THE AMINO PROTON SHIFTS OF SOME SUBSTITUTED ANILINES IN CYCLOHEXANE

1965 ◽  
Vol 43 (10) ◽  
pp. 2668-2677 ◽  
Author(s):  
T. Yonemoto ◽  
W. F. Reynolds ◽  
H. M. Hutton ◽  
T. Schaefer
Keyword(s):  
Negative Deviation ◽  
Hydrogen Bonding Interaction ◽  
Substituted Anilines ◽  
Aqueous Acid ◽  
Low Field ◽  
Low Concentrations ◽  
Bonding Interaction ◽  
Correlation Line ◽  
Hammett Σ Constants ◽  
Infrared Data

The amino proton shifts of 41 ortho, meta, and para substituted anilines at low concentrations in cyclohexane are reported. The shifts for meta and para substituents correlate with Hammett σ constants and it is shown that they are probably proportional to the π-electron density on the nitrogen atom. These shifts also correlate with the pKa values of the corresponding anilinium ions in aqueous acid. The amino proton shifts for the ortho substituents, apart from methyl groups, follow a correlation line which lies about 0.5 p.p.m. to low field from that for the meta and para substituents. This negative deviation is discussed in terms of a weak hydrogen bonding interaction with the ortho substituents and the H—N—H bond angles as derived from infrared data.

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

Investigation of Hydrogen Bonding Interaction between Bolaform Schiff Bases with Barbituric Acid by HPLC

2011 ◽  
Vol 356-360 ◽  
pp. 48-51
Author(s):  
Qi Tong ◽  
Ti Feng Jiao
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Liquid Chromatography ◽  
Schiff Bases ◽  
Barbituric Acid ◽  
Flexible Structure ◽  
Intermolecular Hydrogen Bonding ◽  
Acid Molecule ◽  
Hydrogen Bonding Interaction ◽  
Bonding Interaction

In order to investigate the intermolecular hydrogen bonding of special amphiphiles, two bolaform amphiphilic Schiff bases (GN1 and GN2) with different hydrophilic spacers were designed, and their interaction with barbituric acid were tested by liquid chromatography. The chromatographic properties showed that both the Schiff bases showed hydrogen bonding interaction with barbituric acid. In addition, the influence of various detectors was also studied on both cases. Experimental results show that the test with FLD showed better determination than other detectors. It is proposed that due to the directionality and strong matching of hydrogen bond, one barbituric acid molecule can be encapsulated into the intramolecular area of GN1, while two barbituric acid molecules were trapped into the GN2 molecule through intermolecular H-bonds for GN2 due to the long spacer and flexible structure. A rational complex mode was proposed.

Spectroscopic Evidence forIntermolecularM−H···H−OR Hydrogen Bonding:  Interaction of WH(CO)2(NO)L2Hydrides with Acidic Alcohols

1996 ◽  
Vol 118 (5) ◽  
pp. 1105-1112 ◽  
Author(s):  
Elena S. Shubina ◽  
Natalia V. Belkova ◽  
Aleksandr N. Krylov ◽  
Evgeni V. Vorontsov ◽  
Lina M. Epstein ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonding Interaction ◽  
Spectroscopic Evidence ◽  
Bonding Interaction
Sign in / Sign up

Export Citation Format

Share Document