Light-emitting organic nanoaggregates from functionalized p-quaterphenylenes

Functionalized para-phenylenes are versatile building blocks for generating aligned fiber-like nanostructures by a self-assembly growth process on muscovite mica substrates upon controlled vapor deposition (molecule epitaxy). Functional groups were implemented at the 1,4'-parapositions of p-quaterphenylenes (p4P) using a Suzuki cross-coupling strategy. The nanoaggregates possess outstanding optical properties, which can be modified in a controlled manner by functionalization. Functionalization allows the fluorescence peak emission frequency to shift within the blue spectral range, and the nanoaggregates' three-dimensional shape alters depending on the substitution. In the case of asymmetrically functionalized phenylenes due to the intrinsic non-zero hyperpolarizability of push-pull functionalized oligomers and non-centrosymmetry of the respective nanofibers, they act as frequency doublers.