Construction of coordination polymers based on tetrabromoterephthalic acid and different nitrogen-containing ligands

Highlights: • Four CPs based on H₂tbta ligand were synthesized and structurally characterized. • The auxiliary ligands drastically affect the formation of low-dimensional structures. • The UV–vis spectrum and luminescence properties were studied. -- Abstract: Four coordination polymers (CPs) based on H₂tbta ligand, namely, [Zn(tbta) (bmbp)]_n (1), {[Cd_0.5(tbta) (H₂O)]_n·(Hbia) (H₂O)} (2), [Cu_1.5(tbta) (OH) (bi) (H₂O)]_n (3) and [Cd(tbta) (ei)₂]_n (4) have been synthesized and characterized (H₂tbta = 2,3,5,6-tetrabromoterephthalic acid, bmbp = 4,4'-dimethyl-2,2'-bipyridine, bia = 1H-benzo[d]imidazol-2-amine, bi = 1H-benzo[d]imidazole, ei = 2-ethyl-1H-imidazole). Single-crystal X-ray diffraction analyses illustrate 1 and 4 exhibit 1D chains, and compound 1 and 4 are hydrogen-bonded into a 2D layer to form a 3D supramolecular structure. Compounds 2 and 3 show 2D layered structures and further expand to 3D supramolecular structures through hydrogen bonds. Structural comparisons indicate that the position of coordination sites and substituent groups plays a crucial role in the control of the final structures. Besides, the photoluminescence properties of compounds 1, 2, 4 and UV–vis spectra of 3 have been investigated in the solid state at room temperature.