Cd(II)-Based Coordination Polymer as a Multiresponsive Fluorescent Sensor for Efficiently Detecting Zn<sup>2+</sup>, Cr<sub>2</sub>O<sub>7</sub><sup>2–</sup>, and Phenylglyoxylic Acid
Ruo-Tong Gang, Rong Luo, Wen Wang, Haijun Yu, Yilong Li, Dongmei Zhang, Yongliang Wang, Zhenhui Li, Feng Shao
Abstract
The concentration of Zn 2+ is closely related to the ecological environment and physical health and must be monitored conveniently and accurately. Herein, a novel coordination polymer, namely, {[Cd 2 L 2 (bpy) 2 ]·H 2 O·0.25DMF} n ( CP-1, bpy = 2,2′-bipyridine, H 2 L = 5-(1H-1,2,4-triazole-1-yl)-1,3-phthalic acid) was synthesized under solvothermal conditions and can be used for selective detection of Zn 2+ with an extremely low detection limit. Single-crystal X-ray diffraction analyses revealed that CP-1 exhibits an interspersed two-dimensional (2D) layer and further constitutes a 3D layer by weak interactions. Fluorescence experiments showed that CP-1 can be used as an excellent fluorescent sensor for selectively detecting Zn 2+ with the detection limit as low as 0.073 μM. In addition, CP-1 can also be used for the efficient detection of Cr 2 O 7 2– and phenylglyoxylic acid (PGA) with detection limits of 0.68 and 1.59 μM respectively. Moreover, the mechanism study showed that the turn-on behavior of CP-1 for detecting Zn 2+ can be attributed to absorbance-induced enhancement (ACE), and the turn-off behavior for detecting Cr 2 O 7 2– and PGA can be attributed to the “internal filtering effect” (IFE) and the combined effect of photoinduced electron transfer (PET) and competitive absorption, respectively.