Spin-orbit charge-transfer intersystem crossing in heavy-atom-free orthogonal covalent boron-dipyrromethene heterodimers

Wang，Zeming1; Ma，Lin1; Zhao，Hongmei1; Wan，Yan3; Zhang，Xian Fu2; Li，Yang1; Kuang，Zhuoran1; Xia，Andong1

2023

10.1039/d3cp01934a

Physical Chemistry Chemical Physics   Impact Factor & Quartile

1463-9076

1463-9084

Boron-dipyrromethene (BODIPY) derivatives are prospective organic-based triplet photosensitizers. Since the triplet generation yield of the parent BODIPY is low, heavy atoms are widely used to improve the triplet yield. However, the dimerization of BODIPYs can also significantly improve their ability to produce triplets. Through a comparative study of the triplet formation dynamics of two heavy-atom-free orthogonal covalent BODIPY heterodimers that differ in their dihedral angles, we have demonstrated that the mechanism of spin-orbit charge-transfer intersystem crossing (SOCT-ISC) promotes the triplet generation of BODIPY heterodimers in solution. Different from the general understanding of SOCT-ISC, the heterodimer with a smaller dihedral angle and low structural rigidity showed better triplet generation due to (a) the stronger inter-chromophoric interaction in the heterodimer, which promoted the formation of a solvent-stabilized charge-transfer (CT) state, (b) the more favorable energy level alignment with sizeable spin-orbit coupling strength, and (c) the balance between the stabilized singlet CT state and limited direct charge recombination to the ground state in a weakly polar solvent. The complete spectral characterization of the triplet formation dynamics clarified the SOCT-ISC mechanism and important factors affecting the triplet generation in BODIPY heterodimers.

SCI

English

Others

National Natural Science Foundation of China (NSFCs)["22133001","21827803","22203009","21873013","62074073"] ; Beijing Natural Science Foundation[2232012] ; BUPT Excellent PhD Students Foundation[CX2022161]

Chemistry ; Physics

Chemistry, Physical ; Physics, Atomic, Molecular & Chemical

WOS:001002208600001

ROYAL SOC CHEMISTRY

CHEMISTRY

2-s2.0-85162265569

Scopus

1.State Key Laboratory of Information Photonic and Optical Communications,School of Science,Beijing University of Posts and Telecommunications (BUPT),Beijing,100876,China
2.Department of Materials Science and Engineering,Southern University of Science and Technology,Shenzhen,Guangdong Province,518055,China
3.College of Chemistry,Beijing Normal University,Beijing,100875,China

Wang，Zeming,Ma，Lin,Zhao，Hongmei,et al. Spin-orbit charge-transfer intersystem crossing in heavy-atom-free orthogonal covalent boron-dipyrromethene heterodimers[J]. Physical Chemistry Chemical Physics,2023,25(36).

Wang，Zeming.,Ma，Lin.,Zhao，Hongmei.,Wan，Yan.,Zhang，Xian Fu.,...&Xia，Andong.(2023).Spin-orbit charge-transfer intersystem crossing in heavy-atom-free orthogonal covalent boron-dipyrromethene heterodimers.Physical Chemistry Chemical Physics,25(36).

Wang，Zeming,et al."Spin-orbit charge-transfer intersystem crossing in heavy-atom-free orthogonal covalent boron-dipyrromethene heterodimers".Physical Chemistry Chemical Physics 25.36(2023).