Sharma Rekha, Thomas Michael B, Misra Rajneesh, D'Souza Francis
Department of Chemistry, Indian Institute of Technology, Indore, 453552, India.
Department of Chemistry, University of North Texas, 1155 Union Circle, #305070, Denton, TX, 76203-5017, USA.
Angew Chem Int Ed Engl. 2019 Mar 22;58(13):4350-4355. doi: 10.1002/anie.201814388. Epub 2019 Feb 22.
The C -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.
具有C对称性的星形吩噻嗪取代的并四苯1与电子受体四氰基乙烯（TCNE）和7,7,8,8-四氰基对苯二醌二甲烷（TCNQ）发生反应。环加成-逆电环化反应生成共轭物2和3。对2和3进行的光谱、电化学和光物理研究表明，三键的官能化对其基态和激发态相互作用有显著影响。具体而言，吩噻嗪与电子接受基团之间存在强烈的基态相互作用，导致电荷转移态，随后超快的电荷分离产生电子转移产物。这不仅在吩噻嗪化学中是前所未有的，在源自四氰基丁二烯和二氰基对苯二醌二甲烷的供体-受体共轭物中也是如此。此外，通过处理光谱电化学数据，首次构建了电荷分离物种的光谱，并证明其在解释相当复杂的瞬态光谱方面非常有用。
