Light-controlled enzymatic synthesis of γ-CD using a recyclable azobenzene template.

Cyclodextrins (CDs) are important molecular hosts for hydrophobic guests in water and extensively employed in the pharmaceutical, food and cosmetic industries to encapsulate drugs, flavours and aromas. Compared with α- and β-CD, the wide-scale use of γ-CD is currently limited due to costly production processes. We show how the yield of γ-CD in the enzymatic synthesis of CDs can be increased 5-fold by adding a tetra--isopropoxy-substituted azobenzene template irradiated at 625 nm (to obtain the -()-isomer) to direct the synthesis.