SYNTHESIS OF PHOTORESPONSIVE CROWN-ETHERS HAVING A PHOSPHORIC-ACID FUNCTIONAL-GROUP AS ANIONIC CAP AND THEIR SELECTIVE COMPLEXING ABILITIESTOWARD ALKALI-METAL CATIONS

New photoresponsive crown ethers (3a, 3b and 3c) connected to ionizabl e phosphoric acid moieties by an azobenzene skeleton have been synthes ized. The trans isomers are isomerized to the cis isomers by UV irradi ation and the cis isomers are reversibly thermally isomerized to the t rans isomers. The complexing abilities of these compounds have been es timated by measuring the cis to trans thermal isomerization rate in th e presence of various alkali metals End tetramethylammonium ions and b y the competitive extraction of alkali metal cations. The first-order rate constant for the thermal isomerization of cis-3a to trans-3a is r emarkably suppressed in the presence of Na+ and the extraction ability of cis-3a for Na+ was greatly enhanced: In contrast, the recovery of trans-3c from cis-3c was significantly suppressed by Li+ and the extra ction of Li+ by cis-3c was greatly and selectively enhanced.