The photophysical behavior of the photochromic naphthopyran derivative having photo-switching ability

• The photochromic naphthopyran derivative 9 with photo-switching ability has been investigated.
• The colorimetric change on photoirradiation suggests the conformational changes in the molecule.
• The compound 9 exhibited an auspicious ratiometric fluorescence response on exposure to white light.
• The open form exhibited mono-exponential fluorescence decay curve with τF value of 0.673 ns.

The photophysical behavior of the photochromic naphthopyran derivative 9 with photo-switching ability has been investigated in solution phase as well as in crystalline form. The proposed switching motifs might be a versatile framework in the development of photonic devices whose properties can be toggled between two states on exposure to electromagnetic radiations. The closed form of 9 undergoes reversible transformation upon irradiation with light by changing the molecular structure from ring closed conformation 9 to the ring opened form 10. The compound 9 exhibited first absorption signal at 238 nm with shoulder peak at 261 nm and second absorption signal at 353 nm while on photo-irradiation, the colorless solution of 9 turn to colored and there was ratiometric downfall in the signal intensity for shoulder signal at 261 nm as well as second absorption signal at 353 nm and ultimately results in the disappearance of these both signal after 20 min of irradiations. Meanwhile, the colorimetric change in the reaction solution and considerable shift in the absorption and emission signal intensity as well as position suggest the conformational changes in the molecules from less conjugate conformation 9 to the extended conjugated conformation 10.

The photophysical behavior of the photochromic naphthopyran derivative has been investigated in solution phase as well as in crystalline form.Figure optionsDownload as PowerPoint slide