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International audience; Conducting polymers have been used as support for catalysts towards distinct electrocatalytic reactions. The overall activity of the modified interfaces critically depends on both the processes on the catalyst surface and of the charge compensation within the polymer matrix. Therefore, understand the coupling between surface and volumetric processes in such systems is of utmost importance. In this contribution we report on the experimental investigation of the interplay between surface and volumetric processes during the electrooxidation of formic acid (and also formaldehyde) on platinum modified polyaniline electrodes. The study was performed through in situ nanogravimetry, with the Electrochemical Quartz Crystal Nanobalance (EQCN). We have explored the dynamics of charge and mass changes along several experimental conditions, including the self-organized potential oscillations. The systematic study included the analysis of several configurations: gold electrodes covered with a PANI film and dispersed platinum (Au/PANI/Pt); platinum electrodes covered with PANI (Pt/PANI); and bare platinum electrodes. The methodology introduced includes the detailed analysis of the charge compensation process and of the time-derivative of the mass variations. Typical results for the electro-oxidation of formic acid on PANI supported platinum indicate that the electrocatalysis itself is reflected in the current profile, whereas the charge compensation rules the gravimetric response. This general observation also holds for the oscillatory electro-oxidation of formic acid. The physicochemical description of the support/catalyst systems described here opens interesting perspectives for the investigation of parent systems.

International audience; Core–shell SiO2@Au@TiO2 materials have shown excellent catalytic performances in the base-free oxidation of furfural (FF) to furoic acid (FA). The enhanced catalytic behaviour with respect to that observed over supported SiO2@TiO2@Au catalysts suggests a key role of the TiO2 shell, which could prevent Au deactivation by irreversible FA adsorption, improve metal–oxide interaction and presumably, give rise to the formation of new active sites located at the perimeter of the Au–TiO2 interface.

International audience; Two new ruthenium complexes, [Ru(h 5-Cp)(PPh 3)(2,2'-bipy-4,4'-R)] þ with R ¼-CH 2 OH (Ru1) or dibiotin ester (Ru2) were synthesized and fully characterized. Both compounds were tested against two types of breast cancer cells (MCF7 and MDA-MB-231), showing better cytotoxicity than cisplatin in the same experimental conditions. Since multidrug resistance (MDR) is one of the main problems in cancer chemotherapy, we have assessed the potential of these compounds to overcome resistance to treatments. Ru2 showed exceptional selectivity as P-gp inhibitor, while Ru1 is possibly a substrate. In vivo studies in zebrafish showed that Ru2 is well tolerated up to 1.17 mg/L, presenting a LC 50 of 5.73 mg/L at 5 days post fertilization.

International audience; We present here the synthesis of two new bifunctionalized azachelators, no2th-EtBzNCS and Hno2th1tha, as bioconjugable analogues of two previously described di- and trimethylthiazolyl 1,4,7-triazacyclononane (tacn) ligands, no2th and no3th, for potential uses in copper-64 (64Cu) positron emission tomography imaging. The first one bears an isothiocyanate group on the remaining free nitrogen atom of the tacn framework, while the second one presents an additional carboxylic function on one of the three heterocyclic pendants. Their syntheses required regiospecific N-functionalization of the macrocycles. In order to investigate their suitability for in vivo applications, a complete study of their copper(II) chelation was performed. The acid–base properties of the ligands and their thermodynamic stability constants with copper(II) and zinc(II) cations were determined using potentiometric techniques. Structural studies were conducted in both solution and the solid state, consolidated by theoretical calculations. The kinetic inertness in an acidic medium of both copper(II) complexes was determined by spectrophotometry, while cyclic voltammetry experiments were performed to evaluate the stability at the copper(I) redox state. UV–vis, NMR (of the zinc complexes), electron paramagnetic resonance spectroscopy, and density functional theory studies showed excellent agreement between the solution structures of the complexes and their crystallographic data. These investigations unambiguously prove that these bifunctional derivatives display similar coordination properties as their no2th and no3th counterparts, opening the door to targeted bioapplications. The no2th-EtBzNCS and Hno2th1tha ligands were then conjugated to a bombesin antagonist peptide for targeting the gastrin-releasing peptide receptor (GRPr). To highlight the potential of the two chelators for radiopharmaceutical development, the 64Cu-radiolabeling properties, in vitro stability, and binding affinity to GRPr of the corresponding bioconjugates were determined. Altogether, the results of this work warrant the further development of 64Cu-based radiopharmaceuticals comprising our novel bifunctional chelators.

International audience; Synthesizing molecular knots that mimic the catalytic functionality of stereospecific or stereoselective enzymes are an intriguing task in chemistry. Synthetic anion receptors even with moderate halide binding affinities may catalyze chemical reactions involving carbon-halogen bond cleavage. Herein we report isostructural self-assembled trefoil molecular knots (Cu-TK, Cd-TK, Zn-TK) based on Cu(II), Cd(II), and Zn(II) that are capable of binding and stabilizing bromide within their central cavity and are capable of catalyzing C-Br bond cleavage. We also describe the role of noncovalent interactions between the knots and bromide as well as the size and shape of the knots on their catalytic efficiency. Among the studied three knots, Cu-TK was found to be more effective than Zn-TK and Cd-TK in catalyzing C-Br bond cleavage. The catalytic efficiency of the knots toward C-Br bond cleavage was found to be related to a balance between their attractive electrostatic interactions with bromide as well as cavity size and shape of the knots.

International audience; Folic acid (FA; vitamin B9) and its associated sodium salts, strongly relevant for many scientific and technological applications - from nutrition to pharmacology and nanomedicine, suffer from a lack of characterization combining experimental and theoretical. In this work, a spectroscopic investigation of FA and its synthesized sodium salts in the form of dianion (Na2HFol) or trianion (Na3Fol) was scrutinized in their solid state. The spectroscopic (infrared, Raman, and solid state 13C-nuclear magnetic resonance) data interpretation was supported by theoretical calculations using the Density Functional Theory (DFT). Additionally, the compounds were characterized by UV–VIS diffuse-reflectance spectroscopy, combined thermal analysis (TG/DTG-DSC) coupled to mass spectrometry, and X-ray diffractometry. The main signatures of each species were identified, as well as the influence of the protonation level on their physicochemical properties. These distinct properties for the three compounds are mainly based on signals assigned to glutamic acid (glutamate) and pterin (neutral or anionic) moieties. This work should help developing new products based on FA or its anionic forms, such as theragnostic/drug delivery systems, supramolecular structures, nanocarbons, or metal complexes.

International audience; In the present study, the thermal behaviour of a layered double hydroxide (LDH) intercalated with a carboxymethylcellulose (CMC) polymer was evaluated to inspect the effect of the temperature on the chemical processes that occur during its decomposition under a nitrogen atmosphere, ranging from 500 to 1000 1C, as well as the product properties. The intercalation compound (LDH-CMC) proved to be a suitable precursor to develop inorganic nanocomposites based on Ni metallic nanoparticles (Ni-MNPs) embedded in a carbonaceous matrix by a bottom-up strategy involving a carbothermal reaction. Considering the temperature effect on the LDH-CMC decomposition processes, as well as the dispersion of metallic and carbon sources at the nanoscale level favoured by the intercalated structure, the simple synthetic approach reported in this work permits fine tuning of the production of valuable phases. The nanocomposites with ordered carbonaceous structures and transition metallic nanoparticles are interesting functional materials for electrocatalysis.

A family of three picolinate pyclen based ligands, previously investigated for the complexation of Y3+ and some lanthanide ions (Gd3+, Eu3+), was studied with 161Tb and 177Lu in view of potential radiotherapeutic applications. The set of six Tb3+ and Lu3+ complexes was synthesized and fully characterized. The coordination properties in the solid state and in solution were thoroughly studied. Potentiometric titrations, corroborated by DFT calculations, showed the very high stability constants of the Tb3+ and Lu3+ complexes, which are associated to remarkable kinetic inertness. A complete radiolabeling study performed with both 161Tb and 177Lu radionuclides, including experiments with regard to the stability with and without scavengers and kinetic inertness using challenging agents, proved that the ligands could reasonably compete with the DOTA analogue. To conclude, the potential of using the same ligand for both radiotherapy and optical imaging was highlighted for the first time.

