A Spectroscopic Rule from the Solvatochromism of Aromatic Solutes in Nonpolar Solvents

The UV–vis absorption spectroscopy for a series of selected symmetrical aromatic hydrocarbons, benzene, naphthalene, anthracene, 9,10-diphenylanthracene, perylene, and rubrene in the gas phase or in 2-methylbutane, shows the consistency of a new spectroscopic rule. From a thorough spectroscopic analysis with temperature variation (293–113 K) this rule states that “an aromatic molecule, on Franck–Condon excitation can hardly generate an excited electronic state with a lower polarizability than that of its ground electronic-state.” We have not found any exceptions to this rule.