Assessing the effective factors affecting the conformational preferences and the early and late transition states of the unimolecular retro-ene decomposition reactions of ethyl cyanate, ethyl thiocyanate and ethyl selenocyanate

Atabaki, Hooshang; Nori‐Shargh, Davood; Momen-Heravi, Mohamad

doi:10.1039/c7ra00520b

Cited by 6 publications

(2 citation statements)

References 69 publications

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“…It is well known that conformational preferences of organic compounds can influence their molecular properties, whether through a preferential reaction mechanism or in a molecular self‐assembly to name a few. The conformational stability can be explained in terms of the main intramolecular interactions, such as hydrogen bonds or hyperconjugative interactions, that favor one structural arrangement over another .…”

Section: Introductionmentioning

confidence: 99%

The Role of Intramolecular Interactions on the Bioactive Conformation of Epinephrine

Silva

Silla

Santos

et al. 2019

Molecular Informatics

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The structure of bioactive compounds inside their biological target is mainly dictated by the intermolecular interactions present in the binding side, whereas intramolecular interactions are responsible for the structure of an isolated molecule. Accordingly, this work reports the relative significance of these interactions for the bioactive conformation of the N‐protonated epinephrine. The crystallized structure of epinephrine has a gauche orientation of the O−C−C−N torsion angle. Conformational analysis in the gas phase and implicit water was performed to investigate the main intramolecular forces favoring this conformational preference, which was primarily attributed to the electrostatic interaction between hydroxyl and ammonium groups. However, when the conformers were docked into the active site, intramolecular interactions were surpassed by intermolecular hydrogen bonds with neighboring amino acid residues. Nonetheless, structural modifications aiming at strengthening intramolecular interactions could be used to modulate a bioactive conformation, thereby assisting in the structure‐based design of new chemical entities.

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Section: Introductionmentioning

confidence: 99%

The Role of Intramolecular Interactions on the Bioactive Conformation of Epinephrine

Silva

Silla

Santos

et al. 2019

Molecular Informatics

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“…Effectively, an efficient way to investigate the impacts of the hyperconjugative interactions on the conformational properties of compounds 1 – 3 is the deletion of the effective orbitals mixings from their Fock matrices and rediagonalization and comparison of the current Fock matrices with the original ones. This procedure is a sufficient tool to investigate quantitatively the contribution of a specific hyperconjugative interaction on the total energy differences between different conformations of a molecule. ,,, In this regard, in order to explore the roles and contributions of the hyperconjugative generalized anomeric effects on the anomeric relationships in compounds 1 – 3 , we deleted the orbitals mixings that their overlapping change with the gauche - ⇌ anti -conformational interconversions from the Fock matrices of the gauche - and anti -conformations. Then, by rediagonalization and comparison of the current Fock matrices with their original ones, we evaluated the contributions of the hyperconjugative interactions on the anomeric relationships in compounds 1 – 3 .…”

Section: Introductionmentioning

confidence: 99%

Exploring the Origin of the Generalized Anomeric Effects in the Acyclic Nonplanar Systems

et al. 2017

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Contrary to the published conclusions in the literature concerning the origin of the generalized anomeric relationships in open-chain nonplanar systems, its origin has remained an open question. In order to explore the origin of the generalized anomeric relationships in open-chain nonplanar systems, we assessed the roles and contributions of the effective factors on the conformational properties of methyl propargyl ether (1), methyl propargyl sulfide (2), and methyl propargyl selenide (3) by means of the G3MP2, CCSD(T), MP2, LC-ωPBE, and B3LYP methods and natural bond orbital (NBO) interpretations. We examined the contributions of the hyperconjugative interactions on the conformational preferences of compounds 1-3 by the deletions of the orbitals overlapping from the Fock matrices of the gauche- and anti-conformations. The trend observed for energy changes in the Fock matrices justify the variations of the gauche-conformations preferences going from compound 1 to compound 3, revealing that the hyperconjugative interactions are solely responsible for the generalized anomeric relationships in compounds 1-3. Accordingly, the conclusions published in the literature concerning the origin of the generalized anomeric effect in the acyclic nonplanar compounds should be revised by these findings. The Pauli exchange type repulsions (PETR) are in favors of the gauche-conformations and the variations of the PETR differences between the gauche- and anti-conformations of compounds 1-3 correlate well with their gauche-conformations preferences, revealing that the generalized anomeric relationships in compounds 1-3 have also the Pauli exchange-type repulsions origin. The resemblance between the preorthogonal natural bond orbitals (that are involved in the hyperconjugative interactions) and their corresponding molecular orbitals have been investigated.

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Polyion Covalency: Exotic Species from the Unexplored World of Electrostatically Shielded Molecular Ion Chemistry

Weinhold

2017

Angewandte Chemie

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Standard quantum chemical methods have been employed to describe a variety of kinetically stable polyionic molecular species that are trapped in appreciable potential wells by chemical bonding forces, despite powerful electrostatic opposition that challenges conventional chemical detection and characterization. The studied species are covalent or dative analogs of “anti‐electrostatic” hydrogen‐bonded (AEHB) species, all illustrating how short‐range quantum covalency can overcome the powerful “shielding” opposition of long‐range electrostatic forces to form highly charged molecular species, analogous to known neutral or singly ionic counterparts. Computational predictions of representative structural, spectroscopic, and NBO‐based electronic signatures of multiply charged analogs of common neutral species (CH3CH3, CO2, FeCO) are provided to suggest the unique material properties characteristic of this shielded domain of polyionic chemical phenomena.

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Assessing the effective factors affecting the conformational preferences and the early and late transition states of the unimolecular retro-ene decomposition reactions of ethyl cyanate, ethyl thiocyanate and ethyl selenocyanate

Abstract: The variations of Δ[(HCGAE(X3–C4 weakening) – HCGAE(X3–C4 strengthening)] parameters correlate well with the variations of the retro-ene decomposition reactions barrier heights going from compound 1 to compound 3.

Cited by 6 publications

References 69 publications

The Role of Intramolecular Interactions on the Bioactive Conformation of Epinephrine

The Role of Intramolecular Interactions on the Bioactive Conformation of Epinephrine

Exploring the Origin of the Generalized Anomeric Effects in the Acyclic Nonplanar Systems

Polyion Covalency: Exotic Species from the Unexplored World of Electrostatically Shielded Molecular Ion Chemistry

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