A Brief Review on the Thermal Behaviors of Calixarene-Azocalixarene Derivatives and Their Complexes

Calixarenes have been widely regarded as an important class of macrocyclic host molecules, due to their efficient and highly selective binding properties towards specific metal ions. Azocalixarenes, containing single conjugated chromophore azo (-N=N-) group in p-positions are synthesized by "one-pot" procedures with satisfactory yields. Their structures (as solid and liquid) are elucidated by UV-Vis, FT-IR, H-1 and C-13-NMR spectroscopic methods, as well as elemental analysis techniques. Thermal stability of calixarenes is very important because of their potential applications in high temperature processes such as the dyeing of textile fibers, ink-jet printing and photocopying and in high technology areas such as lasers and electro-optical devices. In this paper all the thermal studies of parent calix[n]arenes, azocalix[4]arene derivatives and their complexes containing lower and upper rim functionalized groups are reported. All the thermo analytical results such as the temperature ranges and peak temperatures of thermal decomposition steps and amount of volatile pyrolysis products were emphasized. The effect of substituted groups and their positions on the thermal stability of calixarenes were investigated.