Bases protons and

Finally, Table 5 shows statistics grouped by structure. For all of the structures, a root-mean-square difference between calculated and observed structural shifts of 0.25 to 0.35 ppm is found. Also shown are the slope and intercept of the best-fit line and the linear correlation coefficient for various portions of the total database. Statistics for all structures are not significantly different than those for the B-form DNA duplexes alone. Again, the best results are obtained for base protons and for the HI position on the sugar. 

The chemistry of the metalloborane polyhedra. including the reactions with Lewis bases, protonation, and elimination of hydrogen, have been described.235 The reactions are illustrated in Scheme 5. 

Correlation of base proton and phosphorous resonances through residual dipolar couplings... 

Base proton and HI dimerization shifts have been used in the past to confirm existence of base-stacking (Ts o et al., 1969 Chan and... 

Supramolecular adducts between the diamine l,4-diazabicyclo-[2.2.2]octane and dicarboxylic adds of variable chain length have been studied by H MAS and CP MAS NMR in order to investigate the presence of intermolecular hydrogen bonds between acid and base. Proton and nitrogen chemical shifts... 

Noble metal based Metal oxide based Protonic and metal zeolites Ceria-Zirconia based Vanadia-(Wolftamia)/Titania based Perovskite based Others... 

Because base protons and sugar protons are separated by a minimum of four bonds, spin couplings are not usually observed between these units and recourse is made to the use of NOE measurements often as 2D NOESY studies. Thus, for example, NOEs observed between the sugar anomeric proton and FI-6 and H-8 of a base serve to identify the base and sugar units of a single residue. NOE measurement can also be used to gain information on the sequence of residues in a nucleic acid. 

Ultimately, the affinity or the basicity scales themselves might be computed. This has been done successfully for the methanol affinity in the gas phase [41]. However, the MP2/aug-cc-pVTZ//B3LYP/6-3H-G(d,p) costly level required to obtain good agreement with experimental affinities has limited the scale to a few small Lewis bases. Proton and cation affinities and basicities in the gas phase are now computed on a routine basis (see Chapter 6). Nevertheless, the size of Lewis bases and cations and the number of bases studied are inversely proportional to the level of theory, that is, to the agreement with experimental data. As far as extended solution basicity scales towards usual Lewis acids... 

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