Ab initio and DFT cation affinity study of selected neurosteroids

Authors

Anthony A. Morrison, University of Newcastle
Mitchell C. Paul, University of Newcastle
Carl H. Parsons, University of Newcastle
Mike B. Calford, University of Wollongong
Ellak I. von Nagy-Felsobuki, University of Newcastle

RIS ID

80083

Publication Details

Morrison, A. A., Paul, M. C., Parsons, C. H., Calford, M. B. & von Nagy-Felsobuki, E. I. (2005). Ab initio and DFT cation affinity study of selected neurosteroids. Journal Of Molecular Structure-Theochem, 723 (1-3), 85-93.

Abstract

Full 3N-6 optimization electronic structure calculations using the HF 6-31G(d)//HF 6-31G(d) and B3LYP 6-31G(d)//B3LYP 6-31G(d) levels of theory have been employed to determine the theoretical gas-phase cation affinities of 5-pregnen-3β-ol-20-one, 5-androsten-3β-ol- 17-one, 4-pregnen-3,20-dione, 5α-pregnan-3, 20-dione, 5α-pregnan-3α-ol-20-one and 5α-pregnan-3β-ol-20-one. For all the selected neurosteroids both theoretical methods predicted the trend of cation affinity as: H⁺»Li+>Na⁺>K⁺. The bonding interactions occur at the carbonyl group of the neurosteroids. The large cation affinities of the neurosteroid–proton adduct was found to be indicative of the formation of a stable complex via a relatively strong polar-covalent mechanism, while the lower cation affinity of the other adducts reflect the weaker ion–dipole mechanism.