Dual-Emission Luminescence of Magnesium Coordination Polymers Based on Mixed Organic Ligands

Design and Multiple Applications of Mixed-Ligand Metal-Organic Frameworks with Dual Emission

Herein, we revealed the factors that affect the emission in mixed-ligand metal-organic frameworks (MOFs) with the combination of terephthalic acid (BDC), 2-aminoterephthalic acid (BDC-NH₂), and 2,5-dihydroxylterephthalic acid [BDC-(OH)₂] as models. The -NH₂ and -(OH)₂ groups change the π-conjugation and luminescence behaviors than BDC, so the ligands show different optical behaviors. The Zn²⁺ ion with a 3d¹⁰ full electronic structure shows little effect on the emission of the ligand and is selected as the metal node. We found that the emission of BDC is weak and incompatible to that of BDC-NH₂, so only the emission of BDC-NH₂ was observed in the BDC/BDC-NH₂-MOF. Crosstalk occurs between the emissions from BDC and BDC-(OH)₂ for the single emission from BDC/BDC-(OH)₂-MOFs, even different ratios are selected. The MOFs prepared with BDC-NH₂ and BDC-(OH)₂ show dual emission at 450 and 550 nm, while the relative intensity was easily tuned with the ligand ratio and excitation wavelength. Thus, abundant optical behaviors and extensive applications were realized, including but not limited to (1) dual emission from single MOFs, (2) tunable color from blue to yellow with the excitation from 290 to 370 nm for information encryption and decryption, (3) white emission obtained under an excitation of 330 nm, and (4) response of -NH₂ groups to HCHO and Fe³⁺ ions for ratiometric fluorescence sensing and visual detection. This work revealed the factors that affect the emission in mixed-ligand MOFs, studied their optical behaviors, and realized different applications with single MOFs.

Achieving a blue-excitable yellow-emitting Ca-LMOF phosphor via water induced phase transformation

The first blue-excitable calcium-based LMOF yellow phosphor is achieved via water induced phase transformation. The compound with high luminescence quantum efficiency can be coated directly onto a commercial blue LED chip to fabricate a white LED.

Crystal structure of catena-poly[di-μ2-chlorido-1,10-phenanthroline-κ2 N,N′-cadmium(II)], C12H8Cl2CdN2

C12H8Cl2CdN2, monoclinic, C2/c (no. 15), a = 16.969(5) Å, b = 10.515(3) Å, c = 7.238(2) Å, β = 110.710(10)°, V = 1208.0(6) Å3, Z = 4, R gt(F) = 0.0245, wR ref(F 2) = 0.0806, T = 298(2) K.

Design and properties of multiple-emitter luminescent metal–organic frameworks

This feature article reviews the design strategies by which multiple different emission sources could be combined for creating multi-emitter luminescent metal–organic frameworks (LMOFs).

Near-White Light Emission from Lead(II) Metal-Organic Frameworks

Reaction of bpy (bpy = 4,4'-bipyridine) with Pb(OAc)₂·3H₂O in DMF (DMF = dimethylformamide) afforded a metal-organic framework (MOF), [Pb₂(μ-bpy)(μ-O₂CCH₃)₂(μ-O₂CCH₃)₂]·H₂O (1). Reaction of bpy with Pb(O₂CCF₃)₂ in a methanol and chloroform mixture furnished another MOF, [Pb(μ-bpy)(μ-O₂CCF₃)₂]·¹/₂CHCl₃ (2). However, the reaction of bpy with Pb(OAc)₂·3H₂O in the presence of trifluoroacetic acid in a similar reaction condition yielded a hydrogen-bonded zwitter-ionic complex of Pb(II), [Pb(bpy-H)₂(O₂CCF₃)₄] (3). All compounds have been characterized by single crystal X-ray crystallography, FT-IR, and ¹H NMR spectroscopies. Compound 1 forms four heptacoordinated Pb(II) joined by (OCCH₃)-O- linkages, resulting in a 3D noninterpenetrated MOF net with a four-connected uninodal sra (SrAl₂) topology. However, in 2, tetra-connected Pb₄(O₂CCF₃)₈ cluster units are linked further through eight bpy ligands to furnish a doubly interpenetrated MOF with a new topology but having the very similar connectivity of 1, whereas 3 forms a zigzag hydrogen-bonded chain structure. The variation of carboxylate anions, pH of the reaction medium, and the ratio of the reactants profoundly affected the final topological structure of the compounds synthesized. The solid-state photoluminescence of 1-3 was investigated at room temperature. Interestingly 1, 2, and 3 achieved close to white light emission when excited at 329, 376, and 330 nm, respectively. The systematic understanding of the photophysical properties of analogous Pb-based compounds may open new perspectives for developing single-phase white-light-emitting materials using Pb(II) based MOFs.

Ultrasound irradiation effect on morphological properties of a 3D nano zinc(II) supramolecular coordination polymer

Nano-structures of [Zn(L)(atpt)]_n (1) (L=1,2-bis(2-methylbenzimidazol-1-ylmethyl)benzene and H₂atpt=2-aminoterephthalic acid) were obtained by hydrothermal and sonochemical approaches, characterized by scanning electron microscopy (SEM), IR, powder X-ray diffraction (PXRD), and elemental analysis. CP 1 features a 2D (4,4) network with the point symbol {4⁴.6²}, the 3D supramolecular architecture in CP 1 is controlled through π⋯π stacking interactions. The influence of various concentrations of initial reagents, power of ultrasound irradiation, and ultrasound time on the morphology and size of nano-structured CP 1 were studied in detail. In addition, the luminescence and photocatalytic properties of the nanoparticles of CP 1 for the degradation of methyl blue (MB) have also been investigated.

Six uranyl-organic frameworks with naphthalene-dicarboxylic acid and bipyridyl-based spacers: syntheses, structures, and properties

Six new uranyl complexes that exhibit promising photocatalytic activities for the degradation of TC under UV light based on 1,4-naphthalene dicarboxylic acid and nitrogen-based ligands were synthesized.

Intrinsic triple-emitting 2D copper thiolate coordination polymer as a ratiometric thermometer working over 400 K range

A new lamellar, [Cu(p-SPhCO₂Me)]_n, coordination polymer exhibits intrinsic triple emission with great potential as optical thermometer working over 400 K range and up to 500 K.