Solvatochromism of heteroaromatic compounds: V. 1-ethyl-2-formylimidazole

The results of nonempirical calculations (6-31G* basis), IR spectra, and di pole moments (253-323 K) show that 1-ethyl-2-formylimidazole in the gas pha se prefers the synperiplanar form, while in nonpolar and weakly polar solve nts, antiperiplanar. Polar media stabilize the antiperiplanar conformer wit h a high dipole moment. Solvatochromism is shown to be useful for qualitati ve conformational analysis of this compound. The dependence of the long-wav e absorption maximum in the UV spectra of the title compound on solvent pol arity (Kamlet-Taft pi* parameter) is described by two correlation equations for different conformers. The most solvent-sensitive is the absorption ban d of the antiperiplanar conformer.