Synthesis, characterization and methylene blue adsorption of anionic porous coordination polymers with symmetric tetracarboxylate

The release of methylene blue (MB), a dye widely used in industrial activities, into the environment causes serious and often irreversible negative effects on ecosystems. Porous coordination polymers (PCPs) stand out as promising adsorbent materials for dye removal due to their large surface areas and the possibility of surface functionalization. In this thesis, two coordination polymers with anionic frameworks, {(pbisoixH2)[Zn(μ4- BIPFA)]·2DMF·4H2O}n (MS18) and {(bisoihH2)[Zn(μ4-BIPFA)]·1,5DMF·5H2O}n (MS54), were synthesized and used as adsorbents for the removal of MB dye from aqueous solution. The structures of the synthesized PCPs were characterized by elemental analysis, FT-IR, single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). According to X-ray analysis, in both MS18 and MS54, BIPFA4 − ligands coordinate to four zinc ions in a monodentate coordination mode, forming an anionic three-dimensional framework. These structures contain both rectangular and square channels. The charge balance of the anionic framework is maintained through the protonation of neutral ligands. Due to the presence of large channels, a 2-fold interpenetrated 3D + 3D → 3D structure is observed as a result of the interlocking of identical units. Both complexes exhibit a pts topology with a point symbol of 42 .84 . In batch systems, the effects of pH, temperature, contact time, and initial MB concentration on adsorption were investigated. The equilibrium times for MB adsorption on MS18 and MS54 were found to be 50 and 40 minutes, respectively. The adsorption data for both complexes were found to fit well with the Langmuir isotherm and pseudo-second-order kinetic models.