Highly Selective Detection of Ni2+ Ion Based on a Luminescent Zn(II) Coordination Polymer

Abstract

A luminescent zinc (II)-based coordination polymer, [Zn(CPDA)(NO₃)₂)] (CPDA=1, 2-cyclopentanedicarboxylic acid) (1), had been successfully synthesized in this paper by the hydrothermal method. Afterward, 1 was characterized through the single crystal and power X-ray diffraction (PXRD), elemental analysis (EA), thermogravimetric analysis (TGA), and infrared spectrum techniques, respectively. Particularly, the stable suspension of 1 in aqueous solution had exhibited highly selective quenching toward Ni²⁺ in physiological buffer solution. Besides, the optimum fluorescence intensity could be found at a pH of 7.0 and the temperature of 25 °C. Under these optimum conditions, the detection limit of Ni²⁺ ions could reach <inline-formula> <tex-math notation= LaTeX >$5.23\\times 10^{\\mathrm {-7}}$ </tex-math></inline-formula> mol<inline-formula> <tex-math notation= LaTeX >$\\cdot \\text{L}^{-1}$ </tex-math></inline-formula>. On the other hand, the effect of foreign ions on the fluorescence intensity of 1 showed low interference response to the detection of Ni²⁺ ions. Additionally, the quenching was recognized as a static quenching procedure, which was proved by the quenching rate constant <inline-formula> <tex-math notation= LaTeX >$K_{q}$ </tex-math></inline-formula> (<inline-formula> <tex-math notation= LaTeX >$5.74 \\times 10^{13}\\,\\,\\text{L}\\cdot {\\mathrm {mol}}^{-1}\\cdot \\text{s}^{-1}$ </tex-math></inline-formula>).