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.

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 IR-spectroscopy of hydrogen bonding in wood: Picea abies.

2017 ◽  
Author(s):  
В.И. Иванов-Омский ◽  
С.М. Герасюта ◽  
Е.И. Иванова
Keyword(s):  
Hydrogen Bonds ◽  
Picea Abies ◽  
Low Frequency ◽  
Temperature Stability ◽  
Experimental Spectrum ◽  
Hydroxyl Groups ◽  
Absorption Bands ◽  
Oh Groups ◽  
Adult Trees ◽  
Before And After

Исследованы ИК-спектры древесины ели обыкновенной в области поглощения валентными колебаниями гидроксильных групп. Изучались как образцы естественной влажности, так и подвергнутые отжигу при 105 °С. Образцы для исследований отбирались из взрослого дерева ели обыкновенной (Picea abies) на высоте 2,5–3 м (возраст в районе спилов 25–30 лет). Из безcучковой зоны вырезались образцы в виде кубиков размером 3×3×3 см3, из которых непосредственно перед записью спектра изготовлялось пять тангенциальных микротомных срезов толщиной 80–100 мкм. Спектральный анализ проводился с помощью ИК-Фурье спектрометра ФСМ-1201 с разрешением 4 см–1. Показано, что реальная микроструктура ели не препятствует разделению рассеянного и поглощаемого излучений. Для характеристики длин и энергий водородных связей использованы известные корреляционные соотношения частот поглощения гидроксильными группами, охваченными водородными связями, с их длиной и энергией. C этой целью экспериментальный спектр в области поглощения ОН-группами аппроксимируется гауссовыми контурами, каждый из которых ассоциируется с определенной разновидностью Н-связи. Сдвиги частот подгоночных контуров относительно частоты ОН-группы, не охваченной Н-связью, использованы для оценки энергий и длин связей, а соотношение их площадей – для оценки их концентраций. Показано, что при термическом отжиге происходит выжигание низкочастотного крыла полосы поглощения ОН-групп. Приводится диаграмма распределения Н-связей по концентрациям до отжига и после. Показано, что при отжиге число наиболее сильных связей незначительно уменьшается, но их энергия уменьшается заметно. Судя по величине частоты эти полосы поглощения относятся к межмолекулярным связям, и уменьшение их энергии означает, что отжиг затрагивает в первую очередь именно эти связи. Самые слабые исчезают совсем. Детальное исследование этого явления позволит обосновать выбор предельных температур тепловой обработки древесины, не нарушающих ее механических свойств. Отмечается более высокая температурная стабильность внутримолекулярных связей с энергией ≈10 кДж/моль. Investigated the IR spectra of spruce wood in the area of absorption of the stretching vibrations of hydroxyl groups. Been studied, as samples with natural moisture, and subjected to annealing at S. Samples for research were collected from adult trees of Norway spruce (Picea abies) at a height of 2.5–3.0 m (age in the area of cut 25–30 years). From cleared areas were cut samples in the form of cubes of size 3×3×3 cm3, of which just before recording the spectrum produced 5 tangential microtome sections with a thickness of 80–100 nm. Spectral analysis was performed using IR-Fourier spectrometer FSM-1201 with a resolution of 4 cm–1. Shows that the real microstructure of spruce does not prevent the separation of scattered and absorbed radiation. For the characteristic lengths and energies of hydrogen bonds used are known from the literature correlation of the ratio between the frequency of absorption of hydroxyl groups covered by hydrogen bonds with their length and energy. To this end, the experimental spectrum in the region of absorption of OH-groups approximated by a Gaussian contours, each of which is associated with a certain kind of H-bonds. The frequency shifts fitting contours of the relative frequency of OH-groups not covered by the H-bond, is used to evaluate energies and bond lengths, and the ratio of their squares to estimate their concentrations. It is shown that under thermal annealing is burning low frequency wing of the absorption bands of OH-groups. A diagram of the distribution of H-bonds energy on concentrations presented before and after annealing. It is shown that annealing the strongest bonds is slightly decreasing, but their energy decreases significantly. The weakest disappear altogether. A detailed study of this phenomenon will allow us to justify the choice of limiting the temperature of the heat treatment of wood that do not violate its mechanical properties. Noteworthy higher temperature stability of intramolecular bonds with energies of ≈10 kJ/mol.

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.

Redshift or Adduct Stabilization—A Computational Study of Hydrogen Bonding in Adducts of Protonated Carboxylic Acids

2009 ◽  
Vol 15 (2) ◽  
pp. 239-248 ◽  
Author(s):  
Solveig Gaarn Olesen ◽  
Steen Hammerum
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Bond Strength ◽  
Bond Length ◽  
Carboxylic Acids ◽  
Computational Study ◽  
Proton Affinities ◽  
Oh Groups ◽  
Hydrogen Bond Strength ◽  
Length Changes

It is generally expected that the hydrogen bond strength in a D–H•••A adduct is predicted by the difference between the proton affinities (Δ PA) of D and A, measured by the adduct stabilization, and demonstrated by the infrared (IR) redshift of the D–H bond stretching vibrational frequency. These criteria do not always yield consistent predictions, as illustrated by the hydrogen bonds formed by the E and Z OH groups of protonated carboxylic acids. The Δ PA and the stabilization of a series of hydrogen bonded adducts indicate that the E OH group forms the stronger hydrogen bonds, whereas the bond length changes and the redshift favor the Z OH group, matching the results of NBO and AIM calculations. This reflects that the thermochemistry of adduct formation is not a good measure of the hydrogen bond strength in charged adducts, and that the ionic interactions in the E and Z adducts of protonated carboxylic acids are different. The OH bond length and IR redshift afford the better measure of hydrogen bond strength.

