Novel highly fluorescent triphenylamine-based oligothiophenes

A homologous series of novel amorphous oligothienyl-triphenylamines, comprised of head-to-tail coupled oligo(3-hexylthiophene)s covalently linked to a triphenylamine core, are disclosed. These hybrid systems, which differ by the length of the oligothiophene units from a monothiophene up to a quaterthiophene, were created via palladium-catalyzed cross-coupling reactions in good yields. The optical and electrochemical properties of these compounds were thoroughly investigated and are compared to the corresponding parent linear non-functionalized oligothiophenes, clearly demonstrating that these newly synthesized hybrid systems are characterized by outstanding absorption and emission properties. These molecules exhibit fluorescence quantum yields as high as 65%, which is unexpectedly high for thiophene-based materials. Based on this available data set, structure-property relationships were established, providing a deeper insight into the electronic nature of these materials and in this respect elucidating electronic differences between these star-shaped structures and their corresponding parent linear oligothiophenes.