scholarly journals Molecular interactions in nanocellulose assembly

2017 ◽  
Vol 376 (2112) ◽  
pp. 20170047 ◽  
Author(s):  
Yoshiharu Nishiyama
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Molecular Modelling ◽  
Hydroxyl Group ◽  
Enthalpy Of Sublimation ◽  
Dispersion Force ◽  
Hydroxyl Groups ◽  
Range Interaction ◽  
Simple Arithmetic ◽  
London Dispersion

The contribution of hydrogen bonds and the London dispersion force in the cohesion of cellulose is discussed in the light of the structure, spectroscopic data, empirical molecular-modelling parameters and thermodynamics data of analogue molecules. The hydrogen bond of cellulose is mainly electrostatic, and the stabilization energy in cellulose for each hydrogen bond is estimated to be between 17 and 30 kJ mol −1 . On average, hydroxyl groups of cellulose form hydrogen bonds comparable to those of other simple alcohols. The London dispersion interaction may be estimated from empirical attraction terms in molecular modelling by simple integration over all components. Although this interaction extends to relatively large distances in colloidal systems, the short-range interaction is dominant for the cohesion of cellulose and is equivalent to a compression of 3 GPa. Trends of heat of vaporization of alkyl alcohols and alkanes suggests a stabilization by such hydroxyl group hydrogen bonding to be of the order of 24 kJ mol −1 , whereas the London dispersion force contributes about 0.41 kJ mol −1  Da −1 . The simple arithmetic sum of the energy is consistent with the experimental enthalpy of sublimation of small sugars, where the main part of the cohesive energy comes from hydrogen bonds. For cellulose, because of the reduced number of hydroxyl groups, the London dispersion force provides the main contribution to intermolecular cohesion. This article is part of a discussion meeting issue ‘New horizons for cellulose nanotechnology’.

scholarly journals Hydrogen bonding systems in birch bark

2020 ◽  
pp. 189-198
Author(s):  
Л.Л. Леонтьев ◽  
И.Д. Лобок ◽  
В.И. Иванов-Омский ◽  
А.С. Смолин
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Frequency Shift ◽  
Hydroxyl Group ◽  
Birch Bark ◽  
Hydroxyl Groups ◽  
Absorption Bands ◽  
Hydrogen Bond Energy ◽  
Absorption Region ◽  
Oh Groups

Произведено сравнение систем водородных связей во внешнем и внутреннем слоях березовой бересты, в сравнении с водородными связями в высококачественной бумаге и в образце выделенной из древесины целлюлозы. Интервал исследуемых частот от 3000 до 3700 см-1, ограничен областью поглощения гидроксильными ОН-группами, частоты которых наиболее чувствительны к возникновению Н-связей. Для оценки параметров Н-связей проводилась деконволюция полос поглощения ОН-групп гауссовыми компонентами. Для корректного выделения поглощения гидроксильными группамипервоначально деконволюции подвергается весь фрагмент, включающий в себя полосы поглощения как метиленовым, так и гидроксильными группами. В дальнейшем анализировались только параметры контуров деконволюции, относящейся к гидроксильным группам. Принималось, что каждый компонент деконволюции может быть ассоциирован с определенным типом водородной связи. Определялся сдвиг частот компонентов деконволюции относительно собственной частоты колебаний изолированной гидроксильной группы, не охваченной по этой причине водородной связью. Для определения энергии водородных связей использовались литературные данные по корреляции энергии водородной связи с частотным сдвигом. Относительная плотность водородных связей оценивалась по отношению площадей контуров деконволюции. A comparison was made of the hydrogen bond systems in the outer and inner layer of birch bark, as well as a comparison of high-quality paper with a sample of pure pulp. The range of frequencies under study from 3000 to 3700 cm-1 is limited by the absorption region by hydroxyl OH groups, the frequencies of which are most sensitive to the occurrence of H bonds. To estimate the parameters of H-bonds, the absorption bands of OH groups were deconvolved by Gaussian components. In order to correctly isolate the absorption by hydroxyl groups, the entire fragment, whichincludes absorption bands of both methylene and hydroxyl groups, is initially deconvolved. In the future, only the parameters of the deconvolution contours related to hydroxyl groups were analyzed. It was assumed that each component of deconvolution can be associated with a certain type of hydrogen bond. The frequency shift of the components of the deconvolution was determined relative to the natural frequency of vibrations of the isolated hydroxyl group, which is therefore not covered by a hydrogen bond. To determine the energy of hydrogen bonds, we used literature data on the correlation of the hydrogen bond energy with a frequency shift. The relative density of hydrogen bonds was estimated by the ratio of the area of the contours of deconvolution.

