Variable-temperature neutron diffraction studies of the short, strong N...O hydrogen bonds in the 1:2 co-crystal of benzene-1,2,4,5-tetracarboxylic acid and 4,4'-bipyridyl

2003 ◽  
Vol 59 (6) ◽  
pp. 794-801 ◽  
Author(s):  
John A. Cowan ◽  
Judith A. K. Howard ◽  
Garry J. McIntyre ◽  
Samuel M.-F. Lo ◽  
Ian D. Williams
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Variable Temperature ◽  
Intermediate Position ◽  
The Other ◽  
Tetracarboxylic Acid ◽  
Other Hand

The 1:2 adduct of benzene-1,2,4,5-tetracarboxylic acid and 4,4′-bipyridyl at 100 K has been studied by single-crystal neutron diffraction at 20, 200 and 296 K. The structure contains two short, strong N...O hydrogen bonds: one O—H...N hydrogen bond [O...N 2.6104 (17) Å at 20 K] and one short N—H...O hydrogen bond [N...O 2.5220 (17) Å at 20 K]. The N—H distance in the N—H...O hydrogen bond changes from 1.207 (3) Å at 20 K to 1.302 (4) Å at 296 K and the N...O distance increases to 2.5315 (16) Å at 296 K. At 200 K the H atom lies in an intermediate position 1.251 (6) Å from the N atom with an N...O separation of 2.520 (4) Å. The O—H...N hydrogen bond, on the other hand, does not change with temperature.

scholarly journals Success or Failure of Chiral Crystallization of Similar Heterocyclic Compounds

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5691
Author(s):  
Cyprian M. Chunkang ◽  
Iris E. Ikome ◽  
Emmanuel N. Nfor ◽  
Yuta Mitani ◽  
Natsuki Katsuumi ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Single Crystal ◽  
Single Crystals ◽  
Heterocyclic Compounds ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
The Other ◽  
X Ray ◽  
Other Hand

Single crystals of two achiral and planar heterocyclic compounds, C9H8H3O(CA1) and C8H5NO2 (CA4), recrystallized from ethanol, were characterized by single crystal X-ray analysis, respectively, and chiral crystallization was observed only for CA1 as P212121 (# 19), whereas it was not observed for CA4 P21/c (# 14). In CA1, as a monohydrate, the hydrogen bonds were pronounced around the water of crystallization (O4), and the planar cyclic sites were arranged in parallel to slightly tilted positions. On the other hand, an anhydride CA4 formed a dimer by hydrogen bonds between adjacent molecules in the crystal, which were aggregated by van der Waals forces and placed in parallel planar cyclic sites.

scholarly journals Variable-temperature neutron diffraction studies of the short, strong hydrogen bonds in the crystal structure of pyridine-3,5-dicarboxylic acid

2005 ◽  
Vol 61 (6) ◽  
pp. 724-730 ◽  
Author(s):  
John. A. Cowan ◽  
Judith A. K. Howard ◽  
Garry, J. McIntyre ◽  
Samuel M.-F Lo ◽  
Ian D. Williams
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Carboxylic Acid ◽  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Dicarboxylic Acid ◽  
Bond Length ◽  
Variable Temperature ◽  
Temperature Dependent ◽  
Proton Migration

Pyridine-3,5-dicarboxylic acid has been studied by single-crystal neutron diffraction at 15 and 296 K. Pyridine-3,5-dicarboxylic acid, in which the carboxylic acid protons have been replaced by deuterons, has also been studied at 15, 150 and 296 K. The protonated structure contains a short N...H...O hydrogen bond [N...O 2.523 (2) Å at 15 K]. Temperature-dependent proton migration occurs where the N—H distance in the hydrogen bond changes from 1.213 (4) Å at 15 K to 1.308 (6) Å at 300 K. In the deuterated structure the overall hydrogen-bond length increased [N...O 2.538 (3) Å at 15 K] and the magnitude of the migration increased so that the N—D distance changes from 1.151 (3) Å at 15 K to 1.457 (4) Å at 300 K.

Location of the proton in the very strong OHO hydrogen bonds in 2-(N,N-diethylamino-N-oxymethyl)-4,6-dichlorophenol. A single crystal neutron diffraction study

1997 ◽  
Vol 212 (2) ◽  
Author(s):  
H. Ptasiewicz-Bak ◽  
R. Tellgren ◽  
I. Olovsson ◽  
A. Koll
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Diffraction Study ◽  
Neutron Diffraction Study ◽  
Crystallographic Symmetry ◽  
O 175.8 ◽  
Oxygen Atoms

AbstractThe crystal structure of 2-(N,N-diethylamino-N-oxymethyl)-4,6-dichlorophenol contains two slightly different molecules A and B, both with very strong intramolecular O … H … O hydrogen bonds, with O–O distances 2.423(4) Å and 2.400(5) Å, respectively, and with no crystallographic symmetry. The bridging oxygen atoms are also chemically different, O1 is bonded to carbon and O2 to nitrogen. The single crystal neutron diffraction study shows quite unambiguously that the proton in both cases is located slightly off-centred. In the A molecule O1–H = 1.167(6) Å, H–O2 = 1.258(6) Å and the angle O–H–O = 175.8(5)°; in the B molecule O1–H = 1.186(7) Å, H–O2 = 1.214(7) Å and the angle O–H–O = 176.5(5)°. As expected the proton is thus closer to the centre in the slightly shorter hydrogen bond.

