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Water intrusion-extrusion isotherms performed at room temperature on hydrophobic pure silica chabazite have shown that the water-Si-CHA system exhibit real spring behavior. The studies have shown that Si-OH clusters have behaved like a real water trap at the origin of two water populations, where a first layer of water has strongly hydrogen bonded with the silanols of the framework and a subsequent layer of liquidlike physisorbed water molecules in interaction with the first layer.

The structure determined from molecular modeling and Rietveld analysis on synchroton data of AlPo4-SOD dehydrated under vacuum at 100 degree Celsius together with some solid state NMR experiments of the rehydrated product is presented. The dehydration/rehydration of AlPo4-SOD, however, is a reversible but very slow process.

AlPO4-SOD, a microporous aluminophosphate, is synthesized in a quasi-nonaqueous medium using dimethylformamide as solvent and template. The as-synthesized, dehydrated, and calcined materials and the corresponding rehydrated phases are investigated by various solid-state NMR and powder X-ray diffraction techniques.

Issues concerning the reflection of the three-dimensional arrangement of P2O(sub 7)(super 4-) units in the TiP2O7 structure in various one- and two-dimensional 31P MAS NMR experiments are discussed. The 31P MAS NMR properties of the isostructural phases TiP2O7 and SiP2O7 are compared.