Browsing by Author "Abrha, Meressa"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Theoretical Studies of Naturally Occuring Homoisoflavonoids
    (Addis Ababa Universty, 2009-07) Abrha, Meressa; Mustefa, Ahmed (PhD)
    Nowadays molecular modelling becomes an alternative way for sophisticated and costly experimental techniques. In this project the structures of five naturally occurring homoisoflavonoids namely; 5, 7-dihydroxy-6-methoxy-3-(4’-hydroxybenzyl) chroman-4-one (A), 7-hydroxy-3-(4’-hydroxybenzyl) flavone (B), (E)-7-hydroxy-3-(4’-methoxybenzylidene) chroman-4-one (C), Brazilin (7, 11b-dihydrobenz[b]indeno [1, 2-d] pyran-3, 6a, 9, 10, (6H)-tetrol) (D) and 5, 7-hydroxy-3’, 4’-dimethoxyspiro {2H-1-benzopyran-3-bicyclo [4.2.0] octa [1’.3’.5’]-trien}-4-one (E) are determined by geometry optimization using Density Functional Theory. Comparison of optimized structural parameters like bond lengths, bond angles and torsional (dihedral) angles are extracted. Computation of molecular properties such as NMR shielding tensors (1H and 13C chemical shifts with respect to TMS), infrared harmonic vibrational frequency (scaled with 0.9614) and UV-absorption transitions of these natural homoisoflavonoids are reported here. Calculated results are found to be in good agreement with the experimentally observed values. Though IR absorption frequency spectra and UV absorption spectra were done in gas-phase, the obtained results are in good agreement with the experimental values.