Search Results (11)

By combining Er^III and Yb^III ions with 3,6-dithiophene-anilate (Th₂An) and scorpionate hydrotris(pyrazol-1-yl)borate (HBpz₃⁻) ligands new luminescent dinuclear complexes are obtained. The two materials formulated as [((HB(pz)₃)₂Yb)₂(μ-th₂An)]·4DCM·1.3H₂O 1Yb and [((HB(pz)₃)₂Er)₂(μ-th₂An)]·4DCM·1.8H₂O 1Er, respectively, have been structurally characterized by SC-XRD and PXRD studies. This study presents a comprehensive investigation of the photophysical properties of the Th₂An ligand for the first time. Our findings reveal the crucial role of the thiophene anilate as an effective optical antenna, which sensitizes near-infrared (NIR)-emitting lanthanide ions, specifically Er^III and Yb^III. The significant impact of vibrational quenching on the Ln^III NIR emission efficiency has been also highlighted. Full article

Here, we illustrate the use of formamide (fma) and anilato-type ligands to build two-dimensional lattices with lanthanoids. Thus, we describe the synthesis and crystal structure of four lattices formulated as [Ln₂(C₆O₄X₂)₃(fma)₆]·6fma with Ln/X = La/Cl (1), La/Br (2), Eu/Cl (3), and Eu/Br (4), where C₆O₄X₂²⁻ = dianion of 3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone with X = Cl (chloranilato) and X = Br (bromanilato). Single crystal X-ray analysis shows that the four compounds crystallize in the triclinic P-1 space group and present two-dimensional, very distorted hexagonal lattices with the lanthanoids ions in the vertex coordinated by three anilato ligands forming the sides of the distorted hexagons that appear as rectangles. The rectangles are disposed parallel to their long sides in a brick wall fashion. The nona-coordination of the lanthanoids is completed by three formamide molecules. These layered compounds include three additional formamide molecules per lanthanoid atom, located in the interlayer space inside the channels formed by the eclipsed packing of the layers. We discuss the differences observed among these compounds due to the change of the lanthanoid ion (La and Eu) and of the substituent group X in the anilato ligand (Cl and Br). Full article

We report the synthesis, structural investigation, and thermal behavior for three zinc-based 1D-coordination polymers with 3,6-di-tert-butyl-2,5-dihydroxy-p-benzoquinone, which were synthesized in the presence of different glycols. The interaction of zinc nitrate with glycols, followed by using the resulting solution in solvothermal synthesis with the anilate ligand in DMF, makes it possible to obtain linear polymer structures with 1,2-ethylene or 1,2-propylene glycols coordinated to the metal. The reaction involving 1,3-propylene glycol under similar conditions gives a crystal structure that does not contain a diol. The crystal and molecular structures of the synthesized compounds were determined using single crystal by X-ray structural analysis. The influence of glycol molecules coordinated to the metal on the thermal destruction of synthesized compounds is shown. Full article

The search for two- and three-dimensional materials with slow relaxation of the magnetization (single-ion magnets, SIM and single-molecule magnets, SMM) has become a very active area in recent years. Here we show how it is possible to prepare two-dimensional SIMs by combining Dy(III) with two different anilato-type ligands (dianions of the 3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone: C₆O₄X₂²⁻, with X = H and Cl) in dimethyl sulfoxide (dmso). The two compounds prepared, formulated as: [Dy₂(C₆O₄H₂)₃(dmso)₂(H₂O)₂]·2dmso·18H₂O (1) and [Dy₂(C₆O₄Cl₂)₃(dmso)₄]·2dmso·2H₂O (2) show distorted hexagonal honeycomb layers with the solvent molecules (dmso and H₂O) located in the interlayer space and in the hexagonal channels that run perpendicular to the layers. The magnetic measurements of compounds 1, 2 and [Dy₂(C₆O₄(CN)Cl)₃(dmso)₆] (3), a recently reported related compound, show that the three compounds present slow relaxation of the magnetization. In compound 1 the SIM behaviour does not need the application of a DC field whereas 2 and 3 are field-induced SIM (FI-SIM) since they show slow relaxation of the magnetization when a DC field is applied. We discuss the differences observed in the crystal structures and magnetic properties based on the X group of the anilato ligands (H, Cl and Cl/CN) in 1–3 and in the recently reported derivative [Dy₂(C₆O₄Br₂)₃(dmso)₄]·2dmso·2H₂O (4) with X = Br, that is also a FI-SIM. Full article

