Effect of the intramolecular hydrogen bond on the electronic structure of organic molecules with a planar quasicycle

By means of the HF/6-311G(d,p) method, the electronic structure of the series of organic molecules, among which are malonaldehyde, acetylacetone, thiomalonaldehyde,?the derivatives of aniline 2-XC6H4NH2, phenol 2-XC6H4OH, benzenethiol 2-XC6H4SH (X = CHO, COOH, COO-, NO, NO2, OH, OCH3, SH, SCH3, F, Cl, Br), 8-hydroxyquinoline, 8-mercaptoquinoline, tropolone, has been studied. The intramolecular hydrogen bond (IHB) has been established to lead to a local electron redistribution in quasicycle, and primarily to the electron density transfer between the direct IHB participants - from the hydrogen atom toward the proton-aceptor atom. On forming the IHB of the S-H???O type, the electron density in general decreases on the sulphohydryl hydrogen atom and increases on the sulphur atom.

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Propagator quantum chemical study of S-cis-(Z)-2-(2-formylethenyl)pyrrole: electronic structure and aspects of intramolecular hydrogen bond manifestation in ionization spectra

Russian Chemical Bulletin ◽

10.1007/s11172-017-2008-0 ◽

2017 ◽

Vol 66 (12) ◽

pp. 2241-2247

Author(s):

B. Trofimov ◽

A. M. Belogolova ◽

D. Yu. Soshnikov ◽

T. E. Moskovskaya ◽

N. M. Vitkovskaya ◽

...

Keyword(s):

Hydrogen Bond ◽

Electronic Structure ◽

Intramolecular Hydrogen Bond ◽

Quantum Chemical ◽

Quantum Chemical Study ◽

Chemical Study ◽

Intramolecular Hydrogen

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Competition between the intramolecular hydrogen bond and the π-electron delocalization in some RAHB systems: A theoretical study

Журнал структурной химии ◽

10.26902/jsc_id40420 ◽

2019 ◽

Vol 60 (5) ◽

Keyword(s):

Hydrogen Bond ◽

Intramolecular Hydrogen Bond ◽

Theoretical Study ◽

Electron Delocalization ◽

Intramolecular Hydrogen

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Effect of the intramolecular hydrogen bond in the active metabolite analogs of leflunomide for blocking the Plasmodium falciparum dihydroorotate dehydrogenase enzyme: QTAIM, NBO, and docking study

Current Computer - Aided Drug Design ◽

10.2174/1573409916666200527133126 ◽

2020 ◽

Vol 16 ◽

Author(s):

Reihaneh Heidarian ◽

Mansoureh Zahedi-Tabrizi

Keyword(s):

Hydrogen Bond ◽

Plasmodium Falciparum ◽

Molecular Orbital ◽

Intramolecular Hydrogen Bond ◽

Active Metabolite ◽

Chemical Hardness ◽

Dihydroorotate Dehydrogenase ◽

Molecular Orbital Analysis ◽

Intramolecular Hydrogen ◽

Orbital Analysis

: Leflunomide (LFM) and its active metabolite, teriflunomide (TFM), have drawn a lot of attention for their anticancer activities, treatment of rheumatoid arthritis and malaria due to their capability to inhibit dihydroorotate dehydrogenase (DHODH) and Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) enzyme. In this investigation, the strength of intramolecular hydrogen bond (IHB) in five analogs of TFM (ATFM) has been analyzed employing density functional theory (DFT) using B3LYP/6-311++G (d, p) level and molecular orbital analysis in the gas phase and water solution. A detailed electronic structure study has been performed using the quantum theory of atoms in molecules (QTAIM) and the hydrogen bond energies (EHB) of stable conformer obtained in the range of 76-97 kJ/mol, as a medium hydrogen bond. The effect of substitution on the IHB nature has been studied by natural bond orbital analysis (NBO). 1H NMR calculations show an upward trend in the proton chemical shift of the enolic proton in the chelated ring (14.5 to 15.7ppm) by increasing the IHB strength. All the calculations confirmed the strongest IHB in 5-F-ATFM and the weakest IHB in 2-F-ATFM. Molecular orbital analysis, including the HOMO-LUMO gap and chemical hardness, was performed to compare the reactivity of inhibitors. Finally, molecular docking analysis was carried out to identify the potency of inhibition of these compounds against PfDHODH enzyme.

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