Crystal engineering using bisphenols and trisphenols. Complexes with 1,10-phenanthroline: hydrogen-bonded chains in adducts with 4,4′-biphenol (1/1) and 4,4′-sulfonyldiphenol (2/3), π–π stacked chains in the (1/2) adduct with 4,4′-thiodiphenol, and pairwise-interwoven nets in 1,1,1-tris(4-hydroxyphenyl)ethane–1,10-phenanthroline–methanol (1/1/1)

1999 ◽  
Vol 55 (4) ◽  
pp. 591-600 ◽  
Author(s):  
George Ferguson ◽  
Christopher Glidewell ◽  
Emma S. Lavender
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Crystal Engineering ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Two Dimensional ◽  
Rotation Axes ◽  
Molecular Components ◽  
Supramolecular Aggregation ◽  
Hydrogen Bonded

In 4,4′-biphenol–1,10-phenanthroline (1/1) [systematic name: 4,4′-biphenyldiol–1,10-phenanthroline (1/1)] the diphenol molecules lie across centres of inversion and the phenanthroline molecules lie across twofold rotation axes; the phenanthroline molecules act as chain-building units and the molecular components are linked into steeply zigzag C(16) chains parallel to [101] by means of O—H...N hydrogen bonds. In the structure of 4,4′-thiodiphenol–1,10-phenanthroline (1/2) the phenanthroline molecules act as chain-terminating units; the supramolecular aggregation is finite, with the bisphenol linked to each phenanthroline molecule by means of a single O—H...N hydrogen bond. π−π stacking interactions between the phenanthroline molecules in neighbouring hydrogen-bonded aggregates serve to link these aggregates into a continuous two-dimensional array. The phenanthroline molecules in 4,4′-sulfonyldiphenol–1,10-phenanthroline (2/3) play two roles: molecules in general positions act as chain-terminating units and are linked to the sulfonyldiphenol molecules by means of three-centre O—H...(N)2 hydrogen bonds, while those lying across twofold rotation axes act as chain builders and are linked to two different sulfonyldiphenol molecules by means of a two-centre O—H...N hydrogen bond in each case; the resulting U-shaped five-component aggregates are further linked by C—H...O=S hydrogen bonds into a C_3^3(17)[R_2^2(12)] `chain of rings' along [001]. In 1,1,1-tris(4-hydroxyphenyl)ethane–1,10-phenanthroline–methanol (1/1/1) [systematic name: 4,4′,4′′-ethylidynetriphenol–1,10-phenanthroline–methanol (1/1/1)] the phenanthroline molecules again act as chain-terminating units: the trisphenol molecules and the methanol molecules are linked by O—H...O hydrogen bonds into two-dimensional nets built from R_6^6(42) rings, and pairs of these nets are interwoven. The formation of each net utilizes two hydroxyl groups per trisphenol molecule as hydrogen-bond donors and the remaining hydroxyl group acts as donor to the phenanthroline molecule in a three-centre O—H...(N)2 hydrogenbond.

