A Cu²⁺ fluorescent chemosensor suitable for quantitative detection of tyrosinase in potatoes over a wide pH range

Cu²⁺ as an important trace element plays an essential role in various biologic processes due to the unique redox active nature. For this reason, much effort has been made to develop effective methods for Cu²⁺ detection. In this study, a novel structure fluorescent chemosensor, 1-(6-(((5-(5, 5-difluoro-1, 3, 7, 9-tetramethyl-5H-4λ⁴, 5λ⁴-dipyrrolo[1, 2-c:2', 1'-f][1, 3, 2] diazaborinin-10-yl)quinolin-8-yl)oxy)methyl)pyridin-2-yl)-N, N-bis(pyridin-2-ylmethyl)methanamine (1), was synthesized and characterized by ¹H and ¹³C nuclear magnetic resonance spectroscopy, and electrospray ionization mass spectrometry. Sensor 1 showed an obviously "on-off" fluorescence response to Cu²⁺ with a 1:1 binding stoichiometry by UV-vis and fluorescence spectrophotometry. The detection limit of sensor 1 to Cu²⁺ was determined to be 1.9 µM, and the stable pH range for Cu²⁺ detection was from 3 to 13. Sensor 1 can be used for recognition and detection of tyrosinase in potatoes.