Solubility of Hydroxyl Cucurbit[6]uril in Different Binary Solvents

The solubility of hydroxyl cucurbit[6]uril in pure water and another five binary solvents, including formic acid aqueous solution, acetic acid aqueous solution, hydrochloric acid aqueous solution, ammonia, and potassium hydroxide aqueous solution, was respectively measured in the temperature range from (273.15 to 353.15) K by the equilibrium method. The results indicate that the solubility of hydroxyl cucurbit[6]uril in all six solvents increases with increasing temperature. The ideal solution equation, Apelblat equation, and Yaws equation were used to correlate the experimental solubility data of hydroxyl cucurbit[6]uril and all exhibit good agreement. The dissolution enthalpy, entropy, and the change of Gibbs free energy of hydroxyl cucurbit[6]ril in these solvents were obtained from the experimental solubility data by the van’t Hoff equation and Gibbs–Helmholtz equation.