Hybrid porous titania phosphonate networks with different bridging functionalities: Synthesis, characterization, and evaluation as efficient solvent separation materials

Hybrid titania phosphonate materials can demonstrate a high added value as tailored sorption materials. They combine high chemical stability with great structural versatility, given the wide diversity of functional groups that can be incorporated. Hereto, a fundamental understanding of the synthesis strategies influencing the material performance is required. Therefore three porous TiO2 phosphonate hybrid structures with different functional groups (octyl, propyl, and phenyl) were evaluated in a solid-phase extraction application aimed towards solvent separation. The synthesis was performed by mixing bridged diphosphonic acids (DPAs) with Ti (OBu)4 in a water-ethanol mixture at 30 degrees C, followed by a hydrothermal post-treatment at 120 degrees C. The materials were characterized by ICP-AES, 31P solid-state CP/MAS NMR, Raman and FTIR spectroscopy, X-ray diffraction, N2-sorption, and transmission electron microscopy. It is shown that the diphosphonic acids are quantitatively incorporated in the hybrid structures, leading to nanosized particles with a complex but uniquely functionalized surface. A study of the pore structure as a function of the incorporated DPA amount showed materials with a maximum BET surface area of 379 m2/g. The alkyl functionalized hybrid titania phosphonates demonstrated excellent and tunable sorption behavior.

Automated summary

Hybrid titania phosphonate materials have great potential as tailored sorption materials with high added value. By incorporating different functional groups, they possess high chemical stability and structural versatility. In this study, three porous titania phosphonate hybrid structures with different functional groups were synthesized and evaluated for solvent separation. The results showed that diphosphonic acids were effectively incorporated into the hybrid structures, resulting in nanosized particles with a complex but uniquely functionalized surface. The materials demonstrated excellent and tunable sorption behavior.