Electronic emission and absorption spectra and the effect of hydrogen bonding on the ground and excited electronic states of some anilines |
| |
Affiliation: | 1. Center for Advanced Materials, Qatar University, P.O. Box 2713, Doha, Qatar;2. Department of Chemistry & Earth Sciences, Qatar University, P.O. Box 2713, Doha, Qatar |
| |
Abstract: | From electronic absorption and emission spectra in solutions it appears that intramolecular hydrogen bonding, strong enough to resist rupture by dioxane, exists in o-chloroaniline in the excited state only. Fluorescence quenching behaviour in the presence of dioxane indicates that intermolecular hydrogen bonding significantly increases intersystem crossing rate in m-chloroaniline only. This and other emission spectral characteristics in this hydrogen bonding solvent at 77 K show that the first excited singlet electronic state S1 of m-chloroaniline is ππ*, whereas the states S1 of aniline, toluidines and p-chloroanilines have some nπ* character. On formation of intermolecular hydrogen bond in dioxane, the corresponding triplet states of the molecules acquire pronounced nπ* character. An examination of phosphorescence decay curves reveals triplet complex formation in m- and p-chloroaniline but there is no evidence of triplet complex in the other aromatic amines studied. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|