溶剂变色
激发态
化学
发色团
轨道能级差
分子内力
偶极子
光化学
对称性破坏
接受者
分子物理学
原子物理学
立体化学
分子
物理
凝聚态物理
有机化学
量子力学
作者
Benedetta Carlotti,Enrico Benassi,Cosimo G. Fortuna,Vincenzo Barone,Anna Spalletti,Fausto Elisei
出处
期刊:ChemPhysChem
[Wiley]
日期:2015-11-18
卷期号:17 (1): 136-146
被引量:42
标识
DOI:10.1002/cphc.201500784
摘要
We report a joint experimental and theoretical investigation of a quadrupolar D-π-A(+) -π-D system, the electron donors being diphenylamino groups and the electron acceptor being a methylpyridinium, in comparison with the dipolar D-π-A(+) system. The emission spectra of the two compounds overlap in all the investigated solvents. This finding could be rationalized by TD-DFT calculations: the LUMO-HOMO molecular orbitals involved in the emission transition are localized on the same branch of the quadrupolar structure that becomes the fluorescent portion, corresponding to that of the single-arm compound. Excited-state symmetry breaking has been rarely observed for quadrupolar systems showing negative solvatochromism and is here surprisingly revealed, even in low polarity solvents. Femtosecond transient absorption measurements revealed that an efficient photoinduced intramolecular charge transfer takes place in the quadrupolar chromophore, more efficient than in its dipolar analogue. This result is promising in view of the application of these compounds as novel two-photon absorbing materials.
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