Structure chemical shifts

Structure Chemical shifts S (p.p.m.) Reference signal Half-width (Hz) Solvent Ref... 

Moseley s law spect The law that the square-root of the frequency of an x-ray spectral line belonging to a particular series is proportional to the difference between the atomic number and a constant which depends only on the series. mOz-lez, 10 Mossbauer spectroscopy spect The study of Mossbauer spectra, for example, for nuclear hyperfine structure, chemical shifts, and chemical analysis. mus,bau-3r spek tras ko pe ... 

Thermodynamic stabilization, structure, chemical shift anisotropies and charge distribution... 

Advances in NMR instrumentation and methodology have now made it possible to determine site-specific proton chemical shift assignments for a large number of proteins and nucleic acids (1,2). It has been known for some time that in proteins the "structural" chemical shifts (the differences between the resonance positions in a protein and in a "random coil" polypeptide (3-5),) carry useful structural information. We have previously used a database of protein structures to compare shifts calculated from simple empirical models to those observed in solution (6). Here we demonstrate that a similar analysis appears promising for nucleic acids as well. Our conclusions are similar to those recently reported by Wijmenga et al (7),... 

Structure Chemical shift 8[ppm]4 (multiplicity)", coupling constant J[Hz]Y... 

Structure Chemical shift Mppm rf (multiplicity), couphng constant J[Hz]f ... 

Structure Chemical shift Sfppm]4 (multiplicity)e, coupling constant J[Hz]A... 

Fares C, Amata I, Carlomagno T. 13C-detection in RNA bases revealing structure-chemical shift relationships. J. Am. Chem. 

Another application of GAs was published by Aires de Sousa et al. they used genetic algorithms to select the appropriate descriptors for representing structure-chemical shift correlations in the computer [69]. Each chromosome was represented by a subset of 486 potentially useful descriptors for predicting H-NMR chemical shifts. The task of a fitness function was performed by a CPG neural network that used the subset of descriptors encoded in the chromosome for predicting chemical shifts. Each proton of a compound is presented to the neural network as a set of descriptors obtaining a chemical shift as output. The fitness function was the RMS error for the chemical shifts obtained from the neural network and was verified with a cross-validation data set. 

Hypothetical %nin model structure chemical shifts are not accurate and are for illustrating expected correlations only. 

The 1 B resonance spectrum, run at 25.2 MHz. on the neat liquid with trimethyl borate as an external standard, shows a pattern which resembles a quintet of 1 4 6 4 1 intensity. Low resolution caused a loss of fine structure. Chemical shift and coupling constants are given in Table II. 

Howard, S.T., Platts, J.A. and Coogan, M.P (2002) Relationships between basicity, structure, chemical shift and the charge distribution in resonance-stabilized iminoamines. Journal of the Chemical Society - Perkin Transactions 2, 899-905. 

NMR of 10% w/v D,L-PLA in deuteriochloroform Structure Chemical shift (ppm) and peak multiplicity... 

Keywords silacycles, crystal structure, chemical shift... 

Eor each predicted structure, chemical shifts were generated with the GIPAW approach described in detail elsewhere [39]. For the set of CM-isomers this included 14 structures, and for the trani -isomers this involved 20 structures. For each structure, measured and calculated shifts were then compared and the corresponding RMSD was obtained. 

The spectra of 18 stereoisomeric methylcyclohexane carboxylic esters and of l-deuterio-4-t-butylcyclohexyl derivatives have been discussed. By comparison with several model cyclohexane derivatives the data of cis- and rrflns-2-methoxy-carbonylcyclohexanol and their acetates have been interpreted. Conformations with an equatorial carboxylic ester moiety are preferred. Structural chemical shift correlations within 36 mono- and di-substituted alkylcyclohexenes have also been made. ... 

Partial Structural Chemical Shift Partial Structural Chemical Shift... 

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