Synthesis, characterization and investigation of victoria blue B adsorption properties of coordination polymers with 3,3'-(thiophene-2,5-diyl)dibenzoic acid

In this thesis, 3,3′-(thiophene-2,5-diyl)dibenzoic acid (H₂tdb) was used as the main ligand and 1,2-bis(imidazol-1-ylmethyl)benzene (obix) as the neutral ligand. Four coordination polymers (1–4) were synthesized using H2tdb with Mn(II), Cu(II), Zn(II), and Cd(II) ions, and three mixed-ligand coordination polymers (5–7) were obtained by combining H2tdb and obix with Co(II), Cu(II), and Cd(II) ions. The structures of compounds were characterized by elemental analysis, FT-IR spectroscopy, and both powder and single-crystal X-ray diffraction techniques. Phase purities were confirmed by powder X-ray diffraction, and their thermal properties were investigated using thermal analysis methods (TG, DTA, and DTG). Based on elemental analysis results, the molecular formulas of the coordination polymers were determined as follows: [Mn2(μ3-tdb)(μ4-tdb)(μ-H2O)(DMF)2]n (1), {[Cu(µ4-tdb)(H2O)]·3H2O·2DMF} (2), {[Zn2(μ3-tdb)(μ4-tdb)(μ-H2O)(H2O)(DMF)]·DMF}n (3), [Cd2(μ4-tdb)(μ4-tdb)(μ-H2O)(DMF)2]n (4), {[Co2(µ3-tdb)(µ4-tdb)(µ-obix)]⸱H2O⸱DMF}n (5), {[Cu(μ4-tdb)(μ-obix)]·H2O·DMF}n (6) ve {[Cd(µ4-tdb)(µ-obix)]⸱H2O⸱2DMF}n (7). Crystallographic analysis revealed that complexes 1, 3–5 crystallized in the triclinic P-1 space group, whereas complexes 2, 6, and 7 crystallized in the monoclinic space groups C2/m and P2₁/c. Structurally, compounds 1, 3, and 4 are similar, where two tdb and one aqua ligand act as bridging ligands between adjacent metal(II) ions, forming 1D polymeric chains. In compound 2, Cu(II) ions coordinate with oxygen atoms from the tdb ligand to form paddlewheel [Cu2(CO2)4] units, which link through tdb ligands to construct a 1D polymeric structure. In complex 5, 1D polymeric chains are formed by coordination of Co(II) ions with tdb ligands. These chains are further connected via the obix ligand acting as a bridge, resulting in a 2D network. Similarly, in compounds 6 and 7, 1D chains are formed through the pentadentate coordination of the tdb ligands. Additionally, the adsorption capacity of complex 1 for Victoria Blue B dye (VBB) was investigated, and it was found to exhibit an adsorption capacity of 265.83 mg/g.