International audience; We report a detailed study of the thermodynamic stability and dissociation kinetics of lanthanide complexes with two ligands containing a cyclen unit, a methyl group, a picolinate arm, and two acetate pendant arms linked to two nitrogen atoms of the macrocycle in either cis (1,4-H3DO2APA) or trans (1,7-H3DO2APA) positions. The stability constants of the Gd3+ complexes with these two ligands are very similar, with log KGdL values of 16.98 and 16.33 for the complexes of 1,4-H3DO2APA and 1,7-H3DO2APA, respectively. The stability constants of complexes with 1,4-H3DO2APA follow the usual trend, increasing from log KLaL = 15.96 to log KLuL = 19.21. However, the stability of [Ln(1,7-DO2APA)] complexes decreases from log K = 16.33 for Gd3+ to 14.24 for Lu3+. The acid-catalyzed dissociation rates of the Gd3+ complexes differ by a factor of ∼15, with rate constants (k1) of 1.42 and 23.5 M–1 s–1 for [Gd(1,4-DO2APA)] and [Gd(1,7-DO2APA)], respectively. This difference is magnified across the lanthanide series to reach a 5 orders of magnitude higher k1 for [Yb(1,7-DO2APA)] (1475 M–1 s–1) than for [Yb(1,4-DO2APA)] (5.79 × 10–3 M–1 s–1). The acid-catalyzed mechanism involves the protonation of a carboxylate group, followed by a cascade of proton-transfer events that result in the protonation of a nitrogen atom of the cyclen unit. Density functional theory calculations suggest a correlation between the strength of the Ln–Ocarboxylate bonds and the kinetic inertness of the complex, with stronger bonds providing more inert complexes. The 1H NMR resonance of the coordinated water molecule in the [Yb(1,7-DO2APA)] complex at 176 ppm provides a sizable chemical exchange saturation transfer effect thanks to a slow water exchange rate of (15.9 ± 1.6) × 103 s–1.; L'arrangement des atomes donneurs de ligand autour de l'ion lanthanide provoque des différences dramatiques dans les stabilités thermodynamiques et la cinétique de dissociation des complexes de lanthanides, comme le démontre l'étude des complexes avec deux ligands à base de régioisomères du cyclen, contenant un bras picolinate et deux bras acétate soit en position 1,7 ou 1,4 de la structure macrocyclique.

International audience; This work explores the synthesis, physicochemical characterization, and in vivo biocompatibility of iron-based layered double hydroxides (LDHs) with molar ratio M2+/(Fe3+ + Al3+) equal to 2, Fe3+/Al3+ equal to 1, and chloride anions as charge-compensating ion (abbreviated Mg4FeAl-Cl and Zn4FeAl-Cl) prepared by the coprecipitation method. The higher structural organization of Zn4FeAl-Cl in comparison to Mg2+ analogous material was noticed by X-ray diffraction and scanning electron microscopy images. Biocompatibility of LDH was evaluated by intramuscular implantation in rats. Tablets of M4FeAl-Cl (M = Mg, Zn) were readily identified macroscopically after 7 and 28 days of implantation, denoting slow dissolution in the internal medium; adjacent to the tablets, blood flow was preserved without tortuosity or pathological dilatations, according to the Sidestream Dark Field Imaging technique. The histological analysis showed no inflammatory response and the presence of angiogenesis and tissue remodeling with the reconstruction of the extracellular matrix and cells around the tablets, besides the induction of collagen type-I formation. Prussian blue histochemical reaction suggested higher solubility of Mg4FeAl-Cl in the extracellular matrix compared to zinc LDH. Considering the positive biocompatibility results obtained for M4IIFeAl-LDH materials, experiments were conducted to intercalate the anti-inflammatory naproxen, as a model drug, into the iron-based LDHs (M4IIFeAl-NAP). The release profile of NAP in phosphate buffer showed 90% of the drug delivered after about 80 h. However, divalent metal leaching was verified mainly for Mg-LDH (around 50%) when compared to Zn2+ (around 1%). Iron-based LDHs have great potential for medical and technological applications as local drug delivery biomaterials exhibiting biocompatibility and biointegration properties.

International audience; The triethylbenzene-bis-cyclen (cyclen = 1,4,7,10-tetraazacyclododecane) compound (tbmce) was designed with an imposed structural rigidity at the m-xylyl spacer to be compared to a less restrained and known parent compound (bmce). The framework of both compounds differs only in the substituents of the m-xylyl spacer. The study was centered in the differences observed in the acid–base reactions of both compounds, their copper(II) and zinc(II) complexation behaviors, as well as in the uptake of phosphate and polyphosphate anions (HPPi3–, ATP4–, ADP3–, AMP2–, PhPO42–, and HPO42–). On the one hand, the acid–base reactions showed lower values for the third and fourth protonation constants of tbmce than for bmce, suggesting that the ethyl groups of the spacer in tbmce force the two cyclen units to more conformational restricted positions. On the other hand, the stability constant values for copper(II) and zinc(II) complexes revealed that bmce is a better chelator than tbmce pointing out to additional conformational restraints imposed by the triethylbenzene spacer. The binding studies of phosphates by the dinuclear copper(II) and zinc(II) complexes showed much smaller effective association constants for the dicopper complexes. Single-crystal X-ray and computational (density functional theory) studies suggest that anion binding promotes the formation of tetranuclear entities in which anions are bridging the metal centers. Our studies also revealed the dinuclear zinc(II) complex of bmce as a promising receptor for phosphate anions, with the largest effective association constant of 5.94 log units being observed for the formation of [Zn2bmce(HPPi)]+. Accordingly, a colorimetric study via an indicator displacement assay to detect phosphates in aqueous solution found that the [Zn2bmce]4+ complex acts as the best receptor for pyrophosphate displaying a detection limit of 2.5 nM by changes visible to naked eye.

International audience; The geometric features of two pyclen-based ligands possessing identical donor atoms but different site organization have a profound impact in their complexation properties toward lanthanide ions. The ligand containing two acetate groups and a picolinate arm arranged in a symmetrical fashion (L1) forms a Gd3+ complex being two orders of magnitude less stable than its dissymmetric analogue GdL2. Besides, GdL1 experiences a much faster dissociation following the acid-catalyzed mechanism than GdL2. On the contrary, GdL1 exhibits a lower exchange rate of the coordinated water molecule compared to GdL2. These very different properties are related to different strengths of the Gd ligand bonds associated to steric effects, which hinder the coordination of a water molecule in GdL2 and the binding of acetate groups in GdL1.

International audience; Carbon dioxide absorption by mixtures of two ionic liquids with a common cation—1-butyl-3-methylimidazolium acetate, [C4C1Im][OAc], and 1-butyl-3-methylimidazolium tricyanomethanide, [C4C1Im][C(CN)3]—was determined experimentally at pressures below atmospheric pressure as a function of temperature between 303 K and 343 K, and at 303 K as a function of pressure up to 10 bar. It is observed that the absorption of carbon dioxide decreases with increasing tricyanomethanide anion concentration and with increasing temperature, showing a maximum of 0.4 mole fraction of carbon dioxide in pure [C4C1Im][OAc] at 303 K. At this temperature, the CO2 absorption in the mixtures [C4C1Im][OAc](1−x)[C(CN)3]x is approximately the mole-fraction average of that in the pure ionic liquids. By applying an appropriate thermodynamic treatment, after identification of the species in solution, it was possible to calculate both the equilibrium constant, Keq, and Henry's law constant, KH, in the different mixtures studied thus obtaining an insight into the relative contribution of chemical and physical absorption of the gas. It is shown that chemical sorption proceeds through a 1 : 2 stoichiometry between CO2 and acetate-based ionic liquid. The presence of the C(CN)3− anion does not significantly affect the chemical reaction of the gas with the solvent (Keq = 75 ± 2 at 303 K) but leads to lower Henry's law constants (from KH = 77.8 ± 0.6 bar to KH = 49.5 ± 0.5 bar at 303 K), thus pointing towards larger physical absorption of the gas. The tricyanomethanide anion considerably improves the mass transfer by increasing the fluidity of the absorbent as proven by the larger diffusivities of all the ions when the concentration of the C(CN)3− anion increases in the mixtures.

International audience; Herein we report a one pot organometallic strategy to access alumina-embedded Pd nanoparticles. Unexpectedly, the decomposition of the organometallic complex tris(dibenzylideneacetone)dipalladium(0), Pd2(dba)3, by dihydrogen in the presence of aluminum isopropoxide, Al(iPrO)3, and without extra stabilizers, was found to be an efficient method to generate a Pd colloidal solution. Careful characterization studies revealed that the so-obtained Pd nanoparticles were stabilized by an aluminum isopropoxide tetramer and 1,5-diphenyl-pentan-3-one, which was produced after reduction of the dba ligand from the organometallic precursor. Moreover, calcination of the obtained nanomaterial in air at 773 K for 2 h resulted in a nanocomposite material containing Pd nanoparticles embedded in Al2O3. This stabilization strategy opens new possibilities for the preparation of transition metal nanoparticles embedded in oxides.

