Herein, we present the study of two complementary intramolecular charge transfer (ICT) transitions in two sets of dialkylamino-substituted halogenated thienyl chalcones. We demonstrate that while the first (and stronger) ICT takes place from the 4-(dialkylamino)phenyl moiety to the enone, the second ICT involves the thienyl substituent as the donor. The former is evidenced by a robust solvatochromic shift in both absorption and emission spectra, implying a large increase in the dipole moment upon excitation to the lowest excited state. The latter, a short-range ICT process, is confirmed upon photoexcitation of the higher energy bands, and its enhancement by the larger polarizability of the iodine substituent. With the help of (TD)-DFT calculations and the solvatochromic method, we quantified the extent of these effects and set the stage for further developments towards the design of new chalcone-based dyes. We demonstrated that theoretical calculations allow fine-tuning the sensitive balance between these complementary ICT processes.

本文中，我们介绍了在两组二烷基氨基取代的卤代噻吩基查耳酮中两个互补的分子内电荷转移（ICT）跃迁的研究。我们证明，虽然第一个（也是更强的）ICT从4-（二烷基氨基）苯基部分到烯酮发生，但第二个ICT包含噻吩基取代基。前者通过吸收光谱和发射光谱中强烈的溶剂化变色证明，这表明当激发到最低激发态时偶极矩会大大增加。后者是一种短距离的ICT工艺，在对高能带进行光激发后得到了证实，并且碘取代基的极化率更高，从而增强了它。借助（TD）-DFT计算和溶剂变色方法，我们量化了这些影响的程度，并为进一步开发基于查尔酮基染料的设计奠定了基础。我们证明了理论计算可以微调这些互补的ICT流程之间的敏感平衡。