Application of quantum chemistry for the interpretation of vibrational spectra

This article illustrates the development of the vibrational spectroscopic research in our group during the last 15 years. The possibilities for the application of quantum chemistry increased during this time. The main reason for this increase was the development of computationally affordable applied methods which changed from Hartree–Fock to density functional theory (DFT). The number and level of the applicable DFT methods and the basis sets expanded during this period giving rise to study chemically complex systems. After a short general introduction, the molecular structures of several nitrogen heterocycles are studied, and their physical and spectroscopic properties are discussed and compared. The next part deals with similar properties of macrocycles, namely those of the porphyrin, calix[4]aren and β-cyclodextrin molecules which are able to form complexes. Their complex-forming abilities are compared. Finally, the properties of a β-cyclodextrin inclusion complex were discussed.