Accessible bidentate diol functionality within highly ordered composite periodic mesoporous organosilicas

Periodic mesoporous organosilicas containing biphenol bridging groups were modified post-synthesis to prepare aryl phosphate esters from the free diols.

Near-IR squaraine dye-loaded gated periodic mesoporous organosilica for photo-oxidation of phenol in a continuous-flow device

Periodic mesoporous organosilica (PMO) has been widely used for the fabrication of a variety of catalytically active materials. We report the preparation of novel photo-responsive PMO with azobenzene-gated pores. Upon activation, the azobenzene gate undergoes trans-cis isomerization, which allows an unsymmetrical near-infrared squaraine dye (Sq) to enter into the pores. The gate closure by cis-trans isomerization of the azobenzene unit leads to the safe loading of the monomeric dye inside the pores. The dye-loaded and azobenzene-gated PMO (Sq-azo@PMO) exhibits excellent generation of reactive oxygen species upon excitation at 664 nm, which can be effectively used for the oxidation of phenol into benzoquinone in aqueous solution. Furthermore, Sq-azo@PMO as the catalyst was placed inside a custom-built, continuous-flow device to carry out the photo-oxidation of phenol to benzoquinone in the presence of 664-nm light. By using the device, about 23% production of benzoquinone with 100% selectivity was achieved. The current research presents a prototype of transforming heterogeneous catalysts toward practical use.

Optimization of the time and temperature of the microwave-assisted amination of phenylene-PMO

Microwave-assisted synthesis allows preparation of nitro- and amino-functionalized phenylene–PMO in just 15 and 30 minutes, respectively, with tunable content and homogeneous distribution of functional groups.