Preparation and first characterisation of a pillared ?-zirconium phosphate derivative containing dibenzo 18-crown-6 groups covalently bound to inorganic layers

A pillared crown ether derivative of y-zirconium phosphate containing 4,4?-bis(dihydroxyphosphoryl)dibenzo-18-crown-6 groups covalently bound to inorganic layers has been prepared by a topotactic reaction in 1:1 water-acetone mixture at 80°C. It was found that the original y-zirconium phosphate was already completely converted into a pillared phase (interlayer distance 1.9 nm) when ~15% of the interlayer dihydrogen phosphate groups were replaced with 4,4?-bis(dihydroxyphosphoryl)dibenzo-18-crown-6. The interlayer distance of this phase was found to increase progressively up to 2.1 nm with the gradual increase of the replacement to 50%. For higher replacement, a discontinuous transition of this latter phase to a new one (interlayer distance 2.6 nm) was finally observed. Some preliminary computer structural models of the crown ether conformations in the interlayer regions of these pillared phases were derived.