EXCIPLEX EMISSION FROM AMPHIPHILIC POLYSILANES BEARING AMMONIUM MOIETIES

We were the first to observe two emission bands in the visible region for some kinds of ammonium-type amphiphilic polysilanes both in soluti ons and in thin films. One, a broad emission band at 400-500 nm not du e to a sigma-->sigma transition, was observed only for methylphenylsi lane-based polymer solutions. The appearance of this low-energy emissi on is reasonably explained by considering the intramolecular exciplex formation between a Si-conjugated main chain and an ammonium site in t he same monomer unit. The other, an emission band at the longer wavele ngth (around 560 nm), was found in the solvent-cast films where each m olecule is randomly located, in addition to that observed for the solu tions. This emission, which was not observed for the oriented LB films , is considered to originate from an intermolecular interaction. (C) 1 997 Elsevier Science B.V.