Experimental and theoretical investigations on the host-guest interaction of diphenylamine with p-sulfonatocalix[4]arene

Abstract

The intermolecular interaction between diphenylamine (DPA) and p-sulfonatocalix[4]arene (p-SC4) is studied by experimental and computational techniques. The 1:1 stoichiometry of the inclusion complex is deduced from fluorescence titration using Job’s method. The tendency of binding of DPA with p-SC4 is analyzed from emission, excited state lifetime and cyclic voltammetry techniques. The binding constant values acquired from all the titrations are around 10³–10⁴ L/mol, reveals the effective binding. The structural interactions and mode of binding of the supramolecular complex are explained by ¹H NMR and ROESY spectral studies. The molecular association of DPA with p-SC4 is confirmed by quantum chemical simulations. The higher complexation energy (-76.94 kJ/mol) declares the existence of strong binding between DPA and p-SC4.