Of residual protons

Table 7.48 Solvent Positions of Residual Protons in Incompletely Deuterated...

These highly fluorinated homopolymers (7,8) derived from hydroxy fluor-ovinyl ethers (5,6), in contrast to typtical highly fluorinated compounds and polymers, exhibit unusually good solubility in common organic solvents. The NMR chemical shifts of residual protons in these polymers are highly sensitive to the polarity of the solvent as shown in Table 4.3. 

Table A3.10 Chemical shifts of residual protons in deuterated solvents 1431...

CHEMICAL SHIFTS AND MULTIPLICITIES OF RESIDUAL PROTONS IN COMMERCIALLY AVAILABLE DEUTERATED APPENDIX G SOLVENTS (MERCK CO., INC.)... 

Chemical Shifts, Multiplicities, and Coupling Constants of Residual Protons in Commercially Available Deuterated Solvents... 

Fig. 1. H- - C CT-HSQC spectrum of a sample of 1.5mM Val, Leu, lie (51) methyl-protonated maltose-binding protein (MBP), 2mM /3-cyclodextrin, 20 mM sodium phosphate (pH 7.2), 3mM NaN(, 200pM EDTA, 0. 1 mg/ml Pefabloc, 1 /ig//d pepstatin and 10% D20 recorded at 37°C, on a Varian Unity-1- 500-MHz spectrometer. Acquisition times of 28 and 64 ms were employed (/, t2) along with a relaxation delay of 1.5 s, fora total measuring time of 3 h. (a) Aliphatic region of the H- - C correlation map of MBP, illustrating the selectivity of labelling. Small amounts of residual protonation are observed at the Cy positions of a number of Pro/Arg residues, the Cp positions of Asp and Ser (aliased) residues, and the Cy2 methyl positions of lie. In all cases, intensities of these cross-peaks are less than 10% of the methyl peaks, (b) Methyl region of the H- - C HSQC. Reproduced with permission from Kluwer Academic Publishers Goto et al.H...

Zumbulyadis et al. [133-135] showed that proton to deuterium CP transfer is also useful to investigate miscibility. For a completely deuterated PMMA (d8-PMMA) homopolymer, a very weak deuterium FID signal, which was created by CP between a small amount of residual protons ( 2%), was detected (Fig. 10.17(a)) [134], For miscible d8-PMMA/PVPh = 18.8/81.2, an appreciable enhancement was observed (Fig. 10.17(c)). However, for the phase-separated blend, the signal enhancement was small as compared to that for the miscible one (Fig. 10.17(b)). They concluded that the signal enhancement in the phase-separated blend comes from interfacial regions (see Section 10.3). 

Another report on NMR studies of perdeuterated proteins by Agarwal et al. has shown that the small amount of residual protonation is sufficient to perform 2D and 3D MAS solid-state NMR experiments. In particular, a HCCH-TOBSY type experiment was suggested, which was successfully employed to assign the methyl resonances in aliphatic side chains in a perdeuterated sample of the SH3 domain of chicken a-spectrin. 

H spectrums of the initial and received compounds registered NMR on the device Bruker WM-400 concerning a signal of residual protons. IR-spectra wrote down on a spectrometer PERKBSI-ELMER 1725-X in crystals a method of difihisive reflectance. 

Similarly, Brough et al. recorded a well-resolved spectrum of the residual protrais in a largely deuterated sample of samarium acetate. However, problems of sensitivity and background suppression were encountered, since only a few percent of residual protonated groups could be afforded to obtain reasonable spectra. 

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