Empirical treatment of the inductive and dispersive components of solute-solvent interactions:: the Tolvent polarizability (SP) scale

By using 3,20-di-tert-butyl-2,2,21,21-tetramethyl-3,5,7,9,11, 13,15,17,19-docosanonaene (ttbP9) as a probe, the inductive and dispersive interactions of solvents were empirically evaluated for the first time. This probe exhibits a very strong first electronic transition with a marked vibronic structure that is very well resolved from the second electronic transition. One hundred solvents were used to construct a solvent polarizability (SP) scale ranging from zero for the gas phase (i.e. the absence of solvent) to unity for carbon disulfide. The probe was found to exhibit an ideal spectroscopic behaviour towards a variety of polar, acidic and basic solvents. The polarizability scale provides an accurate description of the solvatochromism of such interesting apolar chromophores as anthracene, molecular oxygen, and C-60 among a wider variety of solvents spanning very broad ranges of polarity, acidity and basicity.