Unsymmetrical beta-cyclodextrin-conjugated silicon(IV) phthalocyanines as highly potent photosensitisers for photodynamic therapy

A series of unsymmetrical silicon(IV) phthalocyanines with a permethylated beta-cyclodextrin unit and a sugar or a diamino moiety as the axial substituents have been prepared. These compounds are highly photocytotoxic with IC50 values as low as 21 nM, which is ca. sevenfold lower than those of the symmetrical bis(cyclodextrin) analogue.