Dynamics of unidirectional exciton migration to the molecular periphery in a photoexcited compact dendrimer

We have studied dynamical natures of electronic excited states in a compact series of phenylacetylene dendrimers. So as to clarify the mechanism of unidirectional migration of a photogenerated exciton in a compact dendrimer, we theoretically investigated the temporal behavior of the photogenerated exciton in the molecule by numerically solving the time-dependent Schrodinger equation for the electronic excited states. The structure of the dendrimers is optimized in the ground state, and it is fixed during the calculation of the exciton dynamics. The calculated results show that the exciton generated in the dendrimeric framework tends to migrate toward the outside of the molecule rather than the inside, and to itinerate around the periphery via the through-space interaction between the outer crowding benzene units. This is one of the intrinsic properties that originates from a highly branched treelike structure of the compact dendrimers.