scholarly journals Single crystal synchrotron X-ray diffraction for imaging hydrogen bond evolution

2014 ◽  
Vol 70 (a1) ◽  
pp. C559-C559
Author(s):  
Lucy Saunders ◽  
Harriott Nowell ◽  
Lynne Thomas ◽  
Paul Raithby ◽  
Chick Wilson
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Atom Position ◽  
Proton Disorder ◽  
Atom Position

Hydrogen bonding is a valuable intermolecular interaction in "engineering" solid-state materials. This is because of the directionality and relative strength (1) of these bonds. Hydrogen bonds enable charge and energy transfer, via H-bond evolution, in a range of biological and chemical systems (2). Recent work has demonstrated that single crystal X-ray diffraction can be used to image the evolution of hydrogen bonds, including variable temperature proton migration and proton disorder processes. In particular, in a recent study of the temperature dependent proton disorder in hydrogen bonded 3,5-dinitrobenzoic acid (3,5-DNBA) dimers, the proton disorder deduced from data collected on an X-ray laboratory source is in agreement with that found from neutron data (3). This work focuses on variable temperature single crystal synchrotron X-ray diffraction, for the imaging of evolving hydrogen bonds. The development of appropriate methodology is important here, particularly as previous studies have involved laboratory X-ray sources only. Results will be presented from variable temperature data collections on I19, at the Diamond Light Source, and on beamline 11.3.1, at the Advanced Light Source (ALS), on systems such as 3,5-DNBA and co-crystals of benzimidazole, both exhibiting proton disorder across hydrogen bonding interactions. Synchrotron X-ray diffraction measurements have also been used to follow the change in the position of a proton within an intramolecular [N–H···N]+ hydrogen bond across a range of proton-sponge molecular complexes. Importantly, it has been possible to visualise the evolving hydrogen atom position in Fourier difference electron density maps generated from the synchrotron data. In particular, for the 35-DNBA study, the clearest picture of the evolving hydrogen atom position is observed in those generated from data collected at the ALS; even clearer than that observed in X-ray laboratory and neutron measurements on the same system.

scholarly journals Grammaticalization of syntactic conflict resolution: Asymmetric constructions

2013 ◽  
pp. 115-135
Author(s):  
I.M. Boguslavskij
Keyword(s):  
Conflict Resolution ◽  
Intermediate Position ◽  
The Other ◽  
Semantic Structure ◽  
The Core ◽  
Other Hand ◽  
Principal Property ◽  
The One

We consider Russian coordinative constructions with paired conjunctions, such as i?i ?both?and?, ili?ili ?either?or?, ni?ni ?neither?nor?, ne tol'ko?no i ?not only?but also?, ne?a ?not?but?, etc. The paper presents a class of syntactic constructions, so-called asymmetric constructions, which are interesting in several respects. They are closely related to coordinative constructions, although they do not share their principal property - the identity of syntactic functions of coordinated elements. They take up an intermediate position between standard syntax and ungrammaticality. On the one hand, the sentence is within the grammatical norm. On the other hand, its structure underwent a deformation that left a trace. We propose a description that accounts for their closeness to and difference from standard - symmetric - constructions. Symmetric constructions with paired conjunctions are convenient to describe as a result of two transformations occurring in the semantic structure: Deletion and Transfer. Asymmetric constructions are obtained when only one of these transformations is applied. Accordingly, two subclasses of asymmetric constructions can be distinguished - ?Deletion-Without-Transfer? constructions and ?Transfer-Without-Deletion? constructions. The latter class has a strong pragmatic marking. The core of this class are ?failed? symmetric constructions. The speaker begins to build a symmetric construction but faces an obstacle of syntactic nature, which prevents him from completing this plan. ?Transfer-Without-Deletion? constructions constitute a legalized way of overcoming syntactic conflicts.

(1R*,5R*,7R*,8S*)-3-(3,4-Dihydroxybenzoyl)-4-hydroxy-8-methyl-1,5,7-tris(3-methyl-2-butenyl)-8-(4-methyl-3-pentenyl)bicyclo[3.3.1]non-3-ene-2,9-dione

2007 ◽  
Vol 63 (3) ◽  
pp. o1282-o1284 ◽  
Author(s):  
Bruno Ndjakou Lenta ◽  
Diderot Tchamo Noungoue ◽  
Krishna Prasad Devkota ◽  
Patrice Aime Fokou ◽  
Silvere Ngouela ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Medicinal Plant ◽  
Chair Conformation ◽  
The Other ◽  
Aryl Group ◽  
One Dimensional ◽  
Compound C ◽  
Bicyclic System ◽  
Symphonia Globulifera

The title compound, C38H50O6, also known as guttiferone A, was isolated from the medicinal plant Symphonia globulifera. It is a benzophenone derivative where one aryl group is derivatized to give a bicyclic system which has two prenyl groups attached to the bridgehead. One of the cyclohexane rings in the bicyclic system is in a chair form, while the other has a distorted half-chair conformation. In addition to an intramolecular O—H...O hydrogen bond, intermolecular O—H...O hydrogen bonds link molecules into one-dimensional chains.

