Cassandre Quinton

Redox- and Protonation-Induced Fluorescence Switch in a New Triphenylamine with Six Stable Active or Non-Active Forms

The synthesis, photophysical and electrochemical properties as well as theoretical calculation studies of a newly designed triphenylamine derivative are described. This original compound displays one neutral form, three oxidized forms, and two protonated forms with distinct photophysical characteristics. The interplay of the emission with the protonation or the redox state (electrofluorochromism) has been explored and an on-off-on-off fluorescence switching was observed in the case of oxidation and an on-on-off fluorescence switching in the case of protonation.

Redox-controlled fluorescence modulation (electrofluorochromism) in triphenylamine derivatives

The study of the chemical and electrochemical fluorescence switching properties of a family of substituted triphenylamine derivatives is reported. First of all, the synthesis of a family of six compounds is described. They are characterized by electrochemistry, UV-vis and fluorescence spectroscopy and spectroelectrochemistry. Theoretical calculations were performed in order to corroborate the experimental results. While these compounds emit blue to green light under UV irradiation with a large quantum yield (37%) in the case of one molecule, the fluorescence intensity is quenched upon oxidation. The fluorescence behavior can be switched between the strong fluorescent (neutral) state and the non-fluorescent (oxidized) state with a high contrast (around 1500 for the fluorescence intensity for one of these molecules). Furthermore, the chromatic contrast of three of these molecules reaches 70% that can be important for further applications.

Triphenylamine/tetrazine based π-conjugated systems as molecular donors for organic solar cells

Conjugated systems built by connecting one electron-donor triphenylamine to an electron-withdrawing tetrazine have been prepared using various linkers. We describe here the synthesis, the electrochemical properties and some photophysical properties of these molecules, emphasizing the dependence upon the type of linker between the groups and an organic photovoltaic solar cell was prepared with one derivative.

Electron-Rich 4-Substituted Spirobifluorenes: Toward a New Family of High Triplet Energy Host Materials for High-Efficiency Green and Sky Blue Phosphorescent OLEDs

We report herein a detailed structure-properties relationship study of the first examples of electron-rich 4-substituted spirobifluorenes for organic electronic applications, namely, 4-phenyl-N-carbazole-spirobifluorene (4-PhCz-SBF) and 4-(3,4,5-trimethoxyphenyl)-spirobifluorene (4-Ph(OMe)3-SBF). The incorporation of the electron-rich moieties in the ortho position of the biphenyl linkage (position C4) induces unique properties, very different from those previously described in the literature for this family of semiconductors. Both dyes can be readily synthesized, possess high triplet energies and excellent thermal stability, and their HOMO energy levels are highly increased compared to those of other 4-substituted SBFs. We also provide in this work the first rationalization of the peculiar fluorescence of 4-substituted SBFs. Finally, the present dyes have been successfully incorporated as host in green and blue phosphorescent organic light-emitting diodes with high performance either for the green (EQE of 20.2%) or the blue color (EQE of 9.6%). These performances are, to the best of our knowledge, among the highest reported to date for 4-substituted SBF derivatives.

Original electroactive and fluorescent bichromophores based on non-conjugated tetrazine and triphenylamine derivatives: towards more efficient fluorescent switches

The synthesis, photophysical and electrochemical properties and their interplay as well as theoretical calculations studies of newly designed fluorescent and electroactive derivatives are described. These molecules are composed of two fluorophores: one triphenylamine, electron-rich unit, and one tetrazine, electron-poor unit, connected by two different links. While in the neutral state the bichromophores are not fluorescent, due to a photoinduced electron transfer from the triphenylamine unit to the tetrazine unit, the fluorescence is restored in the oxidative state (oxidation of the triphenylamine moiety).

Novel s-tetrazine-based dyes with enhanced two-photon absorption cross-section

This paper reports the synthesis and the linear and non-linear absorption properties of a series of new tetrazine-based D–π–A–π–D and D–π–A type dyes. In these derivatives, a central tetrazine core was connected with one or two terminal triphenylamine moiety(ies) via various π-conjugated spacers. These compounds were efficiently synthesized by Stille or Suzuki–Miyaura cross-coupling as a key step. Their photophysical properties, including one-photon absorption and two-photon absorption (2PA), were investigated with special attention to structure–property relationships. Large 2PA cross-sections (>800 GM) of these tetrazine dyes were evaluated by open aperture z-scan and non-degenerate 2PA techniques. The strong 2PA of these molecules is attributed to the extended π system and to the enhanced intramolecular charge transfer between the triphenylamine donor and the center tetrazine acceptor.