International audience; Considering the current importance of unsymmetrical mono- and di-N-functionalized ethylene side-bridged (sb) cyclams and the need to have their C-appended derivatives bearing an additional function dedicated to a conjugation to an external moiety as a targeting biomolecule, we have developed a general procedure to obtain orthogonally N-protected sb‑cyclams with a benzyl or a Boc group. Despite the lack of symmetry of the compounds, this methodology allows the specific protection of one or the other remaining secondary amine function.; Compte tenu de l’importance actuelle des cyclams à side-bridged (sb) asymétriques mono- et di-N-fonctionnalisés et de la nécessité d’avoir leurs dérivés C-fonctionnels portant une fonction supplémentaire dédiée à la conjugaison à une entité externe telle qu’une biomolécule de ciblage, nous avons mis au point une procédure générale permettant d’obtenir des cyclams sb N-protégés orthogonalement avec un groupe benzyle ou un groupe Boc. Malgré le manque de symétrie des composés, cette méthodologie permet la protection spécifique de l’une ou l’autre des fonctions amines secondaires restantes.

[Abstract] Three tacn (1,4,7-triazacyclononane)-based ligands substituted by methylthiazolylcarboxylate (tha) and/or methylthiazolyl (th) arms have been examined for copper complexation with the aim to study the impact of carboxylate groups on the complexation of Cu(II), which can present an endo- or exo-cyclic coordination. Two new ligands have been synthesised: H3no3tha, tacn bearing three methylthiazolylcarboxylate arms, and H2no1th2tha, tacn with one methylthiazolyl and two methylthiazolylcarboxylate arms, while Hno2th1tha had already been described. Their complexation behaviour with 1 or 1.5 equivalents of metal was studied on the basis of preliminary results showing the tendency of tha arms to form exocyclic polynuclear species. The solid state studies of the Cu(II) and Zn(II) complexes were investigated and some of their structures were characterised by X-ray diffraction. The physicochemical properties of the complexes in solution were also investigated by means of potentiometric measurements, UV-vis spectroscopy, EPR and computational studies, NMR characterisation of the corresponding Zn(II) complexes and redox behaviour by electrochemistry. Mono- and tri-nuclear complexes ML and M3L2 were formed and isolated, highlighting the tendency of methylthiazolylcarboxylate arms, when carried by a tacn platform, to form exo-cyclic and polynuclear complexes. However, this exhaustive study evidences that the “out of cage” and “in cage” present different behaviour in terms of stability. R. T. and V. P. acknowledge the Ministère de l′Enseignement Supérieur et de la Recherche, the Centre National de la Recherche Scientifique and the “Service Commun” of NMR facilities of the University of Brest. R.D. and L.M.P.L. acknowledge Fundação para a Ciência e a Tecnologia (FCT) for the financial support under Project LISBOA-01-0145-FEDER-007660 (Microbiologia Molecular, Estrutural e Celular) funded by FEDER funds through COMPETE2020 – Programa Operacional Competitividade e Internacionalização (POCI) and by national funds through FCT, and L. M. P. L. thanks FCT also for a postdoctoral fellowship (SFRH/BPD/73361/2010). C. P.-I. and D. E.-G. thank Centro de Computación de Galicia (CESGA) for providing the computer facilities Portugal. Fundação para a Ciência e a Tecnologia; LISBOA-01-0145-FEDER-007660 Portugal. Fundação para a Ciência e a Tecnologia; SFRH/BPD/73361/2010

International audience

International audience; H2cb‐te2pa, a cross‐bridged cyclam functionalized by two picolinate arms, was used for the formation of an incredible inert In(III) chelate. For the first time a bifunctional analogue of H2cb‐te2pa was prepared by C‐functionalization to keep its coordination properties intact. However, this strategy leads to the formation of two diastereoisomers, as evidenced and studied by NMR experiments and DFT calculations. Kinetic studies proved nevertheless that both isomers of the complex are equally inert; they were therefore used without distinction for their covalent grafting on polystyrene beads. The so‐called metal‐encoded beads were tested for Imaging Mass Cytometry. The detection of 115In allows the generation of images with high quality, proving the great potential of the bifunctional [In(cb‐te2pa)]+ derivatives for single‐cell analysis by mass cytometry.; H2cb-te2pa, un cyclam renforcé fonctionnalisé par deux bras picolinate, a été utilisé pour la formation d'un chélate d’indium(III) incroyablement inerte. Pour la première fois, un analogue bifonctionnel de H2cb-te2pa a été préparé par C-fonctionnalisation pour conserver ses propriétés de coordination intactes. Cependant, cette stratégie conduit à la formation de deux diastéréoisomères, comme en témoignent les expériences de RMN et les calculs de DFT. Les études cinétiques ont néanmoins prouvé que les deux isomères du complexe étaient également inertes; ils ont donc été utilisés sans distinction pour leur greffage covalent sur des billes de polystyrène. Les billes obtenues ont été testées pour l’imagerie par cytométrie de masse. La détection de l’115In permet de générer des images de haute qualité, prouvant ainsi le potentiel des dérivés bifonctionnels [In (cb-te2pa)]+ pour l'analyse monocellulaire par cytométrie de masse.

[Abstract] We report a detailed study of the photophysical properties of EuIII and TbIII complexes with two ligands based on a 3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane platform containing either four pyridine-2yl-methyl (L1) or four hydroxyethyl (L2) pendant arms. The [TbL1]3+ and [TbL2]3+ complexes present moderate luminescence quantum yields upon excitation through the ligand bands (ϕH2O = 7.4 and 21%, respectively). The [EuL2]3+ complex displays a relatively low quantum yield in H2O (ϕH2O = 1.6%) that increases considerably in D2O (ϕD2O = 5.3%), which highlights the strong quenching effect of the four ligand O–H oscillators. The emission spectrum of [EuL1]3+ is rather unusual in that it shows a relatively high intensity of the 5D0 → 7F5,6 transitions, which appears to be also related to the distorted D4d symmetry of the coordination polyhedron. Surprisingly, the quantum yield of the [EuL1]3+ complex is very low (ϕH2O = 0.10%), considering the good protection of the EuIII coordination environment offered by the ligand. Cyclic voltammograms recorded from aqueous solutions of [EuL1]3+ display a reversible curve with a half-wave potential of −620 mV (versus Ag/AgCl), while [EuL2]3+ presents a reduction peak at more negative potential (−1040 mV). Thus, the L1 ligand provides a rather good stabilisation of divalent Eu compared to the L2 analogue, suggesting that the presence of a low-lying ligand-to-metal charge-transfer (LMCT) state might be responsible for the low quantum yield determined for [EuL1]3+. A density functional theory (DFT) study provides very similar energies for the ligand-centered excited singlet (1ππ*) and triplet (3ππ*) states of [EuL1]3+ and [EuL2]3+. The energy of the 9LMCT state of [EuL1]3+ was estimated to be 20 760 cm−1 by using all-electron relativistic calculations based on the DKH2 approach, a value that decreases to 15 940 cm−1 upon geometry relaxation. Ministerio de Economía y Competitividad; CTQ2016-76756-P Xunta de Galicia; ED431B 2017/59 Xunta de Galicia; ED431D 2017/01

International audience; The Y3+ complex of PCTMB, the tri-n-butyl phosphonate ester of pyclen (3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene), was synthesized as well as its Ho3+ and Lu3+ analogues. X-ray diffraction analyses revealed isomorphous dimeric M2(PCTMB)2·9H2O (M = Y, Ho, Lu) structures that crystallize in the centrosymmetric P1 triclinic space group. 1H NMR and UV studies in aqueous solutions indicated that Y3+ complexation is fast, being quantitative in 167 min at pH 3.8 and in 13 min at pH 5.5 (25 °C, acetate buffer, I = 0.150 M, [Y3+] = [PCTMB] = 0.2 mM). 1H NMR DOSY and photon correlation spectroscopy experiments evidenced the formation of aggregates in chloroform with a bimodal distribution that changes slightly with concentration (11-24 and 240-258 nm). The behavior of the acid-assisted dissociation of the complex of Y3+ with PCTMB was studied under pseudo-first-order conditions, and the half-life of the [Y(PCTMB)] complex in 0.5 M HCl at 25 °C was found to be 37 min, a value that decreases to 2.6 min in 5 M HCl. The Y3+ complex of PCTMB is thermodynamically very stable, with a stability constant of log KY-PCTMB = 19.49 and pY = 16.7 measured by potentiometry. 90Y complexation studies revealed fast radiolabeling kinetics; optimal radiolabeling conditions were obtained for 90Y in acetate medium, PCTMB at 10-4 to 10-2 M in acetate buffer pH = 4.75, 15 min at 45-60 °C. In vitro stability studies in human serum showed that [90Y(PCTMB)] is quite stable, with about 90% of the activity still in the form of the radiotracer at 24 h and 80% from 48 h to 72 h. A comparison with other ligands such as PCTA, DOTA, and DTPA already used for in vivo application shows that [90Y(PCTMB)] is an interesting lipophilic and neutral analogue of these reference chelates for therapeutic applications in aqueous and nonaqueous media. © 2016 American Chemical Society.

