| Abstract
| - Novel 1,3-alternate calix[4]azacrowns having anazo chromophoric pendent group were synthesized, and their1,3-alternate conformations were confirmed by X-ray crystalstructure. In view of the hypsochromical UV band shiftingupon cation complexation, azo-coupled calix[4]azacrown-5 (3)showed the most selective shifting with alkali and alkalinemetal ions. In addition, 3 revealed K+ ion selectivity not onlydue to the size comparability between the K+ ion and theazacrown-5 loop but also due to a significant K+−π interaction between the two aromatic rings and the K+ ion. TheUV band shifting is also dependent on the lipophilicity ofthe species of counteranion used.
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