Synthesis, structural characterization and anion-sensing studies of metal(ii) complexes based on 3,3′,4,4′-oxydiphthalate and N-donor ligands

Abstract

Using a multicarboxylate ligand, 3,3′,4,4′-oxydiphthalic acid (H₄ODPA), and N-donor ligands, five metal(II)-ODPA complexes formulated as Cu₄(ODPA)₂(L1)₄(H₂O)₁₀·2H₂O (L1 = 4-(2-(pyridin-4-yl)vinyl)pyridine) (1), Co(H₂ODPA) (L1)(H₂O) (2), Zn₂(ODPA)₂(H₂PIP)₂·H₂O (PIP = 1,3-bis(4-piperidinyl)propane) (3), Mn₂(ODPA)(phen)(H₂O)₂ (phen = phenanthroline) (4) and Cu₂(H₂ODPA)₂(phen)₄·H₂O (5) have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complex 1 shows a three dimensional (3D) framework with an unprecedented (4.6⁴.8)₂(4².6⁴) topology generated by the polycatenation of 2D layers. Complex 2 exhibits a uninodal 4-connected 3D architecture with 6⁵8-cds topology. Complex 3 shows a uninodal 2D layer with 4⁴-sql topology. Complex 4 has a binodal (4,6)-connected non-interpenetrated 3D architecture with (3.4³.5.6)(3².4³.5⁴.6⁴.7²) topology. Complex 5 is a mononuclear Cu(II) complex. Complexes 1 and 5 can irreversibly and reversibly detect SCN⁻, Cl⁻, Br⁻ and I⁻ in water, respectively. Complexes 2–4 are not feasible candidates for colorimetric detection of anions in aqueous solution. The metal(II) species and the structure of the metal complex play important roles in the colorimetric detection.