Thiacalix[4]arene derivatives containing multiple aromatic groups: High efficient extractants for organic dyes

Click reaction of alkynylthiacalix[4]arene with ethyl 2-azidoacetate, followed by ammonolysis with hydrazine hydrate and Schiff-base condensation with benzaldehyde or salicyic aldehyde, afforded two novel thiacalix[4]arene derivatives containing multiple aromatic groups in yields of 86% and 90%. Their complexation properties for four organic dyes were investigated by liquid-liquid extraction experiments, complexation UV-Vis spectra and mass spectrum. The highest extraction percentage was 97% for Neutral red. The UV-Vis spectra and ESI-MS spectrum indicated the 1:1 complexes in DMSO solution. The association constants were as high as 1 ∼ 8×104 M−1. These complexation experiments showed that thiacalix[4]arene receptors possess excellent complexation capabilities for dyes.