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International audience; Microwave-assisted reactions in DMSO, between a hexa-lanthanide octahedral complex ([Ln(6)(μ(6)-O)(μ(3)-OH)(8)(NO(3))(6)(H(2)O)(12)·2NO(3)·2H(2)O] with Ln = Nd-Yb plus Y) and either 3-halogenobenzoic acid (hereafter symbolized by 3-xbH with x = f or c for fluoro or chloro, respectively) or 4-halogenobenzoic acid (hereafter symbolized by 4-xbH with x = f, c, or b for fluoro, chloro, or bromo, respectively), lead to 1D lanthanide coordination polymers. These coordination polymers are almost iso-reticular. The crystal structure is described on the basis of the coordination polymer with chemical formula [Tb(4-fb)(3)(DMSO)(H(2)O)(2)·DMSO](∞) obtained from 4-fluorobenzoic acid (4-fbH) and the Tb(3+)-based octahedral complex: It crystallizes in the triclinic system, space group P1̅ (n°2), with the following cell parameters: a = 9.8561(9) Å, b = 10.5636(9) Å, c = 15.1288(15) Å, α = 100.840(3)°, β = 95.552(3)°, γ = 110.482(3)°, V = 1426.4(3) Å(3), and Z = 2. It can be described on the basis of 1D molecular chains. Luminescence properties of the Tb and Eu derivatives have been measured and compared vs the halogeno-function and its position (meta or para). Some molecular alloys have also been prepared to estimate the strength of the intermetallic energy transfers. To confirm that the hexa-nuclear complexes (and not the halogenated ligand) have a structuring effect for the formation of the straight chain-like molecular motif, another coordination polymer with chemical formula [Tb(4-npa)(3)DMSO·DMSO·H(2)O](∞) where 4-npaH symbolizes 4-nitro-phenyl-acetic acid has been prepared. It crystallizes in the triclinic system, space group P1̅ (n°2) with the following cell parameters: a = 7.8784(8) Å, b = 14.8719(16) Å, c = 15.2753(17) Å, α = 73.612(4)°, β = 86.406(4)°, γ = 83.104(4)°, V = 1703.8(3) Å(3), and Z = 2. Its crystal structure can be described on the basis of a molecular motif that is similar to the one observed in the five previous crystal structures which confirms the structuring effect of the hexa-nuclear complexes.

International audience; 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 solubility constants of a series of isostructural homo-lanthanide coordination polymers, with general chemical formula [Ln2(bdc)3(H2O)4]infinity with Ln = La-Er plus Y and where bdc2- symbolizes 1,4-benzene-di-carboxylate. Then, we extend the study to two series of isostructural molecular alloys with general chemical formula [Ln2xLn ' 2 -2x(bdc)3(H2O)4]infinity with 0

International audience; 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 Tb(III) ions and nitronyl-nitroxides radicals functionalized with short alkyl chains known to form crystalline supramolecular nanotubes interacting with heptane acting as crystallizing solvent. When the radicals are functionalized with long aliphatic chains a robust gel is formed with similar structural and functional properties respect to its crystalline parent. Indeed, a small-angle X-ray scattering (SAXS) study unambiguously demonstrates that the gel is made of supramolecular nanotubes: the high stability of the gel allows the determination from SAXS data of precise nanotube metrics such as diameter, helical pitch and monoclinic cell of the folded 2D crystal lattice along the tube direction. Additionally, static and dynamic magnetic investigations show the persistence of the SCM behavior in the metallogel. Last, on-surface gelation provides thick films as well as sub-monolayer deposits of supramolecular nanotubes on surface as evidenced by atomic force microscopy (AFM) observations. This paves the road toward magnetic materials and devices made of SCMs profiting of their isolation on surface as individual chains.

International audience; 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. Therefore, a brightness calculation or a luminance measurement are mandatory for a quantitative estimation of the luminescence intensity. The calculated brightness appears to be a convenient quantitative parameter for the estimation of the luminescence intensity in the infrared domain, in which luminance is senseless. It is also a useful parameter in the visible domain, but one must keep in mind that only compounds with similar colorimetric coordinates can be compared. For comparing the luminescence intensities of compounds that exhibit different emission colors, the luminance measurement seems to be the most efficient method. A home-made setup that allows this measurement with high reproducibility is described in detail. The luminance of several lanthanide-based coordination polymers with benzene-poly-carboxylate ligands is measured, and the results are compared with brightness and quantum yield measurements. A standard is suggested for calibration.

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 molecules but ab initio calculations demonstrate that this bridge is inefficient in mediating any magnetic interaction other than a small dipolar antiferromagnetic coupling. Surprisingly the hexanuclears, despite being finite molecules, show a single-chain magnet (SCM) behavior. This results in a magnetic hysteresis at low temperature whose coercive field is almost doubled when compared to the chains. We thus demonstrate that finite linear molecules can display SCM magnetic relaxation, which is a strong asset for molecular data storage purposes because 1D magnetic relaxation is more robust than the relaxation mechanisms observed in single-molecule magnets (SMMs) where under-barrier magnetic relaxation can operate., A stable hexanuclear molecule made of a TbIII building block and a substituted nitronyl-nitroxide radical show a single-chain magnet behavior despite being a finite molecule.

