Abstract: Using the title ionophore DNS MAC(O₅) as the host, its cation recognition properties for Li⁺, Na⁺, K⁺, Mg ²⁺, Ba ²⁺ and Pb ²⁺ in acetonitrile and in aqueous solution were studied by fluorescence and NP RTPmethod, respectively. The corresponding stability constants and the recognition sensitive factors for the host guest complexes were determined. The results proved that the charge of guest cation and the spatial matching requirement between azacrown ring and the cation are the two most important factors on the recognition process. DNS MAC(O₅) undergoes obviously a spectral change upon binding with cation. These changes are mainly controlled by the charge density of the cation. When the azacrown ether moiety of the ionophore was coordinated with a cation, not only the dipole moment of the lumino ionophore was increased, but also it was more favorable for the photoinduced intramolecular charge transfer, so the stability of exited state was increased and the fluorescence spectrum was red shifted. At the same time, the relative fluorescence quantum of DNS MAC(O₅) in water and acetonitrile was determined by the comparative method in this paper.

Key words: Dansyl monoaza-18-crown-6, Cation recognition, Fluorescence, Room temperature phosphorescence