A novel pyridylvinyl naphthalimide-rhodamine dye: Synthesis, naked-eye visible and ratiometric chemodosimeter for Hg2+/Fe3+

In this work, a novel pyridylvinyl rhodamine-naphthalimide ratiometric fluorescent probe , In this work, a novel pyridylvinyl rhodamine-naphthalimide ratiometric fluorescent probe, RNVP , was synthesized and characterized by 1 H NMR, 13 C NMR and HRMS techniques. This probe shows high selectivity and sensitivity towards Fe 3+ and Hg 2+ . At a low concentration of Fe 3+ /Hg 2+ , a new emission peak appeared at 581   nm and enhanced significantly along with naked-eye sensitive color changes, which spirolactam-ring moiety of rhodamine was converted to the open-ring form in the presence of Fe 3+ /Hg 2+ . Further addition of Fe 3+ /Hg 2+ , the fluorescence intensity at 438   nm was enhanced rapidly, which attributed to the suppression of the PET process. The proposed sensing system of probe RNVP represented dual-channel and segment detection behavior, with the fluorescence “turn-On or Off” response and a very low detection limit of 2.72×10 −8   M and 9.08×10 −8   M, and the dissociation constant (Kd) were calculated to be 4.95×10 −7 M 3/2 and 6.68×10 −8 M 3/2 , respectively. RNVP also quick responded linearly to the acidic solution and monitor the pH change in the range of 2.92–4.5, as well as excellent reversibility.