Three Novel Alkaline-Earth Ca(II)/Mg(II)/Ba(II)-Based Coordination Polymers as Fluorescent Probes for Nor and Pef Antibiotic Detection

Three new alkaline-earth Ca(II)/Mg(II)/Ba(II)-based coordination polymers (CPs) with unique structures, namely, {[Ca2(L1)(H2O)]·1.5H2O}n (1), [Mg(L1)0.5(phen)(H2O)]n (2), and {[Ba2(L2)(H2O)4]·H2O}n (3) (H4L1 = 1,2-di((3,5-dicarboxy-1H-pyrazol-1-yl)methyl)benzene, H4L2 = 1,3-di((3,5-dicarboxy-1H-pyrazol-1-yl)methyl)benzene, and phen = 1,10-phenanthroline), were synthesized by hydrothermal method. The three coordination polymers were characterized in detail by single-crystal X-ray diffraction, elemental analyses, infrared spectra, thermogravimetric analyses, and powder X-ray diffraction. The internal molecular interaction forces were also analyzed by Hirshfeld surface analyses. Compounds 1–3 were used as fluorescent probes for the detection of the antibiotics norfloxacin (Nor) or pefloxacin (Pef). The results demonstrated that Nor produced a fluorescence turn-on effect for compounds 1 and 2, and Pef produced a fluorescence turn-on effect for compound 3. The detection limits of compounds 1, 2, and 3 were 0.078, 1.68, and 2.45 μM, respectively, which indicated that these three compounds are excellent fluorescent probe materials.