Intramolecular hydrogen bond in the push–pull CF3-aminoenones: DFT and FTIR study, NBO analysis

Tetrahedron ◽  
2014 ◽  
Vol 70 (6) ◽  
pp. 1207-1213 ◽  
Author(s):  
N.N. Chipanina ◽  
L.P. Oznobikhina ◽  
T.N. Aksamentova ◽  
A.R. Romanov ◽  
A.Yu. Rulev
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Nbo Analysis ◽  
Ftir Study ◽  
Intramolecular Hydrogen

GIAO, DFT, AIM and NBO analysis of the NH···O intramolecular hydrogen-bond influence on the 1 J (N,H) coupling constant in push-pull diaminoenones

2010 ◽  
Vol 48 (9) ◽  
pp. 661-670 ◽  
Author(s):  
Andrei V. Afonin ◽  
Igor A. Ushakov ◽  
Alexander V. Vashchenko ◽  
Evgeniy V. Kondrashov ◽  
Alexander Yu. Rulev
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Nbo Analysis ◽  
Coupling Constant ◽  
Intramolecular Hydrogen ◽  
Aim And Nbo

scholarly journals Computational evidence for intramolecular hydrogen bonding and nonbonding X···O interactions in 2'-haloflavonols

2012 ◽  
Vol 8 ◽  
pp. 112-117 ◽  
Author(s):  
Tânia A O Fonseca ◽  
Matheus P Freitas ◽  
Rodrigo A Cormanich ◽  
Teodorico C Ramalho ◽  
Cláudio F Tormena ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Quantum Theory ◽  
Intramolecular Hydrogen Bond ◽  
Natural Bond Orbital ◽  
Intramolecular Hydrogen Bonding ◽  
Nbo Analysis ◽  
Conformational Isomerism ◽  
Intramolecular Hydrogen ◽  
Stereoelectronic Interactions

The conformational isomerism and stereoelectronic interactions present in 2'-haloflavonols were computationally analyzed. On the basis of the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analysis, the conformer stabilities of 2'-haloflavonols were found to be dictated mainly by a C=O···H–O intramolecular hydrogen bond, but an unusual C–F···H–O hydrogen-bond and intramolecular C–X···O nonbonding interactions are also present in such compounds.

Theoretical study of the substituent effect on the hydrogen atom transfer mechanism of the irigenin derivatives antioxidant action

2014 ◽  
Vol 13 (02) ◽  
pp. 1450010 ◽  
Author(s):  
Meysam Najafi ◽  
Syed Ali Raza Naqvi
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Theoretical Study ◽  
Nbo Analysis ◽  
Hydrogen Atom Transfer ◽  
Hammett Constants ◽  
Dissociation Enthalpy ◽  
B3lyp Method ◽  
Intramolecular Hydrogen ◽  
Novel Antioxidants

In this paper, 21 substituents with various electron donating and electron withdrawing characters were placed in available positions of irigenin in order to study their effect on the O – H bond dissociation enthalpy (BDE) via DFT/B3LYP method. Results indicated the substituents in X3 and X4 positions have exerted stronger influence upon BDE values of irigenin derivatives when compared with same substituents in X1 and X2 positions. The results show that intramolecular hydrogen bond effects are able to considerably stabilize the parents and radicals. The natural bond orbital (NBO) analysis results also confirmed the intramolecular hydrogen bond stabilization. The formation of strong intramolecular hydrogen bonds in several radicals results in low BDEs. The 3- OH BDE values for substituents in X2 position have linear dependencies with Hammett constants (Fig. 2 and Eq. (2)). Found dependencies are suitably linear, that can be important for the synthesis of novel antioxidants based on irigenin.

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

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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