Can metal ion complexation compete with the self-assembly processes of calix[4]arene amine derivatives?

Self-assembly can occur spontaneously through aryl-aryl π-stacking in solution for calix[4]arenes derivatised at both the upper and lower rims with pendant aromatic rings, including pyridine rings. It was hoped that metal ion complexation would help to control the level of self-assembly occurring in solution, by disrupting these interactions. Metal ion titration studies were carried out on 3 with various zinc salts, but it was found that even with 1 : 4 ligand to metal ratio, the self-assembly process still dominated. Furthermore, in an effort to prevent the self-assembly process, the lower rim was completely substituted, but metal complexation reactions with these fully substituted calix[4]arenes still showed that the self-assembly process dominated.