Abstract:

NMR spectroscopy is an excellent tool for the structural anal. of pure compds. However, for mixts. it performs poorly because of overlapping signals. Diffusion can be used to sep. compds. of widely differing mol. wt. but the amt. of sepn. is usually insufficient. Addn. of a solid medium, analogous to the stationary phase in chromatog., can preferentially slow the diffusion of some components of a mixt. permitting sepn. in the diffusion dimension. However, this would usually require a solid-state NMR spectrometer otherwise the signals would be too broad. Susceptibility matching the solvent to the solid medium yields a spectrum with narrow signals allowing the measurement of a DOSY spectrum with enhanced sepn. in the diffusion dimension. [on SciFinder(R)]