Determination of association constant of host–guest supramolecular complex (molecular recognition of carbamazepine, antiseizure drug, with calix(4)arene)

• p-t-Butyl calix(4)arene is used as host and carbamazepine as guest molecule.
• Thermodynamic property of the host–guest, complex formed was studied.
• The stochiometry of the host–guest complex formed was 1:2.
• Dimension of the host molecule plays a vital role in forming the host–guest inclusion.

The thermodynamic property of the host–guest, inclusion complex formed between p-t-butyl calix(4)arene which is a supramolecule, and the antiseizure drug, carbamazepine was studied. p-t-Butyl calix(4)arene has been used as a host molecule and carbamazepine as a guest molecule. Optical absorption spectral studies were carried out to investigate the molecular recognition properties of p-t-butyl calix(4)arene with carbamazepine. The stochiometry of the host–guest complexes formed and the association constant were determined. An interesting 1:2 stochiometric host–guest complex was formed. Job’s continuous method of variation and Benesi–Hildebrand expression were used for the determination of binding constant and the stochiometry of the host–guest complex formed. Molecular dimension of the host molecule plays a vital role in the formation of the host–guest stochiometric complexes.

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