Two new tetraamide calix[4](aza)crowns (5a, 5b) were synthesized and used for optical anion sensors. Addition of host 5a or 5b to the p-NO₂C₆H₄O^－ anion in CHCl₃ resulted in decreasing absorption of band at 423 nm and the yellow solution of p-NO₂C₆H₄O^－ anion became colorless because of the formation of host-guest complexes between host 5a or 5b and p-NO₂C₆H₄O^－. The fluorescence response was observed in the presence of anions such as p-NO₂C₆H₄O^－, F^－,H₂PO₄^－, and the receptors 5a and 5b were highly selective toward p-NO₂C₆H₄O^－. The degree of change in the emission intensity was in the order of p-NO₂C₆H₄O^－＞F^－＞H₂PO₄^－>>Cl^－, Br^－, I^－. The fluorescence spectroscopy titration experiments indicated the formation of a 1∶1 stoichiometry complex between receptor 5a (or 5b) and anion by nonlinear fitting curve.

Key words: tetraamide calix[4](aza)crown, anion recognition, fluorescence, sensing, synthesis