High-Resolution Electronic Spectra of 2-Hydroxy and 2-Aminopyridine. Perturbing Effects of the Nitrogen Atom in the Aromatic Ring

Abstract

High resolution, rotationally resolved electronic spectra of 2-hydroxypyridine (2HP) and 2-aminopyridine (2AP; at ∼277 and ∼299 nm, respectively) have been observed and fit using rigid-rotor Hamiltonians to within lifetime-limited resolutions of 170 and 120 MHz, respectively. The derived values of the rotational constants are very similar to those of phenol and aniline. However, 2HP and 2AP each exhibit inertial axis tilting, large rotations of their S1−S0 electronic transition moments, and intramolecular hydrogen bonds, making them very different from their hydrocarbon analogues. Possible reasons for this behavior are discussed.