Benzotrithiophene-based sp2 carbon-conjugated microporous polymers for green light-triggered oxidation of amines to imines

To optimize the activity at the molecular level, conjugated microporous polymers (CMPs) can be tailored through monomers for visible light photocatalysis. Benzotrithiophene (BTT) is the select monomer for CMPs because of its planar and electron-rich properties. Notably, the sp2-carbon conjugation of BTT is highly desirable to facilitate electron transfer. Herein, the condensation of 1,4-phenylenediacetonitrile and 4,4′-biphenyldiacetonitrile with benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarbaldehyde assembles two CMPs, sp2c-BTT-CMP-1 and sp2c-BTT-CMP-2, respectively. Systematic materials characterizations and density functional theory calculations on sp2c-BTT-CMP-1 and sp2c-BTT-CMP-2 are performed to interpret the essential optoelectronic attributes. Due to the different linkages and π-conjugations, sp2c-BTT-CMP-2 presents a better built-in electric field than sp2c-BTT-CMP-1, edging toward facile dissociation and fast transport of charge carriers. Consequently, sp2c-BTT-CMP-2 is superior to sp2c-BTT-CMP-1 for the green light-triggered oxidation of amines to imines with dioxygen. This study underlines the promising aspect of BTT-based CMPs with a fitting linkage as state-of-the-art functional materials for semiconductor photocatalysis. •Two benzotrithiophene-based CMPs, sp2c-BTT-CMP-1 and sp2c-BTT-CMP-2 are assembled.•The sp2-carbon linkage gives rise to large π-electron delocalization.•The sp2c-BTT-CMP-2 has superior optoelectronic properties.•The sp2c-BTT-CMP-2 exhibits superior photocatalytic activity for the oxidation of amines to imines.•Good compatibility for amine substrates is achieved over sp2c-BTT-CMP-2.