Wide-line separation experiments WISE

Wide Line Separation Spectroscopy (WISE). Wide line separation spectroscopy (WISE) has been applied to correlate the molecular structme and mobility based on the linewidths of static H lines (Figme 48). In this experiment H lines are separated by virtue of a much better resolved chemical shift of C sites in their close proximity. The linewidths of H peaks provide a qualitative estimation of mobility (the wider the peak, the stronger the H H coupling and, hence, a reduced mobility), while the well-resolved C sites provide the information on molecular structme. 

In the solid, dynamics occurring within the kHz frequency scale can be examined by line-shape analysis of 2H or 13C (or 15N) NMR spectra by respective quadrupolar and CSA interactions, isotropic peaks16,59-62 or dipolar couplings based on dipolar chemical shift correlation experiments.63-65 In the former, tyrosine or phenylalanine dynamics of Leu-enkephalin are examined at frequencies of 103-104 Hz by 2H NMR of deuterated samples and at 1.3 x 102 Hz by 13C CPMAS, respectively.60-62 In the latter, dipolar interactions between the 1H-1H and 1H-13C (or 3H-15N) pairs are determined by a 2D-MAS SLF technique such as wide-line separation (WISE)63 and dipolar chemical shift separation (DIP-SHIFT)64,65 or Lee-Goldburg CP (LGCP) NMR,66 respectively. In the WISE experiment, the XH wide-line spectrum of the blend polymers consists of a rather featureless superposition of components with different dipolar widths which can be separated in the second frequency dimension and related to structural units according to their 13C chemical shifts.63... 

The focus of the chapter then shifts to heteronuclear 2D correlation (HETCOR) experiments. The evolution of single quantum coherence (SQC) of two different nuclei in these experiments with a coherence transfer step provides the basic formula for these correlations. In WISE (wide line separation), a wide dipolar... 

The last example of 2D techniques presented here is the wide-line separation (WISE) experiment [26, 49]. In a WISE spectrum, high-resolution C-CPMAS... 

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