H₂L (L=1-(4-carboxyphenyl)-1H-pyrazole-3-carboxylic acid) and Cd²⁺ ions were self-assembled by solvothermal method to prepare the coordination polymer 1 with 1D chain structure. 1 has dual-channel specific recognition ability for moxifloxacin (MXF) and silicate (SiO₃ ²⁻), which can be used as the turn-off sensing material for their detection. 1 is currently the second CP-based fluorescent sensor for MXF detection, and has the best sensing performance, with a sensitivity increase of more than three times. At the same time, as the first CP-based sensor material for detecting SiO₃ ²⁻, 1 shows excellent sensing properties and the limit of detection (LOD) is 0.68 μM.

Abstract

A 1D coordination polymer (CP) [Cd₂L₂(H₂O)₄] ⋅ 3H₂O (1) was prepared by solvothermal method using 1-(4-carboxyphenyl)-1H-pyrazole-3-carboxylic acid (H₂L) as single ligand. Fluorescence sensing experiments show that 1 has dual-function specific recognition ability for moxifloxacin (MXF) and silicate (SiO₃ ²⁻), which can be used as the turn-off sensing material for their detection. When 1 specifically identifies MXF, the Ksv is as high as 6.46×10⁵ M⁻¹ (6–20 μM) and the limit of detection (LOD) is as low as 14 nM. 1 is the second example of a CP-based fluorescent probe for the detection of MXF, which has confirmed that the Ksv is the largest to date for the detection of MXF, with a detection sensitivity increase of more than three times. For SiO₃ ²⁻ ions detection, the fluorescence intensity ratio has a good linear correlation with the concentration of SiO₃ ²⁻ ions in the concentration range of 0–100 μM, with a slope of 1.33×10⁴ M⁻¹, and the LOD is as low as 0.68 μM. According to the reported literature, 1 is the only example of SiO₃ ²⁻ ions sensing by CP-based fluorescence sensor so far. In order to better understand the sensing phenomenon, we also discussed the sensing mechanism for MXF and SiO₃ ²⁻ ions.