Carlotti B, Cesaretti A, Fortuna C G, Spalletti A, Elisei F
Department of Chemistry, Biology and Biotechnology and Centro di Eccellenza sui Materiali Innovativi Nanostrutturati (CEMIN), University of Perugia, via Elce di Sotto 8, 06123 Perugia, Italy.
Phys Chem Chem Phys. 2015 Jan 21;17(3):1877-82. doi: 10.1039/c4cp04963b. Epub 2014 Dec 4.
We report here experimental evidence of dual emission in a cationic push-pull system (bearing a methyl pyridinium group as an electron acceptor and a diphenylamino group as an electron donor), which shows negative solvatochromism. An intriguing blue shift and enlargement of the fluorescence band upon increasing the solvent polarity have suggested a possible contribution of an upper excited state to the stationary emission. Ultrafast transient absorption has indeed revealed the presence of an intermediate transient species in some solvents. The investigation of the fluorescence properties at low temperatures and in the rigid matrix has given a clear indication of this additional emission at shorter wavelengths. Femtosecond up-conversion measurements have shown interesting rise-decay dynamics in the kinetics and two well distinguished emission bands characterized by different deactivations. A single isoemissive point in the time-resolved area-normalized spectra has unambiguously pointed out the presence of two consecutive emissive species: the locally excited and the intramolecular charge transfer excited states.
我们在此报告了一个阳离子推拉体系（带有甲基吡啶鎓基团作为电子受体和二苯胺基团作为电子供体）中双重发射的实验证据，该体系表现出负溶剂化显色现象。随着溶剂极性增加，荧光带出现有趣的蓝移和展宽，这表明上激发态可能对稳态发射有贡献。超快瞬态吸收确实揭示了在某些溶剂中存在中间瞬态物种。在低温和刚性基质中对荧光性质的研究清楚地表明了在较短波长处存在这种额外发射。飞秒上转换测量在动力学上显示出有趣的上升 - 衰减动力学以及两个以不同失活为特征的明显不同的发射带。时间分辨面积归一化光谱中的单个等发射点明确指出存在两个连续的发射物种：局域激发态和分子内电荷转移激发态。