International audience

International audience; The release of uranyl(VI) is ah azardous environmental issue,w ith limited ways to monitor accumulation in situ. Here,wepresent amethod for the detection of uranyl(VI) ions through the utilization of au nique fluorescence energy transfer process to europium(III). Our system displays the first example of a" turn-on" europium(III) emission process with asmall, water-soluble lanthanide complex triggered by uranyl-(VI) ions. The development of nuclear technologies has led to many cases of accidental and intentional release of radionuclides, with accumulation of significant levels of uranium in the environment. [1] Of particular concern is the uranyl(VI) cation, UO 2 2+ .T his species,apotent nephrotoxin, [2] is highly mobile in groundwater and biological systems,l eading to possible problematic spread of radiotoxic material following containment breaches. To date,there has been limited development of probes for UO 2 2+ detection, with scintillation counting and X-ray based methods generally preferred. [1a] While these allow determination of total uranium content they,i mportantly,c annot distinguish between different oxidation states and, compared to fluorescence-based techniques,a re limited in their in situ application. This limitation hinders the real-time and remote monitoring of remediation strategies,s uch as the biotic reduction of UO 2 2+ to more immobile U IV-containing minerals ,astrategy currently under development as abioremedia-tion tool. [1a] Thef ew luminescence-based detection systems reported to date [3] have failed to exploit the intrinsic photo-physical properties of UO 2 2+ ,w hich allow distinct identification over other oxidation states and, with the correct design, afford an opportune and selective handle with which to monitor local concentration fluctuations of this environmentally hazardous species. Theintrinsic photophysical properties of the UO 2 2+ cation arise from formally forbidden charge transfer transitions from oxo-based molecular orbitals to nonbonding,u noccupied f-orbitals. [4] While direct interpretation of these transitions can be complicated by speciation and spectral overlap with optical transitions from biological media, [5] they do provide ameans for indirect UO 2 2+ detection via energy transfer to other longer wavelength (and longer-lived) emissive species.O f particular interest here is the spectral overlap of the UO 2 2+ emission (ca. 520 nm) and the europium(III) excitation bands (principally 5 D 1 ! 7 F 0,1), [6] which enable efficient energy transfer to occur from the former to the latter (Scheme 1). Here,wereport the first exampleofUO 2 2+ to lanthanide energy transfer in aw ater-soluble,m olecular europium(III) complex, [EuL]. [7] We suggest thatthis energy transfercould provide ahighly selective method of UO 2 2+ detection, due to the unique photophysical properties of UO 2 2+ that allow this process to occur. Initial spectrophotometric titrations were performed by following the absorption, steady-state emission and excitation spectra of [EuL] as afunction of addedUO 2 2+ (Figures 1, S1 and S2). In the absence of UO 2 2+ ,t he emission spectrum of [EuL] uponl igande xcitation(280 nm) is typical of Eu 3+ emission with the narrow emission bands corresponding to the 5 D 0 ! 7 F J transitions (578, 595, 613, 654 and 702 nm for J = 0t o4 ,r espectively). [7, 8] Addition of uranyl(VI) nitrate (0-2equivalents) at pH 7.4 led to adecrease of the overall Eu 3+ Scheme 1. "Turn-on" emission of [EuL] at selected excitation wavelengths due to energy transfer from UO 2 2+. Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.

International audience; We report a detailed characterization of lanthanide complexes with two azaligands based on the pyclen macrocycle containing two picolinate and one acetate pendant arms. The two picolinate arms are attached to either opposite (L3) or adjacent (L4) amine nitrogen atoms of the macrocyclic platform. The X-ray structures of the Yb3+ complexes show nine coordination of the ligand to the metal ion, a situation that is also observed for EuL4 in the solid state. The EuL3 complex forms centrosymmetric dimers in the solid state joined by μ2-η1:η1 carboxylate groups, which results in 10-coordinate Eu3+ ions. The emission spectra of EuL3 measured in H2O and D2O solution reveal the presence of a hydration equilibrium involving a nine-coordinate species lacking inner-sphere water molecules and a monohydrated 10-coordinate species. The Eu3+ complexes present modest emission quantum yields in buffered aqueous solution (Φ = 16 and 22% for EuL3 and EuL4, 0.1 M tris buffer, pH 7.4), while the corresponding Tb3+ complexes present very high emission quantum yields under the same conditions (∼90%). 1H NMR studies show that the complexes of L3 present a fluxional behavior in D2O solution, while those of L4 are more rigid. The analysis of the Yb3+-induced NMR shifts of YbL4 indicates that the complex presents a structure in solution similar to that observed in the solid state. The Gd3+ complexes present very high thermodynamic stability constants (log KGdL = 23.56(2) and 23.44(2) for GdL3 and GdL4, respectively). The corresponding pGd values (pGd = −log[Gd3+]free with cL = 1 × 10–5 M and cGd = 1 × 10–6 at pH 7.4) of 20.69 (GdL3) and 21.83 (GdL4) are higher than that of Gd(dota)− (pGd = 19.21). The Gd3+ complexes also show remarkable inertness with respect to their proton-assisted dissociation, with dissociation half-life times of 50 min (GdL3) and 20 h (GdL4) in 1 M HCl.; Deux ligands azamacrocycliques à base de picolinate et d'acétate dans un rapport (2: 1) L3 et L4 et différemment distribué présentent des propriétés très intéressantes en tant que chélateurs pour les ions lanthanides (III), notamment une stabilité thermodynamique élevée, une cinétique de complexation rapide, une cinétique de dissociation lente ainsi qu’un des rendements quantiques d’émission très élevés, en particulier dans le cas des complexes Tb3 +.

International audience; The release of uranyl(VI) is a hazardous environmental issue, with limited ways to monitor accumulation in situ. Here, we present a method for the detection of uranyl(VI) ions through the utilization of a unique fluorescence energy transfer process to europium(III). Our system displays the first example of a “turn‐on” europium(III) emission process with a small, water‐soluble lanthanide complex triggered by uranyl(VI) ions.

International audience; Mixtures of the ionic liquid butyltrimethylammonium bis(trifluoromethylsulfonyl)imide, [N4111][NTf2], with poly(ethylene oxide) polymers, PEO, of different molecular weights were investigated for CO2 capture. The liquid mixtures are close to ideal in terms of their volumetric properties but their enthalpies of mixing are negative, decreasing when the size of the polymer chain increases and being close to those observed for associative compounds mixed with ionic liquids (ΔmixH = −7 kJ mol−1 for [N4111][NTf2] + PEO1000 at 318 K). The favorable interactions between the polymer and the ionic liquid could be related to the dynamic properties of the mixtures, especially for mixtures of polymers of longer chain sizes which have a higher viscosity than that of the pure mixture components. Raman spectroscopy confirmed an association between the cation of the ionic liquid and the polymers that probably surround the cation and thus contribute to slow the dynamics of the mixtures. The increase of the carbon dioxide absorption with the increase of the polymer mole fraction composition in the liquid mixture is explained by the more favorable interactions between the gas and the polymer as evidenced by the analysis of the thermodynamic properties of solvation.

