Yun-Long Wu

A new luminescent Cd(II)-MOF as a highly selective chemical probe for Fe3+ in aqueous solution with mixed metal ions

A new metal–organic framework (MOF) with the formula [Cd(H2La)0.5(H2Lb)0.5(H2O)] (1), where H2La2− and H2Lb2− represent two different coordination modes of H2L2− ligands (H4L = [1,1′:4′,1′′-terphenyl]-2′,4,4′′,5′-tetracarboxylic acid), has been synthesized successfully by solvothermal reaction, and characterized by elemental analysis, FT-IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Interestingly, H2L2− adopted two coordination fashions during the self-assembly process of 1 because of the effect of partially deprotonated H4L ligands, which resulted in the 3D framework of 1 showing a trinodal (4,4,4)-connected PtS topology with a point symbol of (42·84). More importantly, the product of 1 displays greatly intense luminescence in the solid state and high sensitivity and selectivity for Fe3+ ions in aqueous solution with mixed ions, making it a new potential probe for detecting Fe3+. The quenching mechanisms are also further discussed in detail.

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.

Five transition metal coordination polymers driven by a semirigid trifunctional nicotinic acid ligand: selective adsorption and magnetic properties

Five coordination polymers, {[Co3(L)2(H2O)2]·4H2O} (1), {[Cd3(L)2(NMP)2]} (2), {[Cu(HL)]·NMP} (3), {[Cd(HL)(2,2′-bipy)]} (4) and {[Co(HL)(4,4′-bipy)(H2O)2]} (5) with different dimensional structures, have been solvothermally synthesized from a trifunctional N,O-building block, 5-(3,4-dicarboxylphenoxy)nicotinic acid (H3L) that combines three distinct types of functional groups (COOH, N-pyridyl, and O-ether), and an auxiliary co-ligand, 2,2′-bipy or 4,4′-bipy (2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine). H3L contains three different types of functionalities and has eight potential coordination sites, which results in diverse coordination patterns and different dimensionalities depending on the reaction conditions. Complexes 1–3 display 2D layer structures with 1D channels, 4 shows a 2D + 2D → 2D interpenetrated wavy structure, while 5 exhibits a 1D chain structure. 1 demonstrates an effective storage capacity for CO2 as well as high selectivity for CO2 over CH4 under ambient conditions. The magnetic properties revealed antiferromagnetic behaviors for complexes 1, 3 and 5. Also, the alternating-current susceptibility of 5 displays slow magnetic relaxation, showing interesting magnetic behavior with an effective energy barrier of 8.98 K.