Anthracenediylidene derivatives: control of molecular and supramolecular architecture

In the context of new π-donor molecules, extended tetrathiafulvalenes have been widely studies for their use as components of electronically conductive charge-transfer materials. In contrast with the planar π -systems, we have focused our attention on extended tetrathiafulvalenes containing a conjugated anthracenyl spacer (anthracenediylidene derivatives). These TTF derivatives adopt a saddle-shaped conformation in the neutral state and a drastic change of conformation occurs upon oxidation to the dication species. Our main objective was to investigate the molecular and supramolecular architecture of these compounds. At the molecular scale, we synthesised cyclophanes by bridging the preformed anthracene tetrathiafulvalene system and studied their redox properties and crystal packing. We developed the chemistry of anthracenediylidene derivatives in order to direct the supramolecular architecture by secondary interactions (hydrogen-bonding, π-π stacking). Finally, we also investigated the incorporation of anthracenediylidene units inside dendritic structures in order to study the highly charged species formed upon oxidation

Mesoporous TiO2 Thin Films: State of the Art

Mesoporous TiO2 thin films (MTTFs), thanks to their particularly high surface area, controlled porosity, high flexibility in composition, and surface design, are promising candidates in different application fields such as sensors, self-cleaning coatings, lithium-ion batteries (LIBs), photocatalysis, and new-generation solar cells. This chapter is focused on the synthetic and post-synthesis aspects that can affect the TiO2 mesoporous structure and consequently the MTTF properties. In particular, after a brief summary of TiO2 properties, all experimental conditions to prepare MTTFs are reviewed as well as the main characterization techniques employed to study their physicochemical and photocatalytic properties. An overview of the main applications of MTTFs is also proposed, mainly focused on the use of MTTFs in sensors and LIBs

Light-induced reorientation and birefringence in polymeric dispersions of nano-sized crystals

Nanocrystals (50-250 nm) of a Palladium complex within a polyisobutylmethacrylate matrix were prepared by a phase separation method. In these dispersions, a light-induced birefringence with Deltan approximately 10(-3) was induced, without the application of an electric field. This effect was related to the photoconducting properties of the dispersion. Evidence for charge photogeneration without any applied field was obtained. The photorefractive behaviour of the material confirmed that the nanocrystals reorientation is a consequence of photoconducting properties. A light-generated electric field approximaely E 3 V/microm was estimated. These results illustrate the potential of materials with a nano-crystalline dispersion morphology as light-responsive media

Thin Film Electrodeposition of Ir(III) Cyclometallated Complexes

Novel electropolymerizable Ir(III) cyclometallated complexes have been synthesized and characterized. In these complexes the cyclometallated ligands are either 2-phenylpyridine H(PhPy) or benzothiazole-triphenylamine H(BzTh-tpa), while the Ir(III) coordination sphere is completed by a Schiff base substituted with a triphenylamine fragment. A complete electrochemical study has been conducted on all complexes, in order to verify the feasibility of electropolymerization and to elucidate the role of the specific position of the triphenylamine moiety in the molecular structure. Homogeneous thin films of Ir(III) metallopolymers have been successfully obtained through electropolymerization process

investigation of new additives to reduce the fume emission of bitumen during asphalt concrete processing

Pavement materials play an important role in overall pavement sustainability including material acquisition processing, and transportation. The main objective of the present study is to evaluate the effectiveness of new additives, to reduce bitumen's fume emission expelled into the atmosphere, during the processing of asphalt concrete. The new additives act by trapping bitumen's volatile substances avoiding their release at high temperatures. In this paper, we have been tested the performance of 2 types of mesoporous silica-based additives (AntiSmog 1 and AntiSmog 2). The idea of using these additives to reduce the emission of fumes in bitumen has been submitted as a patent. To quantify and characterize the emitted fumes, thermogravimetry (TGA) and gas chromatography-mass spectrometry (GC-MS) technique have been used. Dynamic Shear Rheology (DSR) has been used to check the rheological properties and the possible sedimentation issues that could occur after the addition of the additive

