MOFs, namely JNM-18 and JNM-19, containing both Cu(I) cyclic trinuclear units (CTUs) as an electron acceptor (A) and triphenylbenzene (TPB) or hexaphenylbenzene (HPB) as an electron donor (D) synthesized by Schiff base condensations. With precise spatial distribution of donor and acceptor moieties within the two-dimensional (2D) networks, the obtained D–A MOFs exhibited efficient photocatalytic activity for the aerobic oxidation reaction of benzylamines upon irradiation with a violet LED. Interestingly, JNM-18 with planar TPB moieties showed better photo-electrochemical properties, and thus better photocatalytic performance than JNM-19 containing nonplanar HPB units with propeller arrangement which was possibly due to the stronger electron-donating abilities of the associated building units. This work illustrates a convenient approach to reticularly prepare D–A MOFs as photocatalysts by linkage of dynamic covalent bonds.