Anthracene possessing amide functionality as a turn-on fluorescent probe for Cu2+ and Zn2+ ions

An anthracene appended PET chemosensor, anthracene-9-carboxylic acid (3,4-dimethoxy-phenyl)-amide (A(1) ), has been synthesized through condensation of corresponding acyl chloride and 3,4-dimethoxyaniline containing C = O and NH as receptors. The sensor A(1) exhibited selective fluorescence turn-on behavior towards Cu2+ and Zn2+ ions in CH3CN. Cu2+ ions displayed 18-fold enhancement (phi = 0.006 -> 0.071) in the fluorescence spectrum of A(1) , which are otherwise well known for fluorescence quenching phenomenon. Moreover, A(1) could easily discriminate between Zn2+ and Cd2+ ions, the two metal ions of similar nature. The Job's plots analysis determined 2:1 (A(1) :Cu2+/Zn2+) stoichiometry between the sensor A(1) and Cu2+/Zn2+ ions. The LOD values were calculated to be 1.75 and 3.08 mu M for Cu2+ and Zn2+, respectively.