Synthesis and Applications of Supramolecular-Templated Mesoporous Materials

Abstract

The unique structure of MCM‐41 silicates (shown in the picture) has provided for extremely attractive properties—uniform pore sizes greater than 20 Å, surface areas exceeding 1000 m2 g−1, and long‐range ordering of the pores. Recent research in supramolecular‐templated mesoporous materials has led to a wide range of compositions, to uses in a variety of catalytic reactions, and to a better control of bulk morphologies.

Designed synthesis of nanostructured siloxane–organic hybrids from amphiphilic silicon-based precursors

“…Recently, the self-assembly of amphiphilic molecules has been widely exploited to create nanostructured inorganic-organic composites due to fundamental interest and a wide range of potential applications. [1][2][3][4] Two general approaches have been proposed: (i) solution synthesis of inorganics in the presence of molecular assembly, which usually relies on non-covalent interactions such as hydrogen or ionic bonds between inorganic and organic components, and (ii) design of molecular building blocks capable of self-assembly and subsequent inorganic cross-linking. The latter enables the tailoring of nanomaterials where organic and inorganic components are covalently linked and precisely arranged at the molecular scale.…”

General Synthesis of Ordered Nonsiliceous Mesoporous Materials

“…The classical products from inorganic-organic self-assembly, which is based on the cooperative organization of an organic surfactant and an inorganic precursor, are mesoporous silicates (1)(2)(3)(4). As generally accepted, the organicinorganic interaction between organic templates and inorganic precursor species is the main driving force to form ordered silicate mesostructures (48,49).…”

“…For convenience, nonmetallic alkoxides such as Si(OR) 4 , Ge(OR) 4 (where R is a short-chain alkyl such as CH 3 , C 2 H 5 , C 3 H 7 , C 4 H 9 ) are listed in the metallic alkoxides column. Routes A, B and E are reminiscent of the well-known non-hydrolytic sol-gel process which produces molecular homogenous oxides (61).…”

“…TiCl 4 , ZrCl 4 and P(OR) 3 , or the inorganic precursors with the same metal, e.g. Ti(OR) 4 and TiCl 4 . The latter which was used in the synthesis of ordered mesoporous titania is a good example to explain the efficiency of "acid-base pair" concept.…”

“…In this case, titanium alkoxide was used as the main titanium source and titanium chloride served as the pH "adjuster" and hydrolysis-condensation "controller". Compared with the synthesis from a single titanium source, namely TiCl 4 , the acidity of precursor solution is significantly and controllably reduced by the addition of titanium alkoxide which decreases the amount of TiCl 4 and neutralizes the acid. The added metal alkoxide is also an extra oxygen donor.…”