A solid-state linear dichroic infrared spectral study of 4-aminopyridine

Abstract: A linear dichroic infrared (IR-LD) spectral analysis of solid 4-aminopyridine (4-AP) samples was carried out using two orientation techniques, i.e., as polycrystalline layers and in a nematic mesophase. The so-called reducing-difference procedure was used for the polarized IR-spectra interpretation. By achieving a more precise assignment of a part of the 4-AP characteristic frequencies, the obtained data proved a Fermi-resonance splitting of the symmetrical NH2-stretch and confirmed the predominant aromatic character of the pyridine ring. The possibilities of the difference IR-LD technique used for the study of the supramolecular solid-state structure are also illustrated. [Copyright &y& Elsevier]