International audience; 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)(H(2)O)(6)](∞) for the lightest lanthanide ions (Ln = La-Dy except Pm), while it is [Ln(tma)(H(2)O)(5)·3.5H(2)O](∞) for the heaviest ones (Ho-Lu plus Y). For the heaviest lanthanide ions, reactions at 50 °C lead to a third structural family with the general chemical formula [Ln(tma)(H(2)O)(3)·1.5H(2)O](∞) with Ln = Ho-Lu plus Y. Homo-lanthanide coordination polymers that belong to the latter two families do not exhibit luminescence in the visible region. Therefore, we used a phase induction strategy to obtain molecular alloys that belong to these structural families and show sizeable emission. The random distribution of the lanthanide ions over the metallic sites has been investigated using (89)Y and (139)La solid-state NMR spectroscopy experiments. Luminescent properties of homo- and hetero-nuclear coordination polymers based on Eu(3+) and Tb(3+) have been studied in detail and compared. As a result, this study strongly suggests that exchange-based intermetallic energy transfer mechanisms play an important role in these systems. It also suggests the presence of an intermetallic exchange pathway through π-stacking interactions.

International audience; 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 alloy suspensions and their bulk counterparts are extremely similar. To the best of our knowledge, this series of suspensions constitutes the first example of hetero-lanthanide coordination polymer molecular alloy (LnCPMA)-based colloidal suspensions with sizeable luminescence intensity and a wide range of accessible colors. This high color tunability paves the road toward tagging of technical liquids. We also demonstrate that they can be used in ink-jet printers for luminescent anti-counterfeiting tagging.

International audience; 3,3'-Bipyridine ligand B was reacted with pre-assembled [Cu-2(mu(2)-dppm)(2)] Cu(I) bimetallic flexible precursor A according to coordination-driven supramolecular chemistry synthetic principles. Outcomes obtained revealed the necessity to formally introduce bridging halide X ions (X = Cl, Br or I) in order to conduct selectively and successfully coordination-driven supramolecular syntheses. Therefore, [Cu-2(mu(2)-dppm)(2)(mu(2)-X)] bimetallic connecting nodes presenting a potential coordination angle of ca. 120 degrees are generated, which lead upon reaction with connecting ligand B to the selective formation of new tetranuclear metallacycles C-X. These derivatives are luminescent in the solid-state at room temperature with high emission quantum yields and a study of the temperature dependence of their photophysical properties was conducted, suggesting a ligand B centered triplet origin for their luminescence.

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 400 °C). Their luminescent properties have been studied in detail. Interestingly an insensitivity to water coordination as well as a very strong effect of optical dilution is observed. Therefore, molecular alloys with very high lanthanum concentration have been prepared. Some of them present highly tunable and very intense luminescence. For example, to the best of our knowledge, [Sm0.04La1.96(dcpa)3(H2O)]∞ presents one of the highest overall quantum yields measured so far for a Sm3+-based coordination compound (QSmLigand = 9.2%), and [Nd0.03Sm0.14Eu0.03La1.8(dcpa)3(H2O)]∞ is one of the brightest (12 Cd·m-2 under 0.75 mW·cm-2 UV flux) multiemissive visible and near-infrared lanthanide-coordination polymers reported to date.

International audience; A new highly solid-state luminescent phase of a previously reported weakly luminescent Cu I 8 Pd II 1 dicationic assembly is reported revealing the high geometrical versatility of this moiety that importantly alters its luminescent properties. This very minor new species B c is based on a different conformer scaffold than the one encountered in the previously reported B o form and, essentially differs from B o by displaying shorter Cu I -Cu I intermetallic distances. DFT calculations allow concluding that the predominance in the solid-state of the weakly luminescent and less stable B o phase is due to the extra stability induced by a larger number of intermolecular non-covalent π-CH interactions in its crystalline packing and not by the intrinsic stability of the Cu I 8 Pd II 1 dicationic moiety. Calculations also revealed that a more stable conformation B calc is expected in vacuum, which bears a different distribution of Cu I -Cu I intermetallic distances than the dications in B o and B c phases. Taking into account that the geometrical alterations are associated to drastic changes of luminescence properties, this confer to the Cu I 8 Pd II 1 assembly high potentiality as stimuli-sensitive luminescent materials. Indeed, by applying mechanical or thermal stress to samples of B o phase, new phases B g and B m , respectively, were obtained. Alterations of the solid-state photophysical properties of these new species compared to those recorded for B o are reported together with a combined experimental and computed study of the structures/properties relationships observed in these phases.

International audience; 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, space group P21/c (n°14), with the following cell parameters (for the Dy-derivative): a = 12.3809(10) Å, b = 21.8653(16) Å, c = 7.9119(7) Å, β = 98.709(3)°, V = 2117.2(3) Å3 and Z = 4. The influence of the hexa-nuclear precursors over the final coordination polymer is demonstrated. Indeed, while the hexa-nuclear complexes collapse during the synthetic process their progressive destruction affords a unique 1D coordination polymer that cannot be readily obtained otherwise. Additionally, some iso-structural hetero-lanthanide derivatives with general chemical formulas [EuxTb1-x(2-bb)3]∞ and [YxTb1-x(2-bb)3]∞ with 0 ≤ x ≤ 1 have been prepared from the corresponding hexa-nuclear complexes [Eu6xTb6-6x] and [Y6xTb6-6x], respectively. Luminescent properties have been recorded and colorimetric coordinates have been calculated for all the compounds. These measurements indicate that the molecular chains host strong intermetallic energy transfers. © 2021 Elsevier B.V.

