This article reports on a comprehensive study of the two-photon absorption (2PA) properties of six novel push-pull octupolar triarylamine compounds as a function of the nature of the electron-withdrawing groups. These compounds present an octupolar structure consisting of a triarylamine core bearing two 3,3′-bis(trifluoromethyl)phenyl arms and a third group with varying electron-withdrawing strength (H < CN < CHO < NO2 < Cyet < Vin). The 2PA cross-sections, measured by using the femtosecond open-aperture Z-scan technique, showed significant enhancement from 45 up to 125 GM for the lowest energy band and from 95 up to 270 GM for the highest energy band. The results were elucidated based on the large changes in the transition and permanent dipole moments and in terms of (i) EWG strength, (ii) degree of donor-acceptor charge transfer and (iii) electronic coupling between the arms. The 2PA results were eventually supported and confronted with theoretical DFT calculations of the two-photon transition oscillator strengths.

/pdf/molecular-structure-optical-property-relationships-for-a-4t1xmczmxx.pdf

Molecular Structure – Optical Property Relationships for a Series of Non-Centrosymmetric Two-photon Absorbing Push-Pull Triarylamine Molecules

We demonstrate herein the fabrication of small molecule-based OLEDs where four organic layers from the hole- to the electron-transporting layers have successively been deposited by using an all-solution process The key feature of the device relies on a novel photopolymerizable red-emitting material, made of small fluorophores substituted with two acrylate units, and displaying high-quality film-forming properties as well as high emission quantum yield as nondoped thin films Insoluble emissive layers were obtained upon UV irradiation using low illumination doses, with no further need of postcuring Very low photodegradation was noticed, giving rise to bright layers with a remarkable surface quality, characterized by a mean RMS roughness as low as 07 nm after development Comparative experiments between solution-processed OLEDs and vacuum-processed OLEDs made of fluorophores with close architectures show external quantum efficiencies in the same range while displaying distinct behaviors in terms of curre

All-Solution-Processed Organic Light-Emitting Diodes Based on Photostable Photo-cross-linkable Fluorescent Small Molecules

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.

Redox-controlled fluorescence modulation (electrofluorochromism) in triphenylamine derivatives

The synthesis of a series of push–pull pyrimidine and quinoxaline chromophores with extended π-conjugated cores is reported. Starting from a bromoarylvinyldiazine derivative, the key step in the preparation of the chromophores consists of a Sonogashira cross-coupling reaction. The photophysical properties of the compounds are described. A strong positive emission solvatochromism, typical for dyes presenting Intramolecular Charge Transfer (ICT), is observed, in particular for amino substituted derivatives with larger solvatochromic range than known analogous chromophores with smaller π-conjugated cores. The second order non linear optical (NLO) properties were investigated for some of the compounds and a comparison with the NLO responses of already described diazine chromophores exhibits a significant enhancement of the NLO properties by extension of the π-conjugated core.

/pdf/donor-linker-acceptor-d-p-a-diazine-chromophores-with-4zlxu5x7se.pdf

Donor–linker–acceptor (D–π–A) diazine chromophores with extended π-conjugated cores: synthesis, photophysical and second order nonlinear optical properties

Methoxy supported, deep red emitting mono, bis and tris triphenylamine-isophorone based styryl colorants: Synthesis, photophysical properties, ICT, TICT emission and viscosity sensitivity

A series of emitting push–pull triarylamine derivatives, models of their widely used homologues in photonics and organic electronics, was investigated by steady-state and time-resolved spectroscopy. Their structural originality stems from the sole change of the electron-withdrawing substituent X (–H: 1, –CN: 2, –NO2: 3, –CHC(CN)2: 4), giving rise to efficient emission tuning from blue to red upon increasing the X electron-withdrawing character. All compounds are highly fluorescent in alkanes. The more polar compounds 2–4 undergo considerable Stokes shift and emission quenching in polar solvents. Femtosecond transient absorption data allowed us to identify the nature of the emissive state which varies as a function of the compound and surrounding polarity. A long-lived ππ* excited state with weak charge transfer character was found for 1. This excited state evolves into a long-lived ICT state with red-shifted emission for 2 in polar solvents. For 3 and 4, the ICT state is directly populated in all solvents. Long-lived and emissive in n-hexane, it relaxes in toluene to a new ICT′ conformation with stronger charge transfer character and enhanced Stokes shift. In more polar THF, ethanol, and nitrile solvents, ICT relaxes to a dark excited state ICT′′ with viscosity-dependent kinetics (<10 ps). The ICT′′ state lifetime drops with increasing solvent polarity (150 ps for 3 in THF, 8.5 ps in butyronitrile, 1.9 ps in acetonitrile), denoting an efficient radiationless deactivation to the ground state (back charge transfer). This result reveals a very small S0–S1 energy gap at the relaxed ICT′′ geometry, with a possible close-lying S0–S1 conical intersection, which suggests that the ICT → ICT′′ process results from a structural change involving a large-amplitude molecular distortion. This fast structural change can account for the strong fluorescence quenching observed for 3 and 4 in polar solvents. Finally, the magnitude of intersystem crossing between the singlet and triplet excited states largely depends on the electron-deficient X unit and the solvent itself. These observations help one conclude on the prevailing role played by the electron-withdrawing groups and the surrounding polarity in the photophysical performances of triphenylamine derivatives, largely employed in numerous emissive solid-state devices.

Comprehensive investigation of the excited-state dynamics of push–pull triphenylamine dyes as models for photonic applications

Method for preparing tetrazines

La presente invention concerne un procede de preparation d'un compose de formule (I) suivante : dans laquelle R represente un groupe aryle, heteroaryle ou alkyle substitue par un groupe aryle, ledit procede comprenant : a) une etape de melange d'un nitrile de formule R-CN avec du dichloromethane et du soufre, dans un alcool, b) une etape d'addition de monohydrate d'hydrazine au melange obtenu a l'issue de l'etape a), et melange de l'ensemble ainsi obtenu, et c) une etape d'oxydation du melange obtenu a l'issue de l'etape b).

Procede de preparation de tetrazines

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Comprehensive investigation of the excited-state dynamics of push–pull triphenylamine dyes as models for photonic applications

Method for preparing tetrazines

Procede de preparation de tetrazines