Eight-coordinate mono- and dinuclear Dy(III) complexes containing a rigid equatorial plane and an anisobidentate carboxylate ligand in the axial position: synthesis, structure and magnetism.

A rigid pentadentate chelating ligand (HL) has been utilized to synthesize a series of octacoordinate mononuclear complexes, [Dy(L)(PhPO)(OOCR)] (where R = CH (1), C(CH) (2), CF (3)) and a dinuclear complex, [Dy(L)(PhPO){(OOC)CH}] (4) based on the highly anisotropic Dy(III) ion. All the complexes were structurally characterized by single-crystal X-ray diffraction studies. The complexes were formed by the coordination action of the dianionic pentadentate ligand [L], one phosphine oxide, and carboxylate ligands.

Incorporation of Photo- and Thermoresponsive -Salicylidene Aniline Derivatives into Cobalt and Zinc Layered Hydroxides.

In search of new multifunctional hybrid materials and in order to investigate the influence of chemical modification on the possible synergy between properties, the carboxylate and sulfonate derivatives of photo- and thermochromic N-salicylidene aniline were successfully inserted into Co(II)- and Zn(II)-based layered simple hydroxides, resulting in four novel hybrids: Co--Sali-COO, Co--Sali-SO, Zn--Sali-COO, and Zn--Sali-SO. All synthesized hybrids adopt a double organic layered configuration, which prevents the photoisomerization ability of -Sali-R molecules in the hybrids. However, the Zn hybrids exhibit fluorescence upon exposure to UV light due to the excited-state intramolecular proton transfer (ESIPT) mechanism.

Rhenium Carbonyl Molecular Catalysts for CO Electroreduction: Effects on Catalysis of Bipyridine Substituents Mimicking Anchorage Functions to Modify Electrodes.

Heterogenization of molecular catalysts on (photo)electrode surfaces is required to design devices performing processes enabling to store renewable energy in chemical bonds. Among the various strategies to immobilize molecular catalysts, direct chemical bonding to conductive surfaces presents some advantages because of the robustness of the linkage. When the catalyst is, as it is often the case, a transition metal complex, the anchoring group has to be connected to the complex through the ligands, and an important question is thus raised on the influence of this function on the redox and on the catalytic properties of the complex.

Exchange-driven slow relaxation of magnetization in NiII2LnIII2 (Ln = Y, Gd, Tb and Dy) butterfly complexes: experimental and theoretical studies.

The tetranuclear NiII2LnIII2 complexes, [{L'{Ni(MeOH)(μ-OAc)}(μ-MeO)Ln}, Ln = Y (1), Gd (2), Tb (3), and Dy (4)], were prepared using a Schiff base ligand, HL [HL = 3-{(2-hydroxy-3-methoxybenzylidene)amino}-2-(2-hydroxy-3-methoxyphenyl)-2,3-dihydroquinazolin-4(1)-one, where {L'} is the deprotonated open structure of HL]. X-ray crystallographic analysis of 1-4 revealed that all the complexes crystallized in the orthorhombic () space group, and possessed an isostructural tetranuclear butterfly or defect dicubane like core. Direct current magnetic susceptibility measurements performed on 2-4 revealed that all these complexes show an intramolecular ferromagnetic exchange coupling.

Synthesis and characterization of a new monometallic layered double hydroxide using manganese.

This article reports for the first time the synthesis of an LDH using only manganese as the divalent and trivalent metallic ion. Analysis of the pH, redox potential, and chemical composition during the oxidation of a manganese basic salt using persulfate indicates the oxidation of 1/3 of the initial Mn ions, in agreement with the paramagnetic structure and XPS analysis. Infrared, Raman spectra and thermogravimetric analysis results were similar to the ones obtained with Fe-LDH also known as green rust.

A Single Bioinspired Hexameric Nickel Catechol-Alloxazine Catalyst Combines Metal and Radical Mechanisms for Alkene Hydrosilylation.

Mechanisms combining organic radicals and metallic intermediates hold strong potential in homogeneous catalysis. Such activation modes require careful optimization of two interconnected processes: one for the generation of radicals and one for their productive integration towards the final product. We report that a bioinspired polymetallic nickel complex can combine ligand- and metal-centered reactivities to perform fast hydrosilylation of alkenes under mild conditions through an unusual dual radical- and metal-based mechanism.

A Magnetocaloric Glass from an Ionic-Liquid Gadolinium Complex.

[Gd (L) (H O) ](Tf N) was obtained from reaction of Gd O with 1-carboxymethyl-3-ethylimidazolium chloride (LHCl). The material was found to be an ionic liquid that freezes to glassy state on cooling to -30 °C. Variable-temperature magnetic studies reveal the presence of weak magnetic intramolecular interactions in the glass.

Fast and efficient shear-force assisted production of covalently functionalized oxide nanosheets.

Hypothesis: While controlled and efficient exfoliation of layered oxides often remains a time consuming challenge, the surface modification of inorganic nanosheets is of outmost importance for future applications. The functionalization of the bulk material prior to exfoliation should allow the application of tools developped for Van der Waals materials to directly produce functionalized oxide nanosheets.

