Promoted Exchange Reaction between Alkanethiolate Self-Assembled Monolayers and an Azide-Bearing Substituent

The possibility of ultraviolet (UV) light promoted exchange reaction (UVPER) between the primary alkanethiolate (AT) self-assembled monolayers (SAMs) and an azide-functionalized substituent (12-azido-1-dodecanethiol, C12N3), capable of click reaction with ethynyl-bearing species, is demonstrated. This reaction resulted in the mixed AT/C12N3 films, with the portion of C12N3 precisely controlled by selection of a suitable UV dose. As the primary matrix, either nonsubstituted or oligo(ethylene glycol) (OEG)-substituted AT SAMs were used, targeting mixed SAMs of chemical and biological significance. To demonstrate the flexibility of the approach, UV light with two different wavelengths (254 and 375 nm) was used, applied to the nonsubstituted and OEG-substituted AT SAMs, respectively. The surface density of the chemically active azide groups embedded in the nonreactive primary matrix could be varied according to the composition of the mixed SAMs, as demonstrated by the subsequent click reaction between these SAMs and several representative functional moieties bearing a suitable group for the click reaction with azide. For the OEG-AT/C12N3 films, this resulted in the preparation of templates for specific protein adsorption, comprising biotin-bearing moieties embedded in the protein-repelling OEG-AT matrix. The density of the biotin receptors was varied according to the density of the C12N3 moieties. The templates exhibited much higher affinity to the specific protein (avidin) as compared to a nonspecific one. The surface density of avidin could be varied in accordance with the density of the biotin receptors, i.e., directly controlled by the UV dose within the UVPER procedure. The entire approach was extended to lithography, relying on a commercial maskless UV lithography setup. Representative gradient patterns of specifically attached avidin in the protein-repelling OEG-AT matrix were fabricated

New 4,4'-Bis(9-carbazolyl)-Biphenyl Derivatives with Locked Carbazole-Biphenyl Junctions: High-Triplet State Energy Materials

We synthesized a series of 4,4'-bis(9-carbazolyl)-biphenyl (CBP) derivatives, using methyl groups as spatially demanding groups, locking the angle between the carbazole subunit and the biphenyl backbone as potential matrix material for blue organic light-emitting diodes (OLEDs). The locked rotation was achieved by four methyl groups either in positions 1 and 8 of the carbazole subunit (1) or in positions 3, 5, 3', and 5' of the biphenyl subunit (2), and the fixed spatial arrangement was confirmed by X-ray analysis. The physical properties of CBP derivatives based on parent structure 2 were further tailored by electron-withdrawing CF3 groups in positions 3 and 6 (3) or positions 2 and 7 of the carbazole subunits (4) or alternatively by electron-donating CH3O groups in positions 2 and 7 (5) of the same building blocks. Increased triplet energies (ET) compared to that of the parent compound CBP were found for all synthesized CBP derivatives 1-5. Enhanced glass transition temperatures ranging between 129 and 202 °C further corroborate the application potential of these derivatives for matrix material in blue OLEDs

Electrochemical Multiplexing: Control over Surface Functionalization by Combining a Redox-Sensitive Alkyne Protection Group with "Click"-Chemistry

Local functionalization of surfaces is a current technological challenge. An electrochemically addressable alkyne protection group is presented enabling the site-selective liberation of alkynes exclusively on electrified electrodes. This controlled deprotection is based on a mendione chromophore which becomes a strong enough nucleophile upon reduction to intramolecularly attack the trialkylsilane alkyne protection group. The site-selective liberation of the alkyne is demonstrated by immobilizing the protected alkyne precursor on a transparent TiO2 electrode and subsequently immobilizing red and blue azide dyes by azide-alkyne "click"-chemistry. While the proof-of-principle is based on colorations visible to the bare eye, the technique presented is generic also to nontransparent electrodes, microscale separations, and functional moieties other than dyes. It may open manifold applications where site-selective functionalization is required but hardly realizable with conventional methods

Improved Photostability of a Cu-I Complex by Macrocyclization of the Phenanthroline Ligands

The development of molecular materials for conversion of solar energy into electricity and fuels is one of the most active research areas, in which the light absorber plays a key role. While copper(I)-bis(diimine) complexes [Cu$^{l}$ (L) $_{2}$] $^{+}$ are considered as potent substitutes for [Ru$^{ll}$ (bpy) $_{3}$] $^{2+}$, they exhibit limited structural integrity as ligand loss by substitution can occur. In this article, we present a new concept to stabilize copper bis(phenanthroline) complexes by macrocyclization of the ligands which are preorganized around the Cu$^{l}$ ion. Using oxidative Hay acetylene homocoupling conditions, several Cu$^{l}$ complexes with varying bridge length were prepared and analyzed. Absorption and emission properties are assessed; rewardingly, the envisioned approach was successful since the flexible 1,4-butadiyl-bridged complex does show enhanced MLCT absorption and emission, as well as improved photostability upon irradiation with a blue LED compared to a reference complex

Improved Photostability of a CuI Complex by Macrocyclization of the Phenanthroline Ligands

The development of molecular materials for conversion of solar energy into electricity and fuels is one of the most active research areas, in which the light absorber plays a key role. While copper(I)-bis(diimine) complexes [Cu-I(L)(2)](+) are considered as potent substitutes for [Ru-II(bpy)(3)](2+), they exhibit limited structural integrity as ligand loss by substitution can occur. In this article, we present a new concept to stabilize copper bis(phenanthroline) complexes by macrocyclization of the ligands which are preorganized around the Cu-I ion. Using oxidative Hay acetylene homocoupling conditions, several Cu-I complexes with varying bridge length were prepared and analyzed. Absorption and emission properties are assessed; rewardingly, the envisioned approach was successful since the flexible 1,4-butadiyl-bridged complex does show enhanced MLCT absorption and emission, as well as improved photostability upon irradiation with a blue LED compared to a reference complex

Combining electron-accepting phthalocyanines and nanorod-like CuO electrodes for p-type dye-sensitized solar cells

This is the peer reviewed version of the following article: Angewandte Chemie - International Edition 54.26 (2015): 7688-7692, which has been published in final form at http://dx.doi.org/10.1002/anie.201501550]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingA route is reported for the synthesis of two electron-accepting phthalocyanines featuring linkers with different lengths as sensitizers for p-type dye-sensitized solar cells (DSSCs). Importantly, our devices based on novel nanorod-like CuO photocathodes showed high efficiencies of up to 0.191%: the highest value reported to date for CuO-based DSSCs. The longer the better: Novel electron-accepting zinc phthalocyanines with different linker lengths performed well in combination with nanorod-like CuO electrodes in p-type dye-sensitized solar cells. A particularly high efficiency of 0.191% was observed with a photosensitizer containing a carboxyethynyl anchor (see picture; R is a branched alkyl group)The authors thank the German Science Council (DFG) for the financial support in the framework of the Cluster of Engineering of Advanced Materials (EAM), the MINECO Spain (CTQ2014- 52869/BQU), the Comunidad de Madrid Spain (FOTOCARBON, S2013/MIT-2841), and the European Union within the FP7-ENERGY-2012-1 nr. 309194-2, GLOBALSO

Co-construction d’une formation-action à un outil d’aide à la conception de systèmes de culture agroécologiques avec les futurs utilisateurs, l’exemple de DéciFlorSys. Rapport de stage de fin d'étude, formation ingénieur Agrosup Dijon

DéciFlorSys est un outil stratégique (numérique) qui accompagne son utilisateur à concevoir ou améliorer un système de culture vers des pratiques plus agroécologiques. Conçu avec un point de vue particulier focalisé sur les impacts des adventices, à partir de processus complexes, son utilisation nécessite une formation adaptée. L’outil a été conçu dans une démarche de co-construction avec ses futurs utilisateurs (conseillers et agriculteurs). La formation-action a été construite sur la même démarche.Ce mémoire problématise le processus de co-construction de la formation. Concrètement,un panorama des formations à la reconnaissance et la gestion des adventices et à la prise en main d’outils d’aide à la décision a été effectué. Complété par des entretiens avec des formateurs et de potentiels utilisateurs, ce mémoire s’est notamment intéressé aux représentations qu’ils avaient des adventices et de leur gestion pour construire la formation. Il pose la question suivante : en quoi une diversité de conseillers agricoles peut-elle contribuer à la co-construction d’une formation-action à un outil d’aide à la gestion agroécologique pluriannuelle de la flore adventice ?En termes de résultats, la mise en œuvre de la co-construction a permis de développer la formation-action basée sur les échanges entre pairs, aidant les utilisateurs à se projeter dans l’usage de DéciFlorSys. Ces potentiels participants, bien qu’ayant des visions nuancées de la gestion des adventices, ont su partager le même atelier de formation à l’out

Impact du nouveau parcours de soins dans la prise en charge du lombalgique chronique actif (étude descriptive de 55 cas de patients adressés aux rhumatologues auxerrois)

DIJON-BU Médecine Pharmacie (212312103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Etudes sur des bétons à base de liants ternaires -Focus sur la chaleur d'hydratation

Cet article présente les résultats d'une campagne d'essais dédiée à l'évaluation de la chaleur d'hydratation de bétons à base de liants ternaires principalement. Plusieurs types d'additions ont été utilisées pour constituer les liants ternaires : fillers calcaire, cendres volantes, laitiers de haut-fourneau, métakaolins flash. Les résultats obtenus permettent d'estimer le gain obtenu sur le plan thermique, en particulier la réduction en élévation de température adiabatique (représentative de l'élévation attendue pour une pièce extrêmement massive). Des essais sur béton durci ont également été réalisés (essais de résistance à la compression, essais de sensibilité à la réaction sulfatique interne, mesures de propriétés de transfert). Ces essais permettent de compléter les données de chaleur d'hydratation et d'entrevoir une analyse croisée (gain obtenu sur le plan thermique versus variation de résistance par exemple)

Conception de cellules photovoltaïques à base de semi-conducteurs de type p sensibilisés par un colorant

Ce travail a porté sur la sensibilisation d oxydes semi-conducteurs de type p (SCp) pour la conversion photovoltaïque. Un important travail de synthèse et de caractérisation physicochimique a ainsi été mené à bien : de nouveaux colorants organiques ont été obtenus et ont permis de considérablement améliorer les propriétés photovoltaïques des cellules à base de NiO. De plus, les tout premiers colorants inorganiques pour la sensibilisation de SCp ont été isolés et ont permis de déterminer une fonction d ancrage efficace, alternative aux acides carboxyliques. De nouveaux médiateurs redox ont été également synthétisés et étudiés, permettant notamment de monter une cellule tandem délivrant une tension de circuit ouvert de 950 mV. Enfin, les propriétés intrinsèques de l oxyde de nickel limitent les performances des systèmes photovoltaïques, et plusieurs approches ont été explorées afin de corriger les défauts de ce matériau. Cependant, la mise au point d un nouveau semiconducteur de type p, fonctionnalisable par un colorant, et donnant accès à des performances photovoltaïques améliorées, est la solution la plus séduisante. Dans cette optique, les résultats obtenus avec la delafossite CuGaO2 sont très encourageants, et augurent un bel avenir à cette technologie nouvelle et fascinante.This work deals with the sensitization of p-type semi-conductors for photovoltaic conversion. New organic dyes were synthetised and characterised, which allow us to enhance NiO sensitized solar cells photoconversion yield. Moreover, the first organometallic dyes for ptype semi-conductors sensitization were prepared, which gave us a way to identify an optimal anchoring group instead of a carboxylic acid group which is usually used. New redox mediators were alos studied, and a tandem dye solar cell with a Voc of 950 mV was built. Nickel oxide is by far the major semiconductor used for the fabrication of p-DSSCs. It enables the development of this new type of research field, but it possesses a too accessible valence band potential to permit the fabrication of solar cells delivering a high voltage. Therefore, the use of new p-SCs with deeper valence band potentials would be most certainly beneficial to develop p-DSSCs with much higher solar energy conversion efficiencies. Results which were obtained with CuGaO2 delafossite are very encouraging. Taking into account that we have barely started to explore this new research field and the number of adjustable parameters, there are certainly plenty of exciting discoveries to be made and we can anticipate that important progresses will be achieved in the near future.NANTES-BU Sciences (441092104) / SudocSudocFranceF