J-aggregate structure in a chloroform solvate of a 2,3-dicyanopyrazine dye – Separation of two-dimensional stacking dye layers by solvate formation

Here, we report the J-aggregate structure of a chloroform solvate of 5-t-butyl-2,3-dicyano-6-[4-(dimethylamino)styryl]-pyrazine with a strong intramolecular charge transfer system. The dye was found to form a two-dimensional brick-wall structure separated by chloroform molecules in the solvated crystals, which exhibited intense red fluorescence. The absorption maximum of the solvate was also found to show a bathochromic spectral shift. These observed optical characteristics were interpreted in terms of excitonic intermolecular interaction based on two-dimensional brick-wall structure which is one of the proposed structures for J-aggregates.

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► 5-t-Butyl-2,3-dicyano-6-[4-(dimethylamino)styryl]-pyrazine forms a CHCl3 solvate.
► One of the proposed J-aggregate structures was found in its crystal structure.
► The solvate shows a bathochromic spectral shift in both absorption and fluorescence.
► These spectral shifts were interpreted in terms of exciton interactions.