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In the present study, thermal decomposition of mono- and di-azocalix[4]arene derivatives (A1–A8 and B1–B8) was investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and derivative thermogravimetry (DTG). The exclusion of methanol, hydrolysis of benzoyl ester and methyl ketone groups in lower rim, and decomposition of azo groups in upper rim have occurred during thermal analysis, consecutively. The thermal decomposition degrees amount of volatile pyrolysis products were determined in air atmosphere using TG, DTA and DTG curves. In conclusion, the thermal analyses of azocalix[4]arenes demonstrated that its stability depends on the substituted groups and their positions in the calix[4]arene structure.

In this study, six new calix[n]arene-Fe3+ complexes (n?=?4,?6,?8) were synthesized with parent calix[n]arenes in a DMF solution of FeCl3?•?H2O. The properties and coordination characteristics of the six parent calix[n]arene-Fe3+ complexes were determined by elemental analyses, TG-DTA, UV-vis, FT-IR and 1H NMR spectroscopy. According to UV-vis analysis, in the six complexes the iron(III) coordinated by oxygen donor atoms from calix[n]arene ligands and DMF molecules. The complexes behave as 1?:?1 and 1?:?2 electrolytes in the case of calix[n]arenes (n?=?4,?6) (1-4) and calix[8]arene (5, 6), respectively. 1H NMR studies demonstrate that 1 and 2 are more stable than 3, 4, 5 and 6 in DMF, and indicate cone conformation of the calix[4]arene ligands (1 and 2).