Conformational Terminology for Crystalline Cellulose

1972 ◽  
Vol 50 (6) ◽  
pp. 792-794 ◽  
Author(s):  
P. R. Sundararajan ◽  
R. H. Marchessault
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
The Other ◽  
Crystalline Cellulose ◽  
Chain Model ◽  
Glucose Residue ◽  
Straight Chain ◽  
A Value ◽  
Intramolecular Hydrogen ◽  
Mathematical Interpretation

Two different crystalline models of cellulose have received attention from crystallographers: the "straight chain" model of Meyer and Misch and the "bent chain" model of P. H. Hermans. We have examined these models and have given a mathematical interpretation of each in terms of the conformational angles [Formula: see text] and ψ and the glycosidic angle τ. For a given geometry of the glucose residue, the "straight chain" corresponds to a unique value of τ; for a value of τ greater than the unique value, two "bent chains" are possible, one allowing an intramolecular hydrogen bond (O-3 … O-5′) and the other not. It is suggested that the former only be referred to as the Hermans conformation.

Dipole moments of hydroxamic acids and N,O-diacylhydroxylamines

1981 ◽  
Vol 46 (3) ◽  
pp. 729-739 ◽  
Author(s):  
Aleksandr I. Artemenko ◽  
Inga V. Tikunova ◽  
Evgenii K. Anufriev ◽  
Václav Jehlička ◽  
Otto Exner
Keyword(s):  
Hydrogen Bond ◽  
Dipole Moment ◽  
Intramolecular Hydrogen Bond ◽  
Dipole Moments ◽  
Hydroxamic Acids ◽  
The Other ◽  
Total Dipole Moment ◽  
Statistical Population ◽  
Intramolecular Hydrogen ◽  
Peroxy Acids

Dipole moments of nine aromatic hydroxamic acids Ia-Ii and of nine N,O-diacylhydroxylamines IIa-IIi were measured in dioxan solution. The results for hydroxamic acids are interpreted in terms of the Zsp conformation (A) with an intramolecular hydrogen bond contributing considerably to the total dipole moment; the conformation is similar to that of peroxy acids but the hydrogen bond is weaker. A similar interpretation is possible for N-phenylbenzhydroxamic acids using the dipole moment data from the literature. New data for N,O-diacylhydroxylamine agree with the previously established nonplanar conformation (L). If axially unsymetrical aryl groups are present, they take one of the two coplanar positions independently of the other moiety; hence the effective dipole moments do not differ too much from the assumption of a statistical population of all conformations.

scholarly journals Crystal structure of 1-amino-2-oxo-2,5,6,7,8,9-hexahydro-1H-cyclohepta[b]pyridine-3-carbonitrile

2016 ◽  
Vol 72 (9) ◽  
pp. 1239-1241 ◽  
Author(s):  
Galal H. Elgemeie ◽  
Peter G. Jones
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Title Compound ◽  
Intermolecular Hydrogen Bond ◽  
Membered Ring ◽  
The Other ◽  
Double Layers ◽  
Compound C ◽  
Intramolecular Hydrogen

In the title compound, C11H13N3O, the seven-membered ring adopts a conformation such that the three atoms not involved in the aromatic plane lie on the same side of that plane. One hydrazinic H atom forms an intramolecular hydrogen bond to the O atom; the other forms a classical intermolecular hydrogen bond N—H...O, which combines with a `weak' Har...O interaction to build up double layers of molecules parallel to thebcplane.

2-Hydroxy-7-iodocyclohepta-2,4,6-trien-1-one

2007 ◽  
Vol 63 (3) ◽  
pp. o1297-o1299 ◽  
Author(s):  
Kanji Kubo ◽  
Taisuke Matsumoto ◽  
Akira Mori
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Title Compound ◽  
Crystalline State ◽  
Intermolecular Hydrogen Bond ◽  
The Other ◽  
Intramolecular Hydrogen

