Compounds with π(loc) → π*(deloc) electronic transitions and their solvatochromism |
| |
Authors: | Javier Catalán |
| |
Institution: | Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, Madrid |
| |
Abstract: | Molecular structures possessing atomic sites that contribute a non‐bonding electron pair to their π system (e.g. nitrogen atoms with sp2 hybridization in pyrroles and anilines) usually exhibit a first absorption band whose solvatochromism is, surprisingly, sensitive only to the polarizability of the medium even though they are dipolar. As shown here, this solvatochromic behavior is a result of the first electronic transition in these compounds occurring from a substantially localized π orbital to a substantially delocalized π* orbital in the molecular structure. The high electronic delocalization present leads to a marked bathochromic band shift as the polarizability of the medium increases. It is especially relevant that this solvatochromism, which is because of the polarizability of the medium, explains the spectral shift that is only because of the redistribution of the electrons of the solvent molecules. It is important to take into account that this electronic redistribution happens instantaneously in this process. Copyright © 2015 John Wiley & Sons, Ltd. |
| |
Keywords: | polarizability effect solvatochromism π non‐bonding electron pair π → π * electronic transitions π * electronic delocalization |
|
|