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

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 238nm with shoulder peak at 261nm and second absorption signal at 353nm 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 261nm as well as second absorption signal at 353nm and ultimately results in the disappearance of these both signal after 20min 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.