Crystal structures from 1D to 3D: triggered by the different coordination morphologies of ligands in different reaction systems.

In this report, seven new luminescent metal–organic frameworks (LMOFs), [Zn(L)_0.5(H₂O)₂]·H₂O (1), [Zn(L)_0.5(DMF)] (2), [Zn₃(L)(μ₃-OH)₂(H₂O)₄] (3), [Zn₂(L)(DMA)(H₂O)]·5(H₂O) (4), [Cd(L)]·2(H₃O)·(H₂O) (5), [Cd₂(L)(H₂O)₃] (6), and [Pb(L)_0.5(H₂O)] (7) (H₄L = [1,1′:4′,1′′-terphenyl]-2′,3,3′′,5′-tetracarboxylic acid; DMF = N,N-dimethylformamide; DMA = N,N-dimethylacetamide) have been solvothermally synthesized by using Zn(ii), Cd(ii), Pb(ii) ions and H₄L in different solvent systems, all of which have been routinely characterized by elemental analysis, FT-IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Single-crystal X-ray diffraction analyses show the different dimensionalities (1D, 2D or 3D) of complexes 1–7. Comparative structural studies of 1–7 reveal that the L⁴⁻ ligands adopt different coordination morphologies: 1 (η¹μ₁χ¹), 2 (η²μ₂χ²), 3 (η²μ₂χ²), 4 (η²μ₂χ²; η¹μ₁χ¹), 5 (η²μ₁χ²), 6 (η²μ₂χ²; η²μ₂χ³), and 7 (η²μ₂χ²; η²μ₃χ⁴) with Zn(ii) (74 pm), Cd(ii) (97 pm) and Pb(ii) (119 pm) in different solvent systems, which produce the complexes with different frameworks. Complex 1 displays a 1D dimeric chain. Complexes 2 and 5 present a 2D layer structure with a uninodal 4-connected sql net with a symbol of (4⁴·6²). Complexes 3, 6 and 7 have a 3D dense packing structure based on infinite 1D rod-like secondary building units (SBUs). Complex 3 is designated as a binodal (4, 6)-connected fry topological net with the point symbol (5¹⁰·6³·7⁸)(5⁴·6²). The whole network of 6 can be simplified as a binodal (4, 8)-connected flu topological net with a point symbol of (4¹²·6¹²·8⁴)(4⁶)₂. Complex 7 can be seen as a new binodal (5, 10)-connected topological net with the point symbol (4¹⁰)₂(4²⁸·6¹⁶·8). Complex 4 shows a 3D framework based on a binuclear [Zn₂(CO)₃O₃] SBU, which can be viewed as a uninodal 4-connected sra topological net with the point symbol (4²·6³·8). Further, the solid-state luminescence properties of the complexes were measured and studied intensively at room temperature. [ABSTRACT FROM AUTHOR]