Synthesis of a new cesium selective calix[4]arene based chromoionophore

Abstract

A novel azo-pyridyl calix[4]arene, (5,11, 17,23-tetrakis(4'-azopyridyl)-25,26,27,28-tetrahydroxycalix[4]arene), has been synthesized in the 1,3-alternate conformation by coupling debutylated calix[4]arene with a diazotized solution of 4-aminopyridine. The synthesized chromoionophore gives a large bathochromic shift (119 nm) with an increase in the intensity of absorption on addition of a methanolic solution of CS₂CO₃. The selectivity coefficients for Cr³⁺ and Ni²⁺ has been determined to be <i>K</i>_cr³⁺<i>, </i>_C_s⁺ = 6.6 and <i>K</i>_Ni²⁺ , _C_s⁺ = 66, while other alkali and alkaline earth metal ions do not interfere. The synthesized calixarene derivative has the potential to be used for development of ionic filters.