Jérôme Long

A High‐Temperature Molecular Ferroelectric Zn/Dy Complex Exhibiting Single‐Ion‐Magnet Behavior and Lanthanide Luminescence

Multifunctional molecular ferroelectrics are exciting materials synthesized using molecular chemistry concepts, which may combine a spontaneous electrical polarization, switched upon applying an electric field, with another physical property. A high-temperature ferroelectric material is presented that is based on a chiral Zn(2+) /Dy(3+) complex exhibiting Dy(3+) luminescence, optical activity, and magnetism. We investigate the correlations between the electric polarization and the crystal structure as well as between the low-temperature magnetic slow relaxation and the optical properties.

Investigation on NMR Relaxivity of Nano-Sized Cyano-Bridged Coordination Polymers

We present the first comparative investigation of the Nuclear Magnetic Resonance (NMR) relaxivity of a series of nanosized cyano-bridged coordination networks stabilized in aqueous solution. These Ln(3+)/[Fe(CN)6](3-) (Ln = Gd, Tb, Y) and M(2+)/[Fe(CN)6](3-) (M = Ni, Cu, Fe) nanoparticles with sizes ranging from 1.4 to 5.5 nm are stabilized by polyethylene glycols (MW = 400 or 1000), polyethylene glycol functionalized with amine groups (MW = 1500), or by N-acetyl-D-glucosamine. The evaluation of NMR relaxivity allowed estimation of the Magnetic Resonance Imaging (MRI) contrast efficiency of our systems. The results demonstrate that Gd(3+)/[Fe(CN)6](3-) nanoparticles have r1p and r2p relaxivities about four times higher than the values observed in the same conditions for the commercial Contrast Agents (CAs) ProHance or Omniscan, regardless of the stabilizing agent used, while nanoparticles of Prussian blue and its analogues M(2+)/[Fe(CN)6](3-) (M = Ni, Cu, Fe) present relatively modest values. The influence of the chemical composition of the nanoparticles, their crystal structure, spin values of lanthanide and transition metal ions, and stabilizing agent on the relaxivity values are investigated and discussed.

Near-infrared luminescent and magnetic cyano-bridged coordination polymers Nd(phen)n(DMF)m[M(CN)8] (M = Mo, W).

New cyano-bridged coordination polymers [Nd(phen)(2)(DMF)(2)(H(2)O)Mo(CN)(8)]·2H(2)O (1) and [Nd(phen)(DMF)(5)M(CN)(8)]·xH(2)O [M = Mo (2), W (3); phen = 1,10-phenanthroline] have one-dimensional structures with variable number of phenanthroline ligands. Compounds exhibit photoluminescence in the near-infrared region and ferromagnetic Nd(3+)-M(5+) interactions.

A Heterometallic (Fe6Na8) Cage-like Silsesquioxane: Synthesis, Structure, Spin Glass Behavior and High Catalytic Activity

The exotic “Asian Lantern” heterometallic cage silsesquioxane [(PhSiO1.5)20(FeO1.5)6(NaO0.5)8(n-BuOH)9.6(C7H8)] (I) was obtained and characterized by X-ray diffraction, EXAFS, topological analyses and DFT calculation. The magnetic property investigations revealed that it shows an unusual spin glass-like behavior induced by a particular triangular arrangement of Fe(III) ions. Cyclohexane and other alkanes as well as benzene can be oxidized to the corresponding alkyl hydroperoxides and phenol, respectively, by hydrogen peroxide in air in the presence of catalytic amounts of complex I and nitric acid. The I-catalyzed reaction of cyclohexane, c-C6H12, with H216O2 in an atmosphere of 18O2 gave a mixture of labeled and non-labeled cyclohexyl hydroperoxides, c-C6H11–16O–16OH and c-C6H11–18O–18OH, respectively, with an 18O incorporation level of ca. 12%. Compound I also revealed high efficiency in the oxidative amidation of alcohols into amides: in the presence of complex I, only 500 ppm of iron was allowed to reach TON and TOF values of 1660 and 92 h−1.