Crystal structure of rivastigmine hydrogen tartrate Form I (Exelon®), C14H23N2O2(C4H5O6)

2016 ◽  
Vol 31 (2) ◽  
pp. 97-103 ◽  
Author(s):  
James A. Kaduk ◽  
Kai Zhong ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Powder Diffraction ◽  
Density Functional ◽  
Carbonyl Oxygen ◽  
Strong Hydrogen Bond ◽  
Hydroxyl Groups ◽  
A Chain ◽  
Tartrate Anion

The crystal structure of rivastigmine hydrogen tartrate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Rivastigmine hydrogen tartrate crystallizes in space group P21 (#4) with a = 17.538 34(5), b = 8.326 89(2), c = 7.261 11(2) Å, β = 98.7999(2)°, V = 1047.929(4) Å3, and Z = 2. The un-ionized end of the hydrogen tartrate anions forms a very strong hydrogen bond with the ionized end of another anion to form a chain. The ammonium group of the rivastigmine cation forms a strong discrete hydrogen bond with the carbonyl oxygen atom of the un-ionized end of the tartrate anion. These hydrogen bonds form a corrugated network in the bc-plane. Both hydroxyl groups of the tartrate anion form intramolecular O–H⋯O hydrogen bonds. Several C–H⋯O hydrogen bonds appear to contribute to the crystal energy. The powder pattern is included in the Powder Diffraction File™ as entry 00-064-1501.

scholarly journals Study on the Dissolution Mechanism of Cellulose by ChCl-Based Deep Eutectic Solvents

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 278 ◽  
Author(s):  
Heng Zhang ◽  
Jinyan Lang ◽  
Ping Lan ◽  
Hongyan Yang ◽  
Junliang Lu ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Oxalic Acid ◽  
Deep Eutectic Solvents ◽  
Solvent System ◽  
Hydroxyl Group ◽  
Regenerated Cellulose ◽  
Dissolution Mechanism ◽  
Hydroxyl Groups ◽  
Type I ◽  
Hydrogen Bond Donor

Four deep eutectic solvents (DESs), namely, glycerol/chlorocholine (glycerol/ChCl), urea/ChCl, citric acid/ChCl, and oxalic acid/ChCl, were synthesized and their performance in the dissolution of cellulose was studied. The results showed that the melting point of the DESs varied with the proportion of the hydrogen bond donor material. The viscosity of the DESs changed considerably with the change in temperature; as the temperature increased, the viscosity decreased and the electrical conductivity increased. Oxalic acid/ChCl exhibited the best dissolution effects on cellulose. The microscopic morphology of cellulose was observed with a microscope. The solvent system effectively dissolved the cellulose, and the dissolution method of the oxalic acid/ChCl solvent on cellulose was preliminarily analyzed. The ChCl solvent formed new hydrogen bonds with the hydroxyl groups of the cellulose through its oxygen atom in the hydroxyl group and its nitrogen atom in the amino group. That is to say, after the deep eutectic melt formed an internal hydrogen bond, a large number of remaining ions formed a hydrogen bond with the hydroxyl groups of the cellulose, resulting in a great dissolution of the cellulose. Although the cellulose and regenerated cellulose had similar structures, the crystal form of cellulose changed from type I to type II.

1-(4-Chlorophenyl)-4-(2-furoyl)-3-(2-furyl)-1H-pyrazol-5-ol

2007 ◽  
Vol 63 (3) ◽  
pp. o1289-o1290 ◽  
Author(s):  
Jin-Zhou Li ◽  
Heng-Qiang Zhang ◽  
Hong-Xin Li ◽  
Pi-Zhi Che ◽  
Tian-Chi Wang
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Intermolecular Hydrogen Bond ◽  
Hydroxyl Groups ◽  
Intermolecular Hydrogen Bonds ◽  
Compound C ◽  
Graph Set

The crystal structure of the title compound, C18H11ClN2O4, contains intra- and intermolecular hydrogen bonds that link the ketone and hydroxyl groups. The intermolecular hydrogen bond results in the formation of a dimer with an R 2 2(12) graph-set motif.