International audience; Solvothermal reactions between hexanuclear complexes with the general chemical formula [Ln(6)(μ(6)-O)(μ(3)-OH)(8)(NO(3))(6)(H(2)O)(12)]·2NO(3)·2H(2)O and 2-bromobenzoic acid (2-bbH) lead to a series of isostructural one-dimensional coordination polymers with the general chemical formula [Ln(2)(2-bb)(6)](∞) with Ln = Sm, Eu, Tb, Dy, and Y. These coordination polymers crystallize in the orthorhombic space group Fdd2 (No. 43) with the following cell parameters: a = 29.810(3) Å, b = 51.185(6) Å, c = 11.7913(14) Å, V = 17992(4) Å(3), and Z = 16. The europium- and terbium-based derivatives show sizable luminescence intensities under UV excitation. Isostructural heterolanthanide coordination polymers have also been prepared. Their luminescent properties suggest that during the synthetic process the starting hexanuclear complexes are destroyed but strongly influence the distribution of the different lanthanide ions over the metallic sites of the crystal structure. Indeed, it is possible to prepare heterolanthanide coordination polymers in which lanthanide-ion segregation is controlled.

International audience; Adaptive coordination-driven supramolecular chemistry based on conformationally flexible pre-organized luminescent Cu(I) precursors paves the way to the ready formation of intricate supramolecular scaffold possessing intrinsic luminescence properties. A formal ring extension of a tetrametallic Cu(I) metallacycle bearing Thermally Activated Delayed Fluorescence (TADF) properties can thus be carried out, affording a new hexametallic Cu(I) metallacycle 1 bearing modulated solid-state TADF properties. Attempts to adapt this ring extension process to the formation of targeted heterometallic Au2Cu4 and Pt2Cu8 assemblies led to the unexpected and ready formation of the Au2Cu10 and Pt4Cu11 derivatives 2 and 3, respectively. These outcomes strengthen the scope and perspectives of adaptive coordination-driven supramolecular chemistry compared to those of conventional coordination-driven supramolecular chemistry. Indeed, it guides concerted intramolecular fragmentation and redistribution of the particular building blocks used, affording selectively supramolecular scaffolds of higher nuclearity and complexity. The study of the solid-state photophysical properties of the assemblies 2 and 3 highlights enhanced and original behaviors, in which the heavy metal spin-orbit coupling values significantly influence the relaxation processes centered on the Cu(I) metal centers.

International audience; Conspectus. Lanthanide 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 final compound.In this Account, we review our results on lanthanide-based dimers. We show how a pure fundamental study on lanthanide coordination chemistry allows the investigation of a full continuum of results from the compound to materials and then to devices. The conversion of molecules into materials is a tricky task because it requires strong molecular robustness toward the surface deposition processes as well as the preservation and detectability of the molecular properties in the material. Additionally, the passage of a material toward a device implies a material with a given function, for example, a tailored response to an external stimulus.To do so, we targeted neutral and isolated molecules whose transfer on surfaces by chemi- or physisorption is much easier than that of charged molecules or extended coordination networks. Then, we focused on molecules with very strong evaporability to avoid wet chemistry deposition processes that are more likely to damage the molecules and/or distort their geometries.We thus designed lanthanide dimers based on fluorinated β-diketonates and pyridine-N-oxide ligands. As expected, they show remarkable evaporability but also strong luminescence and interesting magnetic behavior because they behave as single-molecule magnets (SMMs). Ligand substitutions and stoichiometric modifications allow the optimization of the geometric organization of the dimers in the crystal packing as well as their evaporability, SMM behavior, luminescent properties, or their ability to be anchored on surfaces. Most of all, this family of molecules shows a strong ability to form thick films on various substrates. This allows converting these molecules to magnetic materials and luminescent devices.Magnetic materials can be designed by creating thick films of the dimers deposited on gold. These films have been designed and investigated with the most advanced techniques of on-surface imaging (atomic force microscopy, AFM), on-surface physicochemical characterization (X-ray photoelectron spectroscopy (XPS), time of flight-secondary ion mass spectroscopy (Tof-SIMS)), and on-surface magnetic investigation (low-energy muon spin relaxation (LE-μSR)). Contrary to what was previously observed on other SMM films, no depth dependence of the SMM behavior was observed. This means that the dimers do not suffer from the vacuum or substrate interface and behave similarly, whatever their localization. This exceptional magnetic robustness is a key ingredient in the creation of materials for molecular magnetic data storage.Luminescent devices can be obtained by layering molecular films of the dimers with a copper-rich solid-state electrolyte between ITO/Pt electrodes. The electromigration of Cu(2+) ions into films of Eu(3+), Tb(3+), and Dy(3+) dimers quenches their luminescence. This luminescence tuning by electromigration is reversible, and this setup can be considered to be a proof of concept of full solid-state luminescent device where reversible coding can be tailored by an electric field. It is envisioned for optical data storage purposes. In the future, it could also benefit from the SMM properties of the molecules to pave the way toward multifunctional molecular data storage devices.

