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

Abstract

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-(6A-deoxy-α-cyclodextrin-6A-yl)- N′-(6A-deoxy-β-cyclodextrin-6A-yl)urea and 3 is N,N-bis(6A-deoxy-β-cyclodextrin-6A-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.