NMR spectroscopy study

Most recent and NMR spectroscopy studies are in accord with... 

H NMR spectroscopy studies of iron(IIl) a-alkyl and o-aryl porphyrins have been very important in elucidating spin states. Alkyl and most aryl complexes with simple porphyrin ligands (OEP, TPP, or TTP) are low spin, S — I /2 species. NMR spectra for the tetraarylporphyrin derivatives show upheld resonances for the porphyrin pyrrole protons (ca. — 18 to —35 ppm), and alternating upfield and downfield hyperfine shifts for the axial alkyl or aryl resonances. For -alkyl complexes, the a-protons show dramatic downfield shifts (to ca. 600 ppm), upfield shifts for the /3-protons (—25 to — 160 ppm) and downfield shifts for the y-protons (12 ppm). The cr-protons of alkyliron porphyrins are not usually detected as a result of their large downfield shift and broad resonance. These protons were first detected by deuterium NMR in the dcuterated complexes Fe(TPP)CD3 (532 ppm) and Fe(TPP)CD2CDi (562, -117 ppm). ... 

Zinc boryloxides with a tetrameric Zn404 core (45) have only recently been characterized. The single-crystal X-ray structure and multinuclear NMR spectroscopy studies were used as a basis for discussion of deformation of the central core.435 Alkali metal zinc orthoborates MZn4(B03)3 (M = K, Rb, Cs) have been synthesized and single-crystal X-ray structures determined for M = K and Rb.436... 

D. Shaw, Fourier Transform NMR Spectroscopy, Studies in Physical and Theoretical Chemistry, Vol. 30, 2nd ed., Elsevier, Amsterdam, 1984. 

In 1H- and 19F-NMR spectroscopy studies of the metabolites of fluclox-acillin (5.52) in rat urine, the presence of both (5R)- and (5.S )-flucloxacillin penicilloic acids was demonstrated [154], During the first collection period, the concentration of the (R)-epimer largely exceeded that of the f.S )-epimer. The (R)/(S) ratio then decreased progressively until an excess of f.S )-epimer was reached. These findings are in agreement with the hypothesis that the f.S )-cpimer is formed by epimerization in urine (see above) [152],... 

A variable-temperature Li, C, NMR spectroscopy study was carried out on the ligand structure and association behavior of [ Li, N]-enriched lithium bis(trimethylsilyl)-amide in hydrocarbon solntion. The system behaves as shown, for example, in equation 38, with the solnte adopting a dimeric form (209), which tnms to the monomeric 210 on... 

The interesting transformation 45 — 4 was also accomplished by refluxing 45 with DDQ (2,3-dichloro-5,6-dicyano-l,4-benzoquinone) and BSTFA [bis(trimethylsilyl)-tnfluoroacetamide] in dioxane NMR spectroscopy studies suggested the following... 

In this Sect, we describe the starting material impurities and their effect on the processing and cure reactions of TGDDM-DDS epoxies. The cure reactions are characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) studies. The BF3 amine catalysts used to accelerate the cure of TGDDM-DDS epoxies are characterized by nuclear magnetic resonance (NMR) spectroscopy studies. 

The first member of the series was the subject of some controversy since previous IR, UV and pKa measurements137 suggested that tautomer 31a was the most stable form, while 15N NMR spectroscopy studies suggest that an equilibrium exists between forms 31a and... 

Peuravuori, J. (2005). NMR spectroscopy study of freshwater humic material in light of supramolecular assembly. Environ. Sci. Technol. 39, 5541-5549. 

Key references prior to 1993 on 111 and 13C nuclear magnetic resonance (NMR) shifts for oxetanes are found in CHEC(1984) <1984CHEC(7)363>. Further references on 13C NMR coupling constants and chemical shifts, and 170 NMR data on oxetanones are in CHEC-II(1996) <1996CFIEC-II(1)721>. Since 1995, several NMR spectroscopy studies of oxetanes have been used for the structural identification of novel natural products (see Sections 2.05.11 and 2.05.12). 

Fernandez, E.J., Mancuso, A., Clark, D.S. (1988). NMR spectroscopy studies of hybridoma metabolism in a simple membrane reactor. Biotechnol. Prog. 4,173-183. 

Zang, X., Nguyen, R.T., Harvey, R., Knicker, H., and Hatcher, P.G (2001) Preservation of proteinaceous material during the degradation of the green alga Botryococcus braunii a solid-state 2D 15N 13C NMR spectroscopy study. Geochim. Cosmochim. Acta 65, 3299-3305. 

Haraldseth O., Gronas T., Southon T., et al. (1992) The effects of brain temperature on temporary global ischaemia in rat brain. A 31 -phosphorous NMR spectroscopy study. Acta Anaesthesiol. Scand. 36,393-399. 

DnR silicates in solution (4). Absolute amounts of silica present in the form of the various silicates are mentioned, together with (in brackets) their relative amounts, i.e. as if no polymeric silicates were present. These polymeric silicates, i.e., silicates consisting of more than 10 Si atoms, cannot be characterized by the chemical trapping method since the silyl esters are not volatile enough to be detected by GLC/flame ionization detection (FID) (14). Moreover, Si-NMR spectroscopy studies have never been successful in positively identifying higher molecular weight silicates than Si] ones (9). 

M. Lahaye, C. Rondeau-Mouro, E. Deniaud, and A. Buleon, Solid-state 13C NMR spectroscopy studies of xylans in the cell wall of Palmaria palmata (L. Kuntze, Rhodophyta), Carbohydr. Res., 338 (2003) 1559-1569. 

Harris, K. D. M. and Thomas, J. M. (1991). Probing polymorphism and reactivity in the organic solid-state using NMR spectroscopy studies of / -formyl-trans-cinnamic acid. J. Solid State Chem., 93, 197-205. [140]... 

The short chains with MRouse chains with relaxation times on the order of the experimental time-scale. For example, the Rouse times of PSD3 and of PSDIO are approximately 9s and 19s seconds, respectively at 115°C [35,36]. Consequently, the residual orientation at long times for these chains can be attributed to orientational coupling interactions with the long chains of the polymer matrix. Similar orientational correlations have been observed on various systems by NMR spectroscopy studies of stretched elastomers where even dissolved solvent molecules and free chains were shown to possess a very short-length scale local orientation [37]. 

IR and NMR spectroscopy studies have shown the formation of intra-... 

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