Two possible isomers of some 1,3-diaryl-H-benzo[f]chromene have been studied using density functional theory. Structures of E1 and E2 isomers were optimized at the B3LYP and MP2 levels with different basis sets. The total electronic energies show that E2 isomer is about 3-5 kcal/mol more stable than E1 isomer and this energy difference is attributed to the planarity of heterocyclic ring and mor...

Random iron-palladium alloys of BCC structure and containing up to 10.59 at.% of Pd have been investigated by means of 14.4keV Mössbauer spectroscopy in 57Fe at ambient temperature versus Pd concentration. It has been found that the perturbation of the iron hyperfine field caused by Pd impurity extends to the third co-ordination shell around an iron atom. Perturbations caused by single Pd atom ...

High-level ab initio molecular-orbital methods have been employed to determine the relative stability among four neutral and anionic B20 isomers, particularly the double-ring tubular isomer versus three low-lying planar isomers. Calculations with the fourth-order Moller-Plessset perturbation theory [MP4(SDQ)] and Dunning's correlation consistent polarized valence triple zeta basis set as well a...

two possible isomers of some 1,3-diaryl-h-benzo[f]chromene have been studied using density functional theory. structures of e1 and e2 isomers were optimized at the b3lyp and mp2 levels with different basis sets. the total electronic energies show that e2 isomer is about 3-5 kcal/mol more stable than e1 isomer and this energy difference is attributed to the planarity of heterocyclic ring and mor...

Introduction. An increasing number of studies conducted in various countries the field biopharmacy convincingly show differences physiological effects on human body stereoisomers pharmaceutical substances. As a rule, one enantiomers has necessary pharmacological effect, other enantiomer is either inert or negative side effect. Currently, it important to obtain enantiomerically pure substances f...