Synthesis and study of Prussian blue type nanoparticles in an alginate matrix

A new approach for the synthesis of Prussian blue type nanoparticles containing nanocomposites in the form of beads or films, as well as their corresponding aqueous colloids, was developed by using a water-soluble alginate matrix as a template and as a stabilizing agent. This method consists of the step-by-step building of a cyanometallate network in the pores of Mn+/alginate ionotropic gels in order to obtain a large range of nanocomposites containing cyano-bridged coordination polymer nanoparticles Mn+/[M′(CN)m]3−/alginate (where Mn+ = Ni2+, Cu2+, Mn2+, Fe2+, Eu3+ and M′ = Fe3+, Cr3+ (m = 6), Mo5+ (m = 8)). The nanocomposite beads and films, as well as the corresponding aqueous colloidal solutions, were studied by infrared (IR), UV/visible spectroscopy, and transmission electron microscopy (TEM) analyses, which reveal the presence of homogeneously dispersed uniformly sized cyano-bridged coordination polymer nanoparticles of 3–7 nm. These nanocomposite beads and films present superparamagnetic, spin-glass or paramagnetic behaviour depending on the nature of the metal ions used. In addition, the Eu3+-containing nanocomposites are room temperature optically active emitters displaying a characteristic 5D0 → 7F0–4 transition.

Iodine Capture by Hofmann-Type Clathrate NiII(pz)[NiII(CN)4]

The thermally stable Hofmann-type clathrate framework Ni(II)(pz)[Ni(II)(CN)4] (pz = pyrazine) was investigated for the efficient and reversible sorption of iodine (I2) in the gaseous phase and in solution with a maximum adsorption capacity of 1 mol of I2 per 1 mol of Ni(II)(pz)[Ni(II)(CN)4] in solution.

Heterometallic Na6Co3 Phenylsilsesquioxane Exhibiting Slow Dynamic Behavior in its Magnetization

A heterometallic phenylsilsesquioxane [(PhSiO1,5)22(CoO)3(NaO0.5)6]⋅(EtOH)6⋅(H2O) 1 cage architecture of Co(II) ions in a triangular topology exhibits a slow dynamic behavior in its magnetization, induced by the freezing of the spins of individual molecules.

Spin crossover polysaccharide nanocomposites

We report in this paper the synthesis, characterisation and spin-crossover (SCO) properties of a series of nanocomposite materials containing very small (∼3 nm) Hofmann clathrate [Fe(pz){M(CN)4}] (M = Ni2+, Pt2+, Pd2+) nanoparticles embedded into different biopolymer polysaccharide matrices: chitosan and alginate. With the objective to understand the influence of the matrix on the SCO properties in these systems, we have modified the internal structure of the matrix, leading to aerogel, xerogel, beads or thin film samples. We show that the cooperativity associated with the spin crossover behaviour depends not only on the cyanometallate bivalent metal, but also on the nature and morphology of the polysaccharide matrix. Moreover, we confirm that for a specific morphology of the matrix, the bistability is maintained in such 3 nm nanoparticles.

An Organoytterbium(III) Complex Exhibiting Field-Induced Single-Ion-Magnet Behavior.

We present a new mononuclear half-sandwich complex, [Cp*Yb(DAD)(THF)]·C7H8 (1), based on a paramagnetic Yb(III) ion coordinated by diamagnetic Cp* and enediamido[2,6-Me2C6H3NCH═CHNC6H3Me2-2,6](2-) (DAD) ligands exhibiting field-induced single-ion-magnet behavior.

Peculiar Field-Dependent Magnetic Behavior of Cyano-Bridged Coordination Polymer Er(H2O)4[W(CN)8]

The two-dimensional cyano-bridged coordination polymer Er(H(2)O)(4)[W(CN)(8)] exhibits a magnetic transition at 12 K and an unusual field-dependent transition from short-range to ferromagnetic ordering.