Synthesis of ordered mesoporous aluminium alkylenediphosphonates with integrated inorganic–organic hybrid frameworks

Abstract

Ordered mesoporous aluminium alkylenediphosphonates with 2-D hexagonal structures were synthesized by using triblock copolymers and oligomeric surfactants. Integrated inorganic–organic hybrid frameworks of the mesostructured precursors can be maintained through the development of a new method to remove the surfactant molecules containing oligomeric moieties, e.g. poly(oxyethylene) units. Such surfactant molecules were successfully eliminated without decomposition of diphosphonate groups by treating them with dehydrated acetone without stirring, leading to the formation of ordered mesoporous aluminium alkylenediphosphonates with high surface areas. Complete retention of methylene, ethylene and propylene groups in the hybrid frameworks was confirmed by solid-state 31P MAS and 13C CP/MAS NMR measurements. Compared with low temperature calcination to remove surfactants, this method is quite superior because thermal stability of organic groups within the hybrid frameworks is not taken into account during the acetone treatments. The presence of organic groups in the frameworks influences the interaction of the inorganic frameworks with oxyethylene units. The interaction was reduced in accordance with the size of organic groups, and then the surfactant molecules can be removed more easily from the mesostructured material containing propylene groups.