Synthesis of indoaniline-derived calix[4]arenes as alkali cation sensors

Abstract

Derivatives of calix[4]arene containing indoaniline L1, L2 and L3 were obtained from reactions of calyx[4]arene (la) and double calix[4] (3a), respectively with N, N'–dimethlyl-2-methyl-1,4-phenylenediamine monohydrochloride in the presence of sodium hydroxide and potassium hexacyanoferrate(III).Complexation of compounds L1, L2 and L3 with alkali metal ions such as Li[superscript +], Na[superscript +], K[superscript +], Rb[superscript +] and Cs[superscript +] were carried out by UV-visible titration. The results showed that compounds L1 and L2 gave very small changes of spectra while compound L3 showed significant changes of the spectra. Therefore, only compound L3 was subjected to the recognition investigation. The binding abilities of compound L3 with alkali metal ions were as follows; K[superscript +] is more than Li[superscript +] is more than Rb[superscript +] is more than Na[superscript +] is more than Cs[superscript +]. Compound L3 thus bound selectively to K[superscript +].