A series of three novel metal-organic frameworks, [CdL] n (1), [ZnL] n (2), and [Cu 2 L 2 (DMF) 2 ] 3 6H 2 O (3), were successfully prepared by a solvothermal method using 3,3 0 -dimethoxy-4,4 0 -biphenyldicarboxylic acid (H 2 L) as the ligands. X-ray crystallography analysis reveals that complex 1 exhibits a 3D framework with sra topology and a rare eight-coordinated Cd(II) with two bound methoxy groups as secondary building unit (SBU). For complex 2, a 2D coordination network with a four-coordinated Zn(II) as SBU was observed. Complex 3 also shows a 2D layered architecture with 4 4 square lattice topology and a paddle-wheel Cu 2 (-CO 2 ) 4 as SBU. 113 Cd NMR spectrum of 1 showed that the chemical shift of eight-coordinated Cd(II) appeared at δ -108.9 ppm. In addition, both 1 and 2 are robust coordination polymers with high thermal stabilities (>380 °C). Fluorescence measurements of 1 and 2 display medium strong emission peaks at 403 and 401 nm, respectively. Magnetic study of 3 exhibits a strong antiferromagnetic interaction between two Cu(II) ions with -2J = 286 cm -1 .
Metal-organic frameworks (MOFs) as proton conductive materials have attracted increasing attention due to their applications in proton-exchange membrane fuel cells. While the majority of the MOFs are based on transition...
A new lead-bromide hybrid organic–inorganic complex [Et4N]2[PbBr3]2 (Et = ethyl) was synthesized, and its crystal structures could be described as a distorted perovskite-like one and a step-like dielectric anomaly was obtained at around 375/367 K.
The design and preparation of chiral metal–organic frameworks (CMOFs) from achiral ligands are a big challenge. Using 3‐nitro‐4‐(pyridin‐4‐yl)benzoic acid (HL) as a new linker, a total of eight chiral lanthanide–organic frameworks (LOFs), namely poly[diaquatris[μ2‐3‐nitro‐4‐(pyridin‐4‐yl)benzoato‐κ2O:O′]lanthanide(III)], l‐ and d‐[Ln(C12H7N2O4)3(H2O)2]n [(1), Ln = Eu; (2), Ln = Gd; (3), Ln = Dy; (4), Ln = Tb], were hydrothermally synthesized without chiral reagents and determined by X‐ray crystallography. Crystal structure analyses show that l‐(1)–(4) crystallize in the hexagonal P65 space group and are isomorphous and isostructural, while the enantiomers d‐(1)–(4) crystallize in the hexagonal P61 space group. All LnIII ions are octacoordinated by six carboxyl O atoms of six 3‐nitro‐4‐(pyridin‐4‐yl)benzoate ligands and two water molecules in a dodecahedral geometry. A one‐dimensional neutral helical [Ln2(CO2)3]n chain is observed in (1)–(4) as a chiral origin. These helical chains are further interconnected via directional hydrogen‐bonding interactions between pyridyl groups and water molecules to construct a three‐dimensional (3D) homochiral network with hex topology. The present CMOF structure is the first chiral 3D hydrogen‐bonded hex‐net and shows good water stability. Solid‐state circular dichroism (CD) signals revealed that (1)–(4) crystallized through spontaneous resolution. Furthermore, (1) and (4) display a strong red and green photoluminescence at room temperature, respectively, but their intensities reduce to almost half at 200 °C. Notably, upon excitation under visible light (463 nm), a circularly polarized luminescence (CPL) of (1) in the solid state is observed for the first time, with a glum value of 2.61 × 10−2.
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