Silicate xerogels with dopant-induced chirality

A series of silicate xerogels with entrapped chiral amino acids have been o btained via sol-gel technology. The transparent, glassy samples obtained ex hibit chirality in the bulk due to the presence of the entrapped asymmetric molecules. Measurements of the optical activity of the doped xerogel sampl es revealed that the entrapment did not significantly influence the optical activity observed for liquid solutions of the amino acids. Thus, the sol-g el method enables the preparation of amorphous optical materials exhibiting properties of strictly spatially defined molecular systems. Apart from the obvious optical applications, such porous materials with asymmetric center s might find interesting applications in chiral chemical syntheses and sepa rations.