Molecular Conformational Analysis, Spectroscopic Characterization, Intramolecular Hydrogen Bonding and Natural Bond Analysis of (E,Z)-2-(4- Amino-5-oxo-3-(thiophene-2-ylmethyl)-4,5-dihydro-1,2,4-triazole-1-yl)-N'- (thiophene-2-ylmethylene) Acetohydrazide

2019 ◽  
Vol 16 (3) ◽  
pp. 215-225
Author(s):  
Abdurrahman Atalay ◽  
Fatih Çelik ◽  
Yasemin Ünver ◽  
Kemal Sancak ◽  
Kamil Kaygusuz
Keyword(s):  
Hydrogen Bonding ◽  
Density Functional ◽  
Structural Parameters ◽  
Intramolecular Hydrogen Bonding ◽  
Spectroscopic Characterization ◽  
Frontier Molecular Orbital ◽  
Hydrogen Bond Interaction ◽  
Ft Ir ◽  
Intramolecular Hydrogen ◽  
Theoretical Results

The optimized structural parameters and electronic properties including frontier molecular orbital (FMO) analysis, molecular electrostatic potential and NBO charge analysis of (E,Z)-2-(4- amino-5-oxo-3-(thiophene-2-ylmethyl)-4,5-dihydro-1,2,4-triazole-1-yl)-N'-(thiophene-2-ylmethylene) acetohydrazide were investigated by using density functional theory (DFT) at B3LYP/6-311++G(d,p) level. The global reactivity parameters were evaluated in accordance with the energy values of HOMO and LUMO of each determined conformer. The molecule was experimentally characterized by means of FT-IR and NMR spectroscopic methods and also theoretically by B3LYP/6-311++G(d,p) and B3LYP/cc-pVTZ method (FT-IR and NMR, respectively). The theoretical results of spectroscopic analysis show good agreement with experimental outcomes. The natural bond orbital (NBO) analyses for studied conformers were performed at B3LYP/6-311++G(d,p) level to find hyperconjugative interactions as well as intramolecular hydrogen bond interaction. Besides, theoretical results indicate that the optimized structure of conformer E and Z possesses N‒H···N and N‒H···S weak hydrogen bonding, respectively.

STUDY OF INTRAMOLECULAR HYDROGEN BONDING IN ORTHO-SUBSTITUTED ACETANILIDE COMPOUNDS USING COMPUTATIONAL METHODS

2004 ◽  
Vol 03 (04) ◽  
pp. 527-542 ◽  
Author(s):  
SEIFOLLAH JALILI ◽  
MOJDEH AKHAVAN
Keyword(s):  
Hydrogen Bonding ◽  
Density Functional ◽  
Structural Parameters ◽  
Intramolecular Hydrogen Bonding ◽  
Basis Sets ◽  
Structural Factors ◽  
Functional Theory ◽  
Aim Theory ◽  
Moller Plesset ◽  
Intramolecular Hydrogen

The intramolecular hydrogen bonding formation in ortho-substituted compounds of Acetanilide, ortho-hydroxy Acetanilide and ortho-nitro Acetanilide, was investigated using Density Functional Theory (DFT), Møller-Plesset second-order (MP2) method and "Atoms in Molecules (AIM)" theory. It was found that in each case, the cis isomer is more stable than the trans isomer and ortho-nitro Acetanilide forms a stronger hydrogen bond than ortho-hydroxy Acetanilide. The effects of hydrogen bonding on structural parameters of the considered systems were studied using Becke's functional (B3LYP) and at the ab initio MP2 level in conjunction with different basis sets and suitable structural factors. The results are in agreement with the results of AIM theory.

scholarly journals NMR of Natural Products as Potential Drugs

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3763
Author(s):  
Poul Erik Hansen
Keyword(s):  
Natural Products ◽  
Hydrogen Bonding ◽  
Density Functional ◽  
Chemical Shifts ◽  
Isotope Effects ◽  
Density Functional Theory Calculations ◽  
Intramolecular Hydrogen Bonding ◽  
Chemical Equilibria ◽  
Nmr Techniques ◽  
Intramolecular Hydrogen

This review outlines methods to investigate the structure of natural products with emphasis on intramolecular hydrogen bonding, tautomerism and ionic structures using NMR techniques. The focus is on 1H chemical shifts, isotope effects on chemical shifts and diffusion ordered spectroscopy. In addition, density functional theory calculations are performed to support NMR results. The review demonstrates how hydrogen bonding may lead to specific structures and how chemical equilibria, as well as tautomeric equilibria and ionic structures, can be detected. All these features are important for biological activity and a prerequisite for correct docking experiments and future use as drugs.

scholarly journals Intramolecular hydrogen bonding and conformational preferences on 2-fluoro-phenylaminocyclohexanol

