Photorelease of La3+ with turn-on fluorescent detection

Photorelease of La3+ with turn on fluorescent detection is described. Complex (1) is synthesized by treatment 2,2′-(((ethane-1,2-diylbis(oxy)bis(2,1-phenylene))bis(methanylylidene)) bis(azanylylidene))diphenol with LaCl3·7H2O in 1:1 molar ratio. Upon irradiation with UV light, 1 undergoes La3+ release and converts to 1,2-bis(2-(benzoxazol-2-yl)phenoxy)ethane (2). It is found that 2 exhibits strong fluorescence emission and the turn-on fluorescence is detected during the photo-conversion of 1 to 2, which is beneficial for monitoring the photorelease of La3+. Moreover, an excellent (R = 0.9963) linear correlation between the ratio of optical density (OD1/OD2) with irradiation time is obtained when 1 is photo-converted to 2, which is beneficial for controlling or regulating the quantity of La3+-released.