Molecular recognition and photoprotection of riboflavin in water by a biomimetic host.

A water-soluble tetralactam macrocycle with 2,6-diethoxynaphthalene groups as side walls is able to strongly bind riboflavin (Ka >107 M-1) in water through hydrogen bonding and the hydrophobic effect. The encapsulated riboflavin can be stabilized by the host against photo-degradation under UV-vis irradiation, which may be harnessed to extend the shelf life of riboflavin.