Calculation of intramolecular hydrogen bonding strength and natural bond orbital (NBO) analysis of naphthazarin with chlorine substitution

2011 ◽  
Vol 977 (1-3) ◽  
pp. 195-200 ◽  
Author(s):  
M. Zahedi-Tabrizi ◽  
R. Farahati
Keyword(s):  
Hydrogen Bonding ◽  
Bonding Strength ◽  
Natural Bond Orbital ◽  
Intramolecular Hydrogen Bonding ◽  
Nbo Analysis ◽  
Chlorine Substitution ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonding Strength

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.

THE EFFECT OF SUBSTITUTION ON STRUCTURE, INTRAMOLECULAR HYDROGEN BONDING STRENGTH, ELECTRON DENSITY AND RESONANCE IN 3-AMINO 2-IMINOMETHYL ACRYL ALDEHYDE

2012 ◽  
Vol 11 (05) ◽  
pp. 925-939 ◽  
Author(s):  
HEIDAR RAISSI ◽  
MAHDI YOOSEFIAN ◽  
FARIBA MOLLANIA ◽  
FARZANEH FARZAD
Keyword(s):  
Hydrogen Bonding ◽  
Electron Density ◽  
Population Analysis ◽  
Intramolecular Hydrogen Bonding ◽  
Analysis Data ◽  
Covalent Character ◽  
Hydrogen Bonding Interactions ◽  
Hydrogen Bond Strength ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonding Strength

B3LYP/6-311++G** calculations have been carried out to simulate the influence of substitutions in position R1 and R2 of 3-amino 2-iminomethyl acryl aldehyde on intramolecular hydrogen bond strength. The following substituents are taken into considerations: CN, NO2, Cl, F, CH3, CHO, NH2, C2H5, SH, SCH3, CF3 and CH3CO and their vibrational frequencies are calculated at the same level of theory. Quantum theory of "Atoms in Molecules" and Natural Bond Orbitals method were applied to analyzed H-bond interactions. The electron density (ρ) and Laplacian (∇2ρ) properties, estimated by AIM calculations, indicate that N⋯H bond possesses low ρ and positive ∇2ρ values which are in agreement with electrostatic character of the HBs, whereas N–H bonds have covalent character (∇2ρ < 0). Natural population analysis data, the electron density and Laplacian properties, as well as, ν (N-H) and γ (N-H) have been used to evaluate the hydrogen bonding interactions.

Characterization of Hydrogen Bonds in the End-Functionalized Single-Wall Carbon Nanotubes: A DFT Study

NANO ◽  
2015 ◽  
Vol 10 (03) ◽  
pp. 1550036
Author(s):  
Reza Ghafouri ◽  
Fatemeh Ektefa ◽  
Mansour Zahedi
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Bonding ◽  
Computational Study ◽  
Intramolecular Hydrogen Bonding ◽  
Nbo Analysis ◽  
Coupling Constants ◽  
Single Wall Carbon Nanotubes ◽  
Single Wall Carbon ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bondings

A systematic computational study is carried out to shed some light on the structure of semiconducting armchair single-wall carbon nanotubes (n, n) SWCNTs, n = 4, 5 and 6, functionalized at the end with carboxyl (– COOH ) and amide (– CONH 2) from the viewpoint of characterizing the intramolecular hydrogen bondings at the B3LYP/6-31++G(d, p) level. Geometry parameters display different types of intramolecular hydrogen bonding possibilities in the considered functionalized SWCNTs. All of the hydrogen bondings are confirmed by natural bonding orbitals (NBO) analysis as well as nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) parameters. Based on NBO analysis, the calculated [Formula: see text] delocalization energies E(2), 1.15 kcal/mol to 7.04 kcal/mol, are in direct relation with the hydrogen bonding strengths. Differences in the chemical shielding principal components of 13 C and 17 O nuclei correlate well with the strengths of the hydrogen bondings. Participating in stronger hydrogen bondings, a larger SWCNT has a decreasing effect on 13 C (= O ) and 17 O isotropic chemical shieldings, σiso, consistent with the NBO analysis. The considerable changes of 13 C /17 O σiso can be interpreted as a result of shielding tensor component orientation. The 13 C (= O ) and 17 O quadrupole coupling constants C Q decrease under the effect of hydrogen bonding while asymmetry parameters ηQ significantly increase, indicating that 17 O ηQ is more sensitive to hydrogen bondings.

Theoretical study of intramolecular hydrogen bonding and molecular geometry of 2-trifluoromethylphenol

10.1002/jcc.2 ◽  
1996 ◽  
Vol 17 (16) ◽  
pp. 1804-1819 ◽  
Author(s):  
Attila Kov�cs ◽  
Istv�n Kolossv�ry ◽  
G�bor I. Csonka ◽  
Istv�n Hargittai
Keyword(s):  
Hydrogen Bonding ◽  
Theoretical Study ◽  
Molecular Geometry ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Hydrogen
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