Experiments: The Aurivillius phase BiSrTaO is functionalized by a linear aliphatic phosphonic acid via microwave-assisted reactions.

Large Enhancement of Ferromagnetism under a Collective Strong Coupling of YBCO Nanoparticles.

Light-Matter strong coupling in the vacuum limit has been shown, over the past decade, to enhance material properties. Oxide nanoparticles are known to exhibit weak ferromagnetism due to vacancies in the lattice. Here we report the 700-fold enhancement of the ferromagnetism of YBaCuO nanoparticles under a cooperative strong coupling at room temperature.

Quantitative Analysis of the Specific Absorption Rate Dependence on the Magnetic Field Strength in ZnFeO Nanoparticles.

Superparamagnetic ZnFeO magnetic nanoparticles (0 ≤ x < 0.5) with spherical shapes of 16 nm average diameter and different zinc doping level have been successfully synthesized by co-precipitation method. The homogeneous zinc substitution of iron cations into the magnetite crystalline structure has led to an increase in the saturation magnetization of nanoparticles up to 120 Am/kg for x ~ 0.

Synthesis of NiF and NiF·4HO Nanoparticles by Microemulsion and Their Self-Assembly.

Superstructures or self-assembled nanoparticles open the development of new materials with improved and/or novel properties. Here, we present nickel fluoride (NiF) self-assemblies by successive preparatory methods. Originally, the self-assemblies were obtained by exploiting the water-in-oil microemulsion technique as a result of auto-organization of hydrated NiF (NiF·4HO) nanoparticles.

Origin of Ferromagnetism and Magnetic Anisotropy in a Family of Copper(II) Triangles.

Previously reported ferromagnetic triangles (NnBu ) [Cu (μ -Cl) (μ-4-NO -pz) Cl ] (1), (PPN) [Cu (μ -Cl) (μ-pz) Cl ] (2), (bmim) [Cu (μ -Cl) (μ-pz) Cl ] (3) and newly reported (PPh ) [Cu (μ -Cl) (μ-4-Ph-pz) Cl ] (4) were studied by magnetic susceptometry, electron paramagnetic resonance (EPR) spectroscopy and ab initio calculations to assess the origins of their ferromagnetism and of the magnetic anisotropy of their ground S=3/2 state (PPN =bis(triphenylphosphine)iminium, bmim =1-butyl-3-methylbenzimidazolium, pz =pyrazolate). Ab initio studies revealed the d character of the magnetic orbitals of the compressed trigonal bipyramidal copper(II) ions. Ferromagnetic interactions were attributed to weak orbital overlap via the pyrazolate bridges.

M(HO)(POCHOH)·(HO) (M = Co, Mn, Zn, Cu): a new series of layered metallophosphonate compounds obtained from 6-hydroxy-2-naphthylphosphonic acid.

Four new metallophosphonates M(HO)(POCHOH)·(HO) (M = Mn, Co, Cu, Zn) were obtained as single crystal and polycrystalline powders by hydrothermal synthesis from the precursors 6-hydroxy-2-naphthylphosphonic acid and the corresponding metal salts. These analogous hybrids crystalized in the space group P12/c1 in a lamellar structure. Their layered structures consisted of inorganic [M(HO)(POC)] layers stacked with organic bilayers of 6-hydroxy-2-naphthyl moieties "HO-CH" and free water molecules.

Copper complexes for the promotion of iminopyridine ligands derived from β-alanine and self-aldol additions: relaxivity and cytotoxic properties.

In the study presented herein, we explore the ability of copper complexes with coordinated pyridine-2-carboxaldehyde (pyca) or 2-acetylpyridine (acepy) ligands to promote the addition of amines (Schiff condensation) and other nucleophiles such as alcohols (hemiacetal formation). Distinct reactivity patterns are observed: unlike pyca complexes, acepy copper complexes can promote self-aldol addition. The introduction of a flexible chain via Schiff condensation with β-alanine allows the possibility of chelate ring ring-opening processes mediated by pH.

Magnetic and luminescent coordination networks based on imidazolium salts and lanthanides for sensitive ratiometric thermometry.

The synthesis and characterization of six new lanthanide networks [Ln(L)(ox)(HO)] with Ln = Eu, Gd, Tb, Dy, Ho and Yb is reported. They were synthesized by solvo-ionothermal reaction of lanthanide nitrate Ln(NO)·HO with the 1,3-bis(carboxymethyl)imidazolium [HL] ligand and oxalic acid (Hox) in a water/ethanol solution. The crystal structure of these compounds has been solved on single crystals and the magnetic and luminescent properties have been investigated relying on intrinsic properties of the lanthanide ions.

Determination of the Distributions of the Spin-Hamiltonian Parameters in Spin Triangles: A Combined Magnetic Susceptometry and Electron Paramagnetic Resonance Spectroscopic Study of the Highly Symmetric [CrO(PhCOO)(py)](ClO)·0.5py.

