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The 1H and 13C NMR spectra of the anthraquinones physcion, emodin, chrysophanol, aloe‐emodin and rhein were assigned. The previously preferred assignments for C‐2 and C‐4 in physcion were reversed. The NOE technique was used for the assignment of the 1H signals and SEFT and/or heteronuclear decoupling for 13C resonances.

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The pore size distributions of six mesoporous silica materials were determined by measuring the 1H NMR signal from the non-frozen fraction of conÐned acetonitrile as a function of temperature. The average pore size distributions determined by NMR agree fairly well with those obtained by sorption measurements. N 2 However, NMR gives a more detailed picture of the pore size distribution revealing three well-deÐned peaks. The peak at the lower pore size, however, reÑects the surface layer rather than a real pore size distribution. The NMR method to determine pore dimensions in the mesoporous range has a potential to become an alternative approach to the conventional gas sorption technique. In practise, however, pore sizes larger than approximately 400 in diameter will be difficult to determine accurately due to the inverse dependence A between the freezing point depression of the conÐned liquid and the pore diameter.

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