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以2-氨基吡啶衍生物为原料,通过简单而高效的两步反应合成了6个新型N,O-配位吡啶氟硼化合物2a~2f,其结构经~1H(~(13)C、~(19)F)NMR,ESI-MS,IR和X单晶衍射分析表征,并对其光谱性质进行实验和理论计算研究.结果表明,苯环(或吡啶环)上含给电子基的化合物2b,2c,2e,2f的最大吸收峰位于360~420 nm(λ_(abs)=368,400,365,418 nm),且具有较大的摩尔吸光系数(ε=28760,51980,25250,40750 L·mol~(-1)·cm~(-1)).明显不同的是,苯环对位无取代基的化合物2a和含吸电子基的化合物2d的最大吸收峰分别为340和337 nm.同时,化合物2b,2c,2e,2f具有一定的溶剂效应,随着溶剂极性的增加,发射光谱红移且荧光强度降低,说明这些化合物中存在着一定的分子内电荷转移(ICT)效应.此外,实验结果和理论计算验证了化合物2b,2c,2e,2f中存在ICT,并揭示了取代基对化合物的光谱性质具有显著影响.希望通过这些研究可为进一步发展ICT-型荧光染料及其应用打下良好基础.
Six novel 2-aminopyridine derivatives were synthesized via simple and efficient two-step reaction, and their structures were characterized by ~ 1H (~ (13) C, ~ (19) F) Characterization of single crystal by NMR, ESI-MS, IR and X. The experimental results and theoretical calculations of their spectral properties were shown. The results showed that the electron-donating compounds 2b , 2c, 2e and 2f are located at 360-420 nm (λ abs = 368,400,365 and 418 nm) and have large molar absorptivities (ε = 28760, 51980, 25250, 40750 L · mol -1 ) · Cm -1). The obvious difference is that the maximum absorption peak of compound 2a with no substituent at the benzene ring and compound 2d with the electron-attracting group are 340 and 337 nm, respectively. Meanwhile, compounds 2b and 2c , 2e and 2f have certain solvent effect, and the emission spectra are red-shifted and the fluorescence intensity is decreased with the increase of solvent polarity, indicating that there are some intramolecular charge transfer (ICT) effects in these compounds.In addition, the experimental results and theoretical Calculations confirmed the presence of ICTs in compounds 2b, 2c, 2e, 2f and revealed that substituents have a significant effect on the spectral properties of the compounds.It is hoped that these studies will be helpful for the further development of ICT- Type fluorescent dye and its application lay a good foundation.