Sitting above the maze: recent model discoveries in molecular science

Wang, Feng; Ahmed, Marawan

doi:10.1080/08927022.2014.923570

Cited by 4 publications

(1 citation statement)

References 123 publications

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“…Our previous work has combined OVGF calculation and experimental XPS/PES (photoelectron spectroscopy) to accurately study a number of molecules in the past several years, which can be found in an invited review. [50] The measured (adiabatic) first ionization energies are 7.73 eV (62313 cm -1 ) for cis-MEQ and 7.71 eV (62210 cm -1 ) for trans-MEQ. [51] The calculated (vertical) These two orbitals 25a' and 2a" of trans/cis-MEQ can possibly serve as the fingerprint as they exhibit large IP energy differences.…”

Section: Methoxyphenol Conformers In the Core And Valence Spacementioning

confidence: 92%

Probing Intramolecular Interaction of Stereoisomers Using Computational Spectroscopy

2020

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Several model stereoisomers such as ferrocene (Fc), methoxyphenol, and furfural conformers are discussed. It was discovered that the Fc IR spectroscopic band(s) below 500cm−1 serve as fingerprints for eclipsed (splitting 17 (471–488)cm−1) and staggered Fc (splitting is ~2 (459–461)cm−1) in the gas phase. It is revealed that in the gas phase the dominance of the eclipsed Fc (D5h) at very low temperatures changes to a mixture of both eclipsed and staggered Fc when the temperature increases. However, in solvents such as CCl4, eclipsed Fc dominates at room temperature (300K) due to the additional solvation energy. Intramolecular interactions of organic model compounds such as methoxyphenols (guaiacol (GUA) and mequinol (MEQ)) and furfural, ionization energies such as the carbon 1s (core C1s), as well as valence binding energy spectra serve this purpose well. Hydrogen bonding alters the C1s binding energies of the methoxy carbon (C(7)) of anti-syn and anti-gauche conformers of GUA to 292.65 and 291.91eV, respectively. The trans and cis MEQ conformers, on the other hand, are nearly energy degenerate, whereas their dipole moments are significantly different: 2.66 Debye for cis and 0.63 Debye for trans-MEQ. Moreover, it is found that rotation around the Cring–OH and the Cring–OCH3 bonds differ in energy barrier height by ~0.50 kcal⋅mol−1. The Dyson orbital momentum profiles of the most different ionic states, 25a′ (0.35eV) and 3a′ (−0.33eV), between cis and trans-MEQ in outer valence space (which is measurable using electron momentum spectroscopy (EMS)), exhibit quantitative differences. Finally, the molecular switch from trans and cis-furfural engages with a small energy difference of 0.74 kcal mol−1, however, at the calculated C(3)(–H⋅⋅⋅O=C) site the C1s binding energy difference is 0.105eV (2.42 kcal mol−1) and the NMR chemical shift of the same carbon site is also significant; 7.58ppm from cis-furfural without hydrogen bonding.

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Section: Methoxyphenol Conformers In the Core And Valence Spacementioning

confidence: 92%

Probing Intramolecular Interaction of Stereoisomers Using Computational Spectroscopy

2020

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The d-electrons of Fe in ferrocene: the excess orbital energy spectrum (EOES)

Islam

Wang

2015

RSC Adv.

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Theoretical study of valence orbital response to guanine tautomerization in coordinate and momentum spaces

Yang

Duffy

Zhu

et al. 2015

J. Phys. B: At. Mol. Opt. Phys.

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The binding energy spectra and electron momentum spectra of eight stable guanine tautomers are calculated in the complete valence space. The present results show that the canonical keto (C=O) guanine N(9)H tautomer (GU1) possesses the largest dipole moment, molecular electronic spatial extent, molecular hardness value, and the minimum first vertical ionization potential (VIP). Valence orbital profile investigations find that several orbitals remain almost unchanged during tautomerization, such as frontier highest occupied molecular orbital 39a and 18a. Several orbitals with interchanged order and inverse direction in charge spatial orientations are also detected. Outer valence orbitals (with smaller VIPs) show more complex orbital shapes in the momentum space than those of inner ones (larger VIPs) due mainly to the relatively strong inter-orbital interaction and delocalized electronic distributions. Proton rotation along C–O(H) and C–N(H) axes within hexagonal ring causes smaller influence to orbital profiles than those of proton migration within pentagonal and/or hexagonal rings. Orbital variation trends between enol (GU3–GU5) and keto (GU1, GU2, GU6–GU8) tautomers are observed, including the signature orbitals of enol form, the variation tendency of total orbital intensity, and the variation order of the maximum orbital intensity. In the outer valence momentum space (outside 26a), orbital composed by pz electrons show single peak with a gradual increasing peak site from 0.5 a.u. of inner valence orbital to 1.0 a.u. of outer valence orbital, whereas orbitals composed by px,y electrons form double peaks with respective sites at about 0.5 and 1.5 a.u., only three px,y-orbitals present single peaks (33a,34a,36a). The general variation trends in the complete valence space for all the valence orbitals on their intensities, peak sites, and orbital components are concluded.

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Sitting above the maze: recent model discoveries in molecular science

Cited by 4 publications

References 123 publications

Probing Intramolecular Interaction of Stereoisomers Using Computational Spectroscopy

Probing Intramolecular Interaction of Stereoisomers Using Computational Spectroscopy

The d-electrons of Fe in ferrocene: the excess orbital energy spectrum (EOES)

Theoretical study of valence orbital response to guanine tautomerization in coordinate and momentum spaces

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