Uniaxial deformation of nylon-6 and nylon-11: changes in orientation and crystal phase

1998 ◽  
Vol 76 (11) ◽  
pp. 1491-1500
Author(s):  
Sonia Moffatt ◽  
Abdellah Ajji ◽  
Bernard Lotz ◽  
Josée Brisson
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Nylon 6 ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Density ◽  
Α Phase ◽  
Draw Direction ◽  
Chain Axis ◽  
Nylon 11

The effect of uniaxial drawing on orientation of the crystalline fraction of two polymers forming hydrogen bonds, nylon-6 and nylon-11, has been investigated using X-ray diffraction. These two polymers have similar crystal phases, although their hydrogen bond density differs. For both polymers, the deformation occurs in two steps, the first being a plastic deformation of the α-phase spherulites. This leads to two popul ations of crystals, one with the chain axis oriented parallel to the draw direction, the second with the a axis (hydrogen bond direction) aligned along the draw direction. In the second step, the a-axis aligned population gradually tilts, leading to a uniaxial orientation of the samples with chain axis aligned along the draw direction. For nylon-11, the onset of this step corresponds to the emergence of crystals of the γ phase, which rapidly becomes the major phase. It reaches a higher orientation than the α phase, and stems from crystallization upon tension of the polymer. For nylon-6, although the γ phase also appears during drawing, at the maximum draw ratio only a small fraction is present. This difference is attributed to the relative stability of the two phases, which is different for nylon-6 than for nylon-11.Key words: orientation, X-ray diffraction, nylon, hydrogen bonds.

Cross Linking of Collagen by Hydrophobe Bonds

1971 ◽  
Vol 15 ◽  
pp. 527-533
Author(s):  
Edwin H. Shaw
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Collagen Fiber ◽  
Fiber Axis ◽  
Cross Linking ◽  
Methyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
Collagen Lattice ◽  
Rat Tail

Previous work on modification of the collagen lattice, presented at these meetings, has served to confirm the Ramachandran proposal for the structure of this important protein, together with information on the lengths and tensile strengths of these bonds, including hydrogen bonds, hydrophobe bonds, and Vander Waals attractions. Rat tail tendons were suspended in 2 M aqueous solutions of dimethylsulfoxide, acetone, trimethylamineoxide and 1,4-cyclohexanedione, all of which showed evidence of ligation by expansion of the collagen lattice and refinement of the 100 spot in the x-ray diffraction pattern run by rotation on the collagen fiber axis. In the case of trimethylamineoxide and cyclohexanedione, oriented crystallization also occurred, with the long direction of the molecule in the plane perpendicular to the fiber axis of collagen. With the monofunctional ligands, the -C=0 group forms a hydrogen bond to the N-H group in the Ramachandran standard revised model, leaving the methyl groups to form the hydrophobe bond.

Charge-density analysis in polymorphs of urea–barbituric acid co-crystals

2011 ◽  
Vol 67 (2) ◽  
pp. 144-154 ◽  
Author(s):  
Marlena Gryl ◽  
Anna Krawczuk-Pantula ◽  
Katarzyna Stadnicka
Keyword(s):  
Hydrogen Bond ◽  
High Resolution ◽  
Hydrogen Bonds ◽  
Charge Density ◽  
Barbituric Acid ◽  
Van Der Waals Interactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Analysis ◽  
Resolution Single

High-resolution single-crystal X-ray diffraction measurements at 100 K were performed for the two polymorphs of urea–barbituric acid co-crystals: (I) P21/c and (II) Cc. Experimental and theoretical charge density and its properties were analysed for (I) and (II) in order to confirm the previous observation that in the polymorphs studied the barbituric acid molecules adopt different mesomeric forms, leading to different hydrogen-bond systems. Koch and Popelier criteria were applied to distinguish between hydrogen bonds and van der Waals interactions in the structures presented.