International audience; Coordination-driven supramolecular (CDS) syntheses between the pre-assembled tetrametallic flexible precursor A and pseudo-halide dicyanamide N(CN)2− (DCM) and azido N3− ions afforded selectively the discrete Cu8 assembly D and the one-dimensional coordination polymer E, respectively. Upon the reaction of E with M′(II) salts (M′ = Cu, Zn, Cd), straightforward self-dissociation/re-organisation processes take place yielding new discrete Cu8 assemblies FM′. Preservation in a solution of polymetallic Cu(I) CDS assemblies is evidenced for the first time. Solid-state luminescence properties of these derivatives are reported, revealing that D is a moderate room temperature luminophore upon UV-vis light excitation (emission quantum yield of 13%) while derivatives E, FZn and FCd are only weakly luminescent in the solid-state at low temperature

International audience; The ditopic nitrile-capped 1,4-phenylenediacetonitrile linker L3 featuring partial conformational flexibility was reacted with a flexible pre-assembled Cu(I) dimer stabilized by the bis(diphenyl-phosphino)methane dppm ligand along adaptive coordination-driven supramolecular assembling processes. It resulted in the selective and unexpected formation of a compact tetrametallic assembly associating two bimetallic building blocks with three ditopic linkers. The solid-state photophysical studies of this original Cu(I)-based assembly were analysed and showed its attractive luminescence properties.

International audience; 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 have been obtained by slow evaporation. [Ln2(hbdc)3(H2O)6·4H2O]∞ with Ln = Sm-Eu constitute family F2 and have been obtained by solvothermal synthesis. Family F3 includes compounds, obtained by a solvothermal method, with the general chemical formula [Ln2(hbdc)3(H2O)4·4H2O]∞ with Ln = Ho-Lu plus Y and compounds obtained by slow diffusion through gels with Ln = Eu-Tb. [Ln(Hhbdc)(hbdc)(H2O)3·H2O]∞ with Ln = Tb-Dy have been obtained by solvothermal methods and constitute family F4. [Gd2(hbdc)3(H2O)8·6H2O]∞ (F5) has been obtained by slow evaporation. The last family (F6) includes compounds with the general chemical formula [Ln2(hbdc)3(H2O)8·2H2O]∞ with Ln = Nd-Tb that have been obtained by slow diffusion through gel media. Gd-Based micro-crystalline powders can be obtained by direct mixing of aqueous solutions of Gd3+ and hbdc2-. Unexpectedly, the micro-crystalline powder belongs to F5 when the lanthanide solution is added to the ligand one and to F6 when the opposite occurs. This phenomenon is also observed for the Tb- and/or Eu-based heterolanthanide coordination polymers. Their optical properties have been studied in detail.

Isostructural lanthanide-based coordination polymers that are obtained by reactions in water of a lanthanide chloride and the sodium salt of 5-methoxyisophthalate (mip2-) have the general chemical formula [Ln2(mip)3(H2O)8·4H2O]∞ with Ln = Nd-Er except Pm plus Y (symbolized by [Ln2(mip)3]∞). Some of these homo-lanthanide compounds present very high luminescence brightness. The weak intermetallic energy transfer between lanthanide ions observed in these compounds allows the design of hetero-lanthanide coordination polymers with tunable luminescence properties. A molecular alloy that involved six different lanthanide ions (Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+) has been prepared and its luminescent properties have been studied. This compound, under a unique irradiation wavelength (λexc = 325 nm), exhibits almost 20 emission peaks in both the visible and the NIR regions at room temperature. This unprecedented richness of the emission spectrum could be of great interest as far as luminescent bar-codes are targeted.

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 work we demonstrate how sonocrystallization, i.e. application of ultrasounds during the crystallization process, can afford, very quickly, powders made of crystallites with controlled size, morphology and purity. We show that this process drastically diminishes the crystallite‑size distribution (low Polydispersity Indexes, PDI) and crystallite aspect ratio. By comparing sonicated samples with various silent crystallization conditions, we unambiguously show that the improvement of the crystallite morphologies and size‑distribution is not due to any thermal effect but to the sonication of the crystallizing media. The application of sonocrystallization on crystallization batches of Single‑Chain Magnets (SCM) maintains SCMs chemical integrity together with their original magnetic behavior. Moreover, luminescent measurements show that sonocrystallization induces an efficient micromixing that drastically enhances the purity of the SCMs powders. We thus propose that sonocrystallization, which is already used on organic or MOF compounds, can be applied to (magnetic) coordination compounds to readily afford bulk powders for characterization or shaping techniques that require pure, morphology‑ and crystallite‑size‑controlled powder samples.

International audience; Microcrystalline core-shell powders of lanthanide-based coordination polymers with general chemical formula ([Ln(cpbOH)])@([Ln'(cpbOH)]) 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 coordination polymers, also called "molecular alloys", that present the same crystal structure and chemical composition. Study of the photophysical properties of core-shell lanthanide-based coordination polymers reveals that it is possible to control efficiently the intermetallic energy transfers between lanthanide ions. Furthermore, multiemissive compounds, under unique irradiation, in both visible and infrared regions are easily feasible. Core-shell microstructured lanthanide-based coordination polymers have also been prepared with terephthalic (Hbdc) and trimesic (Htma) acids as ligands for evidencing that lanthanide-ion-based coordination compounds are excellent candidates for 3D molecular epitaxial growth.

