Calix[4]azulene is a non-alternant aromatic calixarene composed of four azulene chromophores linked by methylene groups. Its photochemical stability, photophysical properties and an analysis of its electronic spectra are reported using monomeric azulene as a known reference standard. The molecule is stable when excited in its visible and near uv absorptions and, unlike azulene, produces no measurable “anti-Kasha” fluorescence when excited to its second excited singlet state, S₂. This lack of fluorescence places the lifetime of the initially excited, photochemically stable S₂ species at less than 1 picosecond. A significant, bathochromic shift of the S₂ absorption band system in the calixarene, and the appearance of an additional weak, broad absorption immediately to the red signals significant intramolecular chromophore interaction. Femtosecond transient absorption spectroscopy using excitation in this red-shifted tail of the S₂ band system reveals a very weak transient signal most of which decays within one ps, but with suggestions of a slightly longer-lived underlying component. No longer-lived T₁ triplet transient is observed. A complete analysis of the data using monomeric azulene as a reference suggests, following elimination of several alternate mechanisms, that the initially excited S₂ species may be relaxing via a novel singlet-singlet fission process.

Calix [4] azulene是一种非交替的芳族杯芳烃，由四个通过亚甲基连接的a基发色团组成。报告了使用单体氮杂作为已知参考标准的光化学稳定性，光物理性质和电子光谱分析。该分子在可见光和接近uv吸收时被激发时是稳定的，并且与a烯不同，当被激发至其第二激发单重态S ₂时，该分子不产生可测量的“反Kasha”荧光。这种荧光的缺乏使最初激发的光化学稳定的S ₂物种的寿命小于1皮秒。S _2的显着红移在杯芳烃的吸收带系统中，出现了额外的弱，宽吸收，立即向红色信号表明分子内发色团发生明显相互作用。飞秒瞬态吸收光谱法在S ₂波段系统的该红移尾部使用了激发，揭示了一个非常弱的瞬态信号，其中大部分衰减在1 ps之内，但暗示了寿命更长的潜在成分。没有观察到寿命更长的T ₁三重态瞬态。在消除了几种替代机制之后，使用单体氮杂作为参考对数据进行的完整分析表明，最初激发的S ₂物种可能会通过新型单重态-单重裂变过程而松弛。