Kevin Bernot

Institut National des Sciences Appliquées de Rennes | INSA Rennes · Equipe Chimie du Solide et Matériaux SCR/MI-INSA

A 1D coordination compound made of a photochromic dithienylethene linker and [Dy(Tp2−py)F]⁺ units (with Tp2−py=tris(3‐(2‐pyridyl)pyrazolyl)hydroborate) and having tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate counterions is reported. Full photoconversion from the closed isomer to the open isomer of the dithienylethene within single crystals allow...

We are reporting on the use of a low‐coordinate YbIII amide with near‐ideal planar trigonal [Yb{N(SiMe3)2}3] (1) and on a bipyramidal trigonal derivative [Yb{N(SiMe2H)2}3 ⋅ (thf)2] (2) that constitute quintessential cases to investigate luminescent and magnetic properties otherwise usually blurred on less symmetrical compounds. These compounds repr...

Metallogels are versatile and intriguing objects that can be used as media for the deposition of extended molecular architectures on surface. In this work, we investigate the thermodynamic and kinetics...

We here present how rebalancing the interplay between H‐bonds and dispersive forces (Van der Waals/π–π stacking) may induce or not the generation of kinetic metastable states. In particular, we show that extending the aromatic content and favouring the interchain VdW interactions causes a delay into the cooperative supramolecular polymerization of...

We here present how rebalancing the interplay between H‐bonds and dispersive forces (Van der Waals / π‐ π stacking) may induce or not the generation of kinetic metastable states. In particular, we show that extending the aromatic content and favouring the interchain VdW interactions causes a delay into the cooperative supramolecular polymerization...

Lanthanide Single-Molecule Magnets (SMMs) fascinate the scientific community due to their plethora of potential applications ranging from data storage to spintronic devices and quantum computing. This review article proposes a comprehensive description of the influence of the nuclear spin, i.e. hyperfine interaction, on the magnetic properties of l...

An approach to supervised classification and regression of superconductive materials is proposed which builds on the DeepSet technology. This enables us to provide the chemical constituents of the examined compounds as an input to the algorithm, while avoiding artefacts that could originate from the chosen ordering in the list. The performance of t...

A dinuclear metallacycle assembled from a bispyridyl dithienylethene linker and a highly anisotropic dysprosium based Single Molecule Magnet shows magnetic hysteresis at 1.8 K together with photoisomerization in single crystals....

In this study, we investigate the thermodynamics of lanthanide-based coordination polymer molecular alloys. We demonstrate that if lanthanide ions have many chemical similarities, the solubility of homo-lanthanide-based coordination polymers can vary significantly from one lanthanide ion to another. Indeed, we experimentally determine the solubilit...

In this study we demonstrate that single-chain magnets (SCMs) can be assembled in gel phase and transferred intact on surface. We take advantage of a family of SCMs based on TbIII ions and nitronyl-nitroxides radicals functionalized with short alkyl chains known to form crystalline supramolecular nanotubes interacting with heptane acting as crystal...

Measuring the luminance of lanthanide-based coordination polymers under UV excitation is of prime importance for many technological applications. This study highlights that the quantum yield gives no information about the luminescence intensity of a solid-state compound. Indeed, compounds with high quantum yield can actually be poorly luminescent....

Reactions in water at ambient temperature and pressure between a lanthanide ion and benzene-1,3,5-tricarboxylate (or trimesate) lead to two series of iso-structural coordination polymers. Their general chemical formula is [Ln(tma)(H2O)6]∞ for the lightest lanthanide ions (Ln = La-Dy except Pm), while it is [Ln(tma)(H2O)5·3.5H2O]∞ for the heaviest o...

Microwave-assisted reactions, between 2-bromobenzoic acid (2-bbH) and hexa-lanthanide molecular precursors of general chemical formula Ln6(µ6-O)(µ3-OH)8(NO3)6(H2O)12∙2NO3∙2H2O ([Ln6]), lead to iso-structural 1D coordination polymers of general chemical formula [Ln(2-bb)3]∞ with Ln = Eu, Tb or Dy. These compounds crystallize in the monoclinic system...

Crystal growths in gel medium of lanthanide–based coordination polymers with 2,5–dihydroxyterephthalate (dhbdc²⁻) as ligand lead to two different crystal structures depending on the lanthanide ion. Lanthanide–based coordination polymers that crystallize in these two structural type have respective chemical formulas [Ln2(dhbdc)3(H2O)12·6H2O]∞ with L...

