Complexation thermodynamics of dioxovanadium(V) by calix[۴]arene in solution

Calix[n]arenes are one of the three major groups of organic macrocyclic host compounds in supramolecular chemistry [۱]. They are composed of phenol units connected by ortho-methelene bridges and may complex to a variety of guests in solution as well in the solid state [۲]. Several calix[n]arene–metal ion complexes have been reported, most of them require that the hydroxyl groups of the calixarene are derivatized to esters or ethers due to the poor solubility of the para-tert-butylcalix[n]arenes [۳]. Calix[۴]arenes are widely used as building units for construction of preorganized molecules for supramolecular and coordination chemistry applications. The coordination chemistry of the calix[۴]arene-based ligands was recently reviewed. The calix[۴]arene moiety can be substituted on the upper or lower rim with a large variety of substituents. The coordination properties of such ligands are tuned by appropriate choice of substituents, differing in hydrophilicity–hydrophobicity, the number and type of donor atoms present, etc. Another effect of substituents on the coordination ability is based on the change in geometry of calix[۴]arene units due to the steric requirements of substituents [۴].

Keywords:

Calix[۴]arene , Complexation , Dioxovanadium(V) , Coordination