Synthesis of stilbene crown ether p-tert-butylcalix[4]arenes

Photo-switch able calixarene crown ether derivatives were synthesized in order to control the ring sizes and shapes of ionophores by isomerization between two different geometrical isomers. Five stilbene crown ether calix[4]arenes were prepared via McMurry coupling of the corresponding bisbenzaldehyde-calix[4]arene derivatives. The coupling reactions yielded both cis- and trans-stilbenes from o- and m-bisbenzaldehydes while only the cis-isomer was obtained from the reaction of the p-isomer. Unlike diazobenzene analogues, the stilbene crown ether calix[4]arene derivatives did not undergo thermal isomerization. Nevertheless, the isomerization of all synthesized stilbene crown ether calix[4]arenes can be photochemically induced. (C) 2001 Elsevier Science Ltd. All rights reserved.