Unusual hydrogen bonding inL-cysteine hydrogen fluoride

2015 ◽  
Vol 71 (8) ◽  
pp. 733-741
Author(s):  
V. S. Minkov ◽  
V. V. Ghazaryan ◽  
E. V. Boldyreva ◽  
A. M. Petrosyan
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Hydrogen Fluoride ◽  
Fluoride Ion ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Short Hydrogen Bond ◽  
Doubly Charged

L-Cysteine hydrogen fluoride, or bis(L-cysteinium) difluoride–L-cysteine–hydrogen fluoride (1/1/1), 2C3H8NO2S+·2F−·C3H7NO2S·HF or L-Cys+(L-Cys...L-Cys+)F−(F−...H—F), provides the first example of a structure with cations of the `triglycine sulfate' type,i.e.A+(A...A+) (whereAandA+are the zwitterionic and cationic states of an amino acid, respectively), without a doubly charged counter-ion. The salt crystallizes in the monoclinic system with the space groupP21. The dimeric (L-Cys...L-Cys+) cation and the dimeric (F−...H—F) anion are formedviastrong O—H...O or F—H...F hydrogen bonds, respectively, with very short O...O [2.4438 (19) Å] and F...F distances [2.2676 (17) Å]. The F...F distance is significantly shorter than in solid hydrogen fluoride. Additionally, there is another very short hydrogen bond, of O—H...F type, formed by a L-cysteinium cation and a fluoride ion. The corresponding O...F distance of 2.3412 (19) Å seems to be the shortest among O—H...F and F—H...O hydrogen bonds known to date. The single-crystal X-ray diffraction study was complemented by IR spectroscopy. Of special interest was the spectral region of vibrations related to the above-mentioned hydrogen bonds.

The whole range of hydrogen bonds in one crystal structure: neutron diffraction and charge-density studies of N,N-dimethylbiguanidinium bis(hydrogensquarate)

2011 ◽  
Vol 67 (6) ◽  
pp. 552-559 ◽  
Author(s):  
Mihaela-Diana Şerb ◽  
Ruimin Wang ◽  
Martin Meven ◽  
Ulli Englert
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
High Resolution ◽  
Hydrogen Bonds ◽  
Neutron Diffraction ◽  
Electron Density ◽  
Organic Salt ◽  
X Ray Diffraction ◽  
Covalent Character ◽  
X Ray

N,N-Dimethylbiguanidinium bis(hydrogensquarate) features an impressive range of hydrogen bonds within the same crystal structure: neighbouring anions aggregate to a dianionic pair through two strong O—H...O interactions; one of these can be classified among the shortest hydrogen bonds ever studied. Cations and anions in this organic salt further interact via conventional N—H...O and nonclassical C—H...O contacts to an extended structure. As all these interactions occur in the same sample, the title compound is particularly suitable to monitor even subtle trends in hydrogen bonds. Neutron and high-resolution X-ray diffraction experiments have enabled us to determine the electron density precisely and to address its properties with an emphasis on the nature of the X—H...O interactions. Sensitive criteria such as the Laplacian of the electron density and energy densities in the bond-critical points reveal the incipient covalent character of the shortest O—H...O bond. These findings are in agreement with the precise geometry from neutron diffraction: the shortest hydrogen bond is also significantly more symmetric than the longer interactions.

scholarly journals (3-Ammonio-2,2-dimethyl-propyl)carbamate Dihydrate

Molbank ◽  
10.3390/m1015 ◽  
2018 ◽  
Vol 2018 (3) ◽  
pp. M1015
Author(s):  
Jaqueline Heimgert ◽  
Dennis Neumann ◽  
Guido Reiss
Keyword(s):  
Hydrogen Bond ◽  
Raman Spectroscopy ◽  
Acetic Acid ◽  
Hydrogen Bonds ◽  
Chain Structure ◽  
X Ray Diffraction ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
Title Molecule ◽  
Intramolecular Hydrogen

(3-Ammonio-2,2-dimethylpropyl)carbamate dihydrate was synthesised. The title compound was characterised by single crystal X-ray diffraction and IR-/Raman-spectroscopy. It has been demonstrated that a mixture of dilute acetic acid and 2,2-dimethyl-1,3-diaminopropane is able to capture CO2 spontaneously from the atmosphere. An intramolecular hydrogen bond stabilises the conformation of the ylide-type title molecule. Intermolecular hydrogen bonds between all moieties connect them to a strand-type chain structure.

Structure in “Amorphous Regions”, Accessible Segments of Fibrils, of the Cotton Fiber

1988 ◽  
Vol 58 (2) ◽  
pp. 96-101 ◽  
Author(s):  
Stanley P. Rowland ◽  
Phyllis S. Howley
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Cotton Fiber ◽  
Cotton Fibers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chemical Studies

The extent of hydrogen bonding of O(3)H and O(6)H in “amorphous” regions, more specifically in accessible segments of fibrils, of the cotton fiber varied from near perfection to almost complete disorder in samples under examination. Perfection of hydrogen bonding in various samples and segments of cotton fibers decreased with decreasing crystallinity of the cellulose within the fibrils. For the most part, extents of O(3)H hydrogen bonding and O(6)H hydrogen bonding followed similar patterns with substantial differences in degrees of perfection, the O(3)H ranging from about 95% hydrogen bonding down to 8% and the O(6)H) from 92% down to 41%. Details of hydrogen bonds assessed in these chemical studies are discussed relative to crystallinities and assignments of hydrogen bond structures from x-ray diffraction studies.