2018 ◽  
Author(s):  
Cassia Chiari ◽  
Claudio Francisco Tormena ◽  
Kahlil Schwanka Salome ◽  
Laiza Bruzadelle Loureiro ◽  
Renan Vidal Viesser
Keyword(s):  
Hydrogen Bonding ◽  
Driving Force ◽  
Conformational Stability ◽  
Intramolecular Hydrogen Bonding ◽  
Quantum Mechanical ◽  
Resonance Spectroscopy ◽  
Quantum Mechanical Calculations ◽  
Conformational Preferences ◽  
Intramolecular Hydrogen ◽  
Theoretical Results

The aim of this study is to evaluate the influence and strength of possible intramolecular hydrogen bonding (IntraHB) involving N-H--O, O-H--N, O-H--F and N-H--F molecular moieties as a driving force on the conformational preferences of 2-fluoro-phenylaminocyclohexanol. To achieve our purpose we synthesized the compound and performed it's characterization using Nuclear Magnetic Resonance Spectroscopy (NMR). Quantum mechanical calculations were carried out to evaluate the effect of IntraHB on the conformational stability. Experimental and theoretical results showed that N-H--F and O-H--N IntraHB have a greater influence on the conformacional preferably adopted by the molecule.

scholarly journals Crystallographic and spectroscopic characterization of 3-chloro-5-fluorosalicylaldehyde

2020 ◽  
Vol 76 (12) ◽  
pp. 1810-1812
Author(s):  
Christopher T. Triggs ◽  
Joseph M. Tanski
Keyword(s):  
Hydrogen Bonding ◽  
Title Compound ◽  
Intramolecular Hydrogen Bonding ◽  
Spectroscopic Characterization ◽  
Face To Face ◽  
Π Stacking ◽  
Intramolecular Hydrogen

The title compound (systematic name: 3-chloro-5-fluoro-2-hydroxybenzaldehyde), C7H4ClFO2, is a dihalogenated salicylaldehyde derivative that has been studied for its antibacterial characteristics. The salicylaldehyde engages in intramolecular hydrogen bonding with an O—H...O distance of 2.6231 (19) Å while the molecules pack together via weak intermolecular C—H...O, C—H...F and F...O interactions and offset face-to-face π-stacking.

Switching On/Off the Intramolecular Hydrogen Bonding of 2-Methoxyphenol Conformers: An NMR Study

2020 ◽  
Vol 73 (3) ◽  
pp. 222
Author(s):  
Frederick Backler ◽  
Feng Wang
Keyword(s):  
Hydrogen Bonding ◽  
Chemical Shift ◽  
1H Nmr ◽  
Density Functional ◽  
Point Group ◽  
Decomposition Analysis ◽  
Intramolecular Hydrogen Bonding ◽  
Group Symmetry ◽  
Energy Decomposition Analysis ◽  
Intramolecular Hydrogen

Intramolecular hydrogen bonding of 2-methoxyphenol (2-MP, guaiacol) is studied using NMR spectroscopy combined with quantum mechanical density functional theory (DFT) calculations. The hydrogen bonding of OH⋯O and HO⋯H is switched on in the conformers of anti–syn (AS, 99.64% dominance) and anti–gauche (AG), respectively, with respect to the anti–anti (AA) conformer (without either such hydrogen bonding interactions). It confirms that the 13C and 1H NMR chemical shift of AS dominates the measured NMR spectra, as the AS conformer reproduces the measurements in CDCl3 solvent (RMSD of 1.86ppm for 13C NMR and of 0.27ppm for 1H NMR). The chemical shift of hydroxyl H(1) at 5.66 pm is identified as the fingerprint of the OH(1)⋯OCH3 hydrogen bonding in AS, as it exhibits a significant deshielding from H(1) of AA (4.24ppm) and H(1) of AG (4.38ppm) without such OH(1)⋯OCH3 hydrogen bonding. The AG conformer (C1 point group symmetry) possesses a less strong hydrogen bonding of HO⋯HCH2O, with the methoxyl group out of the aromatic phenol plane. The substituent effect of AG due to the resonance interaction of methoxyl being out of plane in a concentrated solution shifts the ortho- and para-aromatic carbons, C(3)/C(5), of the AG to ~125.05/125.44ppm from the corresponding carbons in AS at 108.81/121.60ppm. The hydrogen bonding exhibits inwards reduction of IR frequency regions of AS and AG from AA. Finally, energy decomposition analysis (EDA) indicates that there is a steric energy of 45.01kcal mol−1 between the AS and AG when different intramolecular hydrogen bonding is switched on.

Gold(I) 1,2,3-Triazolylidene Complex Featuring the Interaction Between Gold and Methine Hydrogen

2021 ◽  
Author(s):  
Adi Narayana Mannem ◽  
Moulali Vaddamanu ◽  
Arruri Sathyanarayana ◽  
Kumar Siddhant ◽  
Shohei Sugiyama ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Intramolecular Hydrogen Bonding ◽  
Hydrogen Bonding Interaction ◽  
Bonding Interaction ◽  
Ft Ir ◽  
Intramolecular Hydrogen

Mesoionic N-heterocyclic carbene-gold(I) complex with a unique Au····H–C(methine) intramolecular hydrogen bonding interaction has been investigated in the solid-state. The structure of this new neutral gold(I)-carbene was characterized by FT-IR, NMR...

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