Intramolecular Charge Transfer-Enhanced BODIPY Photosensitizer in Photoinduced Electron Transfer and Its Application to Photoxidation under Mild Condition

Photoinduced electron transfer process is a crucial step in photooxidation to obtain synthetic chemicals. However, the driving forces of electron transfer as priority in all have been rarely studied in stepwise detail. Herein, we report a series of BODIPY derivatives with an emphasis on the intramolecular charge transfer, enhancing the key step of photoinduced electron transfer process and photooxidation performances. A series of novel BODIPY photosensitizers (B-1–B-5) were prepared, wherein diethylamine amino of B-3 as charge injection group was conjugated to the 2,6-diiodo-styryl-BODIPY, and the electron transfer impetus was enhanced 1.6 times due to its more negative redox potentials. These results were also confirmed by the DFT/TDDFT calculation. Without pure oxygen, B-3 still can exhibit an exceptional performance in photoxidative aromatization of 1,4-DHP under mild condition. After irradiation for 28 min, the conversion rate came to 98.2%.