Spin Relaxation and Chemical Exchange in NMR Simulations

Cuperlovic, Miroslava; Meresi, Ghirmai; Palke, William E.; Gerig, J. T.

doi:10.1006/jmre.1999.1812

Cited by 15 publications

(13 citation statements)

References 26 publications

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“…In Table 5, calculated (BPW91/COSMO/6-31G*) frequencies for the amide I, carboxyl group CdO stretching, and NH 2 /NH 3 hydrogen scissoring modes are compared to experiment. The experimental frequency of the CdO stretching in the CO 2 H group in cation AA + is by about 100 cm -1 bigger than that for CO 2 -in AA +-and AA -, which could be reproduced by the calculation. The frequency of amide I is seen at 1685 cm -1 for AA + , above that of zwitterion (at 1677 cm -1 ) and anion (1638 cm -1 ).…”

Section: Geometrysupporting

confidence: 57%

“…For example, due to the intrinsic fast response of the optical spectroscopy, the ROA spectrum is a sum of contributions from individual conformers, while the additivity is often lost in NMR due to the relaxation processes. 2 On the other hand, interpretations of ROA are dependent on extensive computer simulations, which restricts interpretation of the spectra for big molecules. [3][4][5][6] Typically, these quantum mechanical computations have been restricted to rigid molecules in a vacuum, because of computer time and memory limits.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of the Raman Optical Activity of l-Alanyl−l-Alanine

2001

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Raman and Raman optical activity (ROA) spectra of zwitterionic dipeptide L-alanyl-L-alanine (AA) were measured and compared to previous experiments and ab initio computations. The molecule does not exist in a vacuum and classical approaches of quantum mechanics cannot be directly applied. Thus, the dipolar Onsager, ionic, and conductor-like screening (COSMO) continuum solvent models were used for calculation of geometries, harmonic vibrational frequencies, and Raman intensities. Reasonable agreement was found between experiment and the spectra, enabling one to assign most of the observed experimental bands. The results suggest that bulk water significantly increases conformational flexibility of the dipeptide by lowering the energy differences among its conformers. However, detailed conformational analysis was not attempted due to the limited accuracy of the calculations. Supposedly, the nearly extended conformation of the zwitterion prevails under experimental conditions. A simplistic polar model of ROA was used in a preliminary conformer search. The model that led to significant savings in computer time was also successfully applied for monoand trialanine molecules.

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Section: Geometrysupporting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Simulation of the Raman Optical Activity of l-Alanyl−l-Alanine

2001

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“…The approach is based on the inclusion of a random exchange process in product operator calculations on a microscopic level. As compared with other simulation methods that are based on the full analysis of the system of BlochMcConnell equations [14][15][16], this alternative method has the advantage of simplicity and can be easily adapted to evaluate spin dynamics in highly complex systems. Here, it was shown that the method can be used to evaluate existing theoretical approximations and to predict exchange-induced relaxation rates when using complex pulse sequences.…”

Section: Discussionmentioning

confidence: 99%

“…Simulations of the influence of chemical exchange on different pulse sequences have been performed using numerical solutions of the system differential equations [14][15][16]. Among these methods, a preferred approach is based on homogenized Bloch-McConnell equations [16].…”

Section: Introductionmentioning

confidence: 99%

Product operator analysis of the influence of chemical exchange on relaxation rates

Idiyatullin

Michaeli

2004

Journal of Magnetic Resonance

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“…where R i,j,k contains the contributions from the pulses, the local residual quadrupolar couplings and the relaxation mechanisms (see Appendixes A and B), leading to a set of generalized Bloch equations [22,75]. …”

Section: Two-time Stimulated Echo Attenuationmentioning

confidence: 99%

Multi-Quanta Spin-Locking Nuclear Magnetic Resonance Relaxation Measurements: An Analysis of the Long-Time Dynamical Properties of Ions and Water Molecules Confined within Dense Clay Sediments

Porion

Delville

2017

Magnetochemistry

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Solid/liquid interfaces are exploited in various industrial applications because confinement strongly modifies the physico-chemical properties of bulk fluids. In that context, investigating the dynamical properties of confined fluids is crucial to identify and better understand the key factors responsible for their behavior and to optimize their structural and dynamical properties. For that purpose, we have developed multi-quanta spin-locking nuclear magnetic resonance relaxometry of quadrupolar nuclei in order to fill the gap between the time-scales accessible by classical procedures (like dielectric relaxation, inelastic and quasi-elastic neutron scattering) and obtain otherwise unattainable dynamical information. This work focuses on the use of quadrupolar nuclei (like 2 H, 7 Li and 133 Cs), because quadrupolar isotopes are the most abundant NMR probes in the periodic table. Clay sediments are the confining media selected for this study because they are ubiquitous materials implied in numerous industrial applications (ionic exchange, pollutant absorption, drilling, waste storing, cracking and heterogeneous catalysis).

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Spin Relaxation and Chemical Exchange in NMR Simulations

Cited by 15 publications

References 26 publications

Simulation of the Raman Optical Activity of l-Alanyl−l-Alanine

Simulation of the Raman Optical Activity of l-Alanyl−l-Alanine

Product operator analysis of the influence of chemical exchange on relaxation rates

Multi-Quanta Spin-Locking Nuclear Magnetic Resonance Relaxation Measurements: An Analysis of the Long-Time Dynamical Properties of Ions and Water Molecules Confined within Dense Clay Sediments

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