Mediating gel formation from structurally controlled poly(electrolytes) through multiple "head-to-body" electrostatic interactions

Tuning the chain-end functionality of a short-chain cationic homopolymer, owing to the nature of the initiator used in the ATRP polymerisation step, can be used to mediate the formation of a gel of this poly(electrolyte) in water. While a neutral end group gives a solution of low viscosity, a highly homogeneous gel is obtained with a phosphonate anionic moiety, as characterized by rheometry and diffusion NMR. This novel type of supramolecular control over poly(electrolytic) gel formation could find potential use in a variety of applications in the field of electroactive materials

Synthesis and characterization of polymers for nonlinear optical applications

International audienceA difunctional NLO Azo-Dye chromophore has been synthesized and polymerization has been performed with a comonomer bearing a side-chain epoxy group. Deposition of the polymer on glass substrates was performed by spin-coating, resulting in uniform films up to 2 µm thickness. The orientation of the chromophore was performed under a " pin-to-plane " positive corona discharge followed by a heat-treatment in order to obtain reticulation of the films. Molecular orientation has been investigated using UV-Vis. and Raman spectroscopy. Poling of the films results in a decay of absorbency as well as in a blue shift of the spectrum. At the same time, the 1600 cm-1 band disappears from the Raman spectra, indicating orientation of the chromophores. Cross-linking has been studied by FTIR and all-optical poling and showed an improved stability of the electro-optic thin films

Thérapie photodynamique : évolution chimique des photosensibilisateurs

Points clésDomaine : Techniques non invasives de thérapie du cancerDegré de diffusion de la technologie : Émergence | Croissance | MaturitéTechnologies impliquées : synthèse chimique, technologies diodes et lasers, (bio)photoniqueDomaines d'application : thérapie non chirurgicale du cancer et de maladies liées au vieillissement cellulairePrincipaux acteurs français :Pôles de compétitivité :Centres de compétence : 60 centres hospitaliers équipés en France (leader : CHU d'Angers – service d'urologie) ; unité « Conception Synthèse et vectorisation de biomolécules (CNRS UMR 176, Institut Curie, Paris, France) ; laboratoire de Chimie de l'ENSL (UMR 5182, ENSL, université de Lyon, France)Autres acteurs dans le monde :Centres de recherche hospitaliers : PhotoDynamic Therapy Center (Roswell Park Cancer Institute, Buffalo) ; PhotoDynamic Therapy Center-LW Jenkins Cancer Center (Pitt County Memorial Hospital-BrodyScool of Medicine, East Carolina University) ; Moscow PA Gertsen Oncology Research Institute ; Department of Cancer Research and Molecular Medicine (Norwegian University of Science and Technology, NTNU, Trondheim)Photosensibilisateurs : Draxis Pharma, Axcan Pharma, Novartis, Biolitec Pharma, DUSA, GaldermaSources lumineuses : Coherent Inc., Biolitec, Photocure, PhotoMedexInternational audienceLa thérapie photodynamique, appelée aussi PDT, connaît depuis une trentaine d'années un essor constant, l'imposant définitivement comme une alternative thérapeutique majeure dans le traitement de nombreux cancers. À l'origine de cet essor, la compréhension des processus physico-chimiques mis en jeu lors de la PDT et l'identification des paramètres permettant d'améliorer son efficacité ont conduit à une optimisation spectaculaire de la structure des photosensibilisateurs mis en jeu. Ces évolutions sont présentées, avec les dernières stratégies mises en œuvre dans ce cadre

A cheap and efficient method for selective para-iodination of aniline derivatives

International audienc

Determination of Photoinduced Radical Generation Quantum Efficiencies by Combining Chemical Actinometry and 19 F NMR Spectroscopy

International audienc

Modulation of the photochromic properties of TPE and other tetrasubstituted olefins by the “amino conjugation effect”: a quantitative study

Tetraphenylethylene (TPE) derivatives have been a key building block in the development of solid-state fluorophores with tunable emission wavelength and large quantum efficiencies. Recent literature has brought an array of evidence that rotation around the central C=C bond constitutes main route of deexcitation in solution, and that its restriction in solid-state leads to aggregation-induced emission (AIE) in this family of derivatives. However, the influence of substitution on the dynamics of TPEs in solution has so far received little attention, probably because of the difficulty in efficiently separating (E) and (Z) isomers. Here we report the photophysical properties in solution of extended stereopure TPE derivatives. The introduction of triphenylamine (TPA) substituent results in differences in the spectral properties between the (E) and (Z) isomers, thereby allowing modulation of the photostationary state (PSS) and thus switching in the equilibrium between these two forms depending on the irradiation wavelength. Importantly, we show that this photochromism is observed with a very marked decrease in the photoisomerization quantum yields (Φiso) of TPE-TPA, compared to non-extended TPE derivatives, which we attribute to the so called “amino conjugation effect” already reported for several stilbene derivatives. As a generalization of this mechanism, we show that TPA substitution provides similar effect on other stilbenoid derivatives. These results provide important new insight into the photophysics of electron donor substituted TPEs, and their possible use as photochromic materials

