The Temperature-Dependent Hydrogen-Bonding Signature of Lipids Monitored in the Far-Infrared Domain

ChemPhysChem ◽  
2010 ◽  
Vol 11 (2) ◽  
pp. 435-441 ◽  
Author(s):  
Ruth Hielscher ◽  
Petra Hellwig
Keyword(s):  
Hydrogen Bonding ◽  
Far Infrared ◽  
Temperature Dependent

scholarly journals Temperature-Dependent Solid-State NMR Proton Chemical-Shift Values and Hydrogen Bonding

2021 ◽  
Author(s):  
Alexander A. Malär ◽  
Laura A. Völker ◽  
Riccardo Cadalbert ◽  
Lauriane Lecoq ◽  
Matthias Ernst ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hydrogen Bonding ◽  
Solid State ◽  
Chemical Shift ◽  
Hydrogen Bonds ◽  
Solid State Nmr ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Proton Chemical Shift ◽  
Temperature Dependent

Temperature-dependent NMR experiments are often complicated by rather long magnetic-field equilibration times, for example occurring upon a change of sample temperature. We demonstrate that the fast temporal stabilization of the magnetic field can be achieved by actively stabilizing the temperature which allows to quantify the weak temperature dependence of the proton chemical shift which can be diagnostic for the presence of hydrogen bonds. Hydrogen bonding plays a central role in molecular recognition events from both fields, chemistry and biology. Their direct detection by standard structure determination techniques, such as X-ray crystallography or cryo-electron microscopy, remains challenging due to the difficulties of approaching the required resolution, on the order of 1 Å. We herein explore a spectroscopic approach using solid-state NMR to identify protons engaged in hydrogen bonds and explore the measurement of proton chemical-shift temperature coefficients. Using the examples of a phosphorylated amino acid and the protein ubiquitin, we show that fast Magic-Angle Spinning (MAS) experiments at 100 kHz yield sufficient resolution in proton-detected spectra to quantify the rather small chemical-shift changes upon temperature variations.<br>

scholarly journals Twist-Bend Nematogenic Supramolecular Dimers and Trimers Formed by Hydrogen Bonding

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 175 ◽  
Author(s):  
Rebecca Walker ◽  
Damian Pociecha ◽  
Alfonso Martinez-Felipe ◽  
John MD Storey ◽  
Ewa Gorecka ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Phase Behaviour ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Smectic C ◽  
Donor And Acceptor ◽  
Nematic Phases ◽  
Selection Of ◽  
Do So ◽  
Terminal Chain

A selection of novel non-symmetric supramolecular liquid crystal dimers and trimers formed by hydrogen-bonding have been prepared and their phase behaviour characterised by polarised optical microscopy, X-ray diffraction and temperature-dependent Fourier-transform infrared spectroscopy. We mix the bent twist-bend nematogen 4-[6-(4’-cyanobiphenyl-4-yl) hexyloxy]-benzoic acid (CB6OBA) with a series of small stilbazole-based compounds 4-[(E)-2-(n-alkoxyphenyl)ethenyl]pyridines (nOS) of varying terminal chain length (n) to obtain the CB6OBA:nOS complexes. Complexes with n ≤ 7 exhibit nematic and twist-bend nematic behaviour, followed on cooling by a smectic C phase for n = 4–7, and finally, a hexatic-type smectic X phase for n = 3–7. Mixtures with n = 8–10 exhibit a smectic A phase below the conventional nematic phase, and on further cooling, a biaxial smectic Ab phase and the same hexatic-type SmX phase. Supramolecular trimers, CB6OBA:CB6OS and CB6OBA:1OB6OS, formed between CB6OBA and dimeric stilbazoles [(E)-2-(4-{[6-(4’-methoxy[1,1’-biphenyl]-4-yl)hexyl]oxy}phenyl)ethenyl]pyridine (1OB6OS) or 4-[(E)-4’-(6-{4-[(E)-2-(pyridin-4-yl)ethenyl]phenoxy}hexyl)[1,1’-biphenyl]-4- carbonitrile (CB6OS), exhibit nematic and twist-bend nematic phases, and are the first hydrogen-bonded trimers consisting of unlike donor and acceptor fragments to do so.

Hydrogen bonding in the gas phase: the thermodynamic properties of hydrogen fluoride-ether complexes and their far infrared spectra

1971 ◽  
Vol 322 (1548) ◽  
pp. 137-146 ◽  
Keyword(s):  
Hydrogen Bonding ◽  
Gas Phase ◽  
Infrared Spectra ◽  
Equilibrium Constants ◽  
Far Infrared ◽  
Methyl Ethyl ◽  
Rotational Contour ◽  
Stretching Vibration ◽  
Conformational Rearrangements ◽  
Far Infrared Spectra

The equilibrium constants of gas-phase complexes of HF with dimethyl, methyl ethyl and diethyl ether have been measured at several temperatures using the Benesi-Hildebrand approximation on the absorption band of the HF stretching vibration in the complex. From these, values of Δ H of — 43, — 38 and — 30 kJ mol -1 respectively, have been determined. They are interpreted in terms of conformational rearrangements of the ethers when they form hydrogen bonds. The far infrared spectra of the complexes with both HF and DF have also been recorded and in each case a band observed at around 180 cm -1 which is assigned to the intermolecular stretching mode of vibration. For the complex between HF and dimethyl ether a rotational contour has been observed at about 10 cm -1 .

scholarly journals Supramolecular Dimerization in a Polymer Melt from Small-Angle X-ray Scattering and Rheology: A Miscible Model System

