Edge modification of PAHs: the effect of embedded heterocycles on the aromaticity pattern

International audienceAromaticity studies carried out on the condensed model system 2 with different heteroatoms showed that the NICS(1) aromaticity in the five-membered ring correlates with that in the parent five-membered ring having the same heteroelement. Although the local aromaticity pattern is clearly determined by the Clar structure, as evidenced by the local aromaticity values in the reference molecules R1-3, the modifying effect of the heteroatom is significant. The correlation between the NICS(1)5 and NICS(1)6 aromaticities of the neighbouring rings is excellent, by modification of the heterocycle, we can engineer the aromaticity of the connecting six-membered ring as well. Geometry based aromaticity indices do not correlate well with NICS values probably due to annellation effects between rings with different aromatic character. Calculations with the different tested basis sets don’t show significant differences, therefore the use of the computationally cheaper methods is envisaged during further investigations of corresponding systems with extended π-framework

π-Conjugated Phospholes and their Incorporation into Devices; A Component with a Great Deal of Potential

International audienceThis review serves as a brief introduction to phospholes and discusses their unique favorable properties for applications in organic electronic materials. Over the past several years, π-conjugated phospholes have been slowly making their way into devices. We report here the mode of synthesis for these π-conjugated phospholes as well as discuss the performances of the devices

Phosphorus-based chromophores: Emitters for OLEDs

International audienceIn this paper, we present the development of white OLEDs (WOLEDs) using organophosphorus derivatives as fluorescent emitters. The structural changes that we have performed on and around the phosphole ring (functionalization of the phosphorus atom, nature of the substituents at the 2 and 5 position) allow the ability to tune the emission wavelengths and the color emitted by the OLEDs. Using this concept, we developed organophosphorus dopants emitting orange light, which can be mixed with a blue emitting matrix for the development of WOLEDs. The OLEDs structure allows the development of flexible OLEDs with good performance and CIE coordinates which are independent from the current density

Organic photovoltaics: a chemical approach

International audienceThe design of new organic functional molecules able to harvest sun light and efficiently 5 undergo photon to current energy conversion processes is at the forefront of chemical challenges. In this review the fundamental contribution of chemistry to the multidisciplinary field of organic photovoltaics is presented in a systematic way through the wide variety of organic compounds synthesized to be successfully used in photovoltaic devices

Continuous Symmetry Breaking Induced by Ion Pairing Effect in Heptamethine Cyanine Dyes: Beyond the Cyanine Limit

WOS:000276009500058International audienceThe association of heptamethine cyanine cation 1(+) with various counterions A (A = Br(-), I(-), PF(6)(-), SbF(6)(-), B(C(6)F(5))(4)(-), TRISPHAT) was realized. The six different ion pairs have been characterized by X-ray diffraction, and their absorption properties were studied in polar (DCM) and apolar (toluene) solvents. A small, hard anion (Br(-)) is able to strongly polarize the polymethine chain, resulting in the stabilization of an asymmetric dipolar-like structure in the crystal and in nondissociating solvents. On the contrary, in more polar solvents or when it is associated with a bulky soft anion (TRISPHAT or B(C(6)F(5))(4)(-)), the same cyanine dye adopts preferentially the ideal polymethine state. The solid-state and solution absorption properties of heptamethine dyes are therefore strongly correlated to the nature of the counterion

Synthesis and electronic properties of polycyclic aromatic hydrocarbons doped with phosphorus and sulfur

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Competitive Retro-Cycloaddition Reaction in Fullerene Dimers Connected through Pyrrolidino-pyrazolino Rings

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Stable Near-Infrared Anionic Polymethine Dyes: Structure, Photophysical, and Redox Properties

International audienceThe concept of cyanine has been successfully extended to anionic heptamethine dye featuring tricyanofuran (TCF) moieties in terms of structure, reactivity and photophysical properties. Importantly, absorption and emission are red-shifted compared to its classical cationic analog without any cost in term of thermal stability. In addition to its "cyanine" behavior, this molecule exhibits further redox properties: oxidation and reduction led to the reversible formation of radical species whose absorption is in marked contrast with that of cyanines

Pi-extended phosphepines: redox and optically active P-heterocycles with non-planar framework

In this letter, we present the synthesis of a new family of -extended dithieno[b,f]phosphepines. The Pd-catalyzed direct-arylation allows the introduction of various substituents, which tune the absorption/emission in the visible range as well as the redox properties. All those modifications were rationalized through DFT calculations. The physical properties of ambipolar phosphepine with diphenylamino substituents conduct us to use it as a semi-conductor in a p-type organic field-effect transis-tors (OFETs)

Synthesis, Electronic Properties and WOLED Devices of Planar Phosphorus-Containing Polycyclic Aromatic Hydrocarbons

International audienceWe describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P-containing PAHs exhibit properties expected for an emitter in white organic light-emitting diodes (WOLEDs)