Jaroslav Leška

Anomalies in the gas chromatographic behaviour of substances facilitating a ring conformation through their propyl group

Abstract The applicability of precise gas chromatogaphic measurements has been demonstrated for the identification of very fine structural features of compounds. On the basis of the gas chromatographic behaviour of five classes of unsaturated hydrocarbons and four classes of compounds containing hetero-atoms, it is concluded that retention anomalies are to be expected for compounds with molecular structures that make it possible to form a ring conformation of the propyl group with the π-electron system of the remainder of the molecule and that this phenomenon is a common feature of the compounds with such structures.

MNDO CI study of vertical excitation energies

Abstract In order to test the suitability of the MNDO method for the study of molecules in excited states, the singlet and triplet excitation energies were calculated for a set of 30 organic molecules. In the configuration interaction, the singly and doubly excited configurations were included. The method gives somewhat lower values in comparison with experimental ones. The inclusion of a certain number of bi-excited configurations is necessary to obtain the correct order of excited levels.