International audience; New ruthenium methyl-cyclopentadienyl compounds bearing bipyridine derivatives with the general formula [Ru(η 5-MeCp)(PPh 3)(4,4′-R-2,2′-bpy)] + (Ru1, R = H; Ru2, R = CH 3 ; and Ru3, R = CH 2 OH) have been synthesized and characterized by spectroscopic and analytical techniques. Ru1 crystallized in the monoclinic P2 1 /c, Ru2 in the triclinic P1̅ , and Ru3 in the monoclinic P2 1 /n space group. In all molecular structures, the ruthenium center adopts a "piano stool" distribution. Density functional theory calculations were performed for all complexes, and the results support spectroscopic data. Ru1 and Ru3 were poor substrates of the main multidrug resistance human pumps, ABCB1, ABCG2, ABCC1, and ABCC2, while Ru2 displayed inhibitory properties of ABCC1 and ABCC2 pumps. Importantly, all compounds displayed a very high cytotoxic profile for ovarian cancer cells (sensitive and resistant) that was much more pronounced than that observed with cisplatin, making them very promising anticancer agents. ■ INTRODUCTION The increasing research in the area of metallodrugs has positioned ruthenium complexes as promising drugs for cancer therapy, particularly because of the progression through clinical trials of some inorganic ruthenium(III) complexes, namely NAMI-A, [ImH][trans-RuCl 4 (DMSO) Im] (Im = imidazole), and KP1019, [Hind][trans-RuCl 4 (ind) 2 ] (ind = indazole). 1−3 In addition, the growing research on ruthenium organometallic chemistry unveiled important features for the metallodrug field such as the lower toxicity of ruthenium drugs relative to platinum-based drugs (e.g., cisplatin, CDDP) and different cell targets than DNA. 4−6 Thus, different modes of action are possible, resulting in a better efficiency and less toxic side effects than those of the metallodrugs in clinical use. Our research group has focused on the search for new Ru(II) and Fe(II) "piano stool" cationic complexes as anticancer agents. In this frame, diverse sets of complexes of the general formula [M II (η 5-C 5 H 5)(PP)(L)] + were designed and synthesized , with M II = Ru, Fe; PP = monodentate or bidentate

Bioluminescence is a phenomenon that has fascinated mankind for centuries. Today the phenomenon and its sibling, chemiluminescence, have impacted society with a number of useful applications in fields like analytical chemistry and medicine, just to mention two. In this review, a molecular-orbital perspective is adopted to explain the chemistry behind chemiexcitation in both chemi- and bioluminescence. First, the uncatalyzed thermal dissociation of 1,2-dioxetane is presented and analyzed to explain, for example, the preference for triplet excited product states and increased yield with larger nonreactive substituents. The catalyzed fragmentation reaction and related details are then exemplified with substituted 1,2-dioxetanone species. In particular, the preference for singlet excited product states in that case is explained. The review also examines the diversity of specific solutions both in Nature and in artificial systems and the difficulties in identifying the emitting species and unraveling the color modulation process. The related subject of excited-state chemistry without light absorption is finally discussed. The content of this review should be an inspiration to human design of new molecular systems expressing unique light-emitting properties. An appendix describing the state-of-the-art experimental and theoretical methods used to study the phenomena serves as a complement.

International audience; We report the synthesis of two azaligands based on the pyclen macrocyclic platform containing two picolinate and one acetate pendant arms. The two ligands differ in the relative positions of the pendant functions, which are arranged either in a symmetrical (L3) or nonsymmetrical (L4) fashion. The complexation properties of the ligands toward natY3+ and 90Y3+ were investigated to assess their potential as chelating units for radiopharmaceutical applications. The X-ray structures of the YL3 and YL4 complexes show nonadentate binding of the ligand to the metal ions. A multinuclear 1H, 13C, and 89Y NMR study shows that the complexes present a structure in solution similar to that observed in the solid state. The two complexes present very high thermodynamic stability constants (log KYL = 23.36(2) and 23.07(2) for YL3 and YL4, respectively). The complexes also show a remarkable inertness with respect to their proton-assisted dissociation, especially YL4. 90Y radiolabeling was proved to be efficient under mild conditions. The 90YL3 and 90YL4 radiochelates were found to be more stable than 90Y(DOTA).

The contamination of natural environments by trace metals has several adverse effects on human health, which is mainly due to the high toxicity, persistence and reactivity of these species in the environment. To understand the bioavailability of trace metals, it is necessary to know the speciation in equilibrium and the dynamic behavior of the system. In this context, the present work aims to present a bibliographic review about the potentialities of the Stripping Chronopotentiometry (SCP) and Stripping Chronopotentiometry at Scanned Deposition Potential (SSCP) in the study of dynamic trace metal speciation. These techniques have low detection limits and do not suffer interference due to the adsorption of organic matter on the surface of the working electrode. Coupling these techniques with the Absence of Gradients and Nernstian Equilibrium Stripping (AGNES) enables simultaneous determination of free ions, complexation equilibrium constants and diffusion coefficients of the complexes, thus providing information on the dynamic and heterogeneity of the metal complexes in the presence of macromolecules or particles. In this paper we will present the theory of dynamic speciation of trace metals, a detailed description of how to use the techniques to obtain this information, and examples of application in model systems and natural samples.

International audience; In this work, a carbon replica derived from a vinylbenzenesulfonate-intercalated layered double hydroxide (CR-LDH) was applied to remove the Dicamba organochlorine herbicide from aqueous solution. The samples were characterized by several experimental techniques such as X-ray diffraction (XRD), thermogravimetric analysis coupled with differential scanning calorimetry and mass spectrometry (TGA-DSC-MS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Raman spectroscopy, N2 adsorption/desorption and zeta potential analysis. The CR-LDH sample presents a very high specific surface area (2345 m2 g−1). The adsorption experiment typically followed the Langmuir isotherm model and the adsorption kinetics was best fitted with a pseudo second-order model. The maximum adsorption capacity of Dicamba herbicide onto CR-LDH was 279 mg g−1. CR-LDH presented a higher adsorption capacity than other carbon adsorbent materials reported in the literature.

International audience; A series of Gd(3+) complexes exhibiting a relaxometric response to zwitterionic amino acid neurotransmitters was synthesized. The design concept involves ditopic interactions 1) between a positively charged and coordinatively unsaturated Gd(3+) chelate and the carboxylate group of the neurotransmitters and 2) between an azacrown ether appended to the chelate and the amino group of the neurotransmitters. The chelates differ in the nature and length of the linker connecting the cyclen-type macrocycle that binds the Ln(3+) ion and the crown ether. The complexes are monohydrated, but they exhibit high proton relaxivities (up to 7.7 mM(-1) s(-1) at 60 MHz, 310 K) due to slow molecular tumbling. The formation of ternary complexes with neurotransmitters was monitored by (1) H relaxometric titrations of the Gd(3+) complexes and by luminescence measurements on the Eu(3+) and Tb(3+) analogues at pH 7.4. The remarkable relaxivity decrease (≈80 %) observed on neurotransmitter binding is related to the decrease in the hydration number, as evidenced by luminescence lifetime measurements on the Eu(3+) complexes. These complexes show affinity for amino acid neurotransmitters in the millimolar range, which can be suited to imaging concentrations of synaptically released neurotransmitters. They display good selectivity over non-amino acid neurotransmitters (acetylcholine, serotonin, and noradrenaline) and hydrogenphosphate, but selectivity over hydrogencarbonate was not achieved.

International audience; A versatile and efficient bisaminal template approach for the synthesis of cyclam and [13]aneN4 (homocyclen) bifunctional chelating agents (BCAs) bearing a hydroxyethyl function as a C-appended group is presented. The synthesis is rapid (two steps/one week) and does not require fastidious protection–deprotection steps or chromatographic purification. Another reactional route and alternative work-up give access to their oxo-cyclam and oxo-homocyclen analogues. The procedure consists of the cyclization of the preorganized tetraamine 1,4,8,11-tetraazaundecane, in its cis-butanedione-bisaminal form, with an α,β-unsaturated lactone to provide the tetracyclic oxo-intermediate whose bisaminal bridge can be easily removed and/or its amide function reduced under mild conditions. Furthermore, the synthetic route was successfully applied to the synthesis of teta and trita BCAs analogues starting from the linear tetraamine 1,4,7,10-tetraazadecane. Additionally, the appended alcohol functions of various cyclam and homocyclen based ligands were converted into their ethylamine functions following a very convenient procedure. Finally, preliminary analytical and complexation studies highlight that the supplementary hydroxyethyl C-appended chain has only a low impact on the acid–base behaviour and copper(II) or zinc(II) coordination properties of the macrocycle.

International audience; The effect of the addition of a third ion to the ionic liquid 1-butyl-3-methylimidazolium acetate [C4C1Im][OAc] was studied through the measurement of the enthalpy of mixing and of the excess molar volume of its mixtures with 1-butyl-3-methylimidazolium trifluoroacetate [C4C1Im][CF3CO2], 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C4C1Im][NTf2], and tetrabutylphosphonium acetate [P4444][OAc]. Negative enthalpies of mixing (ΔmixH < 0) and positive excess molar volumes (VE > 0) were observed in all cases. The infrared and NMR studies of the pure ionic liquids and their mixtures show that the presence of a third ion with a weaker affinity with the common counterion contributes to prevailing the more favorable hydrogen-bond, herein always between the imidazolium cation and the acetate anion. Both radial and spatial distribution functions calculated by molecular simulation confirm this behavior. The remarkable enhancement of the viscosities of the [C4C1Im][OAc] + [P4444][OAc] mixtures could be discussed in light of the calculated friction coefficients.

