Syntheses, structures, magnetism and photocatalytic degradation of methylene blue dye of two copper complexes based on a semirigid tricarboxylate ligand.

• Two Cu(II)-complexes 1 and 2 were synthesized and characterized. • Complexes 1 and 2 can degrade 86.9 % and 97.0% MB in 24 min, respectively. • Both complexes could be used repeatedly for the degradation of MB. • The main reactive species for MB degradation were ·OH and h+. Two Cu(II)-complexes [Cu(Hcpota)(4,4′-bpy)(H 2 O)] n 1 and [Cu(Hcpota)(1,4-bib)(H 2 O)] n 2 based on a semirigid ligand 2-(4-carboxyphenoxy)terephthalic acid (H 3 cpota) were solvothermally prepared and characterized. Complexes 1 and 2 exhibit an unprecedented 2D 4-connected framework with a {44.62} topology, comprising the Cu(II) ion with square pyramidal coordination. The three-dimensional frameworks are constructed by O–H···O hydrogen bonds. Magnetization analyses were conducted and revealed that complexes 1 and 2 have ferromagnetic properties. The photodegradation of Methylene blue dye was studied based on 1 and 2 as photocatalysts. The results indicated that complexes 1 and 2 exhibited remarkable photodegradation efficiencies of 86.9 % and 97.0 % after 24 min, respectively. Furthermore, pseudo-first-order kinetics was assumed for the photocatalytic reaction with a rate constant of 0.052 and 0.109 min−1 for 1 and 2. The impact of factors, including the initial concentration of MB, catalyst dosage, pH value, H 2 O 2 concentration, and temperature on the degradation process of MB was thoroughly examined. The complexes exhibited excellent recyclability and stability as photocatalysts. Trapping experiments and LC-MS studies revealed that the primary active species responsible for the degradation reaction are hydroxyl radicals (·OH) and holes (h+). Two Cu(II)-based complexes synthesized via the solvothermal method have been utilized as catalysts for UV–vis light-induced dye degradation, the introduction of H 2 O 2 significantly enhances the efficiency. [Display omitted] [ABSTRACT FROM AUTHOR]