Department of Applied chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 2, 23-8522, Japan.
Chem Asian J. 2018 Jul 4;13(13):1683-1687. doi: 10.1002/asia.201800502. Epub 2018 Jun 19.
The compound 5,12-diacetyl-5,12-dihydroquinoxalino[2,3-b]quinoxaline 1 a and its derivatives were prepared, and their solid- and solution-state spectroscopic properties were studied; 1 a shows stronger fluorescence in solution than in the solid state due to aggregation caused by self-quenching. Phenyl- or alkoxy-substituted derivatives 1 b-d show solid-state fluorescence with moderate quantum yields of about Φ=0.12-0.15, although the corresponding values are 0.01-0.07 in solution. The spectroscopic properties of alkoxy-substituted derivatives were hardly changed compared to 1 a and 1 b, although 1 a and 1 b have similar absorption and fluorescence maxima in solution and in the solid state. DFT calculations indicate that orbital switching occurs between HOMO and HOMO-1 and HOMO-2 due to orbital interactions with introduced substituents. Crystal structure analysis revealed that the molecules have bent structures around tertiary nitrogen atoms and form a characteristic dimeric structure.
5,12-二乙酰基-5,12-二氢喹喔啉并[2,3-b]喹喔啉 1a 及其衍生物被制备，并研究了它们的固态和溶液态光谱性质；由于自猝灭引起的聚集，1a 在溶液中比在固态中显示出更强的荧光。苯基或烷氧基取代的衍生物 1b-d 在固态下显示出中等量子产率（约 Φ=0.12-0.15）的荧光，尽管在溶液中的相应值为 0.01-0.07。与 1a 和 1b 相比，烷氧基取代的衍生物的光谱性质几乎没有变化，尽管 1a 和 1b 在溶液和固态中的吸收和荧光最大值相似。DFT 计算表明，由于与引入的取代基的轨道相互作用，HOMO 和 HOMO-1 和 HOMO-2 之间发生轨道跃迁。晶体结构分析表明，分子在叔氮原子周围具有弯曲结构，并形成特征的二聚体结构。
