scholarly journals Understanding the effects of vicinal carbon substituents and configuration on organofluorine hydrogen-bonding interaction

RSC Advances ◽  
2018 ◽  
Vol 8 (68) ◽  
pp. 38980-38986 ◽  
Author(s):  
Qingqing Jia ◽  
Qingzhong Li ◽  
Mo Luo ◽  
Hai-Bei Li
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Hydrogen Bonding Interaction ◽  
Bonding Interaction

The vicinal substituents, with gauche/stagger isomer in CH2XCH2F and cis/trans isomer in CHXCHF, affect the interaction of C(spn)–F⋯H–O organofluorine hydrogen bonds differently.

On the differential hydration of various forms of glycine in diluted aqueous solutions: a Monte Carlo study

2012 ◽  
Vol 31 (2) ◽  
pp. 295
Author(s):  
Biljana Bujaroska ◽  
Kiro Stojanoski ◽  
Ljupco Pejov
Keyword(s):  
Monte Carlo ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Water Molecules ◽  
Hydrogen Bonding Interaction ◽  
Liquid Environment ◽  
Zwitterionic Form ◽  
Solvent Water ◽  
Bonding Interaction ◽  
Solvent Molecules

Rigid-body Monte Carlo simulations were carried out to study the differential hydration of zwitterionic and neutral forms of glycine in water. To account for the solute polarization by the rather polar liquid environment, initial geometries were chosen as minima on the MP2/aug-cc-pVTZ potential energy surfaces of neutral and zwitterionic glycine continuously solvated by water, implementing the polarizable continuum model (PCM) within the integral equation formalism (IEFPCM). The dynamically changing hydrogen bonding network between the solute and solvent molecules was analyzed imposing distance, energy and angular distribution-based criteria. It was found that, on average, the zwitterionic form of glycine acts as an acceptor of 4.53 hydrogen bonds, while it plays the role of a proton donor in (on average) 2.73 hydrogen bonds with the solvent water molecules. In particular, we have found out that 2.73 solvent water molecules are involved in hydrogen bonding interaction with the ammonium group, acting as proton-acceptors. This is in excellent agreement with the recent experimental neutron diffraction studies, which have indicated that 3.0 water molecules reside in the vicinity of the NH3+ group of aqueous zwitterionic glycine. Neutral form of aqueous glycine, on the other hand, on average donates protons in 1.63 hydrogen bonds with the solvent water molecules, while at the same time it accepts 2.53 hydrogen bonds from the solvent molecules. The greater charge polarization in the zwitterionic form thus makes it much more exposed to hydrogen bonding interaction in polar medium such as water, which is certainly the main reason of the larger stability of this form of glycine in condensed media.

Three anilides of 2,2′-thiodibenzoic acid

2012 ◽  
Vol 68 (10) ◽  
pp. o387-o391 ◽  
Author(s):  
Madeleine Helliwell ◽  
Salma Moosun ◽  
Minu G. Bhowon ◽  
Sabina Jhaumeer-Laulloo ◽  
John A. Joule
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Hydrogen Bonding Interaction ◽  
Bonding Interaction

The structures ofN,N′-bis(2-methylphenyl)-2,2′-thiodibenzamide, C28H24N2O2S, (Ia),N,N′-bis(2-ethylphenyl)-2,2′-thiodibenzamide, C30H28N2O2S, (Ib), andN,N′-bis(2-bromophenyl)-2,2′-thiodibenzamide, C26H18Br2N2O2S, (Ic), are compared with each other. For the 19 atoms of the consistent thiodibenzamide core, the r.m.s. deviations of the molecules in pairs are 0.29, 0.90 and 0.80 Å for (Ia)/(Ib), (Ia)/(Ic) and (Ib)/(Ic), respectively. The conformations of the central parts of molecules (Ia) and (Ib) are similar due to an intramolecular N—H...O hydrogen-bonding interaction. The molecules of (Ia) are further linked into infinite chains along thecaxis by intermolecular N—H...O interactions, whereas the molecules of (Ib) are linked into chains alongbby an intermolecular N—H...π contact. The conformation of (Ic) is quite different from those of (Ia) and (Ib), since there is no intramolecular N—H...O hydrogen bond, but instead there is a possible intramolecular N—H...Br hydrogen bond. The molecules are linked into chains alongcby intermolecular N—H...O hydrogen bonds.

Radical Enzymes Control the Chemistry of Their Highly Reactive Intermediates Using the Quantum Coulombic Effect

2020 ◽  
Author(s):  
Hossein Khalilian ◽  
Gino A. DiLabio
Keyword(s):  
Hydrogen Bonding ◽  
Molecular Orbital ◽  
Reactive Intermediates ◽  
Hydrogen Bonding Interaction ◽  
Orbital Ordering ◽  
Dynamic Nature ◽  
Radical Intermediate ◽  
Highest Occupied Molecular Orbital ◽  
Bonding Interaction ◽  
Close Proximity

Here, we report an exquisite strategy that the B12 enzymes exploit to manipulate the reactivity of their radical intermediate (Adenosyl radical). Based on the quantum-mechanic calculations, these enzymes utilize a little known long-ranged through space quantum Coulombic effect (QCE). The QCE causes the radical to acquire an electronic structure that contradicts the Aufbau Principle: The singly-occupied molecular orbital (SOMO) is no longer the highest-occupied molecular orbital (HOMO) and the radical is unable to react with neighbouring substrates. The dynamic nature of the enzyme and its structure is expected to be such that the reactivity of the radical is not restored until it is moved into close proximity of the target substrate. We found that the hydrogen bonding interaction between the nearby conserved glutamate residue and the ribose ring of Adenosyl radical plays a crucial role in manipulating the orbital ordering

Radical Enzymes Control the Chemistry of Their Highly Reactive Intermediates Using the Quantum Coulombic Effect

2020 ◽  
Author(s):  
Hossein Khalilian ◽  
Gino A. DiLabio
Keyword(s):  
Hydrogen Bonding ◽  
Molecular Orbital ◽  
Reactive Intermediates ◽  
Hydrogen Bonding Interaction ◽  
Orbital Ordering ◽  
Dynamic Nature ◽  
Radical Intermediate ◽  
Highest Occupied Molecular Orbital ◽  
Bonding Interaction ◽  
Close Proximity

Here, we report an exquisite strategy that the B12 enzymes exploit to manipulate the reactivity of their radical intermediate (Adenosyl radical). Based on the quantum-mechanic calculations, these enzymes utilize a little known long-ranged through space quantum Coulombic effect (QCE). The QCE causes the radical to acquire an electronic structure that contradicts the Aufbau Principle: The singly-occupied molecular orbital (SOMO) is no longer the highest-occupied molecular orbital (HOMO) and the radical is unable to react with neighbouring substrates. The dynamic nature of the enzyme and its structure is expected to be such that the reactivity of the radical is not restored until it is moved into close proximity of the target substrate. We found that the hydrogen bonding interaction between the nearby conserved glutamate residue and the ribose ring of Adenosyl radical plays a crucial role in manipulating the orbital ordering

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