Cyclodextrin complexation of the stilbene 4-(2-(4-Tert-butylphenyl)ethen-1- yl)benzoate and the self-assembly of molecular devices

E-4-(2-(4-tert-butylphenyl)ethen-1-yl)benzoate, E-1^-, photoisomerizes to the Z-1^- isomer and vice versa in the free state and in the binary complexes 2·E-1^-, 2·Z-1^-, 3·E-1^- and 3·Z-1^- where 2 is the urea-linked cyclodextrin N-(6^A-deoxy-α-cyclodextrin-6^A-yl)- N′-(6^A-deoxy-β-cyclodextrin-6^A-yl)urea and 3 is N,N-bis(6^A-deoxy-β-cyclodextrin-6^A-yl)urea. In 2·E-1^- and 3·E-1^- the stilbene occupies both cyclodextrin (CD) components of 2 and 3, whereas in 2·Z-1^- and 3·Z-1^- it only occupies one CD component while the other CD component is unoccupied. 4-tert-Butylphenolate, 4^-, and its carboxylate, 5^-, and sulfonate, 6^-, analogues form the ternary complex 2·Z-1^-·4^- and its analogues and also 3·Z-1^-·4^- and its analogues. These photoisomerize to 2·E-1^- and 3·E-1^- and either free 4^-, 5^- or 6^- and thereby function as molecular devices.