Organic Materials Lab, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee-247 667, India.
J Org Chem. 2011 Aug 5;76(15):6134-45. doi: 10.1021/jo200857p. Epub 2011 Jun 29.
A new series of alkylamine- or arylamine-substituted benzo[a]phenazines have been synthesized from 1,2-naphthoquinones by employing simple sequential Michael-type addition with a variety of primary and secondary amines and the condensation reaction of the resulting amine-substituted 1,2-naphthoquinones with o-phenylenediamine. They exhibited absorption peaks originating from the charge transfer transition between the amine and pyrazine segments and benzo[a]phenazine localized π-π* transitions. Although the absorption spectra of the dyes were not significantly influenced by the nature of the solvents, addition of TFA led to a prominent red-shift in the absorption spectra owing to the protonation at the quinoxaline segment which enhanced the electron-accepting ability. The qualitative trends observed in the optical properties and acidochromism were supported by density functional theoretical computations. The dyes displayed positive solvatochromism in the emission spectra suggestive of a more polar excited state. The dyes were also characterized by a quasi-reversible reduction couple originating from the pyrazine segment which underwent shifts corresponding to electron-donating strength of the amine segment.
已通过简单的顺序迈克尔型加成反应，利用各种伯胺和仲胺，将一系列新的烷基胺或芳基胺取代的苯并[a]吩嗪从 1,2-萘醌合成得到，并且得到的胺取代的 1,2-萘醌与邻苯二胺进行缩合反应。它们表现出源于胺和吡嗪片段之间的电荷转移跃迁以及苯并[a]吩嗪局域化 π-π*跃迁的吸收峰。尽管染料的吸收光谱不受溶剂性质的显著影响，但加入 TFA 会导致吸收光谱明显红移，这是由于喹喔啉片段的质子化增强了电子接受能力。观察到的光学性质和酸致变色的定性趋势得到了密度泛函理论计算的支持。染料在发射光谱中表现出正溶剂化变色，表明激发态具有更高的极性。染料还具有源于吡嗪片段的准可逆还原偶，该还原偶发生与胺片段的供电子强度相对应的位移。