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 880
Author(s):  
Mariapaola Staropoli ◽  
Margarita Kruteva ◽  
Jürgen Allgaier ◽  
Andreas Wischnewski ◽  
Wim Pyckhout-Hintzen
Keyword(s):  
Hydrogen Bonding ◽  
Small Angle ◽  
Full Range ◽  
Polymer Melt ◽  
Self Healing ◽  
Temperature Dependent ◽  
Base Pairs ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

We present a structural and dynamic study on the simplest supramolecular hetero-association, recently investigated by the authors to prepare architectural homogeneous structures in the melt state, based on the bio-inspired hydrogen-bonding of thymine/diaminotriazine (thy–DAT) base-pairs. In the combination with an amorphous low Tg poly(butylene oxide) (PBO), no micellar structures are formed, which is expected for nonpolar polymers because of noncompatibility with the highly polar supramolecular groups. Instead, a clear polymer-like transient architecture is retrieved. This makes the heterocomplementary thy–DAT association an ideal candidate for further exploitation of the hydrogen-bonding ability in the bulk for self-healing purposes, damage management in rubbers or even the development of easily processable branched polymers with built-in plasticizer. In the present work, we investigate the temperature range from Tg + 20 °C to Tg + 150 °C of an oligomeric PBO using small-angle X-ray scattering (SAXS) and linear rheology on the pure thy and pure DAT monofunctionals and on an equimolar mixture of thy/DAT oligomers. The linear rheology performed at low temperature is found to correspond to fully closed-state dimeric configurations. At intermediate temperatures, SAXS probes the equilibrium between open and closed states of the thy–DAT mixtures. The temperature-dependent association constant in the full range between open and closed H-bonds and an enhancement of the monomeric friction coefficient due to the groups is obtained. The thy–DAT association in the melt is more stable than the DAT–DAT, whereas the thy–thy association seems to involve additional long-lived interactions.

scholarly journals The infrared spectra of protic ionic liquids: performances of different computational models to predict hydrogen bonds and conformer evolution

2020 ◽  
Vol 22 (14) ◽  
pp. 7497-7506 ◽  
Author(s):  
O. Palumbo ◽  
A. Cimini ◽  
F. Trequattrini ◽  
J.-B. Brubach ◽  
P. Roy ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Ionic Liquids ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Infrared Spectra ◽  
Computational Models ◽  
Far Infrared ◽  
Protic Ionic Liquids ◽  
Far Infrared Spectra

DFT calculations with the ωB97-D functional reproduce hydrogen bonding features of the far-infrared spectra of diethylmethylammonium methanesulfonate and diethylmethylammonium trifluoromethanesulfonate.

scholarly journals Temperature-dependent far-infrared reflectance of an epitaxial (BaTiO3)8/(SrTiO3)4 superlattice

2017 ◽  
Vol 95 (21) ◽  
Author(s):  
V. Železný ◽  
O. Caha ◽  
A. Soukiassian ◽  
D. G. Schlom ◽  
X. X. Xi
Keyword(s):  
Far Infrared ◽  
Infrared Reflectance ◽  
Temperature Dependent

Far-infrared investigations and hydrogen bonding of pyridine N-oxides

1973 ◽  
Vol 29 (6) ◽  
pp. 1207-1211 ◽  
Author(s):  
S. Ghersetti ◽  
S. Giorgianni ◽  
P.L. Capucci ◽  
G. Spunta
Keyword(s):  
Hydrogen Bonding ◽  
Far Infrared

Adsorption, desorption, and activity of glucose oxidase on selected clay species

1976 ◽  
Vol 22 (5) ◽  
pp. 684-693 ◽  
Author(s):  
H. W. Morgan ◽  
C. T. Corke
Keyword(s):  
Hydrogen Bonding ◽  
Protein Structure ◽  
Cation Exchange ◽  
Glucose Oxidase ◽  
Isoelectric Point ◽  
Active Form ◽  
Temperature Dependent ◽  
Specific Activities ◽  
Ph Dependent ◽  
Adsorption Desorption

The adsorption of the enzyme glucose oxidase (EC 1.1.3.4) to clays followed the pattern described for other proteins as being pH dependent. Maximum adsorption occurred at or below the isoelectric point of the enzyme. The amount of enzyme adsorbed to clay was influenced by the type of clay used, and also the saturating cations. Initially adsorbed enzyme showed low specific activities, and as amounts of enzyme adsorbed approached maximum saturation of clay, specific activities increased approaching that determined for free enzyme.The adsorption of glucose oxidase involved a temperature-independent cation-exchange mechanism, and enzyme adsorbed to surfaces of clay could be desorbed in active form by elevation of pH of suspending solution. This was followed by a slower temperature-dependent fixation, probably by hydrogen bonding, which resulted in protein being irreversibly adsorbed to clay surfaces.It is proposed that on adsorption of glucose oxidase to clay surfaces unravelling of the protein structure occurred, which allowed penetration of protein into the interlamellar spaces of montmorillonite. This proposal was based on the observed expansion of montmorillonite to 23 Å, and the decreases in amount of a second-protein lysozyme adsorbed with extended incubation times of glucose oxidase – clay complexes at pH 4.5.

Far infrared spectroscopy of hydrogen bonding collective motions in complex molecular systems

2017 ◽  
Vol 53 (60) ◽  
pp. 8389-8399 ◽  
Author(s):  
Youssef El Khoury ◽  
Petra Hellwig
Keyword(s):  
Hydrogen Bonding ◽  
Infrared Spectroscopy ◽  
Far Infrared ◽  
Molecular Structures ◽  
Intramolecular Interactions ◽  
Far Infrared Spectroscopy ◽  
Molecular Systems ◽  
Collective Motions

Far infrared spectroscopy as a tool for the study of inter and intramolecular interactions in complex molecular structures.

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