Applying the Oligomer Approach to Luminescent Conjugated Organoboranes

A series of highly luminescent monodisperse fluoreneborane oligomers (n = 1–6) were prepared using a new iterative synthetic procedure that takes advantage of the highly selective and differential reactivity of bromoboranes with arylsilanes and arylstannanes. Cyclic and square wave voltammetry revealed a gradual decrease of the LUMO energy levels with increasing chain length, while absorption and emission data showed a bathochromic shift and increase in quantum efficiency. An extended conjugation length of nECL = 5 was derived.