A Thermodynamic Study of Charge Transfer Complexes of C60 and Some Macrocyclic Ligands

4 and Schiff base crown ethers 5 and 6 was studied in toluene using UV/ Vis spectrophotometry at five different temperatures. The values of stability constant (Kc) for each complex were determined using Benesi-Hildebrand equation. The obtained Kc values were found to depend on the cavity size, the macrocyclic effect and the substituents on the host. All complexes were found to have 1:1 stoichiometry as obtained by Job’s plot method. In addition, the enthalpy and the entropy of complexation were estimated for all complexes. The complexation between C60 and Ligands 1, 2 and 4 are enthalpy favored and entropy unfavored, while the complexation with 3, 5 and 6 are enthalpy unfavored and entropy favored.