The complex formation between diazocalixdipropyl (1) and diazocalixcrown-6 ether (2) with alkali, alkaline earth and transition metal ions was investigated by voltammetry. Electrochemical properties of compounds 1 and 2 and their selectivity toward metal ions were evaluated in CH3CN solution by comparison of voltammetric behaviors of two phenols in each compound. Compounds 1 and 2 showed almost same voltammetric behavior which is two irreversible oxidation peaks caused by intramolecular hydrogen bonding between two phenols in 1 and 2. While, however, upon interacting with various metal ions, 1 with two propyl ether groups showed no significant changes in voltammetry, 2 with crown ether group caused significant voltammetric changes upon the addition of Ba2+ to 2. Their behavior is closely related to the complex formation by entrapment of metal ion into crown ether cavity, and ion-dipole interaction between metal ion and two phenolic groups in calixcrown-6.
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