Unprecedented J-Aggregated Dyes in Pure Organic Solvents

The design and synthesis of the first organic dyes enabling spontaneous formation of stable J-aggregates in common organic solvents without additives is described. The new dyes are O-BODIPYs with a B-spiranic 4,4-diacyloxyl substitution pattern. Key to the effectiveness of the J-aggregation process is the high conformational rigidity of the B-spiranic molecular design as well as the orthogonal disposition of the B-diacyloxyl substituent and the meso-aryl group with respect to the mean plane of the boradiazaindacene. Atomistic simulations, both in vacuum and in a solvent cage, support the dynamics of the J-aggregation process as well as its dependence on the alkylation pattern of the BODIPY chromophore. A detailed analysis of the photophysical and laser properties of the new dyes provides convincing evidence for the unambiguous assignment of these J-aggregates and their dependence on the environmental conditions.