Crystal structure and spectroscopic properties of 4-acetaminopyridine and its protonated form

4-Acetaminopyridine dihydrate and its protonated form, stabilized as the hydrochloride salt have been synthesized and spectroscopic elucidated in solution and in the solid-state by means of the inear-polarized solid state IR-spectroscopy (IR-LD), UV-spectroscopy, TGA, DSC, and the positive and negative ESI MS. Quantum chemical calculations were used to obtain the electronic structure, vibrational data and the electronic spectra. The spectroscopic and theoretical data are compared with the structure of the first compound obtained by single crystal X-ray diffraction. The effect of N_py protonation on the optical and magnetic properties of a 4-acetaminopyridine is discussed.