Structural and vibrational studies of equilenin, equilin and estrone steroids

Abstract

Three species associated with estrogens have been studied in this work, equilenin, equilin and estrone. Their molecular structures have been theoretically studied in gas phase with the hybrid B3LYP/6-31G* method. NBO, AIM and frontier orbital calculations were computed for the three species at the same level of theory. Higher dipole moment and volume were observed for estrone while equilin presents higher volume than equilenin but lower dipole moment value. Probably, the unsaturated C=C in the B ring of equilin could explain those differences. The differences observed in the properties could be clearly explained by differences in the dihedral angles. The analyses of MK and Mulliken charges evidence the higher variations on the C atoms common to the B, C and D rings in the three species. The mapped MEP surfaces show that both A and B rings of equilenin are different from the other ones because they have aromatic naphthalene core, as was evidenced experimentally. The NBO studies support the higher stability of equilin, in relation to equilenin and estrone while the AIM analyses reveal the higher stability for estrone. The gap values suggest that equilenin is the most reactive species due to its higher global electrophilicity value, in agreement with the higher stability observed for this species while the higher global nucleophilicty values are observed for equilin and estrone. Here, the harmonic force fields, scaled force constants and the complete assignments of 108, 114 and 120 vibration modes for equilenin, equilin and estrone, respectively are reported for first time.

DFT study of species derived from the narcotic antagonist naloxone

“…Thus, in the cationic species the SQM/B3LYP/6-31G* calculations have predicted the N5-H46 stretching mode at 3221 cm -1 while in the hydrochloride one at 2312 cm -1 . In cationic species of cyclizine, scopolamine, heroin, morphine, cocaine and tropane that stretching modes were assigned respectively to 3087, 3300, 3268, 3270, 2989 and 3280 cm -1 [1-3,5,7,9,17] while their hydrochloride species (hydrobromide in the scopolamine case) were assigned to 2316, 1882, 1746, 1776, 2089 and 1760 cm -1 [1][2][3]5,7,9,17]. The rocking modes in the two species of cyclizine were predicted between 1483 and 1402 cm -1 .…”

“…In relation to the five rings of all species of naloxone, for the A, C, D and E rings are expected three deformations and three torsions rings while for the B rings only two deformations and two torsions rings because these rings are of five members. In the three species, all these modes are predicted in the lower wavenumbers region and coupled among them [1][2][3]5,7,9,17]. The assignments of other remain skeletal modes were performed as predicted by calculations and, as shown in Table 12.…”

“…DFT calculations are very useful tools to analyse structures and predict properties of numerous compounds with different fused rings [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], such as tropane alkaloids. These alkaloids contain the >N-CH 3 group and present a wide range of biological properties and different structural, electronic and topological properties some of which were studied by our research group [1][2][3][4][5][6][7].…”

Investigating the behaviors of corticosterone hormone in different solvents by using DFT calculations and experimental data

“…The combination of theoretical density functional theory (DFT) calculations by using hybrid B3LYP methods with different experimental spectroscopic techniques is a very good methodology to elucidate reliably and effectively structural, electronic, topological and vibrational properties of diverse compounds [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The use of this methodology in species containing fused rings such as alkaloids, antihistaminic agents and species steroids, has allowed the optimizations of theoretical structures and the determination of their properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] while the complete assignments of all bands observed in the experimental infrared and Raman spectra were possible by using the normal internal coordinates, the SQMFF methodology and the Molvib program [16][17][18]. Now, the identifications of cocaine, heroin, morphine and scopolamine alkaloids [1,[3][4][5]7], of antihistaminic agents promethazine [8] and of equilenin, equilin and estrone steroids [9] can be easily carried out in all media by using vibrational spectroscopy.…”

“…The use of this methodology in species containing fused rings such as alkaloids, antihistaminic agents and species steroids, has allowed the optimizations of theoretical structures and the determination of their properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] while the complete assignments of all bands observed in the experimental infrared and Raman spectra were possible by using the normal internal coordinates, the SQMFF methodology and the Molvib program [16][17][18]. Now, the identifications of cocaine, heroin, morphine and scopolamine alkaloids [1,[3][4][5]7], of antihistaminic agents promethazine [8] and of equilenin, equilin and estrone steroids [9] can be easily carried out in all media by using vibrational spectroscopy. For instance, in cocaine and scopolamine only two fused rings of five and six members' can be seen, in promethazine three six members`s rings are fused [8], in equilenin, equilin and estrone steroids four fused rings named A, B, C and D can be observed [9] while in morphine and heroin five fused rings [1,[3][4][5]7].…”