The reaction of Zn(NO₃)₂·6H₂O/Cd(NO₃)₂·4H₂O with a semi-flexible ligand 4′-(4-(3,5-dicarboxylphenoxy)phenyl)-4,2′:6′,4′′-terpyridine (H₂dbp) gave two new metal–organic frameworks of [Zn(dbp)]_n (1) and [Cd(dbp)(H₂O)·2H₂O·CH₃CN]_n (2). Single crystal X-ray diffraction analyses reveal that both 1 and 2 show three-dimensional, two-fold interpenetrating four-connected networks with 4⁴.6¹⁰.8 topology. The photoluminescence investigation indicates that both 1 and 2 could be prospective candidates for developing luminescence sensors for the sensing of Mn²⁺, Cr₂O₇ ²⁻ and nitroaromatic analytes. Furthermore, the photocatalysis properties of 1–2 for the degradation of methyl violet and rhodamine B were examined.

The efficient removal of organic contaminants from wastewater is, nowadays, a prominent area of study due to its biological as well as environmental significance. Antibiotics are now found in wastewater because of their high use, which has become a source of aquatic pollution. These antibiotics have dangerous implications for people’s health. Hence, effective pharmaceutical removal from wastewater and contaminated water bodies, especially the removal of antibiotics, is of major interest to global research organizations. This is why it is necessary to investigate this class of toxic material in wastewater discharge. We synthesized three different coordination polymers (CPs) in the presence of various assistant carboxylate linkers, namely, [Zn(Hbtc)(dip)]_n (1), [Zn₄(1,2-bdc)₄(dip)₄]_n (2), and [Zn(1,4-bdc)(dip)]_n (3) (3,5-di(1H-imidazol-1-yl)pyridine = dip, 1,3,5-benzenetricarboxylic acid = H₃btc, 1,2-benzenedicarboxylic acid = 1,2-H₂bdc, and 1,4-benzendicarboxylic acid = 1,4-bdc). These CPs were characterized by using different techniques, including single-crystal X-ray diffraction. The structural studies demonstrated that in 2, there are four Zn(II) centers and both centers are in different coordination environments (Zn2 has distorted tetrahedral geometry, whereas Zn1, Zn3, and Zn4 have square pyramidal geometry). Hirshfeld surfaces analysis revealed that different types of intermolecular interactions (C⋯C, H⋯C, H⋯H, O⋯C, N⋯H, and O⋯H) are present in the synthesized CPs. We examined the different antibiotics, such as metronidazole (MDZ), nitrofurazone (NFZ), dimetridazole (DTZ), sulfasalazine(SLA), and oxytetracycline (OXY), degradation behaviors of the synthesized CPs, which showed remarkable degradation efficiency. 1 showed photocatalytic behavior toward the NFZ antibiotic in an aqueous media. This study also showed that these catalysts are stable and reusable under mild conditions.

A Cd(II)-MOF, {[Cd(L)(4,4′-bipy)]·H₂O·DMF}_n (1) (L = nicotinic acid (2,4-dihydroxybenzylidene)-hydrazide and 4,4′-bipy = 4,4′-bipyridine), has been synthesized and characterized by microanalyses, FTIR, TGA, and single-crystal X-ray diffraction. Additionally, powder X-ray diffraction was performed to check the phase purity of the synthesized compound. Single-crystal X-ray diffraction reveals that 1 has a 2D grid network. Photoluminescent sensing of nitrobenzene, Fe(III) and CrO₄²⁻ ions indicates that 1 could be a candidate for developing selective luminescent sensors for these species. Theoretical calculations have been performed to gain insight into the possible mechanism of quenching effect in emission on addition of nitrobenzene in 1 which supports the mechanism operating through ground state charge transfer between 1 and nitrobenzene.

Coordination polymers (CPs) are an assorted class of coordination complexes that are gaining attention for the safe and sustainable removal of organic dyes from wastewater discharge by either adsorption or photocatalytic degradation. Herein, three different coordination polymers with compositions [Ni(HL)(H₂O)₂·1.9H₂O] (1), [Mn₃(HL)(L)(μ₃-OH)(H₂O)(phen)₂·2H₂O] (2), and [Cd(HL)₄(H₂O)]·H₂O (3) (H₃L = 2-(3,5-dicarboxyphenyl)-6-carboxybenzimidazole; phen = 1,10-phenanthroline) have been synthesized and characterized spectroscopically and by single crystal X-ray diffraction. Single crystal X-ray diffraction results indicated that 1 forms a 2D layer-like framework, while 2 exhibits a 3-connected net with the Schläfli symbol of (4⁴.6), and 3 displays a 3D supramolecular network in which two adjacent 2D layers are held by π···π interactions. All three compounds have been used as photocatalysts to catalyze the photodegradation of antibiotic dinitrozole (DTZ) and rhodamine B (RhB). The photocatalytic results suggested that the Mn-based CP 2 exhibited better photodecomposition of DTZ (91.1%) and RhB (95.0%) than the other two CPs in the time span of 45 min. The observed photocatalytic mechanisms have been addressed using Hirshfeld surface analyses.