Hydrogen-Bonding Interactions between Water and the One- and Two-Electron-Reduced Forms of Vitamin K1: Applying Quinone Electrochemistry To Determine the Moisture Content of Non-Aqueous Solvents

2009 ◽  
Vol 131 (4) ◽  
pp. 1523-1534 ◽  
Author(s):  
Yanlan Hui ◽  
Elaine Lay Khim Chng ◽  
Cheryl Yi Lin Chng ◽  
Hwee Ling Poh ◽  
Richard D. Webster
2014 ◽  
Vol 70 (8) ◽  
pp. 738-741 ◽  
Author(s):  
Graham Smith ◽  
Urs D. Wermuth

The structures of two hydrated salts of 4-aminophenylarsonic acid (p-arsanilic acid), namely ammonium 4-aminophenylarsonate monohydrate, NH4+·C6H7AsNO3−·H2O, (I), and the one-dimensional coordination polymercatena-poly[[(4-aminophenylarsonato-κO)diaquasodium]-μ-aqua], [Na(C6H7AsNO3)(H2O)3]n, (II), have been determined. In the structure of the ammonium salt, (I), the ammonium cations, arsonate anions and water molecules interact through inter-species N—H...O and arsonate and water O—H...O hydrogen bonds, giving the common two-dimensional layers lying parallel to (010). These layers are extended into three dimensions through bridging hydrogen-bonding interactions involving thepara-amine group acting both as a donor and an acceptor. In the structure of the sodium salt, (II), the Na+cation is coordinated by five O-atom donors, one from a single monodentate arsonate ligand, two from monodentate water molecules and two from bridging water molecules, giving a very distorted square-pyramidal coordination environment. The water bridges generate one-dimensional chains extending alongcand extensive interchain O—H...O and N—H...O hydrogen-bonding interactions link these chains, giving an overall three-dimensional structure. The two structures reported here are the first reported examples of salts ofp-arsanilic acid.


2010 ◽  
Vol 82 (5) ◽  
pp. 1928-1934 ◽  
Author(s):  
Yanlan Hui ◽  
Elaine Lay Khim Chng ◽  
Louisa Pei-Lyn Chua ◽  
Wan Zhen Liu ◽  
Richard D. Webster

Author(s):  
Fredrik Lundvall ◽  
Mats Tilset

The title compound, {[MgPtCl2(C12H6N2O4)(C3H7NO)2(H2O)]·C3H7NO}n, is a one-dimensional coordination polymer. The structure consists of Pt-functionalized bipyridine ligands connected by MgIIcations, as well as coordinating and non-coordinating solvent molecules. The PtIIcation is coordinated by the two N atoms of the bipyridine moiety and two Cl atoms in a square-planar fashion. This coordination induces an in-plane bend along the bipyridine backbone of approximately 10° from the linear ideal of a conjugated π-system. Likewise, the coordination to the MgIIcation induces a significant bowing of the plane of the bipyridine of about 12°, giving it a distinct curved appearance. The carboxylate groups of the bipyridine ligand exhibit moderate rotations relative to their parent pyridine rings. The MgIIcation has a fairly regular octahedral coordination polyhedron, in which three vertices are occupied by O atoms from the carboxylate groups of three different bipyridine ligands. The remaining three vertices are occupied by the O atoms of two dimethylformamide (DMF) molecules and one water molecule. The one-dimensional chains are oriented in the [01-1] direction, and non-coordinating DMF molecules can be found in the space between the chains. The shortest intermolecular O...H contacts are 2.844 (4) and 2.659 (4) Å, suggesting moderate hydrogen-bonding interactions. In addition, there is a short intermolecular Pt...Pt contact of 3.491 (1) Å, indicating a Pt stacking interaction. Some structure-directing contribution from the hydrogen bonding and Pt...Pt interaction is probable. However, the crystal packing seems to be directed primarily by van der Waals interactions.


1990 ◽  
Vol 55 (10) ◽  
pp. 2377-2380
Author(s):  
Hamza A. Hussain

Nitroxide free radicals prepared from diethylamine, piperidine and pyrrolidine by oxidation with hydrogen peroxide were studied by ESR spectroscopy. The changes in the 14N splitting constant (aN) caused by the addition of KBr or tetraethylammonium bromide were measured in dependence on the concentration of the ions. For diethylamine nitroxide and piperidine nitroxide, the results are discussed in terms of two equilibria: the one, involving the anion, is associated with a gain or loss of hydrogen bonds to the nitroxide oxygen atom, the other is associated with the formation of solvent shared units involving the cation, which results in changes in the hydrogen bonding strenght. The large increase in the aN value in the case of pyrrolidine nitroxide is explained in terms of an interaction from one side of the positively charged N atom; the increase in aN in the case of diethylamine and piperidine nitroxides is explained in terms of interactions with both sides of the positively charged N atom.


2021 ◽  
Author(s):  
Thufail M. Ismail ◽  
Neetha Mohan ◽  
P. K. Sajith

Interaction energy (Eint) of hydrogen bonded complexes of nitroxide radicals can be assessed in terms of the deepest minimum of molecular electrostatic potential (Vmin).


RSC Advances ◽  
2020 ◽  
Vol 10 (64) ◽  
pp. 39033-39036
Author(s):  
Ayano Awatani ◽  
Masaaki Suzuki

Triply β-dicarbonyl-embedded 1,3,5-triazine derivatives result in formation of circular linkage of resonance-assisted hydrogen bonding interactions, which can be regarded as well-delocalized resonance hybrids.


Soft Matter ◽  
2021 ◽  
Author(s):  
Aliaksei Aliakseyeu ◽  
Victoria Albright ◽  
Danielle Yarbrough ◽  
Samantha Hernandez ◽  
Qing Zhou ◽  
...  

This work establishes a correlation between the selectivity of hydrogen-bonding interactions and the functionality of micelle-containing layer-by-layer (LbL) assemblies. Specifically, we explore LbL films formed by assembly of poly(methacrylic acid)...


Sign in / Sign up

Export Citation Format

Share Document