[Abstract] A series of mono‐, di‐, and trinuclear complexes of Eu and Tb was designed to study the influence of the number of Ln emitting centers on the luminescence properties of discrete polynuclear complexes. The complexes are based on a cyclen scaffold, functionalized by two picolinic acid pendant arms. These coordinating units are separated by a 1,3‐dimethylbenzene spacer for the dinuclear complex and a 1,3,5‐trimethylbenzene bridge in the case of the trinuclear complex. The synthesis and characterization of the ligands are presented, together with the preparation and spectroscopic characterization of the complexes. The luminescence properties of the complexes were determined by UV/Vis absorption spectroscopy and steady‐state and time‐resolved luminescence spectroscopy in buffered aqueous solutions. Comparison of the electronic absorption spectra showed that the absorption properties can almost be considered as extensive parameters within experimental error, as expected for electronically non‐conjugated systems. A small drop of both the excited state luminescence lifetimes and the luminescence quantum yields was observed for the trinuclear complexes in the case of Tb. To understand this behavior, theoretical HF (Hartree–Fock) calculations were performed for the three complexes. Models indicate that the average intermetallic distance in the dinuclear complex is almost the same as in the trinuclear one, disfavoring a possible distance dependence of the observed phenomena. Francia. Agence Nationale de la Recherche; ANR P2N 2012

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[Abstract] Two macrocyclic ligands containing a cyclen unit, a methyl group, a picolinate arm, and two acetate pendant arms attached to two nitrogen atoms of the macrocycle either in trans (1,7-H3Medo2 ampa = 2,2′-(7-((6-carboxypyridin-2-yl)methyl)-10-methyl-1,4,7,10-tetraazacyclododecane-1,4-diyl)diacetic acid) or in cis (1,4-H3Medo2 ampa) positions are reported. These ligands provide eight-coordination to the Ln3+ ions, leaving a coordination position available for a water molecule that occupies a capping position in the twisted square antiprismatic polyhedron (1,4-H3Medo2 ampa) or one of the positions of the square antiprism (1,7-H3Medo2 ampa). The charge neutral [Gd(1,7-Medo2 ampa)] complex presents an unprecedentedly low water-exchange rate (kex298=8.8×103 s−1), whereas water exchange in [Gd(1,4-Medo2 ampa)] is three orders of magnitude faster (kex298=6.6×106 s−1). These results showcase the labile capping bond phenomenon: A ligand occupying a capping position is hindered by the environment and thus is intrinsically labile. Ministerio de Economía y Competitividad; CTQ2009-10721/PPQ Ministerio de Economía y Competitividad; CTQ2013-43243-P Ministerio de Economía y Competitividad; CTQ2015-71211-REDT Xunta de Galicia; CN2012/011 European Commission; GINOP-2.3.2.-15-2016-00008 Hungría. Hungarian Scientific Research Fund; K-109029 Hungría. Hungarian Scientific Research Fund; K-120224

International audience; Addition of Tb3+ salts to a solution of a(YbLD) complex in D2O resulted in the formation of[(YbLD)2Tbx] (x = 1 to 3) complexes that, upon NIRexcitation at 980 nm, showed an unprecedented Yb to Tbupconversion sensitization phenomenon resulting in theobservation of the typical green emission of Tb.

International audience

The presence of capping ligands on the surface of metal nanoparticles (NPs) has been recognized to be a key factor for the control of their size and shape as well as for their stabilization, but their influence on the NP behavior in catalysis is far from being well-understood. Here, we investigated the performance of Rh NPs stabilized by tetraoctylammonium bromide (Rh-TOAB NPs) when applied as precatalyst for hydroformylation reaction. An ehnancement of the catalytic activity was clearly observed after adding monophosphines as a reaction modifier. More interestingly, a much higher effect was observed when a phosphine was directly used as capping ligand for the synthesis of the Rh particles, i.e . in the absence of TOAB. Indeed, triphenylphosphine-stabilized Rh NPs (Rh-PPh 3 NPs) were found to be a unique precursor for hydroformylation active catalytic species, leading to higher activity attributed to the existence of a strong phosphine-rhodium interaction in this case. The Rh-PPh 3 NPs appeared less affected when adding poisoning ligands in catalytic reaction than the Rh-TOAB NPs PPh 3 system which deactivates in the presence of CS 2 . In addition, a large excess (20 equiv. per Rh atom) of PPh 3 was necessary to activate the Rh-TOAB NPs, similarly to the amount typically used in homogeneous catalytic systems. In the contrary, one equiv. of PPh 3 (per Rh atom) was enough to prepare Rh-PPh 3 NPs, which are more active and more stable against CS 2 poisoning. All together our results evidence that a direct interaction of PPh 3 ligand at the surface of Rh NPs plays an important role on their behavior in hydroformylation catalysis.

International audience; Three 1,4,7-triazacyclononane-based (tacn-based) ligands containing picolyl and picolinate pendant arms (no3py, no2pa1py, and no3pa) were synthesized, and their copper(II) complexation properties were studied to evaluate their potentials as chelators for copper radioisotopes. The thermodynamic stability constants of the complexes were determined by potentiometric titrations. These studies evidenced the formation of mononuclear species for no3py and mono- and dinuclear species for no2pa1py and no3pa. The pCu values decreased as the number of carboxypicolyl arms increased. The [Cu(no3py)]2+ complex presented a very high stability constant (log KCuL = 27.4) and a very high selectivity towards Zn2+ ions (log KZnL = 17.25). Vis/NIR (NIR = near-infrared) absorption and electron paramagnetic resonance (EPR) spectroscopy indicated that the three complexes present distorted octahedral geometries with two paramagnetic species, which were identified as the Δ(δδδ) and Λ(δδδ) isomers [and their corresponding enantiomeric forms Λ(λλλ) and Δ(λλλ)] by DFT calculations. The electrochemical properties were investigated by cyclic voltammetry, which revealed quasireversible behavior for the [Cu(no3py)]2+ complex but irreversible Cu2+/Cu+ systems for [Cu(no2pa1py)] and [Cu(no3pa)]–.

International audience; The preparation of bimetallic nanoparticles with controlled size, shape, and composition remains a difficult task, and reproducible methods are highly desired. Here, we report the codecomposition of Ni(cod)2 and Pd2(dba)3 organometallic precursors in the presence of hexadecylamine (HDA) and hydrogen as an efficient approach to get size-controlled bimetallic nickel–palladium nanoparticles. Presynthesized nickel–palladium nanoparticles of different Ni/Pd ratios were further used for the preparation of supported catalysts by the sol–immobilization method onto a magnetic silica. The obtained supported catalysts were investigated in the hydrogenation of cyclohexene and compared to Ni and Pd monometallic catalysts. The catalysts prepared with a 1:9 Ni/Pd molar ratio achieved the highest initial turnover frequency > 50 000 h–1, providing higher activity than the pure Pd monometallic counterpart. This represents an important saving of noble metal. Moreover, the magnetic separation allows excellent separation of the catalyst from the liquid products without metal leaching and exposure to air, leading to an efficient recycling.

International audience; The synthesis of a new cross-bridged 1,4,8,11-tetraazacyclotetradecane (cb-cyclam) derivative bearing a picolinate arm (Hcb-te1pa) was achieved by taking advantage of the proton sponge properties of the starting constrained macrocycle. The structure of the reinforced ligand as well as its acid–base properties and coordination properties with Cu2+ and Zn2+ was investigated. The X-ray structure of the free ligand showed a completely preorganized conformation that lead to very fast copper(II) complexation under mild conditions (instantaneous at pH 7.4) or even in acidic pH (3 min at pH 5) at room temperature and that demonstrated high thermodynamic stability, which was measured by potentiometry (at 25 °C and 0.10 M in KNO3). The results also revealed that the complex exists as a monopositive copper(II) species in the intermediate pH range. A comparative study highlighted the important selectivity for Cu2+ over Zn2+. The copper(II) complex was synthesized and investigated in solution using different spectroscopic techniques and DFT calculations. The kinetic inertness of the copper(II) complex in acidic medium was evaluated by spectrophotometry, revealing the very slow dissociation of the complex. The half-life of 96 days, in 5 M HClO4, and 465 min, in 5 M HCl at 25 °C, show the high kinetic stability of the copper(II) chelate compared to that of the corresponding complexes of other macrocyclic ligands. Additionally, cyclic voltammetry experiments underlined the perfect electrochemical inertness of the complex as well as the quasi-reversible Cu2+/Cu+ redox system. The coordination geometry of the copper center in the complex was established in aqueous solution from UV–vis and EPR spectroscopies.