Coordinative networks containing lanthanide ions attached via phosphonate ester functionalities provide remarkable luminescence properties. On the basis of ditopic phosphonic ester ligands with biphenylene and 9,10-anthracenylene bridges, a series of compounds with formal composition {[M(NO3)3]L}n or {[M(NO3)3]2(L1)3}n (L = C28H40O6P2; L1 = C26H40O6P2) with M = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y have been synthesized, structurally characterized, and the luminescence behavior was explored in the visible and NIR spectral regions, where applicable. In contrast to closely related networks based on biphenyl bisphosphonate esters from previous work, no evidence for ligand-to-metal energy transfer could be observed, despite strong near-infrared emission in some cases. Unique behavior is found for the Eu derivative with the 9,10-anthracenylene bridge, which is nonemissive, showing neither ligand- nor metal-based emission.

International audience; Reactions in water of 4,5-dichlorophthalate (dcpa) with the heaviest lanthanide ions lead to a family of compounds with the general chemical formula [Ln(dcpa)(HO)·3HO], where Ln = Tb-Lu, Y. The synthesis, crystal structure, thermal behavior, and luminescent properties of this series of homonuclear compounds are described. Additionally, this family can be extended to isostructural heteronuclear compounds that can contain some light lanthanide ions and therefore present some original photophysical properties. These compounds show potential interest as multiemissive materials (visible and infrared light between 450 and 1600 nm) and could find application as luminescent bar codes.

International audience; Reaction of hexanuclear octahedral molecular precursors with a 3-chlorobenzoate ligand affords an unprecedented family of isostructural polylanthanide complexes via solvothermal and microwave-assisted syntheses in an acetonitrile medium. The general chemical formula of the compounds that constitute this series is {[Ln(μ-OH)(HO)(NO)(3-cb)]·(CHCN)}, where 3-cb stands for 3-chlorobenzoate and Ln = Eu, Tb, Dy, Ho, Er, or Y. The crystal structure, solubility, and magnetic and luminescent properties of these complexes have been studied. The luminescent properties evidence that the composition of the hexalanthanide precursor is preserved during the synthetic process that is of particular interest for cases in which heterolanthanide complexes are targeted.

The CDIFX of Rennes is acknowledged for single crystal X-ray diffraction data collection.; International audience; Reactions in water between lanthanide chlorides and the di-sodium salt of 1,2-phenylenediacetic acid, Na2(o-pda), lead to two families of coordination polymers with respective chemical formulae [La2(o-pda)3(H2O)4,4H2O]∞ (1) and [Ln2(o-pda)3(H2O)2,2H2O]∞ (2) for Ln = Ce-Nd, Sm-Lu and Y. Compound 1 crystallises in the monoclinic system, space group C2/c (n°15), with a = 28.195(5) Å, b = 12.2305(3) Å, c = 8.7607(1) Å, β = 98.835(1)° and Z = 4. Its crystal structure and thermal properties are described. Compounds of family 2 are isostructural to a previously reported crystal structure. Luminescence properties of Eu- and Tb-based compounds have been studied.

International audience; 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 as a chiral tubular superstructure made of 11 chains wound around each other. The supramolecular tubes have a 4.5 nm internal diameter. Overall, this forms a porous chiral network with almost 44% porosity. Ab-initio calculations highlight that each Tb III ion possesses high magnetic anisotropy. Indeed, notwithstanding the supramolecular arrangement each chain behaves as a SCM. Magnetic relaxation with both finite and infinite-size regimes is observed and confirms the validity of the Ising approximation. This is associated with quite strong coercive field and magnetic remanence (Hc = 2400 Oe MR = 2.09 µB at 0.5 K) for this class of compounds.

International audience; 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 this work we demonstrate how sonocrystallization, i.e. the application of ultrasound during the crystallization process, can afford very quickly powders made of crystallites with controlled size, morphology, and purity. We show that this process drastically diminishes the crystallite-size distribution (low polydispersity indexes, PDI) and crystallite aspect ratio. By comparing sonicated samples with samples obtained by various silent crystallization conditions, we unambiguously show that the improvement in the crystallite morphology and size distribution is not due to any thermal effect but to the sonication of the crystallizing media. The application of sonocrystallization on crystallization batches of single-chain magnets (SCMs) maintains the chemical integrity of the SCMs together with their original magnetic behavior. Moreover, luminescent measurements show that sonocrystallization induces an efficient micromixing that drastically enhances the purity of the SCM powders. We thus propose that sonocrystallization, which is already used on organic or MOF compounds, can be applied to (magnetic) coordination compounds to readily afford bulk powders for characterization or shaping techniques that require pure, morphology- and crystallite-size-controlled powder samples.

