Animated gif with γ-cyclodextrin molecule rotating

A light activated molecular switch could reduce the cost of a useful, but difficult to make γ-cyclodextrin.

Cyclodextrins are ring-shaped structures that typically consist of six to eight glucose units. Their hydrophilic exterior and hydrophobic cavity make them important host molecules in supramolecular chemistry with applications ranging from food chemistry to drug delivery.

γ-cyclodextrin, which consists of eight glucose units, can completely encapsulate bulky compounds such as vitamins. But its high solubility in water makes its synthesis difficult. The energy-consuming steam distillation process required to isolate γ-cyclodextrin is many times more expensive than smaller cyclodextrins.

A team of researchers from Denmark and the USA has now developed a light-controlled synthesis that could significantly facilitate access to γ-cyclodextrin. The strategy is based on a hydrazone template that is placed between E- and Z-Isomers in response to light. The team took advantage of the fact that the Z-Isomer binds to γ-cyclodextrin to stabilize the material during enzymatic synthesis, which leads to a six-fold increase in yield. Because the E-Isomer has a much lower binding affinity, the team could then use light to release the cyclodextrin product.

The researchers hope that their simplified synthesis “paves the way for the development of new adaptive self-assembled γ-cyclodextrin materials”.


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