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 ～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.