作者:Masaki Matsui、Takaya Maehashi、Kazumasa Funabiki
DOI:10.1246/bcsj.80.999
日期:2007.5.15
Novel non-ionic near-infrared (NIR) fluorescent 2,3-dicyanopyrazines were prepared. 5-[6-(9-julolidyl)-1,3,5-hexatrienyl]- and 5-[8-(9-julolidyl)-1,3,5,7-octatetraenyl]-2,3-dicyanopyrazines showed fluorescence maxima (Fmax) at 716 and 751 nm with fluorescence quantum yields (Φf) 0.12 and 0.03 in toluene, respectively. MO calculations showed that these compounds have an intramolecular charge-transfer chromophoric system from the julolidyl to dicyanopyrazine moieties. The calculations also showed that since the HOMO energy level was unstabilized, and at the same time, the LUMO energy level was stabilized by expanding the conjugated system at 5-position, NIR fluorescent derivatives were obtained. They showed clear positive solvatochromism in the fluorescence spectroscopy. The fluorescence intensity drastically decreased in polar solvents.
制备了新型非离子近红外(NIR)荧光 2,3-二氰基吡嗪。5-[6-(9-julolidyl)-1,3,5-hexatrienyl]-和 5-[8-(9-julolidyl)-1,3,5,7-octatetraenyl]-2,3-二氰基吡嗪在甲苯中的荧光最大值(Fmax)分别为 716 纳米和 751 纳米,荧光量子产率(Φf)分别为 0.12 和 0.03。MO 计算表明,这些化合物具有一个分子内电荷转移的发色系统,即从巨烷基到二氰基吡嗪的电荷转移。计算还表明,由于 HOMO 能级不稳定,同时通过扩大 5 位共轭体系使 LUMO 能级稳定,因此得到了近红外荧光衍生物。它们在荧光光谱中显示出明显的正溶色性。在极性溶剂中,荧光强度急剧下降。