The induction of chirality in sol-gel materials

We review the different approaches that lead to chiral sol-gel materials. These methods include the use of silanes bearing a chiral group for silylating the surface of the porous sol-gel (SG) material, the use of such silanes as monomers or co-monomers in SG polycondensations, the physical entrapment of chiral molecules by SG procedures, the imprinting of SG materials with chiral templates and the creation of chiral pores, and the induction of chirality in the matrix skeleton itself. Analytical methods for detecting chirality are reviewed, including fluorescence methods, electrochemical methods, NMR, and induced CD. Applications are reviewed as well, including sensing, catalysis, chromatography, and optics. While most of the examples are focused on silicas and derivatized silicas, the methods and the analytical tools are generally applicable to other oxides and to preparation procedures other than sol-gel processes.