Intermolecular cross-relaxation rates between solute and solvent were measured by {1H} 19F nuclear magnetic resonance experiments in aqueous molecular solutions of ammonium perfluoro-octanoate and sodium trifluoroacetate. The experiments performed at three different magnetic fields provide frequency-dependent cross-relaxation rates which demonstrate clearly the lack of extreme narrowing for nuclear spin relaxation by diffusionally modulated intermolecular interactions. Supplemented by suitable intramolecular cross-relaxation, longitudinal relaxation, and self-diffusion data, the obtained cross-relaxation rates are evaluated within the framework of recent relaxation models and provide information about the hydrophobic hydration. In particular, water dynamics around the trifluoromethyl group in ammonium perfluoro-octanoate are more retarded than that in the smaller trifluoroacetate.
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http://dx.doi.org/10.1063/1.2336199 | DOI Listing |
Biophys Chem
September 2024
School of Chemistry, University of Hyderabad, Hyderabad 50046, India. Electronic address:
H-H nuclear cross-relaxation experiments have been carried out with lysozyme in variable glycerol viscosity to study intramolecular motion, self-diffusion, and isotropic rigid-body rotational tumbling at 298 K, pH 3.8. Dynamics of intramolecular H-H cross-relaxation rates, the increase in internuclear spatial distances, and lateral and rotational diffusion coefficients all show fractional viscosity dependence with a power law exponent κ in the 0.
View Article and Find Full Text PDFNumerical simulations of -doped aluminosilicate fiber lasers for yellow light emission are presented. The → laser transition emitting at approximately 580 nm has been developed experimentally with 445 nm diode pumping and shows promise for higher output power in both silicate and in particular fluoride glass hosts. In this report, we focus on accumulating the published spectroscopic data in order to quantify cross relaxation (CR) in each of these hosts and use it to estimate its role in the laser dynamics.
View Article and Find Full Text PDFJ Phys Chem B
November 2023
NMR, Centre for Analysis, Testing, Evaluation & Reporting Services (CATERS), CSIR-Central Leather Research Institute, Chennai 600020, India.
For the design of an efficient drug delivery system utilizing an ionic liquid (IL) as a carrier, it is prudent to gain molecular/atomistic level insights of a drug with IL in terms of binding and dynamics. In this scenario, the influence of anionic counterpart of imidazolium-based ILs, namely, 1-butyl-3-methyl-imidazolium octyl sulfate [BMIM][OSU] and 1-butyl-3-methyl-imidazolium chloride [BMIM][Cl] in their submicellar region ([IL] = 20 mM) on the model water-soluble anticancer drug doxorubicin hydrochloride (DOX) was probed by employing an arsenal of nuclear magnetic resonance (NMR) approaches. The salient feature of the present study includes the significant interaction of DOX with [BMIM][OSU], whereas the lack of such an interaction with [BMIM][Cl] is gauged by H NMR translation self-diffusometry and is further corroborated by C chemical shift perturbation.
View Article and Find Full Text PDFJ Magn Reson
October 2023
Laboratoire des Biomolécules, LBM, Département de chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 24 rue Lhomond, 75005 Paris, France. Electronic address:
Relaxometry consists in measuring relaxation rates over orders of magnitude of magnetic fields to probe motions of complex systems. High-resolution relaxometry (HRR) experiments can be performed on conventional high-field NMR magnets equipped with a sample shuttle. During the experiment, the sample shuttle transfers the sample between the high-field magnetic center and a chosen position in the stray field for relaxation during a variable delay, thus using the stray field as a variable field.
View Article and Find Full Text PDFChemphyschem
August 2023
Institute of Chemistry, University of Rostock, Albert-Einstein-Str. 27, 18059, Rostock, Germany.
Methods which induce site-specificity and sensitivity enhancement in solid-state magic-angle spinning NMR spectroscopy become more important for structural biology due to the increasing size of molecules under investigation. Recently, several strategies have been developed to increase site specificity and thus reduce signal overlap. Under dynamic nuclear polarization (DNP) for NMR signal enhancement, it is possible to use cross-relaxation transfer induced by select dynamic groups within the molecules which is exploited by SCREAM-DNP (Specific Cross Relaxation Enhancement by Active Motions under DNP).
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