VERTICAL ALUMINOPHOSPHATE MOLECULAR-SIEVE CRYSTALS GROWN AT INORGANIC-ORGANIC INTERFACES

Tubular aluminophosphate molecular sieve crystals were grown at an org anic interface with their channels (7 angstroms in cross section) vert ical to the substrate. To induce surface nucleation and oriented growt h of AlPO4-5 crystals, organophosphonate layers cross-linked with Zr(I V) were assembled on a gold substrate and the modified substrate was i mmersed in a hydrothermal bath containing reagents for the synthesis o f the molecular sieve. Reflection-absorption infrared studies demonstr ated the stability of the phosphonate layers under these conditions. D rastic changes in the morphology of the surface-grown crystals from sp herical agglomerates to vertical needles to thin tilted needles could be achieved by adjusting the water content of the synthesis bath. Nitr ogen sorption in these structures on a piezoelectric device confirmed the presence of zeolitic microporosity.