In this review, we describe all the structurally characterized complexes containing lanthanoids (Ln, including La and group 3 metals: Y and Lu) and any anilato-type ligand (3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone dianion = C₆O₄X₂²⁻). We present all the anilato-Ln compounds including those where, besides the anilato-type ligand, there is one or more coligands or solvent molecules coordinated to the lanthanoid ions. We show the different structural types observed in these compounds: from discrete monomers, dimers and tetramers to extended 1D, 2D and 3D lattices with different topologies. We also revise the magnetic properties of these Ln-anilato compounds, including single-molecule magnet (SMM) and single-ion magnet (SIM) behaviours. Finally, we show the luminescent and electrochemical properties of some of them, their gas/solvent adsorption/absorption and exchange capacity and the attempts to prepare them as thin films. Full article

We report the synthesis and the characterization of six new heterometallic chloranilato-based ferrimagnets formulated as (NBu₄)[MnCr(C₆O₄Cl₂)₃]·nG with n = 1 for G = C₆H₅Cl (1), C₆H₅I (3), and C₆H₅CH₃ (4); n = 1.5 for G = C₆H₅Br (2) and n = 2 for G = C₆H₅CN (5) and C₆H₅NO₂ (6); (C₆O₄Cl₂)²⁻ = 1,3-dichloro,2,5-dihydroxy-1,4-benzoquinone dianion. The six compounds are isostructural and show hexagonal honeycomb layers of the type [MnCr(C₆O₄Cl₂)₃]⁻ alternating with layers containing the NBu₄⁺ cations. The hexagons are formed by alternating Mn(II) and Cr(III) connected by bridging bis-bidentate chloranilato ligands. The benzene derivative solvent molecules are located in the hexagonal channels (formed by the eclipsed packing of the honeycomb layers) showing π-π interactions with the anilato rings. The six compounds behave as ferrimagnets with ordering temperatures in the range 9.8–11.2 K that can be finely tuned by the donor character of the benzene ring and by the number of solvent molecules inserted in the hexagonal channels. The larger the electron density on the aromatic ring and the larger the number of solvent molecules are, the higher T_c is. The only exception is provided by toluene, where the formation of H-bonds might be at the origin of weaker π-π interactions observed in this compound. Full article

Here we show the important role played by the size of the lanthanoid and the solvent used in the final structures of several two-dimensional magnetic coordination polymers with the ligand chlorocyananilato, (C₆O₄(CN)Cl)²⁻. With this aim we have prepared five compounds: [Nd₂(C₆O₄(CN)Cl)₃(DMF)₆] (1) (DMF = dimethylformamide), [Dy₂(C₆O₄(CN)Cl)₃(DMF)₆]·4H₂O (2), [Ho₂(C₆O₄(CN)Cl)₃(DMF)₆]·2H₂O (3), and [Ln₂(C₆O₄(CN)Cl)₃(DMSO)₆] with Ln = Ce (4) and Nd (5) (DMSO = dimethylsulfoxide). These compounds are formed by two dimensional networks with a (6,3)-topology but, depending on the size of the lanthanoid and on the solvent used, show important structural differences, including the size, shape, distortion and content of the cavities as well as the flatness of the layers. The comparison of compounds 1–3 and 4–5 shows the role played by the size of the lanthanoid while keeping constant the solvent, whereas, the comparison of compounds 1 and 5 shows the role of the solvent (DMF vs. DMSO) while keeping constant the lanthanoid. The magnetic properties of all of them show the absence of noticeable magnetic interactions, in agreement with previous results that can be explained by the internal character of the 4f electron and the weak magnetic coupling mediated by these anilato-based ligands. Full article

