Synthesis and characterization of a Schiff base of p-tert-butylcalix[4]arene and its complex with copper(II)

The synthesis and characterization of a Schiff base of p-tert-butylcalix[4] arene (H2L) and its complex with copper( II) is described. The synthesis of H2L has been achieved by the condensation of salicylaldehyde with the amine group of upper rim monoamine-p-tertbutylcalix[4] arene in ethanol. Attempts for the preparation of metal-ligand (1:2) complexes of this Schiff base with some transition metals failed except for Cu(II), which has been prepared from the copper sulfate, by refluxing in ethanol. The ligand and its complex with copper have been characterized on the basis of elemental analysis and spectral data. Solvatochromisity was observed for the ligand and its copper(II) complex, i.e. in different solvents depending on the solvent polarity, their lambda(max) of absorption in electronic spectra appeared in different wavelengths. Therefore these compounds can be good candidates for nonlinear optical active (NLO) applications. The prepared complex contains two p-tert-butylcalix[ 4] arene moieties, which could be expect to have improved calixarene ability in the fields like molecular recognition, host-guest features and other calixarene related capabilities.