Substituent effect of 2,3-dicyanopyrazine dyes on solid-state fluorescence

Some pyrazine dyes based on the same chromophoric system with different steric nature were synthesized to evaluate the correlation between solid-state fluorescence and molecular arrangement. It was confirmed that the solid-state fluorescence is significantly correlated with the prevention of complete stacking between chromophoric systems in the crystalline state. This result suggests that the introduction of bulky substituents to fluorescent dyes should be made on substantial positions for preventing the complete stacking between the chromophoric systems on the basis of the crystal structure.