Hollow Silica Microparticles Based on Amphiphilic Polyphosphazenes.

Hollow microparticles are important materials, offering a larger surface area and lower density than their solid counterparts. Furthermore, their inner void space can be exploited for the encapsulation and release of guest species in a variety of applications. Herein, we present phosphazene-based silica hollow microparticles prepared via a surfactant-free sol-gel process through self-assembly of the alkoxysilyl-containing polymer in water-ethanol solution.

Hybrid Porous Microparticles Based on a Single Organosilica Cyclophosphazene Precursor.

Porous organosilica microparticles consisting of silane-derived cyclophosphazene bridges were synthesized by a surfactant-mediated sol-gel process. Starting from the substitution of hexachlorocyclotriphosphazene with allylamine, two different precursors were obtained by anchoring three or six alkoxysilane units, via a thiol-ene photoaddition reaction. In both cases, spherical, microparticles (size average of ca.

Trends in Degradable Mesoporous Organosilica-Based Nanomaterials for Controlling Drug Delivery: A Mini Review.

The last few years of enhancing the design of hybrid mesoporous organosilica nanoparticleshas allowed their degradation under specific pathologic conditions, which finally is showing a lightin their potential use as drug delivery systems towards clinical trials. Nevertheless, the issueof controlling the degradation on-demand at cellular level still remains a major challenge, even if ithas lately been addressed through the incorporation of degradable organo-bridged alkoxysilanesinto the silica framework. On this basis, this mini review covers some of the most recent examplesof dierent degradable organosilica nanomaterials with potential application in nanomedicine,from degradable non-porous to mesoporous organosilica nanoparticles (MONs), functionalized withresponsive molecular gates, and also the very promising degradable periodic mesoporous organosilicamaterials (PMOs) only consisting of organosilica bridges.

Asymmetric syntheses of three-membered heterocycles using chiral amide-based ammonium ylides.

The use of carbonyl-stabilised ammonium ylides to access chiral glycidic amides and the corresponding aziridines has so far been limited to racemic trans-selective protocols. We herein report the development of an asymmetric approach to access such compounds with high levels of stereoselectivity using easily accessible chiral auxiliary-based ammonium ylides. The use of phenylglycinol as the chiral auxiliary was found to be superior to Evans or pseudoephedrine-based auxiliaries resulting in good to excellent stereoselectivities in both, epoxidation and aziridination reactions.