Photoinduced electron transfer in heterosupramolecular assemblies of TiO2 nanoparticles and terthiophenecarboxylic acid in apolar solvents

Monodisperse stearic acid coated titanium dioxide nanoparticles (<3 nm) have been prepd. and characterized. The nanoparticles are sol. in common apolar org. solvents and bind to carboxylic acid functionalized p-conjugated oligomers to form heterosupramol. assemblies. When [2,2';5',2'']terthiophene-5-carboxylic acid was coupled to the nanoparticles, the fluorescence of the terthiophene moiety of the heterosupramol. system was completely quenched due to a photoinduced electron transfer from terthiophene to titanium dioxide. Time-resolved fluorescence and Stern-Volmer anal. revealed that the quenching is predominantly static rather than dynamic and occurs in apolar solvents