Frédéric Fages

A novel small molecular luminescent gelling agent for alcohols

2,3-Bis-n-decyloxyanthracene can form thermoreversible gels with alcohols at very low concentrations; electronic absorption spectra and fluorescence emission studies suggest that the network of the gel consists of head-to-tail assemblies of the aromatic component coexisting with the alcohol, the organization of the system essentially relying upon dipolar forces and van der Waals interactions.

Pulsed-laser printing of organic thin film transistors

Organic thin-film transistors have been fabricated using laser-induced forward transfer as spatially resolved laser-printing method. Using this technique, source and drain electrodes were deposited from silver nanoparticle ink and the copper phthalocyanine (CuPc) was used to form the active layer. Both kinds of materials were transferred from a donor substrate onto a receiver substrate upon irradiation with laser pulses in the picosecond regime. The latter substrate formed the gate and the dielectric of the transistor. Electrical characterizations showed that the transistors are fully operative, showing well-defined linear and saturation regimes in the I-V curves.

Rational Design of Low Molecular Mass Organogelators: Toward a Library of FunctionalN-Acyl-1,ω-Amino Acid Derivatives

N-Acyl amino acids RCONH(CH2 )n COOR1 represent a new family of organogelators that can be obtained in a combinatorial approach from libraries of activated acids and amino acids. The amounts required for gel formation in solvents such as DMF are less than 1 mg mL-1 and the gels formed are very stable. n=5, 7, 10, 12; R=aromatic or aliphatic group; R1 =H or alkali metal (Na).

Synthesis and photophysical properties of difluoroboron complexes of curcuminoid derivatives bearing different terminal aromatic units and a meso-aryl ring.

The synthesis of nine curcuminoids and their difluoroboron complexes is described, with seven of them containing a meso-phenyl ring. Dynamic (19)F NMR confirmed the fact that rotation of that meso-aryl fragment is restricted in the latter systems at room temperature and become allowed at higher temperature (>45 °C). The molecular structure of a meso-substituted derivative in the solid state showed that the phenyl ring lies in a highly twisted plane with respect to the mean curcuminoid plane. The photophysical properties of the nine compounds were investigated in solvents of different polarity. Meso-substitution with a phenyl ring has little influence on fluorescence emission properties in solution, radiative and nonradiative kinetic constants being similar for meso- and nonsubstituted compounds, which is in contrast to the case of BODIPY derivatives. However, introduction of an electron donor p-methoxy group at the meso-phenyl ring leads to small perturbation of the curcuminoid π-system fluorescence emission. We also report the influence of the meso-phenyl group on the emission properties of the aggregated solids.

Zinc(II)-operated intramolecular charge transfer fluorescence emission in pyrene-2,2′-bipyridine conjugated molecular rods

Abstract The design and synthesis of two conjugated pyrene-2,2′-bipyridine linear rods is described. Zn(II) ion complexation allows the formation of a highly polar emissive excited state through efficient photoinduced intramolecular charge transfer.

Synthesis, cation binding, and photophysical properties of macrobicyclic anthraceno-cryptands

The new cryptands, (1a) and (1b), possess remarkable spectroscopic and photophysical properties which are markedly affected by cation binding and by protonation.

Two-photon excited fluorescence of BF2 complexes of curcumin analogues: toward NIR-to-NIR fluorescent organic nanoparticles

The synthesis of borondifluoride complexes of curcuminoids and one- and two-photon absorption properties of 1 and 2 are described. These compounds allow the preparation of organic nanoparticles that were characterized using DLS, TEM and AFM revealing sizes around 50–60 nm for 2. The fluorescence emission spectra of the nanoparticles are red-shifted compared to those of the dye diluted in dichloromethane solution reaching the NIR region of the spectrum. This effect stems from the occurrence of π–π interactions in the solid state, as revealed from the X-ray crystal structure analysis of 1. Those dyes exhibit a significant two-photon absorption cross-section in solution and nanoparticle suspension in water. The nanoparticles are shown to behave as NIR-to-NIR fluorescent nanomaterials that could be potentially used for studies in the biological transparency window. Two-photon brightnesses of ca. 13–14 GM are obtained for both dyes, which are amongst some of the highest values reported to date for NIR-to-NIR luminophores.

Synthesis and thin film electronic properties of two pyrene-substituted oligothiophene derivatives

The synthesis and the electric properties of two new pyrene end-substituted oligothiophene derivatives (Py-nT, n = 2,4) are described. The highest hole mobility (ca. 10−3 cm2 V−1 s−1) was obtained for vacuum evaporated thin films of Py-4T as the active layer in field effect transistors based on hexamethyldisilazane-treated SiO2/Si substrates. Moreover, Py-nT thin films were doped with molecular iodine, which led to a 106 fold increase of electric conductivity. In the case of Py-4T, a value of 1 S cm−1 was obtained after 21 minutes exposure to iodine vapor.

11-Aminoundecanoic acid: a versatile unit for the generation of low molecular weight gelators for water and organic solvents

The use of 11-aminoundecanoic acid as a synthetic building-block allows the systematic preparation of (oligo)amide organogelators-including chiral ones-which display remarkable gelation properties in organic solvents and water.

PHOTOSTATIONARY FLUORESCENCE EMISSION AND TIME RESOLVED SPECTROSCOPY OF SYMMETRICALLY DISUBSTITUTED ANTHRACENES ON THE meso AND SIDE RINGS: THE UNUSUAL BEHAVIOR OF THE 1,4 DERIVATIVE*

Abstract— Steady state and time resolved fluorescence emission properties of symmetrical dialkoxy‐anthracenes (especially substituted on the side rings) 1‐X, Y were studied in methylcylohexane. At room temperature, the fluorescence spectra of 1‐X, Y show bands in the region of 380–550 nm and quantum yields (φF) in the range of 0.2–1. The fluorescence emission decays were found to be single exponential. The determination of the intersystem crossing quantum yields (φisc) for the weakly fluorescent compounds (1–1,5, 1–1,8 and 1–2,3) demonstrates that internal conversion is negligible compared with fluorescence emission and intersystem crossing, as previously observed for other anthracene derivatives. The fluorescence emission efficiency of compounds 1‐X,Y is controlled by the relative mutual positions of the second triplet T2 (whose energy varies significantly with substitution) and the first excited singlet S1 states, respectively. An unusual solvatochromism was found for compound 1–1,4 which has a very weak permanent dipole moment in the ground state. This behavior was assigned to strong changes in the electronic densities between the excited singlet state and the ground state.