The careful monitoring of crystallization conditions of a mixture made of a TbIII building block and a substituted nitronyl-nitroxide that typically provides infinite coordination polymers (chains), affords a remarkably stable linear hexanuclear molecule made of six TbIII ions and five NIT radicals. The hexanuclear units are double-bridged by water...

Single‐Molecule Magnet (SMM) property is by essence molecular, while commonly measured in solid crystalline state. Solvent crystallization molecules are usually neglected in the analysis and interpretation of solid‐state properties. The solvation/desolvation process in the polyoxometalate(POM)‐based Na9[Er(W5O18)2] ⋅ 35 H2O SMM demonstrates that th...

Isostructural lanthanide-based coordination polymers with general chemical formula [Ln(phen)(glu)(NO3)]∞ with Ln = La-Tm (except Ce and Pm) have been synthesized by hydrothermal methods (H2glu stands for glutaric acid and phen stands for 1,10-phenantroline). They crystallize in the monoclinic system with the P21/c (no. 14) space group. The crystal...

Highly luminescent and color-tunable stable colloidal suspensions of molecular alloys are reported. They are produced via a green synthetic route in ethanol medium. The mean hydrodynamic diameter of the colloids is about 140 nm and the colloidal suspensions are stable for more than a month. The optical properties of the molecular alloys suspensions...

ConspectusLanthanide ions are prime ingredients for the design of compounds, materials, and devices with unique magnetic and optical properties. Accordingly, coordination chemistry is one of the best tools for building molecular edifices from these ions because it allows careful control of the ions' environment and of the dimensionality of the fina...

Reactions in water between lanthanide chlorides and the disodium salt of 2-hydroxyterephthalic acid (H2hbdc) lead to six families of lanthanide-based coordination polymers depending on the lanthanide ion and the crystal growth method. Compounds that constitute family F1 have the general chemical formula [Ln(Hhbdc)(hbdc)·9H2O]∞ with Ln = La–Nd and h...

We report the synthesis of a pyrazine-based bis-tridentate diarylethene (DAE) ligand and the corresponding dinuclear yttrium and dysprosium complexes that all show T-type photochromism. Large changes in the photochromic behaviour are induced by metal coordination, including a tuning of the bleaching rate by several orders of magnitude, characterize...

A series of isostructural homo- and heterolanthanide coordination polymers of formula [Ln2(dcpa)3(H2O)]∞ with Ln = La-Gd have been obtained by reactions in water between the lightest lanthanide chlorides and the disodium salt of 4,5-dichlorophthalic acid (H2dcpa). They present particularly high thermal stability for coordination compounds (up to 40...

Reactions in water of lanthanide chlorides with the sodium salt of 4,5-dichlorophthalate (dcpa2-) lead to two families of isostructural coordination polymers: family F1 that gathers compounds with the general chemical formula [Ln2(dcpa)3(H2O)]∞ with Ln = La-Gd (except Pm) and family F2 that gathers compounds with general chemical formula [Ln2(dcpa)...

The size, morphology, and purity control of coordination compound powders is a key stage for their conversion into materials and devices. In particular, surface science techniques require highly pure bulk materials with a narrow crystallite-size distribution together with straightforward, scalable, and reproducible crystallization procedures. In th...

p> Size, morphology and purity control of coordination compounds powders is a key stage for their conversion into materials and devices. In particular, surface science techniques require highly pure bulk materials with a narrow crystallite‑size distribution together with straightforward, scalable and reproducible crystallization procedures. In this...

Reactions, in hydro thermal conditions, between a lanthanide chloride and the sodium salt of 2 carboxyphenylboronic acid leads to a series of lanthanide based complexes with general chemical formula [Ln2(C7H5O2)4(C7O4H6B)2·4H2O] (hereafter symbolized by [Ln(o cpb)]) with Ln = Eu Dy. During the synthetic process, 2 carboxyphenylboronate ligand decom...

A one-dimensional coordination solid is synthesized by reaction of a bispyridyl dithienylethene (DTE) photochromic unit with the highly anisotropic dysprosium-based single-molecule magnet [Dy(Tppy)F(pyridine)2]PF6. Slow magnetic relaxation characteristics are retained in the chain compound, 1c, and photoisomerization of the bridging DTE ligand indu...

The terbium(III) ion is a particularly suitable candidate for the creation of surface-based magnetic and luminescent devices. In the present work, we report the epitaxial growth of needle-like objects composed of [Tb(hfac)3·2H2O] n (where hfac = hexafluoroacetylacetonate) polymeric units on muscovite mica, which is observed by atomic force microsc...

