The synthesis and characterization of azocalix[4]arene based chemosensors and investigation of their properties

• In this study, azocalix[4]arene tetraester derivatives (4a–f) were synthesized.
• Their thermal decomposition analysis was performed by means of TG, DTA and DTG.
• Azocalix[4]arene derivatives have showed a good selectivity toward Hg2+ and Hg+ ions.

In the present study, azocalix[4]arenes were prepared by linking 4-methoxy, 4-methyl, 4-ethyl, 4-chloro, 4-bromo and 4-nitroaniline to calix[4]arene through a diazo-coupling reaction. A new family of azocalix[4]arene tetraester derivatives, (4a–f), have been prepared with the incorporation of ethyl ester units to azocalix[4]arene. Characterization of the synthesized azocalix[4]arenes was carried using elemental analyses, UV–vis, FT-IR and 1H NMR spectroscopic techniques. The effect of varying pH levels and solvent types on the absorption ability of azocalix[n]arenes substituted with electron-donating and electron-withdrawing groups was examined. Thermal decomposition of azocalix[4]arene derivatives (4a–f) was investigated by means of thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) analyses. In conclusion of the examination of the extraction we found a selectivity characteristic of these compounds toward Ag+, Hg+ and Hg2+ cations.

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