Titanium Phosphonate Porous Materials Constructed from Dendritic Tetraphosphonates

Abstract

An organic–inorganic hybrid material, TPPhA-Ti, was constructed by non-hydrolytic condensation of a dendritic tetrakis-1,3,5,7-(4-phosphonatophenyl)adamantane precursor and titanium(IV) isopropoxide. One preparative pathway yielded insoluble materials with a Ti/P ratio of ∼1 which was confirmed by a combination of FT-IR, TGA, and EDS measurements. N₂ sorption experiments showed that TPPhA-Ti is a porous solid (micropores ∼13 Å; mesopores ∼38 Å) with a high surface area, ∼550 m² g⁻¹. The structure and morphology of the TPPhA-Ti as investigated by transmission and scanning electron microscopy showed a layered-type material. Additional X-ray diffraction data suggest a paracrystalline material; an optimization of possible molecular arrangements of TPPhA-Ti was simulated that was in agreement with the experimental data. A second preparative pathway yielded a Ti oxide–phosphonate with a Ti/P ratio of ∼3.4. Both TEM and SEM revealed that hollow nanospheres were formed with diameters of ∼180–300 nm.