We report a single‐chain magnet (SCM) made of a terbium(III) building block and a nitronyl‐nitroxide radical (NIT) functionalized with an aliphatic chain. This substitution is targeted to induce a long‐range distortion of the polymeric chain and accordingly it gives rise to chains that are curled with almost 20 nm helical pitch. They self‐organize...

Reactions in solvothermal or microwave-assisted conditions between a hexanuclear rare-earth entity ([Ln6] with Ln = Eu-Dy) and m-halogeno-benzoic acids lead to three series of isostructural complexes with respective chemical formulas [Ln6(μ3-OH)2(H2O)2(NO3)2(3-cb)14]·4CH3CN, [Ln6(μ3-OH)2(H2O)2(NO3)2(3-bb)14]·6CH3CN, and [Ln6(μ3-OH)2(H2O)2(NO3)2(3-i...

We report a Single‑Chain Magnet (SCM) made of a Terbium(III) building block and a nitronyl‑nitroxide radical (NIT) functionalized with an aliphatic chain. This substitution is targeted to induce a long range distortion of the polymeric chain and accordingly it gives rise to chains that are curled with almost 20 nm helical pitch. They self‑organize...

Six lanthanides complexes with chemical formula [Ln(phen)2(NO3)3] (Ln = Sm(1), Tb (2), Nd (3), Eu (4), Ho (5) and Y (6), phen = 1,10-phenanthroline) were synthesized. 1 and 2 were obtained as single crystals by slow diffusion. Structural characterization was based on single crystal X-ray diffraction and IR and ⁸⁹Y-NMR spectroscopies. NMR spectrosco...

We report on the synthesis, ab-initio calculations, magnetic and optical characterization of a DyIII-based dimeric compound named DyAZO. The dimers self-organize into a supramolecular chain decorated with photo-isomerizable azobenzene ligands. DyAZO displays a Single-Molecule Magnet (SMM) behavior. However, ab-initio calculations highlight a quite...

Reactions by solvothermal methods of lanthanide nitrates and azoxybenzene-3,3′,5,5′-tetracarboxylic acid (H4aobtc) lead to a family of isostructural lanthanide-based coordination polymers with general chemical formula [Ln(Haobtc)(H2O)2·2H2O]∞ with Ln = Nd − Er plus Y. The crystal structure has been solved on the basis of the Y³⁺-derivative. It crys...

Isostructural lanthanide-based coordination polymers that are obtained by reactions in water of a lanthanide chloride and the sodium salt of 5-methoxyisophthalate (mip ²⁻ ) have the general chemical formula [Ln 2 (mip) 3 (H 2 O) 8 ·4H 2 O] ∞ with Ln = Nd-Er except Pm plus Y (symbolized by [Ln 2 (mip) 3 ] ∞ ). Some of these homo-lanthanide compounds...

The deposition of Single-Molecule Magnets (SMMs) on surfaces is a mandatory step toward their possible use as data-storage units or qubits. In this study we report the structural and magnetic characterization of two parent compounds of a well-known SMM called DyPyNO, ([Dy(hfac) 3 (PyNO)] 2 with hfac = hexafluoroacetylacetonate and PyNO = pyridine-N...

Microcrystalline core-shell powders of lanthanide-based coordination polymers with general chemical formula ([Ln(cpbOH)]∞)1- x@([Ln'(cpbOH)]∞) x with Hcpb = 1,4-carboxyphenylboronic acid have been synthesized and structurally characterized. Their luminescent properties have been studied. They are drastically different from those of heterolanthanide...

Reactions in water of lanthanide chlorides with the sodium salt of 1,4-carboxyphenylboronic acid lead to two series of isostructural compounds with respective general chemical formulas [Ln(cpb)3(H2O)2]∞ for Ln = La or Ce and [Ln(cpbOH)(H2O)2·(cpb)]∞ for Ln = Pr−Lu (except Pm) plus Y. Heterolanthanide coordination polymers that are isostructural to...

Up to now, even if murexide-based complexometric studies are performed with all 3d or 4f ions, the crystal structures of the light-lanthanide derivatives of the lanthanide-murexide series are unknown. In this work, we report the crystal structure of the NdIII derivative named NdMurex. Contrary to all known complexes of the 3d or 4f series, a dimeri...

The rational design of molecular chains made of 4f ions and substituted 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical is presented. The reaction of Ln(hfac)3·2H2O (hfac- = hexafluoroacetylacetonate) and the 4-cyano-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO-CN) radical affords air- and moisture-stable isostructural molecular chains of the f...

