High-field nuclear magnetic resonance

Flexible superconducting tapes provide promise of uses for superconductors in motors, generators, and even electric transmission lines. Meanwhile, superconducting magnets cooled to the temperature of liquid helium already are in use. High-field nuclear magnetic resonance (NMR) spectrometers have become standard instruments in chemical research laboratories, and the same type of machine (called an MRI spectrometer) is used for medical diagnosis in hospitals worldwide. 

The most important advance in determining the structures of proteins in recent years has been the development of high-field nuclear magnetic resonance methods.9,10 These methods enable us to determine the structures of moderately sized (< 30 kDa) proteins in solution.11,12 The principle of the method is quite different from x-ray crystallography in that the overall structure is calculated principally from restraints on the distances between 1H atoms. 

Until recently, probably the best understood oxidation state of vanadium was V(IV). This situation changed with the advent of high field nuclear magnetic resonance (NMR) spectrometers, which provided the means to obtain a detailed understanding of the V(V) oxidation state. Indeed, the past 2 decades have seen the redrawing of the landscape of V(V) science, particularly where the aqueous phase is involved. 

Findlay, J. A., and Radies, L. (1980). On the chemistry and high field nuclear magnetic resonance spectroscopy of rapamycin. Can.J. Chem. 58, 579. 

High-coordination-number complexes of 0-keto-enolates continue to be obtained with the metals such as zirconium(IV),8 hafnium(IV),8 cerium(IV),9 and the lanthanons(III),10 the last being tetrakis anionic species. At least one example of a volatile tetrakis 0-keto-enolate salt has been reported,11 Cs[Y(CF3-COCHCOCF3)4]. The ionic charge on the 0-keto-enolate complex has been shown to produce12 a high field nuclear magnetic resonance for anions and low field shifts for cations, relative to the positions observed for the neutral species. 

The determination of the secondary and tertiary structure—that is, the details of the three-dimensional folding of the polypeptide chain of a protein at high resolution—relies on one of two powerful techniques x-ray diffraction analysis of protein crystals and multidimensional high-field nuclear magnetic resonance (NMR) spectroscopy. Both methods provide very detailed structural in-... 

J. F. Haw,T. E. Glass, and H. C. Dorn, Continuous flow high field nuclear magnetic resonance detector for liquid chromatography analysis of fuel samples. Anal. Chem. 53 (1981), 2327-2332. 

E. Eater, K. Albert, M. Nieder, and E. Grom, On-line coupling of liquid chromatography and high-field nuclear magnetic resonance spectrometry, A a/. Chem. 

The cations [cis-HjRh(dppp)2] and [cis-HjRh[(-l-)-diop]2] are similar to the known [cis-H2Rh[P(CHj)3] ] and show a u(Rh-H) stretch in the IR, a pair of multi-plets in the high-field nuclear magnetic resonance (NMR) at 25°C and two resonances in the P NMR. The lower field resonance for each system is attributed to the mutually trans-P atoms, and that at higher field to the P atoms trans to the hydrides. The presence of two P resonances at all temperatures rules out a cis-trans rearrangement. Both [cis-H2Rh(dppp)2] and [cis-HjRh[(-l-)-diop]2] lose on dissolving in solution under Ar. 

Mutlib AE, Chen H, Nemeth G, et al. Liquid chromatography/mass spectrometry and high-field nuclear magnetic resonance characterization of novel mixed diconjugates of the non-nucleoside human immunodeficiency virus-1 reverse transcriptase inhibitor, efavirenz. Drug Metab Dispos. 1999 27(9) 1045-1056. 

Major centers and facilities provide key infrastructure and capabilities for conducting research and have provided the foundation for U.S. leadership. Key capabilities for chemistry research include advanced light sources, scanning probe instruments, supercomputers, very high field nuclear magnetic resonance spectrometers, advanced mass spectrometers, nuclear reactors and accelerators, and specialized facilities for chemical biology. 

National High Field Nuclear Magnetic Resonance Centre (NANUC), University of Alberta, Edmonton, AB, Canada T6G 2E1... 

Supercritical fluid chromatography was coupled online to Proton High Field Nuclear Magnetic Resonance Spectroscopy by an specially designed pressure-proof continuous-flow probe head. Separation of phthalate esters was carried out under supercritical conditions using carbon dioxide as eluent. ... 

C., and Chippendale, M., Online coupling of supercritical fluid chromatography and proton high-field nuclear magnetic resonance spectroscopy. Anal. Chem., 66, 3042-3046, 1994. 

Rovnyak D, Hoch JC, Stem AS, Wagner G (2004) Resolution and sensitivity of high field nuclear magnetic resonance spectroscopy. J Biomol NMR 30 1-10... 

R 504 L. Mannina, C. Calcagni, E. Rossi and A. Segre, Review about Olive Oil Characterization Using High-Field Nuclear Magnetic Resonance , Ann.,... 

High-field nuclear magnetic resonance spectrometer (>500 MHz)... 

Lilium pardarinum has been isolated and characterized by a variety of high-field nuclear magnetic resonance (NMR) techniques (Shimomura et al, 1989). In many of these compounds, there is an A/B cis relationship (i.e., rings A and B are joined in a cis manner). These compounds also are commonly encountered in the dicotyledonous families Scro-phulariaceae and Solanaceae. Other types of steroidal saponins have been reported from the Arecaceae, Fabaceae, Fou-quieriaceae, and Zygophyllaceae. 

Due to the complexity of food matrices several advanced spectroscopic techniques have recently been successfully employed to solve authenticity problems, including near infrared spectroscopy (NIR), mid infrared spectroscopy (MIR), low- and high-field nuclear magnetic resonance (NMR), site-specific natural isotopic fiactionation (SNIF-NMR) and... 

B. Gillet, D. Nicole, J.-J. Delpuech, B. Gross, High field nuclear magnetic resonance spectra of hydroxyl protons of aldoses and ketoses, Org. Magn. Reson. 1981, 17, 28. 

In EMSL there are a number of first-of-a-kind and one-of-a-kind instruments that could be made available to the community via the Internet. We decided to focus on the instruments in the High-Field Nuclear Magnetic Resonance Facility as a test case. When we began, this facility included one of the first 750-MHz NMRs in the United States it now includes an 800-MHz NMR, and a 9(X)-MHz NMR is expected to come on-hne shortly. The NMRs were very attractive candidates for this test since the software for field servicing the NMRs provided much of the basic capability needed to make them accessible over the Internet. 

The recent advent of various analytical techniques has made it possible to carry out the practical studies of the end groups of polymers. The radioactive isotope labelling method has been used over a long period to determine the initiator fragment incorporated at chain ends by measuring the specific activities of radioactive samples prepared with C-labelled initiator [4-8]. In recent years, high-field nuclear magnetic resonance (NMR) techniques have been successfully applied to study polymer chain ends [1-7,9,10]. A number of reports have been published on the NMR studies of the... 

---