Supramolecular binary hydrogels from calixarenes and amino acids and their entrapment-release of model dye molecules

A series of supramolecular binary hydrogels based on tetra-proline modified calix[4]arenes and basic amino acids (arginine, histidine and lysine) were constructed in acidic condition. The obtained results show that different amino acids lead to distinguishable backbones of hydrogels, which were identified by the combination of atomic force microscopy, transmission electron microscopy and scanning electron microscopy. Moreover, all the prepared low molecular weight hydrogels are thermoreversible and the gel-to-sol transition temperature (T-gel) depends on the concentration of calixarene, which endows these hydrogels with the capability of entrapment-release of model dye molecules.