Metal Organic Frameworks Assembled from Y(III), Na(I), and Chiral Flexible-Achiral Rigid Dicarboxylates

A 12-Connected [Y4((μ3-OH)4]8+ Cluster-Based Luminescent Metal-Organic Framework for Selective Turn-on Detection of F- in H2O

Fluoride ion (F-) is one of the most hazardous elements in potable water. Over intake of F- can give rise to dental fluorosis, kidney failure, or DNA damage. As a result, developing affordable, equipment-free and credible approaches for F- detection is an important task. In this work, a new three dimensional rare earth cluster-based metal-organic framework assembled from lanthanide Y(III) ion, and a linear multifunctional ligand 3-nitro-4,4'-biphenyldicarboxylic acid, formulated as {[Y(μ3-OH)]4[Y(μ3-OH)(μ2-H2O)0.25(H2O)0.5]4[μ4-nba]8}n (1), where H2nba = 3-nitro-4,4'-biphenyldicarboxylic acid, has been hydrothermally synthesized and characterized through infrared spectroscopy (IR), elemental and thermal analysis (EA), power X-ray diffraction (PXRD), and single-crystal X-ray diffraction (SCXRD) analyses. X-ray diffraction structural analysis revealed that 1 crystallizes in tetragonal system with P4¯21m space group, and features a 3D framework with 1D square 18.07(3)2 Å2 channels running along the [0,0,1] or c-axis direction. The structure of 1 is built up of unusual eight-membered rings formed by two types of {Y4O4} clusters connected to each other via 12 μ4-nba2- and 4 μ3-OH- ligands. Three crystallographic independent Y3+ ions display two coordinated configurations with a seven-coordinated distorted monocapped trigonal-prism (YO7) and an eight-coordinated approximately bicapped trigonal-prism (YO8). 1 is further stabilized through O-H⋯O, O-H⋯N, C-H⋯O, and π⋯π interactions. Topologically, MOF 1 can be simplified as a 12-connected 2-nodal Au4Ho topology with a Schläfli symbol {420·628·818}{43}4 or a 6-connected uninodal pcu topology with a Schläfli symbol {412·63}. The fluorescent sensing application of 1 was investigated to cations and anions in H2O. 1 exhibits good luminescence probing turn-on recognition ability toward F- and with a limit detection concentration of F- down to 14.2 μM in aqueous solution (Kec = 11403 M-1, R2 = 0.99289, σ = 0.0539). The findings here provide a feasible detection platform of LnMOFs for highly sensitive discrimination of F- in aqueous media.

Coordination frameworks containing compounds as catalysts

This article describes a collection of MOF containing compounds as catalysts in a diverse range of organic transformation reactions.

Synthesis, Structures and Luminescence Properties of Metal-Organic Frameworks Based on Lithium-Lanthanide and Terephthalate

Metal-organic frameworks assembled from Ln(III), Li(I) and rigid dicarboxylate ligand, formulated as [LiLn(BDC)₂(H₂O)·2(H₂O)] (MS1-6,7a) and [LiTb(BDC)₂] (MS7b) (Ln = Tb, Dy, Ho, Er, Yb, Y_0.96Eu_0.04, Y_0.93Tb_0.07, and H₂BDC = terephthalic acid), were obtained under hydrothermal conditions. The isostructural MS1-6 crystallize in monoclinic P2₁/c space group. While, in the case of Tb³⁺ a mixture of at least two phases was obtained, the former one (MS7a) and a new monoclinic C2/c phase (MS7b). All compounds have been studied by single-crystal and powder X-ray diffraction, thermal analyses (TGA), vibrational spectroscopy (FTIR), and scanning electron microscopy (SEM-EDX). The structures of MS1-6 and MS7a are built up of inorganic-organic hybrid chains. These chains constructed from unusual four-membered rings, are formed by edge- and vertex-shared {LnO₈} and {LiO₄} polyhedra through oxygen atoms O3 (vertex) and O6-O7 (edge). Each chain is cross-linked to six neighboring chains through six terephthalate bridges. While, the structure of MS7b is constructed from double inorganic chains, and each chain is, in turn, related symmetrically to the adjacent one through the c glide plane. These chains are formed by infinitely alternating {LiO₄} and {TbO₈} polyhedra through (O2-O3) edges to create Tb–O–Li connectivity along the c-axis. Both MS1-6,7a and MS7b structures possess a 3D framework with 1D trigonal channels running along the a and c axes, containing water molecules and anhydrous, respectively. Topological studies revealed that MS1-6 and MS7a have a new 2-nodal 3,10-c net, while MS7b generates a 3D net with unusual β-Sn topology. The photoluminescence properties Eu- and Tb-doped compounds (MS5-6) are also investigated, exhibiting strong red and green light emissions, respectively, which are attributed to the efficient energy transfer process from the BDC ligand to Eu³⁺ and Tb³⁺.

Luminescence and slow magnetic relaxation of isostructural 2D lanthanide metal–organic frameworks derived from both nicotinate N-oxide and glutarate

The isostructural 2D lanthanide coordination polymers may exhibit either luminescence or slow magnetic relaxation, depending on the lanthanide ions.

Synthesis, Crystal Structure, and Luminescence Properties of a New Calcium(II) Coordination Polymer Based on L-Malic Acid

A new calcium coordination polymer [Ca(HL-MA)]n(H3L-MA = L-malic acid) has been solvothermally synthesized. The structure of the newly synthesized complex has been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, reflectance UV-Vis & IR spectra, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). The single crystal structure analysis showed that the complex forms three-dimensional framework. The new Ca(II) complex has displayed very high thermal stability which was inferred from TGA and PXRD results. As far as the optical property of the new complex is concerned, the complex emitted its own characteristic sensitized luminescence.

Luminescent multifunctional lanthanides-based metal-organic frameworks

Metal-organic frameworks based on trivalent lanthanides (LnMOFs) are a very promising class of materials for addressing the challenges in engineering of luminescent centres. Lanthanide-bearing phosphors find numerous applications in lighting, optical communications, photonics and biomedical devices. In this critical review we discuss the potential of LnMOFs as multifunctional systems, which combine light emission with properties such as microporosity, magnetism, chirality, molecule and ion sensing, catalysis and activity as multimodal imaging contrast agents. We argue that these materials present a unique chance of observing synergy between several of these properties, such as the coupling between photoluminescence and magnetism. Moreover, an integrated approach towards the design of efficient, stable, cheap, environmentally-friendly and multifunctional luminescent LnMOFs is still missing. Although research into LnMOFs is at its early stage and much basic knowledge is still needed, the field is ripe for new ideas, which will enable sensor devices and photonic prototypes to become a commercial reality (81 references).