Charge-transfer interaction between C60 fullerene and alkylnaphthalenes

A series of alkylnaphthalenes, namely 1,4-dimethylnaphthalene, 2,6-diethylnaphthalene, 2-ethylnaphthalene and pure naphthalene are not able to form Diels-Alder adducts with C₆₀ fullerene but produce a series of 1:1 charge-transfer complexes (CTC) where the aromatic compounds act as donor and C₆₀ as acceptor. The spectrophotometric analysis of these CTC has permitted to determine the equilibrium constants of the CTC formation at four different temperatures and the relative enthalpies and entropies of formation. The C₆₀-alkylnaphthalenes and C₆₀-naphthalene were identified as weakly bound CTC. Using the Mulliken theory of the CTC also the degree of charge transfer α was determined, confirming the results already suggested by the equilibrium constants, i.e., the weakly interaction between the donor and the acceptor considered.