Substituent Effects of Fluorescein on Photoredox Initiating Performance under Visible Light

Won Oh Choi; Young Jae Jung; Minyoung Kim; Hoyun Kim; Jingjing Li; Hyebin Ko; Hong-In Lee; Hye Jin Lee; Jungkyu K Lee

doi:10.1021/acsomega.3c04324

Substituent Effects of Fluorescein on Photoredox Initiating Performance under Visible Light

ACS Omega. 2023 Oct 18;8(43):40277-40286. doi: 10.1021/acsomega.3c04324. eCollection 2023 Oct 31.

Authors

Won Oh Choi¹, Young Jae Jung¹, Minyoung Kim¹, Hoyun Kim¹, Jingjing Li¹, Hyebin Ko¹, Hong-In Lee¹, Hye Jin Lee¹, Jungkyu K Lee¹

Affiliation

¹ Department of Chemistry and Green-Nano Materials Research Center, Kyungpook National University, Daegu 41566, South Korea.

Abstract

We demonstrated the effects of substituents in fluorescein on the photoredox catalytic performance under visible light. For the systematic investigation, the phenyl ring of fluorescein was substituted with six different functional groups (i.e., amine, amide, isothiocyanate, aminomethyl, bromo, or nitro group) at the 5- or 6-position. The fluorescein derivatives were carefully characterized through photophysical and electrochemical analyses. The substituent effects were estimated by comparing the photopolymerization of poly(ethylene glycol) diacrylate (PEGDA) and N-vinylpyrrolidone (VP) in the presence of triethanolamine (TEOA) under aerobic conditions to that of intact fluorescein. As a result, the amine and nitro groups exhibited the lowest performances, presumably due to intramolecular photoinduced electron transfer (PET) promoted by the strong electron push-pull effect. The others, representative moderate or weak deactivators and activators, exhibited inferior performances than intact fluorescein, presumably owing to the more negative ΔG_PET values, resulting in a decreased rate of intermolecular PET. These results are crucial for understanding the structure-performance relationship and the development of visible-light photoredox catalysts with improved performance and functionality.