Nearly-freestanding supramolecular assembly with tunable structural properties

The synthesis and design of two-dimensional supramolecular assemblies with specific functionalities is one of the principal goals of the emerging field of molecule-based electronics, which is relevant for many technological applications. Although a large number of molecular assemblies have been already investigated, engineering uniform and highly ordered two-dimensional molecular assemblies is still a challenge. Here we report on a novel approach to prepare wide highly crystalline molecular assemblies with tunable structural properties. We make use of the high-reactivity of the carboxylic acid functional moiety and of the predictable structural features of non-polar alkane chains to synthesize 2D supramolecular assemblies of 4-(decyloxy)benzoic acid (4DBA;C[Formula: see text] H[Formula: see text] O[Formula: see text] ) on a Au(111) surface. By means of scanning tunneling microscopy, density functional theory calculations and photoemission spectroscopy, we demonstrate that these molecules form a self-limited highly ordered and defect-free two-dimensional single-layer film of micrometer-size, which exhibits a nearly-freestanding character. We prove that by changing the length of the alkoxy chain it is possible to modify in a controlled way the molecular density of the “floating” overlayer without affecting the molecular assembly. This system is especially suitable for engineering molecular assemblies because it represents one of the few 2D molecular arrays with specific functionality where the structural properties can be tuned in a controlled way, while preserving the molecular pattern

Photoconductive properties and electronic structure in 3,5-disubstituted 2-(2′-pyridyl)pyrroles coordinated to a Pd(II) salicylideneiminate synthon

The synthesis and the electrochemical, photophysical, structural, and photoconductive properties of three new heteroleptic Pd(II) complexes with various 3′,5′- disubstituted-2-(2′-pyridil) pyrroles H(N^N) as coordinated ligands are reported. The coordination of the metal center was completed by a functionalized Schiff base H(O^N) used as an ancillary ligand. The [(N^N)Pd(O^N)] complexes showed highly interesting photoconductive properties which have been correlated to their electronic and molecular structures. Theoretical density functional theory (DFT) and time-dependent DFT calculations were performed, and the results were confronted with the organization in crystalline phase, allowing to point out that the photoconductive properties are mainly a consequence of an efficient intramolecular ligand-to-metal charge transfer, combined to the proximity between the central metal and the donor moieties in the solid-state molecular stacks. The reported results confirm that these new Pd(II) complexes form a novel class of organometallic photoconductors with intrinsic characteristics suitable for molecular semiconductors applications.Supported by Ministero dell’Istruzione, dell’Universitàe della Ricerca by the ELIOTROPO.Peer reviewe

Water soluble Ir(III) complexes towards organised phases and nanostructured IrO2 thin films

Dottorato di Ricerca in Scienze e Tecnologie Fisiche, Chimiche e dei Materiali. Ciclo XXXThis thesis comprises three main macro-topics: water-soluble Iridium (III) complexes, Iridium-based metallogels and nanostructured Iridium Oxide (IrO2). More specifically, the synthesis of new water-soluble cationic Ir(III) complexes has been performed through a simple methodology which involves the incorporation of hydrophilic counterions into the final compounds. Some of the synthesized complexes have shown supramolecular organization in water. These self-assembling architectures have been thoroughly investigated through the combination of complementary characterization techniques, in particular Polarized Optical Microscopy (POM), Transmission Electron Microscopy (TEM), Powder X-Ray Diffraction (PXRD), etc. According to the nature of the featuring ligands, the water-soluble Ir(III) complexes display features of metallogels or lyotropic liquid crystals. The use of these highly organized metallo-hydrogels as Structural Directing Agent (SDA), and concomitantly as direct metal source, has been exploited for the preparation of nanostructured IrO2 powders and thin films. All the presented materials display appealing features for specific applications: water-soluble Ir(III) complexes could represent interesting candidates for anticancer drugs or bioimaging probes, Ir(III) metallogels could find applications in thermosensing or as templating agents, and finally nanostructured IrO2 could be employed in electrochromic devices and catalytic processes.Università della Calabri

AvBD11, une protéine naturelle de l’œuf au potentiel thérapeutique prometteur

Communiqué de presse, INRAECOMMUNIQUE DE PRESSE - L’œuf de poule renferme l’ensemble des éléments nécessaires au développement et à la protection d’un embryon. Il constitue une véritable mine de molécules aux activités biologiques diverses, dont la plupart restent à caractériser. Un consortium réunissant des scientifiques d’INRAE, du CNRS, de l’Inserm et de l’Université de Tours (1), a étudié la structure et la fonction physiologique d’un constituant majeur de la membrane vitelline (2) de l’œuf de poule, la protéine AvBD11. Pour la première fois, les scientifiques ont mis en évidence les caractéristiques uniques de cette petite protéine qui lui confèrent des activités biologiques variées, à la fois antimicrobiennes, anti-invasives (3) et cytotoxiques. Ces résultats, publiés le 23 décembre 2019 dans la revue Proceedings of the National Academy of Sciences, apportent de nouvelles données sur le rôle des protéines de l’œuf dans le développement embryonnaire et sur les spécificités de l’œuf d’oiseau