International audience; The reaction of the pre-assembled bimetallic Cu(i) [Cu-2(mu(2)-dppm)(2)](2+) fragment with the ligand 1,4-dicyanobenzeneB(0)in non-distilled CH(2)Cl(2)allowed the characterisation of an unexpected one-dimensional coordination polymerD, while no reaction occurred when dry CH(2)Cl(2)was used as the solvent. The X-ray crystal structure resolution performed on air-stable single crystals ofDrevealed that this coordination polymer contained the first reported bridging aqua ligand coordinated on Cu(i) bimetallic units connected byB(0)ligands within zig-zag chains. Consequently,Dwas obtained in very good yield when the synthesis was conducted in dry CH2Cl2, in which water was added as a reactant in excess. In the solid state at room temperature under UV lamp excitation,Dpresented blue-cyan eye-perceived luminescence that contrasted with the green-yellow eye-perceived luminescence emitted by single crystals ofDin the crystallisation solution. Related to this property, reversible luminescent vapochromic behaviour was observed upon the exposure of dry single crystals ofDto vapors of CH2Cl2, EtOH, CH(3)NO(2)and THF solvents. The X-ray crystal structure resolution analysis revealed that this vapochromic response occursviasingle crystal to single crystal transitions, along which the volatile solvent molecules are taken up in the very low porous dry single crystals ofD, leading to the formation of one-dimensional channels of included solvent molecules, which are mobile in the crystalline solid at room temperature. The detailed temperature -dependent photophysical studies suggest that this mobility impacts the relaxation processes within these molecular solids, resulting in luminescence vapochromic effects. The results also highlight the complexity of the relaxation processes that can take place in these heteroleptic polymetallic Cu(i) supramolecular assemblies, which are based on highly easy, affordable and quick synthetic procedures.

International audience; Reactions, under hydrothermal conditions, between lanthanide chlorides and the sodium salt of 2-carboxyphenylboronic acid lead to a series of lanthanide-based complexes with general chemical formula [Ln2(C7H5O2)4(C7O4H6B)2·4H2O] with Ln = Eu–Dy. During the synthetic process, the 2-carboxyphenylboronate ligand decomposes leading to benzoate (C7H5O2) and bis(hydroxy)benzoxaborolone (C7O2H6B). The crystal structure was solved on the basis of the Tb-derivative. It crystalizes in the triclinic system, space group P[1 with combining macron] (n° 2) with a = 9.3329(13) Å, b = 16.012(2) Å, c = 16.212(2) Å, α = 107.789(5)°, β = 90.226(5)°, γ = 97.585(5)°, V = 2284.16(52) Å3 and Z = 2. Its crystal structure can be described on the basis of di-lanthanides entities surrounded by ligands. Compounds that constitute this series are thermally stable up to 190 °C. Solid-state luminescence properties have been studied in detail. The magnetic properties of the Dy-derivative have also been explored. It exhibits single molecule magnet behavior. Single crystals of the sodium salt of 2-carboxyphenylboronic acid with chemical formula [Na(C7O4H6B)(H2O)]∞ have also been obtained during this study. This compound crystallizes in the orthorhombic system, space group P212121 (n° 19) with a = 4.5881(13) Å, b = 6.5905(16) Å, c = 29.644(8) Å, V = 897.0(4) Å3 and Z = 4. Its crystal structure is 2D and can be described as zigzag chains of sodium 2-carboxyphenylboronate bound to each other by coordination water molecules.

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)3(H2O)5·3H2O]∞ with Ln = Tb-Lu plus Y. Heterolanthanide molecular alloys that contain both Eu3+ and Tb3+ ions have been prepared in both structural families. Their luminescence properties have been studied, especially from the brightness point of view. This study revealed that structural family F1 provides molecular alloys that are much more luminescent than those of structural family F2. Therefore, a phase-induction strategy was followed that allowed the design of some molecular alloys (La/Tb/Eu and La/Dy) that are, to the best of our knowledge, among the most luminescent coordination polymers reported so far. This study opens the way to bright luminescent bar codes as well as to bright white luminescent lanthanide-based coordination polymers.

International audience; Dedicated to Professor Miguel Julve on the occasion of his 65 th birthday, and for its outstanding contribution to the field of coordination chemistry and molecular magnetism. Abstract 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-oxide), that are targeted to be deposited on gold surfaces. Thio-substitution of the pyridine ring of these dimers is expected to provide good anchoring group toward deposition on gold. We have investigated two significantly different geometries of the anchoring groups in dimers 1 and 2. Interestingly, despite these strong differences, SMM behavior is remarkably well-preserved in the polycrystalline material offering possibilities to graft these SMMs on surface.

International audience; 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 crystallizes in the triclinic system, space group P-1 (n°2) with the following cell parameters: a = 6.6890(18) Å, b = 10.052(3) Å, c = 13.879(4) Å,α = 75.756(9)°, β = 77.551(9)°, γ = 83.964(9)° and Z = 2. The crystal structure is two-dimensional (2D). Thermal properties and luminescent properties of the Nd3+-containing compound have been studied.

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 the second series have been synthesized, and their photophysical properties have been studied. This study evidences that it is possible to design multiemissive lanthanide-based coordination polymers that could find their application as multigauge luminescent thermometric probes.

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 microscopy. The needle-like shape mimics the structure observed in the crystalline bulk material. The growth of this molecular organization is assisted by water adsorption on the freshly air-cleaved muscovite mica. This deposition technique allows for the observation of a significant amount of nanochains grown along three preferential directions 60° apart from another. The magnetic properties and the luminescence of the nanochains can be detected without the need of surface-dedicated instrumentation. The intermediate value of the observed luminescence lifetime of the deposits (132 µs) compared to that of the bulk (375 µs) and the CHCl3 solution (13 µs) further reinforces the idea of water-induced growth.