Biomass Biodegradable Starch Material Cushioning Packaging Products and Plasticizing Properties of Compatibility

2014 ◽  
Vol 541-542 ◽  
pp. 343-348
Author(s):  
Xiu Jie Jia ◽  
Jian Feng Li ◽  
Fang Yi Li
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Infrared Spectrum ◽  
Ethylene Glycol ◽  
Environmental Protection ◽  
Spectrum Analysis ◽  
Packaging Material ◽  
Hydroxyl Group ◽  
Group Content ◽  
Electronegative Group

Biomass cushioning packaging material has been gaining attention in the properties of the materials because of biodegradable and green environmental protection, and the starch plastics play an important role. Urea, formamide, glycerol, ethylene glycol four material compounded with starch respectively, for the purpose to forming hydrogen bonds by the test in this paper, the ability to hydrogen bond with the starch has been observed by infrared spectrum analysis. The results showed that urea, formamide as strong electronegative group stronger binding, glycerol and ethylene glycol are more preferably to form hydrogen bonds with the starch because of more hydroxyl group content.

Molecular dynamics simulations of N-methylacetamide (NMA) in water by the ABEEM/MM model

2009 ◽  
Vol 87 (12) ◽  
pp. 1738-1746 ◽  
Author(s):  
Ping Qian ◽  
Li-Nan Lu ◽  
Zhong-Zhi Yang
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Potential Model ◽  
Lone Pair ◽  
Static Properties ◽  
Range Interaction ◽  
Hydrogen Bond Interaction ◽  
Lone Pair Electron ◽  
Dynamics Simulations

The N-methylacetamide (NMA) is a very interesting kind of compound and often serves as a model of the peptide bond. The interaction between NMA and water provides a convenient prototype for the solvation of peptides in aqueous solutions. We have carried out molecular dynamics (MD) simulations of a NMA molecule in water under 1 atm and 298 K. The simulations make use of the newly developed NMA–water fluctuating charge ABEEM/MM potential model ( Yang, Z. Z.; Qian, P. J. Chem. Phys. 2006, 125, 064311 ), which is based on the combination of the atom-bond electronegativity equalization method (ABEEM) and molecular mechanics (MM). This model has been successfully applied to NMA–water gas clusters, NMA(H2O)n (n = 1–6), and accurately reproduced many static properties. For the NMA–water ABEEM/MM potential model, two characters must be emphasized in the simulations. Firstly, the model allows the charges in system to fluctuate, responding to the ambient environment. Secondly, for two major types of intermolecular hydrogen bonds, which are the hydrogen bond forming between the lone-pair electron on amide oxygen and the water hydrogen, and the one forming between the lone-pair electron on water oxygen and the amide hydrogen, we take special treatments in describing the electrostatic interaction by the use of the parameters klpO=,H and klpO–,HN–, respectively, which explicitly describe the short-range interaction of hydrogen bonds in the hydrogen bond interaction region. All sorts of properties have been studied in detail, such as, radial distribution function, energy distribution, ABEEM charge distribution and dipole moment, and so on. These simulation results show that the ABEEM/MM-based NMA–water potential model appears to be robust, giving the solution properties in excellent agreement with other dynamics simulations on similar systems.

scholarly journals Two orthorhombic polymorphs of hydromorphone

2016 ◽  
Vol 72 (5) ◽  
pp. 730-733
Author(s):  
Jaroslaw Mazurek ◽  
Marcel Hoffmann ◽  
Ana Fernandez Casares ◽  
D. Phillip Cox ◽  
Mathew D. Minardi ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Cyclic Ether ◽  
Hydroxyl Group ◽  
Analgesic Drug ◽  
Orthorhombic Space Group ◽  
Methyl Amine ◽  
Polymorphic Forms ◽  
Crystalline Forms ◽  
Crystallization From Solution

