Strong Ground‐ and Excited‐State Charge Transfer in C3‐Symmetric Truxene‐Derived Phenothiazine‐Tetracyanobutadine and Expanded Conjugates

作者：Rekha Sharma, Michael B. Thomas, Rajneesh Misra, Francis D’Souza · 发表于：Angewandte Chemie International Edition · 年份：2019 · DOI：10.1002/anie.201814388 · 被引用次数：55 · 研究领域：Photochemistry and Electron Transfer Studies、Porphyrin and Phthalocyanine Chemistry、Luminescence and Fluorescent Materials

-symmetric star-shaped phenothiazene-substituted truxene 1 was reacted with the electron acceptors tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The cycloaddition-retroelectrocyclization reaction yields the conjugates 2 and 3. A combination of spectral, electrochemical, and photophysical investigations of 2 and 3 reveals that the functionalization of the triple bond has a pronounced effect on their ground and excited-state interactions. Specifically, the existence of strong ground-state interactions between phenothiazine and the electron-accepting groups results in charge-transfer states, while subsequent ultrafast charge separation yields electron transfer products. This is unprecedented not only in phenothiazine chemistry but also in tetracyanobutadiene- and dicyanoquinodimethane-derived donor-acceptor conjugates. Additionally, by manipulating spectroelectrochemical data, a spectrum of the charge-separated species is construed for the first time, and shown to be highly useful in interpreting the rather complex transient spectra.