A visible BODIPY-based sensor for ‘Naked-Eye’ recognition of Ag+ and its application on test paper strips

In this study, a novel, highly sensitive fluorescent sensor (E)-2-((2-(benzo[d] thiazol-2-yl) quinolin-8-yl) oxy)-N’-(4-(5, 5-difluoro-1, 3, 7, 9-tetramethyl-5H-4λ 4 , 5λ 4 -dipyrrolo [1, 2- c :2’, 1’- f ] [1, 3, 2] diazaborinin-10-yl) benzylidene) acetohydrazide ( TQB ) was developed for dual mode of Ag + detection (colorimetric/fluorescence), and its structural and spectral properties were characterized by 1 H NMR, ESI-MS, X-ray, ultraviolet and fluorescence photometry. It is found that TQB could specifically and efficiently identify Ag + among many other metal ions in CH 3 OH/H 2 O (7:3 v/v, pH = 7.23) buffer. The maximum absorption wavelength of TQB is red-shifted while its fluorescence is quenched with a quenching rate of 88.7%. The energy difference between TQB and TQB -Ag + complex was calculated by DFT, and the applicability of TQB was verified by paper strip test. In addition, TQB has been successfully applied to the determination of Ag + in real water samples with good reversibility and recoveries.