Metal-controlled aggregation-deaggregation in calix[4]arene-based self-assemblies

Supramolecular self-assemblies of complementary components 1 or 2 (calix[4]arene derivatives with two or four 2,6-diaminopyridine units, respectively) and 3 (5,5-dialkyl barbituric acids) in chloroform-acetonitrile solution were confirmed by ¹H NMR spectroscopy and light scattering. While derivative 1 interacts with 3 only after addition of Na⁺ cation, which disrupts intramolecular hydrogen bonds, compound 2 creates a complex with 3 even without the presence of Na⁺ cation, indicating much weaker intramolecular bonds in this derivative.