scholarly journals Hydrogen Bonds in Bis(1H-benzimidazole-κN3)cadmium(II) Dibenzoate: Hirshfeld Surface Analysis and AIM Perspective

2021 ◽  
Vol 68 (1) ◽  
pp. 239-246
Author(s):  
Jia-Jun Wang ◽  
Li-Nan Dun ◽  
Bao-Sheng Zhang ◽  
Zhong-Hui Wang ◽  
He Wang ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Closed Shell ◽  
Hirshfeld Surface ◽  
X Ray Diffraction ◽  
Single Crystal Diffraction ◽  
Aim Analysis ◽  
X Ray ◽  
Hirshfeld Analysis ◽  
Diffraction Structure

The coordination complex bis(1H-benzimidazole-κN3)cadmium(II) dibenzoate has been synthesized and characterized by single crystal diffraction analysis. Cadmium center is six coordinated and formed a distorted octahedron coordinated geometry. The Hirshfeld analysis shows that in the dnorm-surface of the compound, there are dark red spots near the hydrogen-bonds acceptor and donor atoms, while intermolecular interactions result in faint-red spots. The AIM analysis was performed, there exist a BCP in each N(C)–H∙∙∙O hydrogen bond, the bond paths also can be seen, the |V(b)|/G(b) < 1 and the H(b) > 0, the interaction is indicative of being a closed shell. The TG results are consistent with the X-ray diffraction structure.

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.

Properties of a strong intramolecular OHO hydrogen bond in 2-(N,N-diethylamino-N-oxymethyl)-4,6-dichlorophenol

1986 ◽  
Vol 64 (9) ◽  
pp. 1850-1854 ◽  
Author(s):  
A. Koll ◽  
M. Rospenk ◽  
L. Sobczyk ◽  
T. Glowiak
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Diffraction Study ◽  
Mannich Base ◽  
Direct Method ◽  
Uv Spectra ◽  
X Ray Diffraction ◽  
Intramolecular Hydrogen Bonds ◽  
X Ray ◽  
Intramolecular Hydrogen

The crystals of 2-(N,N-diethylamino-N-oxymethyl)-4,6-dichlorophenol chosen as a representative of the Mannich base N-oxides were found to be monoclinic, P21/c space group, with a = 11.729(3), b = 16.232(4), c = 13.689(3) Å, β = 107.37(3)°, and Z = 8. The structure solved by the direct method was refined to R = 0.033 for 3170 independent reflections. Two slightly different molecules denoted as A and B in the unit cell with very short (2.42 and 2.40 Å) OHO intramolecular hydrogen bonds were detected. Both a X-ray diffraction study and the ir and uv spectra indicate a symmetric type of bridge in this compound.

Synthesis and Structural Characterization of Diisopropylammonium Trifluoroacetate and Diisoproplyammonium Pentafluoropropionate

2010 ◽  
Vol 65 (4) ◽  
pp. 479-484 ◽  
Author(s):  
Guido J. Reiß ◽  
Michaela K. Meyer
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Van Der Waals Interactions ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Donor Acceptor ◽  
Double Hydrogen

Diisopropylammonium trifluoroacetate ({[iPr2NH2][CF3COO]}; dip tfa; 1) and diisopropylammonium pentafluoropropionate ({[iPr2NH2][C2F5COO]}; dip pfp; 2) have been synthesized and structurally characterized by X-ray diffraction and spectroscopic methods. Both compounds form hydrogen-bonded cyclic dimers (Etter symbol: R44 (12)) in the solid state. The asymmetric unit of 1 contains one trifluoroacetate anion and one dip cation in the centrosymmetric space group Pī. The asymmetric unit of 2 consists of two crystallographically independent pentafluoropropionate anions and two independent dip cations forming dimers in the form of rings, both lying around centers of symmetry in the space group Pī. In dip tfa and dip pfp the cations act as double hydrogen bond donors, and each of the two oxygen atoms of the carboxyl group are single hydrogen bond acceptors. The donor acceptor distances of the N-H...O hydrogen bonds are within the expected range for medium strong hydrogen bonds. The quasi-molecular cyclic dimers are connected with neighboring units only by van der Waals interactions.

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