The present study details the experimental and theoretical characterization of the photophysical properties of 14 examples of 2‐(phenylamino)‐1,10‐phenanthrolines (1). The absorption spectra of 1 are substituent‐dependent but in a general manner present absorption bands at wavelengths of ~230; ~300; ~335 and a shoulder at ~380 nm. Electron‐donating groups (EDG) and electron‐withdrawing groups (EWG), respectively, result in bathochromic and hypsochromic shifts. Compounds 1 are highly luminescent, in contrast to phenanthroline, and emit in the region between 350 and 500 nm with substituent‐dependent λmax emission. The emission spectra show a redshift for EDG (4‐OMe 62 nm; 4‐Me 19 nm) and a blueshift for EWG (4‐CN 41 nm; 4‐CF3 38 nm) relative to the emission of the unsubstituted parent compound 1a. Plotting the λmaxEM against Hammett σ+ constants gave an excellent linear correlation demonstrating the electron‐deficient nature of the excited state and how the substituents (de)stabilize S1. Theoretical calculations revealed a HOMO‐LUMO π‐π* electronic transition to S1 which in combination with difference (S1–S0) in electron density maps revealed charge‐transfer character. Strongly electron‐withdrawing substituents switch off the charge transfer to give rise to a local excitation.

中文翻译：

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荧光 2-(苯基氨基)-1,10-菲咯啉衍生物的光物理性质

本研究详细介绍了 2-(苯基氨基)-1,10-菲咯啉 (1) 的 14 个实例的光物理特性的实验和理论表征。1 的吸收光谱取决于取代基，但通常在~230 波长处呈现吸收带；~300; ~335 和 ~380 nm 处的肩峰。供电子基团（EDG）和吸电子基团（EWG）分别导致红移和深移。与菲咯啉相比，化合物 1 具有很强的发光性，并且在 350 到 500 nm 之间的区域内发射具有取代基依赖的 λmax 发射。相对于未取代的母体化合物 1a 的发射，发射光谱显示 EDG（4-OMe 62 nm；4-Me 19 nm）和 EWG（4-CN 41 nm；4-CF3 38 nm）蓝移。将 λmaxEM 与 Hammett σ+ 常数作图给出了极好的线性相关性，证明了激发态的缺电子性质以及取代基如何（去）稳定 S1。理论计算揭示了向 S1 的 HOMO-LUMO π-π* 电子跃迁，结合电子密度图中的差异（S1-S0）揭示了电荷转移特性。强吸电子取代基关闭电荷转移以引起局部激发。