Polymorphs of phenazine hexacyanoferrate(II) hydrate: supramolecular isomerism in a 2D hydrogen-bonded network

2021 ◽  
Vol 77 (2) ◽  
pp. 211-218
Author(s):  
Ivica Cvrtila ◽  
Vladimir Stilinović
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
The Other ◽  
Two Dimensional ◽  
Structural Motifs ◽  
Supramolecular Isomerism ◽  
Other Hand ◽  
Π Stacking ◽  
Hydrogen Bonded

The crystal structures of two polymorphs of a phenazine hexacyanoferrate(II) salt/cocrystal, with the formula (Hphen)3[H2Fe(CN)6][H3Fe(CN)6]·2(phen)·2H2O, are reported. The polymorphs are comprised of (Hphen)2[H2Fe(CN)6] trimers and (Hphen)[(phen)2(H2O)2][H3Fe(CN)6] hexamers connected into two-dimensional (2D) hydrogen-bonded networks through strong hydrogen bonds between the [H2Fe(CN)6]2− and [H3Fe(CN)6]− anions. The layers are further connected by hydrogen bonds, as well as through π–π stacking of phenazine moieties. Aside from the identical 2D hydrogen-bonded networks, the two polymorphs share phenazine stacks comprising both protonated and neutral phenazine molecules. On the other hand, the polymorphs differ in the conformation, placement and orientation of the hydrogen-bonded trimers and hexamers within the hydrogen-bonded networks, which leads to different packing of the hydrogen-bonded layers, as well as to different hydrogen bonding between the layers. Thus, aside from an exceptional number of symmetry-independent units (nine in total), these two polymorphs show how robust structural motifs, such as charge-assisted hydrogen bonding or π-stacking, allow for different arrangements of the supramolecular units, resulting in polymorphism.

scholarly journals 1-[N-Methyl-N-(Phenyl)amino]-3- (4-Methylphenyl)Thiourea

Molbank ◽  
10.3390/m1052 ◽  
2019 ◽  
Vol 2019 (1) ◽  
pp. M1052 ◽  
Author(s):  
Chien Yeo ◽  
Edward Tiekink
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Elemental Analysis ◽  
Title Compound ◽  
Molecular Conformation ◽  
Phenyl Hydrazine ◽  
X Ray ◽  
X Ray Crystallography

The title compound, 1-[N-methyl-N-(phenyl)amino]-3-(4-methylphenyl)thiourea (1), was synthesized by the reaction of 1-methyl-1-phenyl hydrazine and 4-tolyl isothiocyanate, and was characterized by spectroscopy (1H and 13C{1H} NMR, IR, and UV), elemental analysis as well as by single crystal X-ray crystallography. In the solid state, the molecule exists as the thioamide tautomer and features an anti-disposition of the thioamide–N–H atoms; an intramolecular N–H⋯N hydrogen bond is noted. The molecular conformation resembles that of the letter L. In the molecular packing, thioamide-N1–H⋯S1(thione) hydrogen bonds lead to centrosymmetric eight-membered {⋯HNCS}2 synthons. The dimers are assembled into a supramolecular layer in the bc-plane by phenyl- and methyl-C–H⋯π(phenyl) interactions.

Phenomena of the Mechanical Deformation of Rubber

1931 ◽  
Vol 4 (1) ◽  
pp. 54-63
Author(s):  
H. Mark ◽  
E. Valko
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Mechanical Deformation ◽  
The Other ◽  
Considerable Progress ◽  
Organic Substances ◽  
Normal Position ◽  
Regular Lattice ◽  
Other Hand ◽  
Crystalline System

Abstract It is only during recent years that it has become possible by the use of new technic to detect molecular phenomena produced in the mechanical deformation of substances. As far as metallic substances are concerned, and crystalline substances in particular, the problem has already been solved for the most part. On the other hand, in spite of considerable progress during recent years the study of the deformation of organic substances and of fibers in particular, in which group rubber is included, has not yet been carried on. The mechanical properties of a crystalline system vary according to whether there is a single crystal or an aggregate of crystals. However, in both cases the extensibility of the products originates in a displacement of parallel layers, i. e., a sliding of the parts of the crystal along definite crystalline planes, this phenomenon of sliding being irreversible in these substances. In fact, in these cases the reversible part of the elongation is very weak, and amounts to only a few thousandths of the entire phenomenon. In brief, the phenomena of hardening brought about by deformation (sometimes observable) are due to disturbances of the regular lattice. In particular, the displacement of the atom and the change from its normal position can cause the appearance of irregularities on the surface of sliding.

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