Reevaluating the Solution Photophysics of Tetraphenylethylene at the Origin of their Aggregation‐Induced Emission Properties

International audienceAlthough tetraphenylethylene (TPE) and its derivatives have been the most commonly used building blocks in the construction of molecules with Aggregation-Induced Emission (AIE) properties, no absolute consensus exists regarding the mechanisms at the origin of the phenomenon. Restriction of Intramolecular Rotations (RIR) of peripheral phenyls has historically been a dominant paradigm which has served as a valuable guideline in the molecular engineering of AIEgens. Yet, an increasing number of recent works have established that photoisomerization or photocyclization may actively participate in the nonradiative dissipation of the excitation energy. In this paper, we bring the first experimental evaluation of the quantum efficiencies of these different processes, and show that photoisomerization is by far the dominant photophysical pathway in solution, accounting for virtually all nonradiative decay of the molecule's excited state in degassed solution

Synthèse de nouveaux matériaux organiques et organo-métalliques pour l'optique non-linéaire du deuxième-ordre

Ce travail a porté sur la synthèse de nouveaux matériaux pour des applications en optique non-linéaire du deuxième ordre. Le premier volet a concerné la synthèse à l'échelle de 10 g et la caractérisation complète d'un polymère d'étude réticulable construit autour d'un chromophore azoïque (DR1). Le mécanisme de réticulation a été caractérisé. L'évolution de son spectre UV-visible après réticulation a pu être rationalisée par une étude théorique. Dans un deuxième volet, un nouveau polymère réticulable a été développé, intégrant comme chromophore une porphyrine " push-pull " ( 1.06= 3500.10-30 esu). Une voie de synthèse efficace du polymère a été mise au point. Ce dernier a pu être déposé sur substrat de verre sous forme de films minces. Le troisième volet a concerné la synthèse de complexes de platines comportant dans sa sphère de coordination un ligand riche et un ligand pauvre en électrons. Plusieurs cibles de ce type ont été synthétiséesThis work deals with the synthesis of new materials for second order nonlinear optical applications. The first section concerned the synthesis on a 10 g scale and the complete study of a cross-linkable model polymer made of an azo-chromophore (DR1). The cross-linking mechanism has been characterized. The evolution of its UV-vis spectrum has been fully rationalized by a theoretical study. In a second section a new cross-linkable polymer has been developped, which includes a " push-pull " porphyrinic chromophore ( 1.06= 3500.10-30 esu). An efficient synthetic route for the preparation of this polymer has been developped. Thin-films of this material have been spin-coated on glass subtracts. The third section concerned the synthesis of terpyridine platinum complexes acting as a link between an electron-rich and an electron-poor ligand. Several complexes of this kind have been synthesised.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Photophysical insights on the influence of excited states reorganization processes on the visible and near infra-red luminescence of two-photon quadrupolar chromophores

International audienceWe synthesized three different families of quadrupolar dyes, differing by the nature of their aromatic central cores (phenyl, fluorenyl, anthracenyl), in which we systematically varied the length of the π-conjugated backbone and the nature of the central bridge. We compared their linear and non-linear spectroscopic and photophysical features. We showed that the introduction of a diyne bridge is efficient in consistently increasing the Stokes shifts in these fluorophores, especially in high polarity solvents. By a combined theoretical and spectroscopic study we show that this feature is favoured by distortion of their π-conjugated skeleton at the electronic ground state. Unfortunately, this distortion process is generally detrimental to their fluorescence quantum yields. However, in the course of this study, we identify a particularly promising dye, that combines a large two-photon absorption (650 GM@760 nm) while keeping efficient emission (ϕf = 0.3) in the far-red/NIR (ca 700 nm) in polar solvent (DMSO)

Synthesis of new crosslinkable co-polymers containing a push–pull zinc porphyrin for non-linear optical applications

International audienceIn this paper, the synthesis of a crosslinkable co-polymer containing new push–pull arylethynyl zinc porphyrins is described. The synthesis of porphyrin chromophores, analogous to Therien's porphyrin (J. Am. Chem. Soc. 1996, 118, 1497–1503) functionalized with a methacrylic polymerizable group and a carboxylic acid crosslinking group was achieved with a new synthetic procedure leading to a higher overall yield compared to what was previously reported in the literature for similar and simpler structures. Radical copolymerization of the porphyrin chromophore with glycidyl methacrylate has then been carried out with success. This work opens a perspective on the possibility to integrate porphyrinic chromophore with high first-order molecular quadratic hyperpolarizability coefficient in opto-electronic devices.This work describes an efficient synthetic route to prepare a methacrylate co-polymer containing push–pull zinc porphyrin and glycidyl units