Structural analysis of calix[n]arene-iron(III) complexes (n=4, 6, 8) and thermal decomposition of the parent calix[n]arenes

Abstract

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).

Keywords:

• Calix[n]arene
• Iron(III) complexes
• TG/DTA
• Thermal analysis
• FT-IR, ¹H NMR spectroscopy