Aqueous Phase Behavior of Tetraethylene Glycol Decanoyl Ester (C9COE4) and Ether (C10E4) Investigated by Nuclear Magnetic Resonance Spectroscopic Techniques

Langmuir ◽  
2007 ◽  
Vol 23 (23) ◽  
pp. 11443-11450 ◽  
Author(s):  
Anne-Gaëlle Fournial ◽  
Ying Zhu ◽  
Valérie Molinier ◽  
Gaston Vermeersch ◽  
Jean-Marie Aubry ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Phase Behavior ◽  
Aqueous Phase ◽  
Tetraethylene Glycol ◽  
Spectroscopic Techniques ◽  
Nuclear Magnetic

Uses of Nuclear Magnetic Resonance Spectroscopy Technique in Pharmaceutical Analysis: A Review

2017 ◽  
Vol 8 (02) ◽  
Author(s):  
Imad Hadi Zohra ◽  
Abeer Fauzi Al-Rubaye ◽  
Mohanad Jawad Kadhim
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Ratio Method ◽  
Resonance Spectroscopy ◽  
Spectroscopic Techniques ◽  
Nuclear Magnetic

Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a magnetic field absorb and re-emit electromagnetic radiation. Many scientific techniques exploit NMR phenomena to study molecular physics, crystals, and non-crystalline materials through nuclear magnetic resonance spectroscopy. NMR phenomena are also utilized in low-field NMR, NMR spectroscopy and MRI in the Earth's magnetic field (referred to as Earth's field NMR), and in several types of magnetometers. Modern NMR spectroscopy has been emphasizing the application in biomolecular systems and plays an important role in structural biology. NMR spectroscopy is very important to identify a drug or an excipient, evaluate the level of impurities (and to elucidate the structure), observe the course of a decomposition, to evaluate residual solvents, determine the isomeric composition, i.e. the ratio of diastereomers and the enantiomeric excess by means of chiral additive, assess a single drug or drug composition, characterize a polymer mostly being a mixture and used as excipients, identify counter ions (if of organic origin and having protons), characterize an entire formulation, e.g. a tablet. Fundamentals of quantitative NMR spectroscopy NMR spectroscopy can be considered as a primary ratio method of measurement being characterized by the fact that the ratio of substances can be determined directly from the physical context of the measurement without referencing to another substance. NMR has become one of the most powerful and versatile spectroscopic techniques for the analysis of biomacromolecules, allowing characterization of biomacromolecules and their complexes up to 100 kDa. Together with X-ray crystallography.

Nuclear Magnetic Resonance Detection of the Consequences of Transgene Expression

Physiology ◽  
1994 ◽  
Vol 9 (5) ◽  
pp. 197-202 ◽  
Author(s):  
AP Koretsky
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Transgene Expression ◽  
Spectroscopic Techniques ◽  
Resonance Imaging ◽  
Neuronal Function ◽  
Physiological Processes ◽  
Specific Manner ◽  
Resonance Detection ◽  
Nuclear Magnetic

Physiological processes can be altered in a very specific manner using transgenic mouse techniques. Physiological processes can be noninvasively monitored using nuclear magnetic resonance imaging and spectroscopic techniques. Three illustrations of the combination of these two rapidly developing techniques to study neuronal function, energy metabolism, and sickle cell anemia are discussed.

An Application of the Polarizable Continnum Model for Obtaining Chalcones Magnetic Properties

2020 ◽  
Vol 12 (7) ◽  
pp. 939-950
Author(s):  
Agnes Jalowitzki Silva ◽  
Thaís F. Giacomello ◽  
Gunar V. da S. Mota ◽  
Antônio M. de J. Chaves ◽  
Fabio L. P. Costa
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Population Distribution ◽  
Chemical Shifts ◽  
Biological Activities ◽  
Geometry Optimization ◽  
Analytical Techniques ◽  
Spectroscopic Techniques ◽  
Nuclear Magnetic

Chalcones exhibit a wide variety of beneficial biological activities. In addition, these compounds include the prevention of diseases related to oxidative stress. The structural characterization of these molecules by means of analytical techniques can become a difficult task due to the complexity of some structures. However, cases of erroneously established natural product structure review are still found in the literature despite recent advances in spectroscopic techniques. Therefore, it is necessary to develop quantum calculation protocols that can aid in the correct structural ascertainment of these compounds. Thus, in this work, we tried to develop a parameterized protocol for calculations of chemical shift of carbon-13 nuclear magnetic resonance, in order to ensure a correct structural determination of polyphenols, with a focus on chalcones. For this, a series of molecules belonging to this class, with complex and varied structural skeletons, reliably elucidated in the literature, was selected and subjected to stochastic conformational searches using the Monte Carlo method and the Merk molecular force filed. The lower energy conformations of each molecule were selected for the geometry optimization step, performed at the mPW1PW91/6-31G(d) level. The chemical shifts of carbon-13 were calculated at the same level of theory, taking into account the population distribution of Boltzmann. The calculations were affected in both liquid phases, using the Polarizable Continuous Model as an implicit solvation model. The results show that the level of theory applied in the liquid phase allows a good reproduction of the experimental data. The application of the scaling factor allows the cancellation of systematic errors, which means that the values of scaled chemical shift are closer to the experimental ones. Thus, the parameterized protocol proved to be an important tool for the structural elucidation of polyphenols by calculations of carbon-13 nuclear magnetic resonance chemical shifts.

Simultaneous In Situ Monitoring of Trimethoxysilane Hydrolysis Reactions Using Raman, Infrared, and Nuclear Magnetic Resonance (NMR) Spectroscopy Aided by Chemometrics and Ab Initio Calculations

2018 ◽  
Vol 72 (9) ◽  
pp. 1404-1415
Author(s):  
Xiaoyun Chen ◽  
Donald Eldred ◽  
Jing Liu ◽  
Hsu Chiang ◽  
Xianghuai Wang ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Reaction Rates ◽  
In Situ Monitoring ◽  
Spectroscopic Techniques ◽  
Wide Range ◽  
Nuclear Magnetic ◽  
Hydrolysis Reactions

Sol-gels are found in many different scientific fields and have very broad applications. They are often prepared by the hydrolysis and condensation of alkoxysilanes such as trimethoxysilanes, which are commonly used as precursors in the preparation of silsequioxanes via the sol-gel process. The reaction rates of such reactions are influenced by a wide range of experimental factors such as temperature, pH, catalyst, etc. In this study, we combined multiple in situ spectroscopic techniques to monitor the hydrolysis and partial condensation reactions of methyltrimethoxysilane and phenyltrimethoxysilane. A rich set of kinetics information on intermediate species of the hydrolysis reactions were obtained and used for kinetics modeling. Raman and nuclear magnetic resonance (NMR) spectroscopy provided the most information about hydrolysis and NMR provided the most information about condensation. A quantitative method based on Raman spectra to quantify the various transient intermediate hydrolysis products was developed using NMR as the primary method, which can be deployed in the field where it is impractical to carry out NMR measurements.

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