On the use of β-carotene as a probe for solvent polarizability

摘要

The solvatochromism of β-carotene confirms its high sensitivity not only to the polarizability of the medium, but is also contaminated by additional solute/solvent interactions due to its dipolarity and acidity, as well as to changes in its molecular structure in some solvents. A thermochromic analysis of β-carotene dissolved in 2-methylbutane and 1-chlorobutane (ClB) revealed the influence of the solvent dipolarity on its UV/Vis-spectroscopy behavior in these solvents. Applying Abe’s method to the solvent-induced shift of the first Vis absorption band of β-carotene in ClB revealed that the electronic excitation substantially increases its polarizability and its dipole moment. Other experimental evidence also confirms that β-carotene is not a suitable polarizability probe of the medium.