Synthesis, Structures,\nand Properties of Complexes\nBased on 3,5-bis(triazol-1-yl)\nBenzoic Acid as the Main Ligand

In\nthis paper, 3,5-bis(triazol-1-yl)-benzoic acid (<b>L</b>) is\nselected as the main ligand to combine with Cd(NO<sub>3</sub>)<sub>2</sub>·4H<sub>2</sub>O to synthesize two complexes\nof\nCd(L)<sub>2</sub> (<b>1</b>) and [Cd(L)(PCA)(H<sub>2</sub>O)]·H<sub>2</sub>O (<b>2</b>) (PCA = 2-pyrazinecarboxylic acid) under\nsolvothermal conditions. Single-crystal X-ray diffraction analysis\nshows that complexes <b>1</b> and <b>2</b> exhibit different\nthree-dimensional framework structures of the network and waveform,\nrespectively. Solid-state fluorescence experiments show that <b>1</b> and <b>2</b> have excellent fluorescence properties.\nIon sensing experiments illustrate that complex <b>1</b> can\ndetect Fe<sup>3+</sup> with a detection limit (LOD) of 0.132 μM,\nand complex <b>2</b> can selectively sense Cr<sub>2</sub>O<sub>7</sub><sup>2–</sup> (LOD: 0.066 μM). In addition, amino\nacid and antibiotic sensing experiments reveal that complex <b>1</b> has the ability to selectively sense tryptophan (LOD: 0.120\nμM) by the fluorescence enhancement effect and tetracycline\nhydrochloride (LOD: 0.023 μM) by fluorescence quenching. Complex <b>2</b> can test sulfadiazine antibiotics (LOD: 4.780 μM)\nby fluorescence enhancement.