Muon spin relaxation (μSR) experiments on a single molecule magnet enriched in different Dy isotopes detect unambiguously a slowing down of the zero field spin dynamics for the non-magnetic isotope....

Ferromagnetic interactions induced by metal—organic framework (MOF) architecture turn a poor single‐molecule magnet (SMM) into a slow relaxing material. The MOF is made of nine‐coordinated DyIII magnetic building blocks (MBBs) with poor intrinsic SMM behavior. However, the MOF architecture constrains the MBBs in a one‐dimensional structure that ind...

Reactions in water of 4,5-dichlorophthalate (dcpa2-) with the heaviest lanthanide ions lead to a family of compounds with the general chemical formula [Ln2(dcpa)3(H2O)5·3H2O]∞, where Ln = Tb-Lu, Y. The synthesis, crystal structure, thermal behavior, and luminescent properties of this series of homonuclear compounds are described. Additionally, this...

Single crystal diffraction studies reveal the formation of the following 10 new complexes of lighter Ln(III) ions of general formula {[Ln(µ2-L1)3.(H2O)2].H2O}n (Ln = Nd (I), Eu (II)), [Nd(µ2-L2)2.(CH3COO).(H2O)2]n (III), [Ln2(µ2-L2)5.(L2).(H2O)4]n (Ln = Sm (IV), Ce (V), Pr (VI)), [La2(µ2-L2)6.(H2O)3.(DMF)]n (VII) (DMF = dimethylformamide), [Ln(µ2-L...

We report the study of a Dy-based metal-organic framework (MOF), with unprecedented magnetic properties. The compound is made of nine-coordinated DyIII magnetic building blocks (MBBs) with poor intrinsic single-molecule magnet behaviour. However, the MOF architecture constrains the MBBs in a one-dimensional structure that induces a ferromagnetic co...

We report the synthesis of two lanthanide complexes including a chelating merocyanine (MC) ligand and obtained from the reaction of a bis(pyridinemethyl)amine substituted spiropyran with yttrium(III) or dysprosium(III) triflate salts, which structures were confirmed both in solid state and in solution by single crystal X-ray diffraction studies and...

Reaction of hexanuclear octahedral molecular precursors with a 3-chlorobenzoate ligand affords an unprecedented family of isostructural polylanthanide complexes with the general chemical formula {[Ln6(μ3-OH)2(H2O)2(NO3)2(3-cb)14]·(CH3CN)4}, where 3-cb⁻ stands for 3-chlorobenzoate and Ln = Eu, Tb, Dy, Ho, Er, or Y. The crystal structure, solubility,...

Single-molecule magnet (SMM) behavior on Dy-based dimers has been optimized by substitution of DyIII ancillary ligand (hfac- in previously reported DyPyNO, for tta- in Dy). Clear hysteresis opening is visible at 0.5K on Dy that allows for the determination of an antiferromagnetic coupling of -2.92 cm.-1 (S=1/2, gz=19.58) that is confirmed by ab-ini...

Lanthanides ions allows for the design of remarkable magnetic compounds with unique magnetic properties.[...]

The insertion of Single Molecule Magnets (SMMs) in spintronic devices has drawn much attention thanks to their fascinating quantum and classical magnetic properties. Although many efforts have been done in this direction, we are still in search of optimal molecules, which preserve intact the magnetic bistability at the nanoscale. In this frame, we...

Reactions in water between lanthanide chlorides and the di-sodium salt of 5-methoxy-isophtalic acid, Na2(mip)•7H2O, lead to the first three series of lanthanide-based coordination polymers based on this ligand. The first series contains only one compound with chemical formula [Ce(mip)3/2(H2O)5•2H2O]. The second series has general chemical formula...

The use of lanthanide-based poly-nuclear complexes as molecular precursor for the design of extended molecular frameworks is still an innovative synthesis strategy. Oxo-hydroxo poly-nuclear complexes are generally obtained by controlling pH conditions during reaction process. After a short description of the lanthanide hydrolysis phenomenon and a n...

Reactions in water between lanthanide chlorides and the di-sodium salt of 1,2-phenylenediacetic acid, Na 2 (o-PDA), lead to two families of coordination polymers with respective chemical formulae {[La 2 (o-PDA) 3 (H 2 O) 4 ]·4H 2 O} n (1) and {[Ln 2 (o-PDA) 2 (H 2 O) 2 ]·2H 2 O} n with Ln = Ce-Nd and Sm-Lu plus Y (2). Compound 1 crystallises in the...

