Vibronic interactions and Jahn-Teller effects in the monocations of triphenylene and coronene are discussed. The E' mode of 1634 cm(-1) and the E-2g mode of 1668 cm(-1) afford large electron-phonon coupling constants in the monocations of triphenylene and coronene, respectively. The single charge transfer through the molecules in these positively charged species are discussed. The reorganization energies for elementary charge transfer are estimated to be 0.045 and 0.028 eV for triphenylene and coronene, respectively. The optimized structures of the monocations are discussed in terms of the frontier orbitals and the vibrational modes. (C) 2004 Published by Elsevier B.V.