The title compound, also known as 7-iodotropolone, C7H5IO2, exists in the crystalline state as the 2-hydroxy-7-iodocyclohepta-2,4,6-trien-1-one tautomer and not as 2-hydroxy-3-iodocyclohepta-2,4,6-trien-1-one. There is a bifurcated O—H...O bond with two acceptor O atoms. One of these acceptors is involved in an intramolecular hydrogen bond, and the other in an intermolecular hydrogen bond. There is also a C—H...O interaction in the structure. In addition, there is a C—O...π-cycloheptatriene interaction.

scholarly journals (S,E)-3-[(2-Hydroxybenzylidene)amino]-2-(2-hydroxyphenyl)-2,3-dihydroquinazolin-4(1H)-one

2012 ◽  
Vol 68 (8) ◽  
pp. o2374-o2375 ◽  
Author(s):  
Daniel Tinguiano ◽  
Adama Sy ◽  
Ibrahima Elhadj Thiam ◽  
Mohamed Gaye ◽  
Pascal Retailleau
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Intramolecular Hydrogen Bond ◽  
Title Compound ◽  
The Other ◽  
Boat Conformation ◽  
Compound C ◽  
The Mean ◽  
Intramolecular Hydrogen

In the title compound, C21H17N3O3, the dihydroquinazoline ring adopts a screw-boat conformation and its stereogenic C atom has anSconfiguration. The dihedral angle between the mean planes of the two hydroxyphenyl rings is 86.61 (12)°. The amino H atom forms an intramolecular hydrogen bond with a phenol O atom, while the hydrazine N atom acts as an acceptor for the H atom of the other phenol group. In the crystal, O—H...N and O—H...O hydrogen bonds and weak C—H...centroid(π-ring) intermolecular interactions are observed, forming chains along [1-10] and [110].

Effect of the intramolecular hydrogen bond in the active metabolite analogs of leflunomide for blocking the Plasmodium falciparum dihydroorotate dehydrogenase enzyme: QTAIM, NBO, and docking study

2020 ◽  
Vol 16 ◽  
Author(s):  
Reihaneh Heidarian ◽  
Mansoureh Zahedi-Tabrizi
Keyword(s):  
Hydrogen Bond ◽  
Plasmodium Falciparum ◽  
Molecular Orbital ◽  
Intramolecular Hydrogen Bond ◽  
Active Metabolite ◽  
Chemical Hardness ◽  
Dihydroorotate Dehydrogenase ◽  
Molecular Orbital Analysis ◽  
Intramolecular Hydrogen ◽  
Orbital Analysis

: Leflunomide (LFM) and its active metabolite, teriflunomide (TFM), have drawn a lot of attention for their anticancer activities, treatment of rheumatoid arthritis and malaria due to their capability to inhibit dihydroorotate dehydrogenase (DHODH) and Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) enzyme. In this investigation, the strength of intramolecular hydrogen bond (IHB) in five analogs of TFM (ATFM) has been analyzed employing density functional theory (DFT) using B3LYP/6-311++G (d, p) level and molecular orbital analysis in the gas phase and water solution. A detailed electronic structure study has been performed using the quantum theory of atoms in molecules (QTAIM) and the hydrogen bond energies (EHB) of stable conformer obtained in the range of 76-97 kJ/mol, as a medium hydrogen bond. The effect of substitution on the IHB nature has been studied by natural bond orbital analysis (NBO). 1H NMR calculations show an upward trend in the proton chemical shift of the enolic proton in the chelated ring (14.5 to 15.7ppm) by increasing the IHB strength. All the calculations confirmed the strongest IHB in 5-F-ATFM and the weakest IHB in 2-F-ATFM. Molecular orbital analysis, including the HOMO-LUMO gap and chemical hardness, was performed to compare the reactivity of inhibitors. Finally, molecular docking analysis was carried out to identify the potency of inhibition of these compounds against PfDHODH enzyme.

scholarly journals CP/MASS 13C NMR Spectra of Cellulose Solids: An Explanation by the Intramolecular Hydrogen Bond Concept

1985 ◽  
Vol 17 (5) ◽  
pp. 701-706 ◽  
Author(s):  
Kenji Kamide ◽  
Kunihiko Okajima ◽  
Keisuke Kowsaka ◽  
Toshihiko Matsui
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectra ◽  
Intramolecular Hydrogen
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