A Highly Copper-Selective Ratiometric Fluorescent Sensor Based on BODIPY

A new ratiometric fluorescent sensor (1) for Cu2+ based on 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) with di(2-picolyl)amine (DPA) as ion recognition subunit has been synthesized and investigated in this work. The binding abilities of 1 towards different metal ions such as alkali and alkaline earth metal ions (Na+, K+, Mg2+, Ca2+) and other metal ions ( Ba2+, Zn2+, Cd2+, Fe2+, Fe3+, Pb2+, Ni2+, Co2+, Hg2+, Ag+) have been examined by UV-vis and fluorescence spectroscopies. 1 displays high selectivity for Cu2+ among all test metal ions and a similar to 10-fold fluorescence enhancement in I582/I558 upon excitation at visible excitation wavelength. The binding mode of 1 and Cu2+ is a 1:1 stoichiometry determined via studies of Job plot, the nonlinear fitting of the fluorometric titration and ESI mass.