Elaboration of hybrid organic-inorganic materials for ammonium ions retention: Electron microscopy bipolarized observations and 129Xe solid-state NMR

Translucent organic-inorganic hybrid porous silica materials have been prepared via the acid-catalysed hydrolysis and condensation of TEOS and various p-sulphonatocalix[n]arene derivatives. Xerogels and aerogels have been prepared. The morphology of the gels was characterized by electron microscopy (SEM and ESEM) and by hyperpolarized 129Xe NMR. The aerogels showed a porous structure not influenced by the size of the calixarene derivative incorporated in the gel. The efficiency of these new materials towards the retention of ammonium ions was discussed.