Photoinduced electron flow in a self-assembling supramolecular extension cable

We report the design, bottom-up construction, characterization, and operation of a supramolecular system capable of mimicking the function played by a macroscopic electrical extension cable. The system is made up of a light-powered electron source, an electron drain, and a cable as the molecular components programmed to self-assemble by means of two distinct plug/socket junctions. Such connections are reversible and can be operated independently by orthogonal chemical inputs. In the source-connector-drain supermolecule, photoinduced electron transfer from source to drain occurs, and it can be switched off by dual-mode chemically controlled disassembling of the molecular components.Ferrer Ribera, RB.; Rogez, G.; Credi, A.; Ballardini, R.; Gandolfi, MT.; Balzani, V.; Liu, Y.... (2006). Photoinduced electron flow in a self-assembling supramolecular extension cable. Proceedings of the National Academy of Sciences. 103(49):18411-18416. doi:10.1073/pnas.060645910318411184161034

Tunable synthesis of Prussian Blue in exponentially growing polyelectrolyte multilayer films.

Polyelectrolyte multilayer (PEM) films have become very popular for surface functionalization and the design of functional architectures such as hollow polyelectrolyte capsules. It is known that properties such as permeability to small ionic solutes are strongly dependent on the buildup regime of the PEM films. This permeability can be modified by tuning the ionization degree of the polycations or polyanions, provided the film is made from weak polyelectrolytes. In most previous investigations, this was achieved by playing on the solution pH either during the film buildup or by a postbuildup pH modification. Herein we investigate the functionalization of poly(allylamine hydrochloride)/poly(glutamic acid) (PAH/PGA) multilayers by ferrocyanide and Prussian Blue (PB). We demonstrate that dynamic exchange processes between the film and polyelectrolyte solutions containing one of the component polyelectrolyte allow one to modify its Donnan potential and, as a consequence, the amount of ferrocyanide anions able to be retained in the PAH/PGA film. This ability of the film to be a tunable reservoir of ferrocyanide anions is then used to produce a composite film containing PB particles obtained by a single precipitation reaction with a solution containing Fe(3+) cations in contact with the film. The presence of PB in the PEM films then provides magnetic as well as electrochemical properties to the whole architecture.journal article2009 Dec 15importe

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

The synthesis and characterization of six new lanthanide networks [Ln(L)(ox)(H2O)] with Ln = Eu3+, Gd3+, Tb3+ , Dy3+ , Ho3+ and Yb3+ is reported. They were synthesized by solvo-ionothermal reaction of lanthanide nitrate Ln(NO3)(3)center dot xH(2)O with the 1,3-bis(carboxymethyl)imidazolium [HE] ligand and oxalic acid (H(2)ox) in a water/ethanol solution. The crystal structure of these compounds has been solved on single crystals and the magnetic and luminescent properties have been investigated relying on intrinsic properties of the lanthanide ions. The synthetic strategy has been extended to mixed lanthanide networks leading to four isostructural networks of formula [Tb1-xEux(L)(ox)(H2O)] with x = 0.01, 0.03, 0.05 and 0.10. These materials were assessed as luminescent ratiometric thermometers based on the emission intensities of ligand, Tb3+ and Eu3+ . The best sensitivities were obtained using the ratio between the emission intensities of Eu3+ (D-5(0) -> F-7(2) transition) and of the ligand as the thermometric parameter. [Tb0.97Eu0.03 (L)(ox)(H2O)] was found to be one of the best thermometers among lanthanide-bearing coordination polymers and metal-organic frameworks, operative in the physiological range with a maximum sensitivity of 1.38%.K-1 at 340 K