[Abstract] Recently developed dynamic nuclear polarization (DNP) technology offers the potential of increasing the NMR sensitivity of even rare nuclei for biological imaging applications. Hyperpolarized 89Y is an ideal candidate because of its narrow NMR linewidth, favorable spin quantum number (I= ), and long longitudinal relaxation times (T1). Strong NMR signals were detected in hyperpolarized 89Y samples of a variety of yttrium complexes. A dataset of 89Y NMR data composed of 23 complexes with polyaminocarboxylate ligands was obtained using hyperpolarized 89Y measurements or 1H,89Y-HMQC spectroscopy. These data were used to derive an empirical equation that describes the correlation between the 89Y chemical shift and the chemical structure of the complexes. This empirical correlation serves as a guide for the design of 89Y sensors. Relativistic (DKH2) DFT calculations were found to predict the experimental 89Y chemical shifts to a rather good accuracy. Ministerio de Economía y Competitividad; CTQ2013-43243-P Ministerio de Economía y Competitividad; CTQ2015-71211-REDT Estados Unidos. National Institutes of Health; EB-015908 Estados Unidos. National Institutes of Health; CA-115531 Estados Unidos. Robert A. Welch Foundation; AT-584

[Resumen] Los materiales con orden magnético, dieléctrico, elástico, y aquellos que combinan al menos dos de estas propiedades (multiferroicos), son fundamentales en el desarrollo de nuevas tecnologías. Tradicionalmente estas propiedades se han estudiado en óxidos metálicos con muy buenos resultados, sin embargo, la aparición de nuevos materiales híbridos, que combinan componentes orgánicos e inorgánicos en una misma estructura, ha abierto un nuevo campo de posibilidades. En esta tesis se han preparado y caracterizado híbridos porosos [M2(NH2- bdc)2(dabco)][G], y densos con estructura perovskita: [CH3NH3]M(HCOO)3, [NH4]Cd(HCOO)3 y [(CH3)4N]Mn(N3)3. Los híbridos porosos [M2(NH2-bdc)2(dabco)][G] presentan dos anomalías dieléctricas debidas a la rotación del ligando NH2-bdc y al movimiento de las moléculas de disolvente ocluidas. Estos híbridos se emplearon como precursores de los óxidos ZnO y Co3O4 nanoestructurados. Los fomiatos [CH3NH3]M(HCOO)3 con M= Mn+2, Co+2, Ni+2 y Cu+2 presentan ferromagnetismo débil a baja temperatura. Además, [NH3CH3]Co(HCOO)3 es uno de los pocos materiales híbridos con acoplamiento magnetoeléctrico. El compuesto [NH4]Cd(HCOO)3 presenta polarización eléctrica neta en condiciones ambientales y ésta se puede incrementar al aplicar altas presiones. El híbrido [(CH3)4N]Mn(N3)3 presenta una transición estructural antiferroeléctrica y ferroelástica a 310 K junto con biestabilidad magnética, siendo uno de los pocos materiales que muestra simultáneamente orden magnético, dieléctrico y elástico., [Resumo] Os materiais con orde magnética, dieléctrica, elástica e aqueles que combinen polo menos dúas destas propiedades (multiferroicos), son fundamentais no desenrolo de novas tecnoloxías. Tradicionalmente estas propiedades téñense estudado nos óxidos metálicos con moi bos resultados, sen embargo, a aparición de novos materiais híbridos, que combinan compoñentes orgánicos e inorgánicos nunha mesma estrutura, abriu un novo campo de posibilidades. Nesta tese preparáronse e caracterizáronse híbridos porosos [M2(NH2- bdc)2(dabco)][G], e densos con estrutura perovskita: [CH3NH3]M(HCOO)3, [NH4]Cd(HCOO)3 e [(CH3)4N]Mn(N3)3. Os híbridos porosos [M2(NH2-bdc)2(dabco)][G] presentan dúas anomalías dieléctricas debidas á rotación do ligando NH2-bdc e ao movemento das moléculas de disolvente ocluídas. Estes híbridos empregáronse coma precursores dos óxidos ZnO y Co3O4 nanoestruturados. Os formiatos [CH3NH3]M(HCOO)3 con M= Mn+2, Co+2, Ni+2 e Cu+2 presentan ferromagnetismo débil a baixa temperatura. Ademais, [NH3CH3]Co(HCOO)3 é un dos poucos materiais híbridos con acoplamento magnetoeléctrico. O composto [NH4]Cd(HCOO)3 presenta polarización eléctrica neta en condicións ambientais que se pode incrementar ao aplicar altas presións. O híbrido [(CH3)4N]Mn(N3)3 presenta unha transición estrutural antiferroeléctrica e ferroelástica a 310 K xunto con biestabilidade magnética, sendo un dos poucos materiais que mostra simultaneamente orde magnético, dieléctrico e elástico., [Abstract] Materials which exhibits magnetic, dielectric or elastic ordering, and those that combine two of these properties (multiferroics) are fundamentals for the developing of new technologies. These properties were traditionally searched and successfully found in metal oxides. However, the occurrence of new hybrid materials that combine organic and inorganic components in the same structure have opened a new field of possibilities. In the present thesis it has been synthesized and characterized several hybrid materials: porous [M2(NH2-bdc)2(dabco)][G], and dense with perovskite architecture: [CH3NH3]M(HCOO)3, [NH4]Cd(HCOO)3 and [(CH3)4N]Mn(N3)3. The porous hybrids [M2(NH2-bdc)2(dabco)][G] present two dielectric anomalies due to the rotation of the NH2-bdc ligand and the movement of the solvent molecules occluded. These hybrids were employed as precursors of the nanostructured oxides ZnO and Co3O4. The [CH3NH3]M(HCOO)3 formates where M= Mn+2, Co+2, Ni+2 and Cu+2, show weak ferromagnetism at low temperature. Furthermore, [NH3CH3]Co(HCOO)3 is one of the few examples of hybrid materials with magnetoelectric coupling. The [NH4]Cd(HCOO)3 compound displays electric polarization at ambient conditions which can be increased by the application of high pressures. The [(CH3)4N]Mn(N3)3 hybrid shows an structural, antiferroelectric and ferroelastic transition at 310 K, together with magnetic bistability. This is one of the few examples of material which shows simultaneous magnetic, dielectric and elastic ordering.

Programa Oficial de Doutoramento en Química Ambiental e Fundamental. 5031V01, [Resumo] Esta disertación explora o deseño e síntesis de novos ligandos, basados en 4,4´-bipiridina e 2,7- diazapireno, así como a súa posterior autoensamblaxe con centros metálicos de Pd(II) e Pt(II) para dar lugar aos respectivos metalociclos. O estudo do comportamento receptor en medio acuoso dun dos metalociclos, derivado de 2,7- diazapireno, permitiu a preparación de complexos de inclusión e de moléculas mecánicamente entrelazadas con sustratos aromáticos derivados de hidroquinona e de diferentes isómeros de dioxinaftaleno. A creación destas supraestruturas prodúcese como resultado dun proceso de recoñecemento molecular entre o metalociclo, π-deficiente, e o sustrato incluído na cavidade do metalociclo, π-excedente, baixo a forza impulsora do efecto hidrofóbico. Estudiouse tamén a capacidade dun metalociclo de Pt(II), basado en 2,7-diazapireno, como catalizador para a reacción de SNAr entre halodinitrobencenos e azida sódica en medio acuoso. Observouse que o efecto catalítico é promovido pola asociación do anión azida ás subunidades catiónicas de diazapireno no catalizador. Ademais demostrouse que a formación dun complexo de inclusión co metalociclo ten un efecto regulatorio sobre o sistema, resultando nunha inhibición de tipo alostérico da reacción de SNAr., [Resumen] Esta disertación explora el diseño y síntesis de nuevos ligandos, basados en 4,4´-bipiridina y 2,7-diazapireno, así como su posterior autoensamblaje con centros metálicos de Pd(II) y Pt(II) para dar lugar a los respectivos metalociclos. El estudio del comportamiento receptor en medio acuoso de uno de los metalociclos, derivado de 2,7-diazapireno, ha permitido la preparación de complejos de inclusión y de moléculas mecánicamente entrelazadas con sustratos aromáticos derivados de hidroquinona y de diferentes isómeros de dioxinaftaleno. La creación de estas supraestructuras se produce como resultado de un proceso de reconocimiento molecular entre el metalociclo, π-deficiente, y el sustrato incluído en la cavidad metalocíclica, π-excedente, bajo la fuerza impulsora del efecto hidrofóbico. Se ha estudiado también la capacidad de un metalociclo de Pt(II), basado en 2,7-diazapireno, como catalizador para la reacción de SNAr entre halodinitrobencenos y azida sódica en medio acuoso. Se observó que el efecto catalítico es promovido por la asociación del anión azida a las subunidades catiónicas de diazapireno en el catalizador. Además se demostró que la formación de un complejo de inclusión con el metalociclo posee un efecto regulatorio sobre el sistema, resultando en una inhibición de tipo alostérico de la reacción de SNAr., [Abstract] This dissertation explores the design and synthesis of new ligands, based on 4,4´-bipyridine and 2,7-diazapyrene, as well as their subsequent self-assembly with Pd(II) and Pt(II) square metal centers leading to the respective metallacycles. The study of the behavior as a receptor in aqueous medium of one of the metallacycles, based on 2,7-diazapyrene, has enabled us the preparation of inclusion complexes and mechanically interlocked molecules with aromatic substrates derivatives of hydroquinone and different dioxynaphthalene isomers. The creation of these suprastructures occurs as a result of a molecular recognition process between the metallacycle, π-deficient, and the substrate included into the cavity of the metallacycle, π-excedent, under the driving force of the hydrophobic effect. It was also studied the capacity of a Pt(II) metallacycle, based on 2,7-diazapyrene, as catalyst for the SNAr reaction between halodinitrobenzenes and sodium azide in aqueous media. It was observed that the catalytic effect is promoted by the association of the azide anion to the diazapyrenium cationic subunits in the catalyst. In addition, it was shown that the formation of an inclusion complex by the metallacycle has a regulatory effect over the system, resulting in an allosteric-like inhibition of the SNAr reaction.

