Exploring inclusion complexes of amino acids with p-sulfonatothiacalix[4]arene by experimental and computational approach

Abstract

The supramolecular complexations of two natural amino acids, viz., L-Valine and L-Aspartic acid, with p-sulfonatothiacalix[4]arene have been investigated by means of DSC, SEM, PXRD, ESI-MS, 1H NMR spectroscopy and molecular docking study. 1H NMR spectral study suggested possible mode of molecular interactions, while ESI-MS analysis confirm that the inclusion complexes have been formed with 1:1 stoichiometry. Binding constants of the inclusion complexes were evaluated by NMR titrations, and the estimation of free energy of binding indicates the inclusion process to be thermodynamically feasible. PXRD and SEM image studies revealed the formation of inclusion complexes. DSC analysis showed that the thermal stability of amino acids has increased on encapsulation with p-sulfonatothiacalix[4]arene. Further, the molecular docking study presented the most stable binding orientation of L-Valine and L-Aspartic acid within the cavity of p-sulfonatothiacalix[4]arene.