Tetrathiafulvalene‐Fused Heterabuckybowl: Protonation‐Induced Electron Transfer and Self‐Sensitized Photooxidation
Lei Liu, Chaoxian Yan, Yecheng Li, Zhe Liu, Chengshan Yuan, Hao‐Li Zhang, Xiangfeng Shao
Abstract
Abstract The electron donor tetrathiafulvalene (D 1 ) was fused onto the electron‐rich heterabuckybowl trichalcogenasumanene (D 2 ) through an electron‐deficient pyrazine unit (A) to give 1 c , 1 d , 2 c , and 2 d , featuring the D 1 –A–D 2 structure. Both D 1 and D 2 play a pivotal role in intramolecular charge‐transfer (ICT) transitions, consequently 1 c , 2 d , 2 c , and 2 d show a broad ICT band at 450–720 nm in steady state. They exhibit two charge‐separated transient states, CS 1 and CS 2 , that appear in sequence. CS 1 has a short lifetime (542 fs), and the D 1 moiety on CS 1 is in the radical cation state with an absorption maximum ( λ max ) at 889 nm. CS 1 then converts into CS 2 ( λ max , 1105 nm) through an ICT between D 1 .+ and D 2 , affording D 1 (1− δ ).+ and D 2 δ .+ . Compounds 1 c , 1 d , 2 c , and 2 d show protonation‐induced intramolecular electron transfer that leads to absorption at λ =700–1300 nm. Owing to the existence of an electron‐rich C=C bond on the D 1 moiety and in situ generation of 1 O 2 by the pyrazine‐fused D 2 moiety, compounds 1 c , 1 d , 2 c , and 2 d display self‐sensitized photooxidation in 50 s.