PHOTOREGULATED-METAL BINDING WITH AN AZOBENZENE-CAPPED CALIX[4]ARENE

The photoresponsive calix[4]arene(1), which is modified with an azobenzene moiety on the lower rim of the calix, has been prepared. Photoisomerization of 1 was performed with photoirradiation by a 500W-Xe lamp using a Corning 7-37 filter. The liquid-liquid extraction of various ions by 1 in the form of both cis and trans isomers using picrate counter ion has been studied. Calixarene 1 shows a higher binding ability to the metal cations examined in the trans form than for cis isomer and exhibits over twice the binding ability, except for Cu2+ and Al3+, compared to the non-modified calix[4]arene (2), which has same structure on the upper rim of the calix.