Kinetics and Solvent-Dependent Thermodynamics of Water Capture by a Fullerene-Based Hydrophobic Nanocavity

Kinetic and thermodynamic properties of water encapsulation from organic solution by an open-cage [60]fullerene derivative have been investigated. 2D exchange NMR spectroscopy (EXSY) measurements were employed to determine the association and dissociation constants at 300 330 K (k(a) = 4.3 M-1 x s(-1) and k(d) = 0.42 s(-1) at 300 K) in 1,1,2,2-tetrachloroethane-d(2) as well as the activation energies (E-a,E-ass = 27 kJ mol(-1) E-a,E-diss 50 kJ mol(-1)). The equilibrium constants and thermodynamic parameters in various solvents (benzene-d(6), 1,2-dichlorobenzene-d(4), and dimethylsulfwdde-d(6)) were estimated using 1D-H-1 NMR spectroscopy. The parameters were dependent on the polarity of the solvent; Delta H depended linearly on the solvent polarity, becoming increasingly unfavorable as polarity increased. Mixtures of polar dimethylsulfoxide-do in less polar 1,1,2,2-tetrachloroethane-d(2) showed a similar trend.