Hierarchically porous nanostructures through phosphonate–metal alkoxide condensation and growth using functionalized dendrimeric building blocks

Abstract

Controlled titanium alkoxide mineralization in the presence of phosphonated, dendrimeric nano-building blocks provides a new family of hierarchically porous dendrimer-bridged titanium dioxide materials.

Biological Activity of Mesoporous Dendrimer-Coated Titanium Dioxide: Insight on the Role of the Surface–Interface Composition and the Framework Crystallinity

“…45,46 Second, the dendrimer core is built from an extremely hydrophobic cyclotriphosphazene ring, while the peripheries are constructed from polar hydrophilic ammoniums or phosphonates. 32,33 This confers to these dendrimers an amphiphilic character and constitutes a key feature to derive water and polar monomers to the interfacial peripheries creating a strong, rich and confined environment for the sol-gel nucleation and growth of mineral objects. This mechanistic pathway is somewhat reminiscent of that observed using ionic liquids as a medium during titanium oxide formation.…”

“…31 We recently discovered that some challenging aspects of titanium alkoxide mineralization could be solved by the use of phosphorus dendrimers as amphiphilic nano-reactors. 32,33 Specifically, discrete anatase nanoparticles of ~ 5 nm entangled in a mesoporous network were accessible by thermal-free and even hydrothermal-free sol-gel synthetic mineralization at a moderate temperature of 60°C. By sharp contrast, the use of branch-mimicking dendrimers (isolated single molecules featuring similar reactive-surface chemistry) as organo-modifiers during the sol-gel mineralization allowed only the isolation of amorphous titanium dioxide phase.…”

Phosphorhydrazones as Useful Building Blocks for Special Architectures: Macrocycles and Dendrimers

“…Other inorganic materials incorporating phosphorhydrazone dendrimers (Figure ) concerned first titanium oxo clusters Ti 16 O 16 (OEt) 32 bridged with small dendrimers functionalized with alcohols or carboxylic acids . Recently, generation 4 dendrimers with different terminal functions were used as mould for controlling the nucleation and growth of titanium‐oxo‐species . Unexpectedly, the dendritic medium provided at low temperature (60 °C) discrete anatase nanocrystals, and prevented up to 800 °C, the commonly observed anatase‐to‐rutile phase transformation .…”

Molecular and Macromolecular Engineering with Viologens as Building Blocks: Rational Design of Phosphorus–Viologen Dendritic Structures

“…[13] Among other unique properties of phosphorus dendrimers, [14] their key roles as catalysts in some reactions of industrial interest with a so-called "strong dendritic effect" [15] and their utility in the synthesis of so-called "organic-inorganic hybrid materials" should be noted. [16] In light of these examples on the properties and applications of both viologens and phosphorus dendrimers, which are far from exhaustive, it appeared to us of great interest to develop new methodologies for the preparation of dendrimers by mixing viologen units and phosphorus linkages into the same framework. The goal was not to propose a strategy that would be one more synthetic pathway to dendrimers with a limited extension, but to propose a large panel of possibilities to build and tailor the dendrimers through multistep synthesis and by using a variety of original building blocks, "mixed" dendrons and dendrimers, and related macromolecules, which, taking into account the properties briefly reported above, would be fruitful nanoobjects for new applications.…”