Gasiorski P, Matusiewicz M, Gondek E, Uchacz T, Wojtasik K, Danel A, Shchur Ya, Kityk A V
Faculty of Electrical Engineering, Częstochowa University of Technology, Al. Armii Krajowej 17,42-200 Częstochowa, Poland.
Institute of Physics, Cracow University of Technology, Podhorążych 1, 30-084 Kraków, Poland.
Spectrochim Acta A Mol Biomol Spectrosc. 2017 Nov 5;186:89-98. doi: 10.1016/j.saa.2017.05.060. Epub 2017 Jun 6.
Paper reports the synthesis and spectroscopic studies of two novel 1,3-diphenyl pyrazoloquinoxaline (PQX) derivatives with 6-substituted methyl (MePQX) or methoxy (MeOPQX) side groups. The optical absorption and fluorescence emission spectra are recorded in solvents of different polarity. Other photophysical constants, such as the fluorescence lifetime and quantum yield, radiationless and radiative rate constants, electronic transition dipole moments, give complete characterization of MePQX and MeOPQX dyes as materials for potential luminescence or electroluminescence applications. Measured optical absorption and fluorescence emission spectra are compared with the results of quantum-chemical analysis using density functional theory (DFT/TDDFT) methods based on hybrid and long range corrected (LRC) exchange-correlation (xc) functionals in combination with solvation self consistent reaction field model. Comparing to conventional hybrid xc-functionals, the DFT/TDDFT calculations using LRC xc-functionals yield considerably more accurate description of optical absorption and fluorescence emission spectra. The best description of the absorption-emission circle provides the model assuming that optical absorption takes place from preferably flat or weakly twisted molecular conformations in the ground state, as particularly is suggested by the geometrical DFT optimization, whereas the fluorescence emission would be expected from more twisted molecular conformations in the excited state.
论文报道了两种新型的带有6-取代甲基（MePQX）或甲氧基（MeOPQX）侧基的1,3-二苯基吡唑并喹喔啉（PQX）衍生物的合成及光谱研究。在不同极性的溶剂中记录了光吸收和荧光发射光谱。其他光物理常数，如荧光寿命和量子产率、无辐射和辐射速率常数、电子跃迁偶极矩，完整地表征了MePQX和MeOPQX染料作为潜在发光或电致发光应用材料的特性。将测得的光吸收和荧光发射光谱与基于混合和长程校正（LRC）交换相关（xc）泛函并结合溶剂化自洽反应场模型的密度泛函理论（DFT/TDDFT）方法的量子化学分析结果进行了比较。与传统的混合xc泛函相比，使用LRC xc泛函的DFT/TDDFT计算对光吸收和荧光发射光谱的描述要准确得多。吸收-发射循环的最佳描述提供了这样一个模型，即假设光吸收发生在基态中优选为平面或弱扭曲的分子构象，这尤其由几何DFT优化所表明，而荧光发射预计来自激发态中更扭曲的分子构象。