The invention relates to a chelate resulting from the complexing of a trans-di-N-picolinate tetraazacycloalkane ligand with a metal cation, said ligand corresponding to formula (A) wherein n is equal to 0 or to 1, R is H or a C1-C18 alkyl radical, and R' is H or a C1 -C18 alkyl radical, said metal cation being a cation of a metal selected from the group consisting of lead (II) and bismuth (III). The invention is applicable in the field of lead trapping and alpha-radioimmunotherapy.

International audience; A tacn based ligand bearing two methylthiazolyl arms (no2th) was synthesized with the aim to find ligands forming very stable and inert complexes with Cu(II) and Cu(I) in aqueous medium for radiopharmaceutical applications. The no2th ligand was efficiently prepared following the orthoamide intermediate synthesis. The complexes with Cu2+ and Zn2+ were obtained and analyzed by X-ray diffraction. The [Cu(no2th)]2+ complex presents a pentacoordinated distorted square pyramidal coordination geometry, while the metal ion in [Zn(no2th)]2+ adopts a hexacoordinated distorted trigonal prismatic geometry involving the coordination of a perchlorate counter ion. The acid–base properties of no2th have been studied using potentiometric titrations, and the stability constants of Cu2+ and Zn2+ complexes were determined by potentiometric and UV-vis titrations using H4edta as a competitor ligand. The stability constant determined for the Cu2+ complex is rather high (log KCuL = 20.77 and pCu = 17.15), and moreover no2th exhibits a high selectivity for copper(II) in relation to zinc(II). The kinetics of the copper(II) complexation process is very fast even in acidic medium. In addition, the [Cu(no2th)]2+ complex was found to be inert under rather harsh conditions (up to 2 M HCl and 60 °C), displaying a very high half-life time of about 15 days in 2 M HCl at 90 °C. The electrochemical reduction of the copper(II) complex in water leads to the reversible formation of a stable copper(I) species. Spectroscopic studies performed by NMR, UV-vis and EPR, assisted by theoretical calculations, show that the [Cu(no2th)]2+ complex presents a structure in solution similar to that observed in the solid state. When compared to its cyclam di-N-methylthiazolyl counterpart, the results reported in this paper unambiguously show that replacing the cyclam unit by a tacn moiety improves the stability and inertness of its Cu(II) and Cu(I) complexes.

The coordination properties toward the lanthanide ions of two macrocyclic ligands based on a cyclam platform containing picolinate pendant arms have been investigated. The synthesis of the ligands was achieved by using the well-known bis-aminal chemistry. One of the cyclam derivatives (cb-tedpa(2-)) is reinforced with a cross-bridge unit, which results in exceptionally inert [Ln(cb-tedpa)](+) complexes. The X-ray structures of the [La(cb-tedpa)Cl], [Gd(cb-tedpa)](+), and [Lu(Me2tedpa)](+) complexes indicate octadentate binding of the ligands to the metal ions. The analysis of the Yb(3+)-induced shifts in [Yb(Me2tedpa)](+) indicates that this complex presents a solution structure very similar to that observed in the solid state for the Lu(3+) analogue. The X-ray structures of [La(H2Me2tedpa)2](3+) and [Yb(H2Me2tedpa)2](3+) complexes confirm the exocyclic coordination of the metal ions, which gives rise to coordination polymers with the metal coordination environment being fulfilled by oxygen atoms of the picolinate groups and water molecules. The X-ray structure of [Gd(Hcb-tedpa)2](+) also indicates exocyclic coordination that in this case results in a discrete structure with an eight-coordinated metal ion. The nonreinforced complexes [Ln(Me2tedpa)](+) were prepared and isolated as chloride salts in nonaqueous media. However, these complexes were found to undergo dissociation in aqueous solution, except in the case of the complexes with the smallest Ln(3+) ions (Ln(3+) = Yb(3+) and Lu(3+)). A DFT investigation shows that the increased stability of the [Ln(Me2tedpa)](+) complexes in solution across the lanthanide series is the result of an increased binding energy of the ligand due to the increased charge density of the Ln(3+) ion.

International audience; Aiming to develop new copper chelates for application in nuclear medicine we report two new chelators, te1th and te2th, based on a cyclam backbone mono-N- or di-N1,N8-functionalized by methylthiazolyl arms. The acid–base properties of both ligands were investigated as well as their coordination chemistry, especially with Cu2+, when possible in aqueous solution and in the solid state. Single-crystal X-ray diffraction structures of complexes were determined. Stability constants of the copper(II) and zinc(II) complexes showed that the complexes of both ligands with Cu2+ are thermodynamically very stable, and they exhibit an important selectivity for Cu2+ over Zn2+. The kinetic inertness in acidic medium of both copper(II) complexes was evaluated revealing a quite good resistance to dissociation (the half-life times of complexes with te1th and te2th are 50.8 and 5.8 min, respectively, in 5 M HCl and 30 °C). The coordination geometry of the metal center in the complexes was established in aqueous solution based on UV–visible, electron paramagnetic resonance (EPR) spectroscopy, DFT studies, and NMR by using the zinc(II) complex analogues. The [Cu(te1th)]2+ and [Cu(te2th)]2+ complexes adopt trans-I and trans-III configurations both in the solid state and in solution, while the [Zn(te2th)]2+ complex crystallizes as the cis-V isomer but exists in solution as a mixture of trans-III and cis-V forms. Cyclic voltammetry experiments in acetonitrile point to a relatively easy reduction of [Cu(te2th)]2+ in acetonitrile solution (Epc = −0.41 V vs NHE), but the reduced complex does not undergo dissociation in the time scale of our electrochemical experiments. The results obtained in these studies revealed that despite the limited solubility of its copper(II) chelate, te2th is an attractive chelator for Cu2+ that provides a fast complexation process while forming a complex with a rather high thermodynamic stability and kinetic inertness with respect to dissociation even upon electrochemical reduction.

International audience; The equilibrium and transport properties of mixtures of two ionic liquids – [C4C1Im][OAc] and [C4C1Im][C(CN)3] – were determined and interpreted at the molecular level using vibration spectroscopy, NMR and molecular dynamics simulation. The non-ideality of the mixtures [C4C1Im][OAc](1−x)[C(CN)3]x was characterized by VE = +0.28 cm3 mol−1 (293 K, x = 0.65) and HE = −2.2 kJ mol−1 for x = 0.5. These values could be explained by a rearrangement of the hydrogen-bond network of the mixture that favours the interaction of the acetate anion with the imidazolium cation at position C2. The dynamic properties of the mixture are also dramatically influenced by the composition with a decrease of the viscosity and an increase of self-diffusion coefficients of the ions when the amount of tricyanomethanide anion increases in the mixture.