1H, 29Si and 1H, 23Na heteronuclear shift correlation in octosilicate via cross-polarisation

Solid-state magic-angle spinning was used to study octosilicate, a layered sodium polysilicate hydrate. Conventional one-dimensional NMR spectra detect two distinct proton and silicon sites and a single sodium species. Heteronuclear shift correlation experiments have shown that only one type of proton is involved in efficient cross-polarisation to all the silicon and sodium sites. Such selectivity could be caused by a favourable position for, and suitable rigidity of, this strongly hydrogen-bonded proton. The latter requirement can be used to propose a simple model of the interlayer space in octosilicate.