Synthesis and optical recognition properties of calix[4]arene containing fluorophores

Abstract

New fluoroionophores 17 and 18 derived from p-tert-butylcalix[4]arene triester monoacid chloride with 2-amino-4-(1,3-benzothiazol-2yl)phenol and 4-aminoquinaldine respectively, were synthesized. The quantum yield of compounds 17 and 18 were 0.67 and 0.01 respectively. Complexation studies of compounds 17 and 18 with alkali metal ions such as Li[superscript +], Na[superscript +] and K[superscript +] were carried out by fluorimetric titration. The fluorescence intensity of compound 18 was very low. Only compound 17 was subjected to the recognition investigation. Compound 17 was selective to Na[superscript +], while Li[superscript +] and K[superscript +] showed no significant change under the same experimental condition. In methanol, the fluorescence intensity of compound 17 was quenched by Na[superscript +] and decreased linearly with increasing Na[superscript +] concentration with the stability constant of log K = 2.91