PHOTORESPONSIVE CRYPTAND WITH AN AZOPYRIDINE BRIDGE

A new photoresponsive “cryptand” with an azopyridine-bridge (2) was synthesized. Trans-(2) was able to extract heavy metal ions (Cu2+, Ni2+, Co2+, and Hg2+) from aqueous solution to organic (o-dichlorobenzene +n-butyl alcohol) phase, whereas photoisomerized cis-(2) scarcely extracted heavy metal ions. The difference is rationalized in terms of the structural change of the azopyridine-bridge which is induced by photo(u.v.)-irradiation.