Stimuli‐Responsive Properties on a Bisbenzofuropyrazine Core: Mechanochromism and Concentration‐Controlled Vapochromism

Abstract Stimulus‐responsive organic materials with luminescence switching properties have attracted considerable attention for their practical applications in sensing, security, and display devices. In this paper, bent‐type bisbenzofuropyrazine derivatives, Bent‐H and Bent‐ s Bu , with good solubilities were synthesized, and their physical and optical properties were investigated in detail. Bent‐H gave three crystalline polymorphs, and they showed different luminescence properties depending on their crystal packing structures. In addition, Bent‐H exhibited mechanochromic luminescence in spite of its rigid skeleton. Bent‐sBu exhibited unique concentration‐dependent vapochromic luminescence. Ground Bent‐ s Bu was converted to blue‐emissive, green‐emissive, and green‐emissive high‐viscosity solution states at low, moderate, and high concentrations of CHCl 3 vapor, respectively. This finding represents a concentration‐dependent multi‐phase transition with an organic solvent, which is of potent interest for application in sensing systems.