Intramolecular excimer emission is observed for cis-1,4-di(1-pyrenyl)decamethylcyclohexasilane in nonpolar solvents. Time-resolved fluorescence spectroscopy and kinetic modelling indicate that the driving force of excimer formation is very small, and that the process is governed by the flexibility of the silicon ring. In the polar solvent acetonitrile, photoinduced electron transfer occurs, with the cyclohexasilane ring acting as electron donor and the pyrenyl group as electron acceptor. (C) 2002 Elsevier Science B.V. All rights reserved.