Spiropyran-Isoquinoline Dyad as a Dual Chemosensor for Co(II) and In(III) Detection

Spiropyran derivatives have been studied as light-regulated chemosensors for a variety of metal cations and anions, but there is little research on chemosensors that simultaneously detect multiple metal cations. In this study, a spiropyran derivative with isoquinoline, , was prepared and it functions investigated as a light-regulated sensor for both Co and In cations. A colorless nonfluorescent converts to a pink-colored fluorescent by UV irradiation or standing in the dark, and returns to with visible light. Upon UV irradiation with the Co cation for 7 min, the stronger absorption at 540 nm and the similar fluorescence intensity at 640 nm are observed, compared to when no metal cation is added, due to the formation of a Co complex with pink color and pink fluorescence. When placed in the dark with the In cation for 7 h, the colorless solution of changes to the In complex with yellow color and pink fluorescence, which shows strong absorption at 410 nm and strong fluorescence at 640 nm. Selective detection of the Co cation with UV irradiation and the In cation in the dark could be possible with by both absorption and fluorescence spectroscopy or by the naked eye.