A spiropyran-based switchable ligand isomerizes upon reaction with lanthanide(III) precursors to generate complexes with unusual N3O5 coordination sphere. The air stable dysprosium(III) complex shows a hysteresis loop at 2 K and a very strong axial magnetic anisotropy generated by the merocyanine phenolate donor.

Switching luminescence of lanthanide-based molecules through external electric field is considered as a promising approach toward novel functional molecule-based devices. Classic routes use casted films and liquid electrolyte as media for redox reactions. Such protocol, even if efficient, is relatively hard to turn into an effective solid-state dev...

Correction for 'Single-molecule magnet behaviour in polynuclear assembly of trivalent cerium ions with polyoxomolybdates' by A. Ben Khélifa, et al., Dalton Trans., 2015, 44, 16458-16464.

The organization of single-molecule magnets (SMMs) on surfaces via thermal sublimation is a prerequisite for the development of future devices for spintronics exploiting the richness of properties offered by these magnetic molecules. However, a change in the SMM properties due to the interaction with specific surfaces is usually observed. Here we p...

Lanthanide ions have unique physical properties and are essential for numerous technological devices. Indeed, much research has been undertaken in order to understand and optimize their luminescent behavior. From a chemical and more specific point of view, lanthanides can be used to build coordination polymers (CPs). CPs are materials in which meta...

Reactions in water between the sodium salt of benzene-1,2,4,5-tetracarboxylic acid (H4btec) and lanthanide ions (Sm-Dy) led to a series of isostructural lanthanide-based coordination polymers with the general chemical formula [Ln4(btec)3(H2O)12·20H2O]∞ with Ln = Sm-Dy. The family has been structurally characterized. From a luminescent point of view...

Heteronuclear lanthanide-based coordination polymers are microcrystalline powders, the luminescence properties of which can be precisely tuned by judicious choice of the rare-earth ions. In this study, we demonstrate that such materials can also be obtained as stable solutions of nanoparticles in non-toxic polyols. Bulk powders of the formula [Ln2-...

A Dy(III)-based single-molecule magnet is reported. Ab initio calculations highlight that molecular symmetry plays a predominant role over site symmetry in determining the shape and orientation of Dy(III) magnetic anisotropy. Moreover the dipolar component of the electrostatic potential created by the surrounding ligands is shown to be the driving...

An isopolyoxomolybdate-based POM is coordinated to trivalent cerium ions to afford a hybrid complex namely, [Ce(dmso)8][Ce(η2-NO3)2(dmso)4(α-Mo8O26)0.5][Mo6O19]. The original electrostatic environment created around the Ce(III) by its coordination to the isopolyoxomolybdate core induces complex single-molecule magnet behavior.

For the first time, hexanuclear complexes with general chemical formula [Ln6O(OH)8(NO3)6(H2O)n](2+) with n = 12 for Ln = Sm-Lu and Y and n = 14 for Ln = Pr and Nd were stabilized as nanoaggregates in ethylene glycol (EG). These unprecedented nanoaggregates were structurally characterized by (89)Y and (1)H NMR spectroscopy, UV-vis absorption and lum...

Reactions in water between the sodium salt of 4-carboxyphenylboronic acid (Hcpb) and lanthanide ions (Pr-Nd, Sm-Lu, and Y) led to a family of lanthanide-based coordination polymers with general chemical formula {[Ln(cpbOH)(H2O)2](cpb)}∞. Structural characterizations were ensured by single-crystal X-ray diffraction and solid-state NMR spectroscopy (...

Optimization of the reaction of [Ln(hfac)3]·2H2O and pyridine-N-oxide (PyNO), which is known to afford double-bridged dimers, leads to triple-bridged dimers of formula [(Ln(hfac)3)2(PyNO)3] (Ln = Gd (1), Dy (2)) from which the Dy derivative (2) behaves as a single-molecule magnet (SMM). The pseudo threefold axis symmetry of this zero-dimensional bu...

The title compound precipitates from a solution of Y2O3 in aq.

A novel coordination polymer with chemical formula {[Tb(bdc)1.5(H2O)]⋅(DMF)(H2O)}∞ (1) has been synthesized by reaction between 1,4-benzene-dicarboxylic acid (H2bdc) and di-cationic hexanuclear entity [Tb6O(OH)8(NO3)6(H2O)12]2+ in an ethylene glycol (EG)/N,N-dimethylformamide (DMF) mixture. This compound has been obtained as single crystals by slow...