Oxidation of Tetraphenyl­hexaaza­anthracene: Accessing a Scissor Dimer of a 16π Biscyanine

Tetraphenylhexaazaanthracene (TPHA), a fluorescent zwitterionic biscyanine with a closed-shell singlet ground state, on treatment with manganese dioxide or phenyliodine bis­(trifluoroacetate) (PIFA), undergoes oxidative dimerization to give a near-zero dipole scissor 5,5′-dimer DI-TPHA. Both acene components of the new dimer DI-TPHA maintain their biscyanine closed-shell singlet ground state motifs, as judged by analysis of both single crystal X-ray crystallographic and density functional theory computational studies; however, unlike TPHA, DI-TPHA is only very weakly fluorescent.

四苯基六氮杂蒽（Tetraphenylhexaazaanthracene, TPHA）是一种具有闭壳层单重态基态的荧光两性离子双花青染料。经二氧化锰或二(三氟乙酸)碘苯（PIFA）处理后，该化合物可发生氧化二聚反应，生成近零偶极剪刀型5,5'-二聚体DI-TPHA。通过单晶X射线衍射与密度泛函理论计算分析可知，该新型二聚体DI-TPHA的两个并苯结构单元均保留了双花青类化合物的闭壳层单重态基态结构基元；但与TPHA不同的是，DI-TPHA仅表现出极弱的荧光性。