A structural and spectroscopic study on carquejol, a relevant constituent of the medicinal plant Baccharis trimera (Less.) DC. (Asteraceae)

Minteguiaga, Manuel; Dellacassa, Eduardo; Iramain, Maximiliano Alberto; Catalán, César A.N.; Brandán, Silvia Antonia

doi:10.1016/j.molstruc.2017.08.068

Cited by 29 publications

(47 citation statements)

References 45 publications

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“…Moreover, in equilin the presence of a C=C in the B ring increase the number of C=C increasing the corresponding force constant to 6.86 mdyn Å -1 . The force constants predicted for the three species present value similar to the observed in other species containing similar groups [32,[34][35][36][37][38][39][40][41][48][49][50][51][52][53][54].…”

Section: -10 CM -1 Regionsupporting

confidence: 72%

“…A careful detail of the assignments of those modes for the three species can be seen in Table 7 where the most intense bands are assigned to the C=O and C=C stretching modes. Hence, the intense IR and Raman bands between 1751 and 1496 cm -1 can be easily assigned to the C=O and C=C stretching modes corresponding to the three species, as reported for species containing these groups [34][35][36][37][38][39][40][41]. Obviously, those C=O and C=C bonds present double bond characters and, for these reasons, their vibration modes are observed at higher wavenumbers but, the C-C bonds with partial double bond characters are predicted at lower wavenumbers, thus, they can be assigned between 1454 and 1325 cm -1 , as observed in Table 7.…”

Section: Atomic Mk and Mulliken Charges And Molecular Electrosctatic mentioning

confidence: 58%

“…Here, the assignments oh three species were performed considering the corresponding normal internal coordinates, transferable scaling factors and only contributions ≥ 10%. In addition, the frontier orbitals and some remarkable descriptors were used to predict reactivities and behaviours of three species [31][32][33][34][35][36][37][38][39][40][41]. The predicted Raman spectra in activities were converted to intensities for a better correlation with the experimental one [42,43].…”

Section: Methodsmentioning

confidence: 99%

“…Another form different of analyzing the stabilities of these species is through of the Bader's theory of atoms in molecules (AIM) where is possible to examine possible H bonds and/or intra-molecular interactions by using the topological properties with the AIM2000 program [46,47]. This study request the calculations of electron density, (r), the Laplacian values,  2 (r), the eigenvalues (1, 2, 3) of the Hessian matrix and, the |λ1|/λ3 ratio in the bond critical points (BCPs) and ring critical points (RCPs) by using the B3LYP/6-31G* method, according to other species with different rings [32][33][34][35][36][37][38][39][40][41][42]. The results for equilenin, equilin and estrone in gas phase species are presented in Table 5.…”

Section: Atomic Mk and Mulliken Charges And Molecular Electrosctatic mentioning

confidence: 99%

“…The frontier orbitals are parameters frequently used in the determination of gap values, as suggested by Parr and Pearson [31], because from their differences can be predict the reactivities and, also, with the gap values it is possible to calculate some descriptors of great interest to predict the behaviours of species in different media [32][33][34][35][36][37][38][39][40][41]. Hence, the frontier molecular HOMO and LUMO orbitals, gap values and the chemical potential (μ), electronegativity (χ), global hardness (η), global softness (S), global electrophilicity index (ω) and global nucleophilicity index (E) descriptors of equilenin, equilin and estrone in gas phase by using the B3LYP/6-31G* method are summarized in Table 6.…”

Section: Atomic Mk and Mulliken Charges And Molecular Electrosctatic mentioning

confidence: 99%

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Structural and vibrational studies of equilenin, equilin and estrone steroids

2019

Biointerface Res Appl Chem

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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.

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Section: -10 CM -1 Regionsupporting

confidence: 72%

Section: Atomic Mk and Mulliken Charges And Molecular Electrosctatic mentioning

confidence: 58%

Section: Methodsmentioning

confidence: 99%

Section: Atomic Mk and Mulliken Charges And Molecular Electrosctatic mentioning

confidence: 99%

Section: Atomic Mk and Mulliken Charges And Molecular Electrosctatic mentioning

confidence: 99%

See 3 more Smart Citations

Structural and vibrational studies of equilenin, equilin and estrone steroids

2019

Biointerface Res Appl Chem

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Exploring properties of potassium 6-X-2-isonicotinoyltrifluoroborate (X=H, F, Cl, Br) salts and their anions by using ab initio calculations

Iramain

Brandán

2019

J Mol Model

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S(-) and R(+) species derived from antihistaminic promethazine agent: structural and vibrational studies

Manzur

Brandán

2019

Heliyon

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Structural and vibrational properties of free base, cationic and hydrochloride species derived from both S(-) and R(+) enantiomers of antihistaminic promethazine (PTZ) agent have been theoretically evaluated in gas phase and in aqueous solution by using the hybrid B3LYP/6-31G* calculations. The initial structures of S(-) and R(+) enantiomers of hydrochloride PTZ were those polymorphic forms 1 and 2 experimentally determined by X-ray diffraction. Here, all structures in aqueous solution were optimized at the same level of theory by using the polarized continuum (PCM) and the universal solvation model. As was experimentally reported, variations in the unit cell lead to slight energy, density, and melting point differences between the two forms but, this behavior is not carried through in isotropic condition, like in solution with non-chiral solvents. Hence, the N–C distances, Mulliken, atomic natural population (NPA) and Merz-Kollman (MK) charges, bond orders, stabilization and solvation energies, frontier orbitals, some descriptors and their topological properties were compared with the antihistaminic cyclizine agent. The frontier orbitals studies show that the free base species of both forms in solution are more reactive than cyclizine. Higher electrophilicity indexes are observed in the cationic and hydrochloride species of PTZ than cyclizine while the cationic species of cyclizine have higher nucleophilicity index than both species of PTZ. The presences of bands attributed to cationic species of both enantiomers are clearly supported by the infrared and Raman spectra in the solid phase. The expected 114, 117 and 120 vibration normal modes for the free base, cationic and hydrochloride species of both forms were completely assigned and the force constants reported. Reasonable concordances among the predicted infrared, Raman, UV-Vis and Electronic Circular Dichroism (ECD) with the corresponding experimental ones were found.

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A structural and spectroscopic study on carquejol, a relevant constituent of the medicinal plant Baccharis trimera (Less.) DC. (Asteraceae)

Cited by 29 publications

References 45 publications

Structural and vibrational studies of equilenin, equilin and estrone steroids

Structural and vibrational studies of equilenin, equilin and estrone steroids

Exploring properties of potassium 6-X-2-isonicotinoyltrifluoroborate (X=H, F, Cl, Br) salts and their anions by using ab initio calculations

S(-) and R(+) species derived from antihistaminic promethazine agent: structural and vibrational studies

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