Construction of luminescent three-dimensional Ln(iii)–Zn(ii) heterometallic coordination polymers based on 2-pyridyl imidazole dicarboxylate

Abstract

Four three-dimensional (3D) Ln(III)–Zn(II) heterometallic coordination polymers, {[LnZn₆(μ₄-mPyIDC)₄Cl₂(H₂O)₆]·Cl}_n [Ln = Sm (1), Eu (2), Tb (3); H₃mPyIDC = 2-(pyridine-3-yl)-1H-4, 5-imidazoledicarboxylic acid], and {[LnZn(μ₅-pPyIDC)(μ₂-SO₄)(H₂O)₃]·3H₂O}_n [Ln = Tb (4); H₃pPyIDC = 2-(pyridine-4-yl)-1H-4,5-imidazoledicarboxylic acid], were prepared under hydrothermal conditions. Isostructural complexes 1–3 were constructed using 1D [Zn₃(mPyIDC)₂Cl(H₂O)₃]_n chains in a plywood-like packing mode jointed by Ln(III) ions. These compounds display unusual trinodal (3,4)-connected 3D networks with a point symbol of (4·6²)₄(4·6³·8²)₄(6²·8²·11²). Complex 4 has a highly connected framework with (3⁶·4²²·5¹⁶·6) network topology based on a rare planar heterometallic hexanuclear [Tb₂Zn₄(pPyIDC)₂] secondary building block. The luminescent properties of complexes 2–4 were also investigated.