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-ib)14]·6CH3CN, where 3-cb-, 3-bb-, and 3-ib- represent 3-chloro-, 3-bromo-, and 3-iodo-benzoate, respectively. These three series of compounds are almost isostructural. Their luminescent properties, in the solid and solution states, have been studied in detail and compared. This study shows that hexanuclear complexes own strong intermetallic energy transfers. This makes these complexes good candidates for thermometric probes in solid state or in solution state.

International audience; We report the synthesis, ab initio calculations, magnetic and optical characterization of a Dy-based dimeric compound named DyAZO. The dimers self-organize into a supramolecular chain decorated with photo-isomerizable azobenzene ligands. DyAZO displays single-molecule magnet (SMM) behavior. However, ab initio calculations highlight a quite strong admixture of M states of the H level of Dy ions, the presence of low-lying excited M states and antiferromagnetic Dy-Dy dipolar coupling. This favors zero-field fast tunneling. Accordingly the Dy-doped analogue YDyAZO (5.5% Dy doping) displays enhanced magnetic relaxation with a hysteresis that is observed at 0.5 K. The influence of the cis- to trans-isomerization of the decorating azobenzene ligand on magnetic properties has been tested for both solid samples and solutions of DyAZO and YDyAZO. This provides hints for the synthesis of future Dy-based photo-isomerizable molecules.

International audience; The reaction of [ReIBr(CO)3(THF)]2 with phenanthroline in solution leads to the diimine rhenium(I)tricarbonyl [(phen)Re(CO)3Br] and the dimer [(CO)3(phen)Re(µ-OH)(phen)Re(CO)3]+Br− (1+Br−) as a by-product (~5% yield). This latter bimetallic compound crystallizes as a mixture of three polymorphs, with variable amount of solvent 1+Br−·CHCl3 (triclinic and orthorhombic) and 1+Br−·2(CHCl3) (triclinic). Rietveld analysis showed 38, 54 and 8% of 1+Br−·CHCl3 (triclinic), 1+Br−·CHCl3 (orthorhombic) and 1+Br−·2(CHCl3) (triclinic) respectively. The 1+ cation shows two [ReI(phen)(CO)3]+ units connected by means of a central hydroxyl group. Noteworthy, the bridging Re–O–Re angle varies between 130.9(7)° to 140.7(2)° along the polymorphic series. UV–Vis spectrum for the 1+ shows a broad absorption band around 390 nm in CH2Cl2 which has been attributed to has MLCT character (Re(dπ) → π*(phen)) as confirmed by DFT. Excitation at 405 nm in solution leads to emission at 595 nm (DCM), 605 nm (DMF) and 625 nm (CH3CN). The emission follows a mono-exponential law of decay and has lifetime of 405.8 ns (DCM). The solid-state polymorphic mixture absorbs around 460 nm. Excitation of the solid at 320 nm leads to emission with a maximum at 575 nm, which follow a bi-exponential law of decay with two components, a short one τ1 of 27.0 ns and longer one τ2 of 178.5 ns. These results suggest that the emitting state does not vary as function of the molecular geometry.

International audience; A thermally activated delayed fluorescence (TADF) tetrametallic Cu(I) metallacycle A behaves as a conformationally adaptive preorganized precursor to afford, through straightforward and rational coordination-driven supramolecular processes, a variety of room-temperature solid-state luminescent polymetallic assemblies. Reacting various cyano-based building blocks with A, a homometallic Cu(I) 1D-helical coordination polymer C and CuM discrete circular heterobimetallic assemblies D (M = Ni, Pd, Pt) are obtained. Their luminescence behaviors are studied, revealing notably the crucial impact of the spin-orbit coupling offered by the central M metal center on the photophysical properties of the heterobimetallic D derivatives.

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 formula [Ln(hfac)3TEMPO-CN] n for Ln = GdIII and TbIII, whereas zero-dimensional complexes of the formula [Dy(hfac)3(TEMPO-CN)2][Dy(hfac)3(H2O)2]2 are obtained for Ln = DyIII. To the best of our knowledge, the Gd derivative, Gd-TEMPO-CN, shows one of the strongest antiferromagnetic (AF) couplings for Gd-radical pairs ever reported with JGd-rad/ kB = -21.18 K, 14.72 cm-1 ( H = - JSrad SGd spin Hamiltonian convention). The TbIII derivative, Tb-TEMPO-CN, also shows strong Tb-radical AF coupling, which has been rationalized using the ab initio CASSCF approach ( JTb-rad = -23.02 K, -16.7 cm-1) and confirmed by luminescence measurements. Tb-TEMPO-CN shows remarkable properties for a Tb-radical-based single-molecule magnet ( Ueff = 69.3 ± 1 K; τ0 = 1.3 × 10-7 s) and two different relaxation processes triggered by interchain magnetic coupling.

International audience; 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 non-exhaustive inventory of existing complexes with increasing nuclearity, the present review focuses on lanthanide-based hexa-nuclear oxo-hydroxo complexes. Their syntheses and crystal structures are described and their interest as building blocks for the design of new coordination compounds with unprecedented physical properties is highlighted.

International audience; Reactions in water between lanthanide chlorides and the disodium salt of 5-methoxyisophthalic 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 [Ln(mip) (Hmip)(H2O)5·H2O]∞ with Ln = La–Ce. The last family is constituted by compounds with general chemical formula [Ln2(mip)3(H2O)8·4H2O]∞ with Ln = Sm–Er plus Y. Luminescent properties of the compounds that belong to this family have been studied. The Tb-based compound presents one of the brightest luminescences reported to date for a lanthanide-based coordination polymer. The weak intermetallic energy transfer evidenced on the third family of compounds allows easy and predictable color modulation of the heterobimetallic powders through additive colors strategy.