Five new anilato-based, Ln(III)-containing, layered compounds have been prepared with the asymmetric ligand chlorocyananilato (C₆O₄(CN)Cl)²⁻; different Ln(III) ions Ce(III), Pr(III), Yb(III), and Dy(III); and the three different solvents H₂O, dimethylsolfoxide (DMSO), and dimethylformamide (DMF). Compounds [Ce₂(C₆O₄(CN)Cl)₃(DMF)₆]·2H₂O (1), [Pr₂(C₆O₄(CN)Cl)₃(DMF)₆] (2), [Pr₂(C₆O₄(CN)Cl)₃(DMSO)₆] (3), [Yb₂(C₆O₄(CN)Cl)₃(DMSO)₄]·2H₂O (4) and [H₃O][Dy(C₆O₄(CN)Cl)₂(H₂O)]·4H₂O (5) show the important role that the Ln(III) size, as well as the size and shape of the solvent may play in the crystal structure of each compound. Compounds 1–4 present (6,3)-2D hexagonal lattices, with important differences in the coordination number and geometry of the Ln(III) ion, as well as in the distortion of the hexagonal cavities, depending on the Ln(III) and solvent size. Compound 5 (the only one prepared with water) presents a (4,4)-2D square lattice, where the Dy(III) ions are surrounded by four chelating anilato ligands. Compounds 2–4 are essentially paramagnetic, confirming the presence of weak (if any) magnetic coupling mediated by the anilato ligands when connecting Ln(III) ions. Compounds 2–4 showed a red shift and a broadening of the emission band of the ligand. Compound 4 also showed a strong emission band attributed to the Yb(III), suggesting an antenna effect of the ligand. An energy transfer diagram is proposed to explain these luminescent properties. Full article

The aim of the present work is to highlight the unique role of anilato-ligands, derivatives of the 2,5-dioxy-1,4-benzoquinone framework containing various substituents at the 3 and 6 positions (X = H, Cl, Br, I, CN, etc.), in engineering a great variety of new materials showing peculiar magnetic and/or conducting properties. Homoleptic anilato-based molecular building blocks and related materials will be discussed. Selected examples of such materials, spanning from graphene-related layered magnetic materials to intercalated supramolecular arrays, ferromagnetic 3D monometallic lanthanoid assemblies, multifunctional materials with coexistence of magnetic/conducting properties and/or chirality and multifunctional metal-organic frameworks (MOFs) will be discussed herein. The influence of (i) the electronic nature of the X substituents and (ii) intermolecular interactions i.e., H-Bonding, Halogen-Bonding, π-π stacking and dipolar interactions, on the physical properties of the resulting material will be also highlighted. A combined structural/physical properties analysis will be reported to provide an effective tool for designing novel anilate-based supramolecular architectures showing improved and/or novel physical properties. The role of the molecular approach in this context is pointed out as well, since it enables the chemical design of the molecular building blocks being suitable for self-assembly to form supramolecular structures with the desired interactions and physical properties. Full article

The first complexes with lanthanoid ions and the nitroanilato ligand have been synthesized (nitroanilate dianion = [C₆O₄(NO₂)₂]²⁻ = dianion of the 3,6-dinitro-2,5-dihydroxo-1,4-dibenzoquinone ligand). This family of dimers can be formulated as [Ln₂(C₆O₄(NO₂)₂)₃(H₂O)₁₀]·6H₂O with Ln(III) = Sm (1), Gd (2), Tb (3), Dy (4), Ho (5), and Er (6). The X-ray structure of this family of isostructural complexes shows that they all present a dimeric structure where the Ln³⁺ ions are connected by a bis-bidentate nitroanilato ligand. Each metal completes its nonacoordination environment with a terminal bidentate nitroanilato ligand and five water molecules in a slightly distorted tri-capped trigonal prismatic geometry. The magnetic properties of this family show the expected contributions of the lanthanoid ions without any noticeable magnetic interaction through the nitroanilato ligand. The compounds present luminesce of the nitroanilato ligand superimposed with a weaker emission from the lanthanide ion in compound 5 (Ho). Full article

In order to synthesize new coordination polymers with original architectures and interesting magnetic properties, we used the nitranilate ligand (C₆O₄(NO₂)₂²⁻ = C₆N₂O₈²⁻), derived from the dianionic ligand dhbq²⁻ (2,5-dihydroxy-1,4-benzoquinone = H₂C₆O₄²⁻). The use of this bis-bidentate bridging ligand led to [(DAMS)₂{FeNa(C₆N₂O₈)₃}·CH₃CN]_n (1) (DAMS⁺ = C₁₆H₁₇N₂⁺ = 4-[4-(dimethylamino)-α-styryl]-1-methylpyridinium), a 2D heterometallic coordination polymer presenting an unprecedented structure for any anilato-based compound. This structural type is a 3,6-connected 2D coordination polymer derived from the well-known honeycomb hexagonal structure, where Fe(III) ions alternate with Na⁺ dimers (as Na₂O₁₂ units) in the vertices of the hexagons and with an additional [Fe(C₆N₂O₈)₃]³⁻ anion located in the center of the hexagons connecting the three Na⁺ dimers. The magnetic properties of compound 1 show the presence of paramagnetic isolated high spin Fe(III) complexes with a zero field splitting, |D| = 8.5 cm⁻¹. Full article