Mechanofluorochromic properties of 1-phenylanthracene derivatives with extremely simple structures

Abstract

Several types of 1-phenylanthracene derivatives 1–4 were prepared and their photophysical properties were observed in the solution and solid states. Interestingly, the fluorine-substituted 1-phenylanthracene derivative 1c was found to exhibit a higher fluorescence quantum yield (Φf=0.57) in the solid state than in the solution state, probably due to the formation of intermolecular Ar–F•••H–Ar hydrogen bonds. Additionally, some of the 1-phenylanthracene derivatives exhibited mechanofluorochromic properties depending on the substituents of the phenyl group, with the derivatives having CF3, OMe, and CN substituents (1d-1f, 2, 3) showing a significant change in luminous color from a bluish to greenish color at “room temperature” after grinding. However, no change in the luminous color was observed for the derivatives having H, Me, and F substituents (1a-1c) at “room temperature” but luminous color change was observed with low temperature grinding (−78 °C), especially for the CN substituent, in which a significant change in the luminous color was observed at “room temperature” probably due to the formation of Ar-CN•••H–Ar hydorogen bond interactions. Interestingly, for the 1-phenylanthracene derivative 3 substituted with two CN groups, which exhibited a solvatochromic phenomenon, the luminous color recovered with controllable rate from green to bluish when heated and fumed with solvent vapor in the solid state, and the luminous color change with controllable recovery rate was repeatedly successfully observed. These anthracene derivatives have extremely simple structures and could probably be applied as new mechanofluorochromic materials.