Elaboration de systèmes moléculaires multi-chromophoriques pour l'électronique moléculaire

Over the past decade many efforts have been focused on the synthesis, modification and application of multi-responsive molecular systems. Up to now, two main strategies have been conducted to elaborate such systems: either by connecting different molecular switches through covalent links or by mixing them within supramolecular assemblies to obtain multiresponsiveness through the combination of various stimulations (i.e., photon, electron, proton, etc…). In thisthesis, we report a different approach based on the employment of identical indolinooxazolidine (BOX) unit as multi-modal switch. Indeed, the opening of the oxazolidine ring can be reversibly and selectively achieved either under UV irradiation, electrochemical stimulation or acidity changes. According to our first strategy, two BOX units were connected around a simple linear aromatic plate forms, such as bithiophene and EDOT-Thiophene-EDOT unit as spacer. Interestingly, these systems are able to commute between 3 different metastable states in a stepwise manner with all kinds of stimulations. Going further, in order to promote the metastable states, it was possible to increase the number of BOX by connecting three of them on more elaborated pi systems which are potentially able to exhibit up to four discriminate metastable states. Complementary to that, a second strategy was to synthesize various nitrogen ligands functionalized by at least one BOX unit and their coordination chemistry with zinc and ruthenium metals. The response of the ligands as well as their corresponding complexes under photo, electro and acidic stimulation were also investigated and fully characterized.Au cours des dernières décennies, de nombreux efforts se sont focalisés sur la synthèse, la modification et l’utilisation de systèmes moléculaires multi-adressables. Afin d’élaborer de tels systèmes capables de répondre à des stimulations de différentes natures (par exemple : photon, électron, proton, etc…) les deux principales stratégies consistaient à ce jour à connecter différents types d’unités stimulables soit par liaison covalente soit par dispersion au sein d’assemblages supramoléculaires. Au cours de cette thèse, nous nous sommes attachés à développer une nouvelle approche basée sur l’utilisation d’un unique switch multi-mode : les indolino-oxazolidine (BOX). En effet, cette unité est capable de commuter entre deux états métastables (ouvert et fermé) et ce de façon indifférenciée par application d’une stimulation lumineuse, électrochimique ou encore par variation du pH. En suivant une première stratégie, deux unités BOX ont été connectées via l’utilisation d’un simple système conjugué linéaire tels qu’une unité bithiophène et un enchainement EDOT-Thiophène-EDOT (ETE) comme espaceur. Nous avons démontré que ces systèmes multi-stimulables sont capables de commuter de façon pas à pas entre 3 états métastables différents et ce quel que soit la nature du stimulus. Afin de démontrer les nombreuses possibilités de cette approche et augmenter le nombre d’états métastables, 3 unités BOX ont été connectés par l’utilisation de systèmes conjugués plus élaborés permettant ainsi de conduire à des interrupteurs moléculaires capables de présenter jusqu’à 4 états différents. En complément de cette approche purement organique, une seconde stratégie a consisté à fonctionnaliser différents ligands azotés par au moins une entité BOX afin d’élaborer des systèmes plus complexes par chimie de coordination avec des ions métalliques de zinc et de ruthénium. Les ligands préparés ainsi que les complexes correspondants ont été pleinement caractérisés et leur addressabilité sous stimulation chimique, électrique et lumineuse étudiée

Elaboration of multimodal ligands based on BOX units: Toward full zinc release in Zn(II) complexes by external stimulation

International audienc

When Light and Acid Play Tic-Tac-Toe with a Nine-State Molecular Switch

International audienceCombining different molecular switching functions in a single molecule is a simple strategy to develop commutable molecules featuring more than two commutation states. The present study reports on two molecular systems consisting of two indolino-oxazolidine (Box) moieties connected to an aromatic bridge (phenyl or bithiophene) by ethylenic junctions. Such systems, referenced as BiBox, are expected to show up multiaddressable and multiresponsive behaviors. On one hand, the oxazolidine ring opening/closure of Box moieties can be addressed by chemical stimuli, and on the other hand, the trans-to-cis isomerization of the ethylenic junctions is induced by visible light irradiation (with a thermal back conversion). NMR and UV−visible spectroscopies allowed to characterize up to nine out of the ten theoretically expected commutation states as well as to measure the kinetics of the interconversions. Also, steady state fluorescence spectroscopy measurements highlighted the strong influence of the open/closed states of the Box moieties on their emission properties

Combining Benzazolo-Oxazolidine Twins toward Multi-state Nonlinear Optical Switches

International audienc

A molecular loaded dice: When the π conjugation breaks the statistical addressability of an octastate multimodal molecular switch

International audienc

Expanding the carbo ‐Benzene Chemical Space for Electron‐Accepting Ability: Trifluorotolyl/Tertiobutyl Substitution Balance

International audienceWith the view to altering the lipophilicity and electron accepting ability of the tetraphenyl-carbo-benzene scaffold, peripheral fluorination of the C18 ring through aromatic linkers was envisaged from the C18Ph6 and o-tBu2C18Ph4 references, by replacement of two Ph substituents with two p-CF3-C6H4 counterparts (FTol). The synthesis relied on a [8+10] macrocyclization involving a common bis(trifluorotolyl)-tetraynedione, followed by reductive aromatization of the resulting [6]pericyclynediols. While p-FTol2C18Ph4 proved to be hardly tractable due to an extremely low solubility, p-FTol2-o-tBu2C18Ph2 could be extensively studied by X-ray crystallography, NMR and UV/Vis spectroscopy, voltammetry, STM imaging of monolayers, and AFM imaging of binary films with P3HT or PC71BM fabricated by spin-coating for organic photovoltaic cells and J−V curve measurement thereof. The electronic and polarity properties are correlated with moderate but consistent electron-withdrawing effects of the CF3 groups, in agreement with the DFT-calculated frontier orbitals and multipole moments. The results provide guidelines for optimization of fluorinated carbo-benzene targets