The incremental use of antibiotics is now posing a pollution problem in the aquatic system. Therefore, it is necessary to decompose this class of harmful components existing in wastewater. Metal–organic frameworks (MOFs) are a peculiar class of multidimensional materials that can be employed as a photocatalyst to decompose antibiotics present in the wastewater discharged. Herein, a stable Cd(II)-based metal–organic framework with the composition {[Cd₄(L)₂(dib)(H₂O)₃]·H₂O}_n (1), (H₄L = 3-(2,4-di-carboxyphenoxy)phthalic acid, dib = 1,4-bis(1-imidazolyl)benzene) has been synthesized hydrothermally and characterized. The single-crystal X-ray diffraction results indicate that 1 is a 3D 8-connected uninodal net with the point (3⁶·4¹⁸·5³·6). Further, 1 was employed as a catalyst for the oxidation of antibiotics viz. ornidazole (ODZ), nitrofural (NZF), and oxytetracycline (OXY) in an aqueous medium, amongst which the MOF exhibited the best photocatalytic decomposition performance against OXY. The plausible photocatalytic mechanism has been explained with the help of density of states calculations and Hirshfeld surface analysis.

Four new solvent-induced Co(II) complexes with chemical formulae [{CoL(μ₂-OAc)(MeOH)}₂Co] (1), [{CoL(μ₂-OAc)(EtOH)}₂Co] (2), [{CoL(μ₂-OAc)(Py)}₂Co] (3) and [{CoL(μ₂-OAc)(DMF)}₂Co] (4) (H₂L = 4-nitro-4′-chloro-2,2′-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol) have been synthesized and characterized by elemental analyses, FT–IR, UV–Vis spectra and single-crystal X-ray diffraction. Each of the prepared complexes, crystallizing in the space groups P–1 (1 and 4), P2₁/n (2) and P2₁/c (3), consists of three Co(II) atoms, two completely deprotonated (L)²⁻ units, two μ₂-acetato ligands and two coordinated solvent molecules. Although the four complexes 1–4 were synthesized in different solvents, it is worthwhile that the Co(II) atoms in the four complexes 1–4 adopt hexa–coordinated with slightly distorted octahedral coordination geometries, and the ratio of the ligand H₂L to Co(II) atoms is 2:3. The complexes 2–4 possess a self-assembled infinite 1D, 2D and 1D supramolecular structures via the intermolecular hydrogen bonds, respectively. Magnetic measurement was performed in the complex 3.

The increasing use of antibiotics in our society is now another source of aquatic pollution as these antibiotics now exist in wastewater discharge. Therefore, it is necessary to identify this class of harmful components present in wastewater discharge. Metal–organic frameworks (MOFs) are a peculiar class of multidimensional materials that can be employed as sensors to selectively and sensitively detect the antibiotics that are present in wastewater discharge. Herein, a stable Cd(II)-based MOF, with the composition {[Cd₂L(H₂O)_1.5]}_n (1) (H₄L = 4,5-di(4′-carboxylphenyl)phthalic acid), has been synthesized and characterized. Single-crystal X-ray analysis reveals that the MOF possesses a 3,8-connected topology with 1D channels occupied by lattice water molecules with the Schläfli symbol (3·⁵¹4⁷⁸·5²⁴). The MOF has been employed as a luminescent sensor to detect antibiotics in aqueous media. The results reveal that 1 sensitively detects trace amounts of the antibiotic sulfasalazine (SLA) up to 2.66 × 10⁻⁶ M via the decline in its emission intensity. Hence, 1 is an appropriate luminescent sensor for the SLA antibiotic in aqueous media. Further, attempts have been made to explain the sensing mechanism both experimentally and using theoretical calculations, which suggest that photoinduced electron transfer and competitive absorption are responsible for the decline in the emission intensity of 1 in the presence of antibiotic analytes.