Front Microbiol

Since 2021, 3 variants of concern (VOC) have spread to France, causing successive epidemic waves. To describe the features of Alpha, Delta and Omicron VOC circulation in the Nouvelle-Aquitaine region, France, between February 2021 and February 2022. Data from the three university hospitals (UH) of Nouvelle-Aquitaine were used to describe regional SARS-CoV-2 circulation (RT-PCR positive rates and identified VOC) as well as its consequences (total number of hospitalizations and admissions in intensive care unit). They were analyzed according to the predominant variant and compared with national data. A total of 611,106 SARS-CoV-2 RT-PCR tests were performed in the 3 Nouvelle-Aquitaine UH during the study period. The 37,750 positive samples were analyzed by variant-specific RT-PCR or whole-genome sequencing. In 2021, Alpha VOC was detected from week 5 until week 35. Delta became the most prevalent variant (77.3%) in week 26, reaching 100% in week 35. It was replaced by Omicron, which was initially detected week 48, represented 77% of positive samples in week 52 and was still predominant in February 2022. The RT-PCR positive rates were 4.3, 4.2, and 21.9% during the Alpha, Delta and Omicron waves, respectively. The ratio between intensive care unit admissions and total hospitalizations was lower during the Omicron wave than during the two previous waves due to the Alpha and Delta variants. This study highlighted the need for strong regional cooperation to achieve effective SARS-CoV-2 epidemiological surveillance, in close association with the public health authorities

Robust spin crossover and memristance across a single molecule

A nanoscale molecular switch can be used to store information in a single molecule. Although the switching process can be detected electrically in the form of a change in the molecule's conductance, adding spin functionality to molecular switches is a key concept for realizing molecular spintronic devices. Here we show that iron-based spin-crossover molecules can be individually and reproducibly switched between a combined high-spin, high-conduction state and a low-spin, low-conduction state, provided the individual molecule is decoupled from a metallic substrate by a thin insulating layer. These results represent a step to achieving combined spin and conduction switching functionality on the level of individual molecules

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

Producción CientíficaIn the study presented herein, we explore the ability of copper complexes with coordinated pyridine-2-carboxaldehyde (pyca) or 2-acetylpyridine (acepy) ligands to promote the addition of amines (Schiff condensation) and other nucleophiles such as alcohols (hemiacetal formation). Distinct reactivity patterns are observed: unlike pyca complexes, acepy copper complexes can promote self-aldol addition. The introduction of a flexible chain via Schiff condensation with β-alanine allows the possibility of chelate ring ring-opening processes mediated by pH. Further derivatization of the complex [CuCl(py-2-C(H)[double bond, length as m-dash]NCH2CH2COO)] is possible by replacing its chloride ligand with different pseudohalogens (N3−, NCO− and NCS−). In addition to the change in their magnetism, which correlates with their solid-state structures, more unexpected effects in their cytotoxicity and relaxitivities are observed, which determines their possibility to be used as MRI contrast agents. The replacement of a chloride by another pseudohalogen, although a simple strategy, can be used to critically change the cytotoxicity of the Schiff base copper (II) complex and its selectivity towards specific cell lines.Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación - FEDER (projects PGC2018-096880-A-I00 / PGC2018-099470-B-I00)Ministerio de Economía, Industria y Competitividad - Agencia Estatal de Investigación - FEDER - UE (contract RYC-2015-19035)Junta de Castilla y León (project VA130G18)Laboratory of Excellence of Nanostructures in Interaction with their Environment (project ANR-11-LABX-0058-NIE within the Investissement d'Avenir program ANR-10-IDEX-0002-02)

Modulation des propriétés électroniques et de l'anisotropie magnétique de complexes mono et polynucléaires :<br />influence des ligands pontants et périphériques.

