Inclusion of hydrazinophthalazine insight into the cavity of β-cyclodextrin: A study of surface tension and UV-vis spectroscopy

Surface tension, conductivity, and ultraviolet spectroscopic methods have been employed to study the dimensional fit molecular encapsulation of hydrazinophthalazine hydrochloride insight into the cavity of β-cyclodextrin in aqueous media. The equilibrium constant and 1:1 stoichiometry of the complex has been analyzed by surface tension (plot against reciprocal of concentration), and Job’s plot (drawn from UV-vis data). The binding constants computed from the tensiometric and spectroscopic method were found to be 59.91 μM-1 and 12.02-96.58 μM-1, respectively, that return the comfort zone of the results. The noteworthy upshot has also come out from standard Gibbs energy for inclusion complex formation. The free energy for inclusion complex is negative and lower in magnitude than adsorption by 6.11 kJ mol-1. 1HNMR and SEM picture also certified the formation of the inclusion complex. The results demonstrated that the driving force for formation of the inclusion complex inside the bucket-like cavity of β-cyclodextrin was a combination of hydrophobic effect and reduction of the surface energy, while in adsorption is only hydrophilic effect.