Engineering Stacks of V-Shaped Polyaromatic Compounds with Alkyl Chains for Enhanced Emission in the Solid State

A V-shaped bisanthracene derivative with three butyl groups formed two types of emissive solids that display bluish green and blue fluorescence (ΦF =72 and 32 %, respectively), depending on the preparation conditions. The crystal and powder X-ray analyses reveal that the highly emissive solid adopts a head-to-head arrangement with discrete stacks of the anthracene moieties, whereas the moderately emissive solid adopts a head-to-tail arrangement without the stacks. The obtained molecular arrangements are transformed by thermal stimuli accompanying the change in fluorescence. Furthermore, large enhancements of dye emissions (12-45-fold) through highly efficient host-guest energy transfer were achieved in the solid state by adding minute amounts of various fluorescent dyes (e.g. rubrene and Nile red) to the V-shaped compound.