The work described here shows the role played by the organic ligand in the modulation of the electronic properties of mono- and polynuclear transition metal complexes.The first part reports first the study of the influence of the electronic effects (donor and acceptor) of the chelating ligand on the electrochemical behaviour of a family of Fe(III) mononuclear complexes. We also showed that it is possible to tune the optical properties of polynuclear mixed-valence complexes of the form FeIIBS(FeIIIHS)x (x = 4 and 6). Finally, we proposed a model that explains the origin of the ferromagnetic interaction in Prussian blue, one of the first coordination compound, for which complexes FeIIBS(FeIIIHS)x are models.The second part deals with the study of magnetic anisotropy in Ni(II) mononuclear compounds. We show that it is possible to tune the amplitude and the nature of the magnetic anisotropy (axial, planar or rhombic) thanks to the judicious choice of the chelating ligands.Finally, playing with the bridging and peripheral chelating ligands in binuclear Ni(II) complexes allows to tune the energy of the spin states of these complexes and then to show off a field induced spin crossover phenomenon. Hence, it is possible to determine the magnetic anisotropy of the excited spin states of polynuclear complexes possessing a ground state S =0.Au cours de ce travail de thèse, nous avons montré le rôle du ligand organique pour moduler les propriétés électroniques de complexes de métaux de transition mono- et polynucléaires.La première partie de ce travail étudie tout d'abord l'influence des effets électroniques (donneurs et accepteurs) des ligands chélatants sur les propriétés électrochimiques de complexes mononucléaires de Fe(III). Nous avons également montré qu'il est possible de moduler les propriétés optiques de complexes polynucléaires à valence mixte FeIIBS(FeIIIHS)x (x = 4 et 6). Enfin, un modèle a été proposé pour expliquer l'origine de l'interaction ferromagnétique au sein d'un des premiers composés de la chimie de coordination, le bleu de Prusse dont les complexes FeIIBS(FeIIIHS)x sont des modèles.La deuxième partie concerne l'étude de l'anisotropie magnétique au sein de complexes mononucléaires de Ni(II). Ce travail montre qu'il est possible d'influencer l'amplitude et la nature (axiale, planaire ou rhombique) de l'anisotropie magnétique grâce au choix des ligands chélatants.Enfin, une modulation de l'énergie des états de spin de systèmes binucléaires en jouant sur les ligands pontants et périphériques permet de mettre en évidence le croisement de deux niveaux MS issus de deux états S différents sous l'action d'un champ magnétique extérieur. Ainsi il est possible d'accéder aux propriétés d'anisotropie dans les états excités de complexes polynucléaires possédant un état fondamental de spin S = 0

Modulation des propriétés électroniques et de l'anisotropie magnétique de complexes mono et polynucléaires (influence des ligands pontants et périphériques)

Au cours de ce travail de thèse, nous avons montré le rôle du ligand organique pour moduler les propriétés électroniques de complexes de métaux de transition mono- et polynucléaires. La première partie de ce travail étudie tout d'abord l'influence des effets électroniques (donneurs et accepteurs) des ligands chélatants sur les propriétés électrochimiques de complexes mononucléaires de Fe(III). Nous avons également montré qu'il est possible de moduler les propriétés optiques de complexes polynucléaires à valence mixte (Fe II)_BS((Fe III)_HS)_x (x = 4 et 6). Enfin, un modèle a été proposé pour expliquer l'origine de l'interaction ferromagnétique au sein d'un des premiers composés de la chimie de coordination, le bleu de Prusse dont les complexes (Fe II)_BS((Fe III)_HS)_x sont des modèles. La deuxième partie concerne l'étude de l'anisotropie magnétique au sein de complexes mononucléaires de Ni(II). Ce travail montre qu'il est possible d'influencer l'amplitude et la nature (axiale, planaire ou rhombique) de l'anisotropie magnétique grâce au choix des ligands chélatants. Enfin, une modulation de l'énergie des états de spin de systèmes binucléaires en jouant sur les ligands pontants et périphériques permet de mettre en évidence le phénomène de transition de spin induite par le champ. Ainsi il est possible d'accéder aux propriétés d'anisotropie dans les états excités de complexes polynucléaires possédant un état fondamental de spin S = 0.The work described here shows the role played by the organic ligand in the modulation of the electronic properties of mono- and polynuclear transition metal complexes. The first part reports first the study of the influence of the electronic effects (donor and acceptor) of the chelating ligand on the electrochemical behavior of a family of Fe(III) mononuclear complexes. We also showed that it is possible to tune the optical properties of polynuclear mix-valence complexes of the form (Fe II)_BS((Fe III)_HS)_x (x = 4 and 6). Finally, we proposed a model that explains the origin of the ferromagnetic interaction in Prussian blue, one of the first coordination compound, for which complexes (Fe II)_BS((Fe III)_HS)_x are models. The second part deals with the study of magnetic anisotropy in Ni(II) mononuclear compounds. We show that it is possible to tune the amplitude and the nature (axial, planar or rhombic) of the magnetic anisotropy thanks to the judicious choice of the chelating ligands. Finally, playing with the bridging and peripheral chelating ligands in binuclear Ni(II) complexes allows to tune the energy of the spin states of these complexes and then to show off a field induced spin transition phenomenon. Hence, it is possible to determine the magnetic anisotropy of the excited spin states of polynuclear complexes possessing a ground state S =0.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF