A selective fluorescence probe based on naphthalene for the detection of barium(II).

A designed naphthalene derivative (potassium 2,2'-(naphthalen-1-ylazanediyl)diacetate, ND) was synthesized successfully which characterized by spectroscopic techniques (NMR, IR and HRMS-ESI-TOF). The sensitivity and selectivity were high toward Ba2+ in aqueous solution (100.0 mM HEPES buffer, 100.0 mM KNO3, pH 7.4) over a wide variation of metal ions such as Li+, Na+, K+, Cs+, Mg2+, Ca2+, Al3+, Pb2+, Fe2+, Fe3+, Co2+, Ni2+, Cu+, Cu2+, Ag+, Zn2+, Cd2+ and Ce3+. The limit of detection (LOD) was found to be 9.56×10-8 M. Density functional theory (DFT) calculations at the B3LYP level employing the 6-31G(d,p) and LANL2DZ basis set were performed for optimization of ND and ND-Ba2+ complex. The calculated results were consistent with a favorable complexation corresponding to the proposed coordination.