Highly ordered mesoporous silica families

In 1992, a new family of MPS was invented by The Mobil Corporation Laboratories named MCM-X (Mobil Crystalline Material Kresge et al. 1992). These ordered mesoporous silicas (OMSs) were initially developed for catalyst applications and were only later studied as a drug delivery technology. These silicas were synthesized from surfactant micelles under basic conditions. They have unique properties such as their pore diameter, high surface area (up to 1500 m /g), large pore volumes (up to 1.5cm /g), and silanol-rich surface which can be functionalized. Recently, the first pharmacompliant OMS materials have been developed. 

Karimi et al. reported a variety of water-tolerant ordered nanoporous silicas functionalized with sulfonic acids for the Pechmann reaction, satisfying both recyclability and reactivity [65]. More recently, some of the authors developed a new family of periodic mesoporous silica chloride (PMSCl) synthesized by direct chlorination of SBA-15 with thionyl chloride the resulting material with 2D-hexagonal symmetry showed both high loading of Si-Cl moieties and thermal stability [66]. PMSCl efficiently catalyzed the synthesis of coumarins from a variety of phenols and ethyl acetoacetate, at 403 K, even much more than other sulfonic acids supporting mesoporous silicas, yielding coumarin 17 in almost quantitative yield in only Ih of reaction time. 

Other interesting solids for the catalytic degradation of polymeric wastes are the various silica-based mesophases which have recently been discovered.4,5 These materials are characterized by the presence of ordered and regular pore systems and high surface areas, typically over 1000 m2 g l. The most common member of this family is MCM-41, which has a hexagonal array of uniform pores with diameters that can be tailored in the range 1.5-10 nm by varying the synthesis conditions. These mesoporous materials can be prepared with a wide... 

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