On the solvatochromism, dimerization and tautomerism of indazole

A careful study of the solvatochromism of indazole was for the first time conducted in this work. The study revealed that indazole solvatochromism is governed mainly by the polarizability of the medium and, to a lesser extent, by its acidity and basicity. Based on the results of the solvatochromic analysis and their processing with Abe's model, this polar compound undergoes no significant change in dipole moment from its ground electronic state to its first excited state, which contradicts the predictions of other authors. Indazole dimerizes in both 2-methylbutane and 1-chlorobutane. However, neither its monomer nor its dimer undergoes tautomerization to 2H-indazole in the ground state in response to an increase in dipolarity of the medium. Also, based on experimental evidence, no tautomerization occurs in the first excited singlet or triplet of the compound.