Photoresponsive Covalent Organic Frameworks with Diarylethene Switch for Tunable Singlet Oxygen Generation

: Incorporation of molecular switches with light, heat, and electricity responsibility into arti fi cial solids has been developed as a successful strategy to construct stimuli-responsive functional materials. However, precise manipulation of their molecular geometries and electronic structures to control the properties of macroscopic materials still remains a fundamental challenge. Herein, a photoresponsive covalent organic framework ( o -COF) with the square lattice was fabricated from the dynamic covalent chemistry reaction of ring-open dithienylethene − dialdehyde with 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (H 2 TAPP). UV irradiation of the dithienyle-thene-based units in o -COF a ff orded its reversible photoisomer ( c -COF) in the ring-closed form. In addition to a range of di ff raction, microscopic, and gas physical sorption characterizations, spectroscopic investigations with the help of theoretical simulations revealed di ff erent photocatalytic activities toward the evolution of singlet oxygen and corresponding photocatalytic oxidation of amines due to the di ff erent energy transfer pathways from the porphyrin unit to BBTP photoisomers in these two COFs. Most interestingly, such di ff erent photocatalytic behaviors for two COFs could be easily tuned in a reversible manner by adjusting the ring-closed/ open form of dithienylethene units by means of UV and visible light. mg) were added into 1.0 mL of CD 3 CN in a 5 mL quartz tube. The resultant mixture was stirred at room temperature upon irradiation with a 25 W blue LED light under air. Conversion of the product was determined by 1 H NMR in CD 3 CN. For the recycle test, the catalyst was separated by centrifugation, washed by CH 3 OH after every cycle, and dried at 25 ° C under vacuum for next use.