Gas phase ionization energies of some important unsaturated steroids

Abyar, Fatemeh; Farrokhpour, Hossein; Tabrizchi, Mahmoud

doi:10.1007/s11224-014-0469-4

Cited by 8 publications

(2 citation statements)

References 29 publications

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“…In the following study, Abyar et al [40] used symmetryadapted cluster configuration interaction (SAC-CI) with single and double excitation operators to calculate the ionization energies and photoelectron spectra of the following sex steroids: estr-4-ene-3,17-dione, estr-5(l0)-ene-3,17-dione, progesterone, pregn-5-ene-3,20-dione, 20b-hydroxypregn-4-ene-3-one, androsta-5-ene-17-one, androst-4-ene-3,17-dione, androst-5-ene-3,17-dione, androsta-l,4-diene-3,17-dione, testosterone, and dehydroepiandrosterone. The results of the calculations revealed a good agreement between the shifted calculated photoelectron spectra and the experimental spectra.…”

Section: Issuementioning

confidence: 89%

Interplay of thermochemistry and Structural Chemistry, the journal (Volume 26, 2015, Issues 1–2) and the discipline

2016

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The contents of issues 1 and 2 of Structural Chemistry from the calendar year 2015 are summarized in the present review. A brief thermochemical commentary and possible guidelines for future research are added to the summary of each paper. Abbreviations AdNDP Adaptive natural density partitioning AIM Atoms in molecules BNNT Boron nitride nanotube CBS Complete basis set DFT Density functional theory HF Hartree-Fock GIAO Gauge-independent atomic orbital HOMO Highest occupied molecular orbital LMO-EDA Localized molecular orbital energy decomposition analysis LUMO Lowest unoccupied molecular orbital MD Molecular dynamics MP2 Second-order Møller-Plesset perturbation NBO Natural bond orbital NMR Nuclear magnetic resonance NT Nanotube ONIOM Our own N-layered integrated molecular orbital and molecular mechanics PCM Polarized continuum model QM/MM Quantum mechanics molecular mechanics QSAR Quantitative structure activity relationship QTAIM Quantum theory of atoms in molecules SAC-CI Symmetry-adapted cluster configuration interaction SAPT Symmetry-adapted perturbation theory SW Stone-Wales TD Time-dependent

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Section: Issuementioning

confidence: 89%

Interplay of thermochemistry and Structural Chemistry, the journal (Volume 26, 2015, Issues 1–2) and the discipline

2016

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“…Despite many investigations on the chemical and structural properties of biotin, there are no literature data on its ionization energies or photoelectron spectra. As a continuation of our earlier work, − the ionization energies were calculated and the photoelectron spectrum was simulated for conformers of biotin by using general-R-SAC-CI and OVGF methods.…”

Section: Introductionmentioning

confidence: 99%

Electronic Structure of Biotin Conformers Studied with SAC-CI and OVGF Methods

Abyar¹,

Novak

2018

J. Phys. Chem. A

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In this work, the study was performed with 37 gas-phase conformers of biotin and two biologically active conformers of biotin in the ligand-receptor complexes with astavidin and streptavidin. The ionization energies and photoelectron spectra of conformers were calculated by two methods: the general-R symmetry-adapted cluster-configuration interaction (general-R-SAC-CI) method and the outer-valence Green's function (OVGF) method. The photoelectron spectrum of each conformer was calculated using basis set D95 (df,pd) for both methods. The simulated photoelectron spectra of free molecules and bioactive conformers calculated by the two methods were compared. Natural bonding orbital (NBO) calculations were also performed for the assignment of ionization bands of each conformer. NBO calculation indicated that the first to five ionization bands correspond to ionizations from orbitals localized in the two rings. The most important point about the ionization of all conformers is that the removal of an electron from the σ-bonding orbital (C-S) takes place above 10.0 eV.

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Improving convergence of experimental and computed vertical ionization energies using the ionization potential equation‐of‐motion coupled‐cluster with singles and doubles method

Buzzanca

Brummeyer

Gutow

2020

Int J of Quantum Chemistry

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Comparison of statistically evaluated experimental vertical ionization energies (IEs) for 53 medium‐sized molecules (6‐34 atoms) with ionization potential equation‐of‐motion coupled‐cluster with singles and doubles (IP‐EOMCCSD) computations shows that discrepancies between computed and experimental results can be accounted for with a combination of experimental and theoretical contributions. Discrepancies can be minimized by extrapolating computations to the complete basis set limit and correcting for vibrational zero‐point energy (ZPE) while comparing with experimental IEs calculated as the intensity‐weighted mean band position to account for band asymmetries. This procedure reduced the average discrepancy for ethylene, (E)‐2‐butene, 2,5‐dihydrofuran, and pyrrole from 0.25 to 0.05 eV. Agreement between reported vertical IEs and computations without either making adjustments as described in this paper or using complete simulation of the ionization spectrum should be considered fortuitous. The comparisons made in this work show that estimates of vertical and adiabatic IE made using IP‐EOMCCSD extrapolated to the complete basis set limit and corrected for vibrational ZPE can be used with reasonable confidence when experimental values are not available.

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Gas phase ionization energies of some important unsaturated steroids

Cited by 8 publications

References 29 publications

Interplay of thermochemistry and Structural Chemistry, the journal (Volume 26, 2015, Issues 1–2) and the discipline

Interplay of thermochemistry and Structural Chemistry, the journal (Volume 26, 2015, Issues 1–2) and the discipline

Electronic Structure of Biotin Conformers Studied with SAC-CI and OVGF Methods

Improving convergence of experimental and computed vertical ionization energies using the ionization potential equation‐of‐motion coupled‐cluster with singles and doubles method

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