A series of optically pure carboxylate ligands based on a fluorene backbone were synthesized and used for the elaboration of four chiral metal–organic frameworks (6, 7, 8, and 9) containing Cu-based paddle-wheels. The positions and numbers of coordinating carboxylate functions on the ligand core govern the resulting MOF topologies, leading to a 1D framework (8), 2D grids with (7) or without interpenetration (6), and a 3D (9) framework and showing calculated porosities ranging from 8 to 47% of the unit-cell volumes. Ligands as well as corresponding MOFs possess luminescence properties with blue emission. The most porous MOF (9), made of a tetracarboxylate ligand, exhibits a BET apparent surface area of 467 m2 g−1 and methane and carbon dioxide storage capacities of 26.5 cm3 g−1 and 129 cm3 g−1, respectively, at 303 K and 30 bar.

A spiropyran-based switchable ligand isomerizes upon reaction with lanthanide(III) precursors to generate complexes with an unusual N

International audience; 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 metal ions are associated with organic molecules (ligands) to form extended networks. They present great structural diversity and a wide range of unique properties such as great porosity, strong catalytic activities, and original magnetic and luminescent behaviors. In this Account, we highlight recent research advances obtained by our team in the field of lanthanide-based CPs. However, rather than present a simple chronological description of successive investigations, we have chosen present our own experience in order to show how standard academic studies can be successfully turned into applied research and finally into a viable startup that commercializes these products as anticounterfieting taggants. A taggant is a compound that can be dispersed in a host matrix at parts per million rates for it to be labeled. Its economic advantages over traditional anticounterfeiting techniques (labels, chips, etc.) are its very low cost and its ability to label a raw material at every stage of its processing, unlike traditional techniques that label only the final product. It thus permits traceability of a given material over a wide range of suppliers/subcontractors/sellers or customers at every step of its life. After 15 years of fundamental crystallogenesis research, we identified a very stable phase of lanthanide-based CPs in which strong lanthanide luminescence can be observed. We investigated this phase further and showed that a heteronuclear approach can give access to billions of different compositions and makes it possible to turn these powders into taggants. After the creation of a startup, we refocused on fundamental studies in order to ensure its future development. This permitted the design of future generations of taggants and provided brightness- or color-tunable compounds as well as temperature-sensitive and soluble taggants. We hope to demonstrate here that strong fundamental research is a very effective tool to create a technological breakthrough that allows the development of efficient applicative research and competitive products and finally contributes to economic growth

Spotting trends: Upon going from TbIII to YbIII centers in the complexes of the DOTA4- ligand, a reorientation of the easy axis of magnetization from perpendicular to parallel to the Ln-O bond of the apical water molecule is experimentally observed and theoretically predicted (see picture; SMM = single-molecule magnet). Only ions with an odd number of electrons show slow relaxation of the magnetization. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim., This work was supported by the European Research Council through the AdG “NoINanoMaS” (grant number 267746), by the Italian MIUR (PRIN 2008), Spanish research project MAT2011-27233-C02-02, Région Bretagne, Rennes Métropole, and by the Italian CINECA through the award number HP10AI85MB, 2011.

Reactions in acetonitrile between 1,4-benzene-dicarboxylic acid (C8H6O4) and a hexanuclear complex of lanthanide [Ln6O(OH)8(NO3)6·2NO3] with Ln = Y or Tb lead to 1D-coordination polymers with the general chemical formula {[Ln6O(OH)8](NO3)2(bdc)(Hbdc)2·2NO3·H2bdc}∞ where H2bdc stands for 1,4-benzene-dicarboxylic acid (or terephthalic acid). These two compounds are isostructural. The crystal structure has been solved on the basis of the X-ray powder diffraction diagram of the Y-containing compound. This compound crystallizes in the triclinic system, space group P1 (no. 2) with a = 10.4956(6) A, b = 11.529(2) A, c = 12.357(2) A, α = 86.869(9)°, β = 114.272(6)°, γ = 71.624(7)°, V = 1264.02 A3, and Z = 2. The crystal structure can be described as the juxtaposition of linear chains of hexanuclear entities linked to each other by terephthalate ligands. Two additional partially protonated terephthalate ligands spreading laterally to the chain are bound to each hexanuclear entity. Another diprotonated terephthali...

Lanthanide containing octahedral hexanuclear complexes with general chemical formula [Ln6O(OH)8(NO3)6(H2O)x].2NO3.yH2O where Ln = Ce-Lu (except Pm) or Y, x = 0, 6, 12, 14 or 16 and y = 0, 2, 4 or 5 constitute a great family of polymorphic compounds. The synthesis and the crystal structures of all these compounds are overviewed. The hydration/dehydration processes that allow the structural transitions from one compound to another are described. The crystal structure of compounds with general chemical formula [Ln6O(OH)8(NO3)6(H2O)6].2NO3 where Ln = Ce-Lu (except Pm) or Y is described. It has been solved on the basis of a powder XRD diagram. The use of such hexanuclear complexes as molecular precursors for new materials is also discussed.