Solid state NMR characterisation of encapsulated molecules in mesoporous silica

Ibuprofen molecules have been encapsulated in mesoporous MCM-41 type-silica functionalised or not by amino groups. They have been characterised by C-13 and H-1 solid state NMR spectroscopy. The C-13 MAS single pulse or cross polarization NMR spectra, as well as the H-1 MAS NMR spectra demonstrate an extremely high mobility of the ibuprofen molecules when the matrix is not functionalised. On the contrary, when the silica matrix is functionalized by amino groups, the C-13 NMR response shows less mobility suggesting the existence of interactions between the amino groups and the carboxylic groups. Benzoic acid as well as benzamide have also been encapsulated and their NMR responses compared to that of ibuprofen.