Proton spin–spin coupling constants and intramolecular hydrogen bonding in bromine derivatives of 1,3-dihydroxybenzene

1976 ◽  
Vol 54 (14) ◽  
pp. 2228-2230 ◽  
Author(s):  
Ted Schaefer ◽  
J. Brian Rowbotham
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Proton Spin ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Derivatives Of

The conformational preferences in CCl4 solution at 32 °C of the hydroxyl groups in bromine derivatives of 1,3-dihydroxybenzene are deduced from the long-range spin–spin coupling constants between hydroxyl protons and ring protons over five bonds. Two hydroxyl groups hydrogen bond to the same bromine substituent in 2-bromo-1,3-dihydroxybenzene but prefer to hydrogen bond to different bromine substituents when available, as in 2,4-dibromo-1,3-dihydroxybenzene. When the OH groups can each choose between two ortho bromine atoms, as in 2,4,6-tribromoresorcinol, they apparently do so in a very nearly statistical manner except that they avoid hydrogen bonding to the common bromine atom.

scholarly journals Synthesis and biotical activity of bacterial cellulose 6-(2-phthalimidoethanesulfonate)

2020 ◽  
Vol 61 (2) ◽  
pp. 29-36
Author(s):  
Zoya P. Belousova ◽  
Keyword(s):  
Bacterial Cellulose ◽  
Side Reaction ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Cellulose Derivatives ◽  
Wound Surface ◽  
Reaction Products ◽  
Absorption Bands ◽  
Hydroxymethyl Group ◽  
Antibacterial And Antifungal

Bacterial cellulose obtained by culturing Gluconacetobacter sucrofermentans in HS environment was converted to sulfonate derivatives using methane-, toluene- and 2-phthalimidoethanesulfonic acids in pyridine. When the ratio of the starting reagents is 1 : 1, the modification of bacterial cellulose according to the primary hydroxyl group of glucopyranose fragments is most likely. The formation of 6-substituted bacterial cellulose derivatives was observed in the reaction mixture. The IR spectra of the reaction products contain absorption bands, which are specific for (O–SO2) group in the region 1377-1338 cm−1 (as), 1178-1154 cm−1 (s), fragments of the corresponding sulfonic acids, as well as free hydroxyl groups of glucopyranose in the region 3495-3382 cm−1. Bacterial cellulose 2-phthalimidoethanesulfonate was dissolved in pyridine. After drying with a desiccant in a desiccator, it turned into a dense transparent film of brown color. The increased molecular film allows to explain the side reaction occurring between the oxo group and fragments of one of the chains of modified cellulose and the non-substituted hydroxymethyl group. The IR spectrum of bacterial cellulose 6-(2-phthalimidoethanesulfonate) contains absorption bands in the region 1711 cm−1, which are specific for (Ar–CO–O) group, and absorption bands in the region 1618 cm−1, which prove the presence of (CO–NH) group. In order to impart antibiotic properties to the bacterial cellulose 6-(2-phthalimido-ethanesulfonate) film, it was physically modified with clotrimazole. The obtained experimental data showed that the films subjected to treatment with a 1% solution of clotrimazole have antibacterial and antifungal effects and prevent the growth of pathogenic microbiota on the wound surface. The exit rates of clotrimazole from the bacterial cellulose 6-(2-phthalimidoethanesulfonate) film and from the pure bacterial cellulose film differed, but only slightly. 2-Phthalimidoethanesulfonate bacterial cellulose films can be used to form composites of effective wound covering, since in addition to the unique properties of bacterial cellulose itself (low allergenicity and adhesion to the wound surface, high hygroscopicity) they will have a regenerating effect.

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.

scholarly journals Hydroxyl-Group Identification Using O K-Edge XAFS in Porous Glass Fabricated by Hydrothermal Reaction and Low-Temperature Foaming

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3488 ◽  
Author(s):  
Masanori Suzuki ◽  
Shigehiro Maruyama ◽  
Norimasa Umesaki ◽  
Toshihiro Tanaka
Keyword(s):  
Low Temperature ◽  
Surface Area ◽  
Porous Glass ◽  
Hydrothermal Reaction ◽  
Group Identification ◽  
Fluorescence Yield ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Xafs Spectroscopy

Porous glass was prepared by the hydrothermal reaction of sodium borosilicate glass, and oxygen-ion characterization was used to identify the hydroxyl groups in its surface area. A substantial amount of “water” was introduced into the ionic structure as either OH− groups or H2O molecules through the hydrothermal reaction. When the hydrothermally treated glass was reheated at normal pressures, a porous structure was formed due to the low-temperature foaming resulting from the evaporation of H2O molecules and softening of the glass. Although it was expected that the OH− groups would remain in the porous glass, their distribution required clarification. Oxygen K-edge X-ray absorption fine structure (XAFS) spectroscopy enables the bonding states of oxygen ions in the surface area and interior to be characterized using the electron yield (EY) and fluorescence yield (FY) mode, respectively. The presence of OH− groups was detected in the O K-edge XAFS spectrum of the porous glass prepared by hydrothermal reaction with a corresponding pre-edge peak energy of 533.1 eV. In addition, comparison of the XAFS spectra obtained in the EY and FY modes revealed that the OH− groups were mainly distributed in the surface area (depths of several tens of nanometers).

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.

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