Conditions to obtain two polymorphic forms by crystallization from solution were determined for the analgesic drug hydromorphone [C17H19NO3; systematic name: (4R,4aR,7aR,12bS)-9-hydroxy-3-methyl-1,2,4,4a,5,6,7a,13-octahydro-4,12-methanobenzofuro[3,2-e]isoquinolin-7-one]. These two crystalline forms, designated as I and II, belong to theP212121orthorhombic space group. In both polymorphs, the hydromorphone molecules adopt very similar conformations with some small differences observed only in theN-methyl amine part of the molecule. The crystal structures of both polymorphs feature chains of molecules connected by hydrogen bonds; however, in form I this interaction occurs between the hydroxyl group and the tertiary amine N atom whereas in form II the hydroxyl group acts as a donor of a hydrogen bond to the O atom from the cyclic ether part.

Analysis of the less common hydrogen bonds involving ester oxygen sp 3 atoms as acceptors in the crystal structures of small organic molecules

2004 ◽  
Vol 60 (4) ◽  
pp. 424-432 ◽  
Author(s):  
Krešimir Molčanov ◽  
Biserka Kojić-Prodić ◽  
Nenad Raos
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Crystal Packing ◽  
Noncovalent Interactions ◽  
Secondary Amines ◽  
Structural Function ◽  
Hydroxyl Groups ◽  
Donor Group ◽  
Acta Cryst ◽  
Bifurcated Hydrogen Bond

An analysis of hydrogen bonds involving ester Osp 3 atoms as acceptors has been performed based on the data extracted from the Cambridge Structural Database [Allen (2002). Acta Cryst. B58, 380–388; version 5.25, November 2003], using the ConQuest package to evaluate the stereochemical and electronic properties of the acceptors. Evidence for the existence of this particular type of hydrogen bond and its structural function in crystal packing is presented. Using a cut-off limit on residual indices of R < 0.05 (for the structures with hydrogen bonds involving an oxygen as part of the donor group) and R < 0.085 (for nitrogen as part of the donor group), 230 structures out of the total CSD entries of 298 100 were found to contain hydrogen bonds with the ester Osp 3 atoms as acceptors. The hydrogen-bond donors include water molecules, hydroxyl groups, primary and secondary amines and, in a few cases, imino groups. Four modes of the participation of the ester Osp 3 atoms in hydrogen bonding are detected: as a single acceptor, as a double acceptor, as a single acceptor of a H atom involved in an intermolecular bifurcated hydrogen bond, and as a shared acceptor function with the ester Osp 2 atom in a bifurcated hydrogen bond. The role of such directed noncovalent interactions in crystal packing is demonstrated by a small gallery of selected structures.

Crystal structure of antimony oxalate hydroxide, Sb(C2O4)OH

2010 ◽  
Vol 25 (1) ◽  
pp. 19-24 ◽  
Author(s):  
James A. Kaduk ◽  
Mark A. Toft ◽  
Joseph T. Golab
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Rietveld Method ◽  
Three Dimensional ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
X Ray ◽  
Oxalate Anion ◽  
Fourier Techniques ◽  
Difference Fourier

The crystal structure of Sb(C2O4)OH has been solved by charge flipping in combination with difference Fourier techniques using laboratory X-ray powder data exhibiting significant preferred orientation and refined by the Rietveld method. The compound crystallizes in Pnma with a=5.827 13(3), b=11.294 48 (10), c=6.313 77(3) Å, V=415.537(5) Å3, and Z=4. The crystal structure contains pentagonal pyramidal Sb3+ cations, which are bridged by hydroxyl groups to form zigzag chains along the a axis. Each oxalate anion chelates to two Sb in approximately the ab plane, linking the chains into a three-dimensional framework. The H of the hydroxyl group is probably disordered in order to form stronger more-linear hydrogen bonds. The highest energy occupied molecular orbitals are the Sb3+ lone pairs. The structure is chemically reasonable compared to other antimony oxalates and to Bi(C2O4)OH.

Sign in / Sign up

Export Citation Format

Share Document