Magnetic susceptibility and X-band electron paramagnetic resonance (EPR) studies have been carried out on the highly symmetric [CrO(PhCOO)(py)](ClO)·0.5py (1; py = pyridine), whose cation exhibits a D crystallographically imposed molecular symmetry. While magnetic susceptibility data can be interpreted with an equilateral magnetic model described by the effective multispin Hamiltonian Ĥ = -2 J(Ŝ·Ŝ + Ŝ·Ŝ + Ŝ·Ŝ), EPR data require an isosceles model described by the multispin Hamiltonian Ĥ = -2 J( Ŝ· Ŝ + Ŝ· Ŝ) - 2 J' Ŝ· Ŝ, where Δ J = J - J' ≠ 0.

Microwave-assisted functionalization of the Aurivillius phase BiSrTaO: diol grafting and amine insertion alcohol grafting.

Microwave-assisted functionalization of the layered Aurivillius phase BiSrTaO by alcohols is thoroughly investigated. The grafting of linear aliphatic and bulky alcohols is studied as a function of the starting material, underlining the importance of the prefunctionalization of the layered perovskite, for instance by butylamine. In addition, the functionalization by α,ω-alkanediols is explored.

Towards ionic liquids with tailored magnetic properties: bmim salts of ferro- and antiferromagnetic Cu triangles.

Complexes (bmim)[Cu(μ-Cl)(μ-pz)Cl] (1), (bmim)[Cu(μ-OH)(μ-pz)Cl] (2) and (bmim)[Cu(μ-OH)(μ-Cl)(μ-pz)Cl] (3) were synthesized (bmim = 1-butyl-3-methylimidazolium, pz = pyrazolato anion). Dianionic complexes 1 and 3 were obtained as crystalline solids, whereas the monoanionic complex 2 was obtained as a viscous paste. Magnetic susceptibility and X-band EPR studies revealed intramolecular ferromagnetic interactions for 1 with small magnetoanisotropy in its ground state (D∼ 10 cm) and intramolecular antiferromagnetic interactions for 2 and 3 (-285 and -98 cm average J, respectively) with important magnetic anisotropy in their ground states stemming from a combination of low magnetic symmetry and antisymmetric exchange interactions.

Post-Synthesis Modification of the Aurivillius Phase BiSrTaO via In Situ Microwave-Assisted "Click Reaction".

A new strategy for the functionalization of layered perovskites is presented, based on the in situ post-synthesis modification of a prefunctionalized phase by copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC). The microwave-assisted protonation and grafting of an alkyne alcohol provides the alkyne-functionalized precursor within a few hours, starting from BiSrTaO. The subsequent microwave-assisted in situ "click reaction" allows the post-synthesis modification of the precursor within ∼2 h, providing a layered perovskite functionalized by an alcohol-grafted 1,4-disubstituted-1H-1,2,3-triazole.

Efficient Microwave-Assisted Functionalization of the Aurivillius-Phase Bi2SrTa2O9.

A new method of acidification and subsequent functionalization of the Aurivillius-phase Bi2SrTa2O9 (BST), using microwave irradiation, was developed. This method enables to obtain hybridized phases from layered BST. Functionalization of BST by various kinds of amines and diamines can be achieved in a few hours only, compared to much longer time (over a week) using conventional heating.

Assembly, disassembly, and reassembly: conversion of homometallic coordination networks into mixed metal-organic frameworks.

A strategy for the conversion of homometallic coordination networks into mixed metal-organic frameworks (MM'MOFs) is proposed. Ni(II) complexes of dipyrrin (dpm) ligands bearing peripheral pyridyl or imidazolyl units have been shown to self-assemble into coordination polymers with the metal cation in an octahedral environment coordinated to two bis-pyrrolic chelates and two neutral monodentate coordinating units such as pyridyl or imidazolyl moieties. Taking advantage of the chelate effect, the two monodentate units may be replaced by a diimine ligand leading to the disassembly of the networks by the formation of discrete soluble complexes.

Hexanuclear, heterometallic, Ni₃Ln₃ complexes possessing O-capped homo- and heterometallic structural subunits: SMM behavior of the dysprosium analogue.

The reaction of hetero donor chelating mannich base ligand 6,6'-{(2-(dimethylamino)ethylazanediyl)bis(methylene)}bis(2-methoxy-4-methylphenol) with Ni(ClO4)2·6H2O and lanthanide(III) salts [Dy(III) (1); Tb(III) (2); Gd (III) (3); Ho(III) (4); and Er(III) (5)] in the presence of triethylamine and pivalic acid afforded a series of heterometallic hexanuclear Ni(II)-Ln(III) coordination compounds, [Ni3Ln3(μ3-O)(μ3-OH)3(L)3(μ-OOCCMe3)3]·(ClO4)·wCH3CN·xCH2Cl2·yCH3OH·zH2O [for 1, w = 8, x = 3, y = 0, z = 5.5; for 2, w = 0, x = 5, y = 0, z = 6.5; for 3, w = 15, x = 18, y = 3, z = 7.