Rachel Méallet-Renault

Designing dye-nanochannel antenna hybrid materials for light harvesting, transport and trapping.

We discuss artificial photonic antenna systems that are built by incorporating chromophores into one-dimensional nanochannel materials and by organizing the latter in specific ways. Zeolite L (ZL) is an excellent host for the supramolecular organization of different kinds of molecules and complexes. The range of possibilities for filling its one-dimensional channels with suitable guests has been shown to be much larger than one might expect. Geometrical constraints imposed by the host structure lead to supramolecular organization of the guests in the channels. The arrangement of dyes inside the ZL channels is what we call the first stage of organization. It allows light harvesting within the volume of a dye-loaded ZL crystal and also the radiationless transport of energy to either the channel ends or center. One-dimensional FRET transport can be realized in these guest-host materials. The second stage of organization is realized by coupling either an external acceptor or donor stopcock fluorophore at the ends of the ZL channels, which can then trap or inject electronic excitation energy. The third stage of organization is obtained by interfacing the material to an external device via a stopcock intermediate. A possibility to achieve higher levels of organization is by controlled assembly of the host into ordered structures and preparation of monodirectional materials. The usually strong light scattering of ZL can be suppressed by refractive-index matching and avoidance of microphase separation in hybrid polymer/dye-ZL materials. The concepts are illustrated and discussed in detail on a bidirectional dye antenna system. Experimental results of two materials with a donor-to-acceptor ratio of 33:1 and 52:1, respectively, and a three-dye system illustrate the validity and challenges of this approach for synthesizing dye-nanochannel hybrid materials for light harvesting, transport, and trapping.

New on-bead near-infrared fluorophores and fluorescent sensor constructs.

The facile synthesis and photophysical characterization of new on-bead fluorophores and fluorescent sensors are described. The unique covalent immobilization strategy results in highly fluorescent beads with sharp emission profiles between 650 and 800 nm. Illustrative examples include imaging in an aqueous cellular environment and adaptation to include off/on sensing functionality, proven by a prototypical detection of gaseous HCl.

Time- and Space-Resolved Luminescence of a Photonic Dye–Zeolite Antenna

In a radiationless process, electronic excitation energy can be transported in the photonic antennae presented herein from the borders to the center of cylindrical zeolite L crystals (ca. 2 μm). These antennae are formed by supramolecular organization of a cationic and a neutral dye in the parallel channels of the crystal. The rectangles symbolize adsorption sites, for which the red ones are filled with red-emitting dyes and blue ones with blue-emitting dyes.

General Route to Symmetric and Asymmetric meso-CF3-3(5)-Aryl(hetaryl)- and 3,5-Diaryl(dihetaryl)-BODIPY Dyes

A general efficient route to hitherto inaccessible symmetric and asymmetric meso-CF(3)-BODIPY dyes has been developed. The key stages include the reduction of available 2-trifluoroacetylpyrroles to the corresponding alcohols which are further condensed with pyrroles. The method allows the BODIPY with 3(5)aryl(hetaryl) and 3,5-diaryl(hetaryl) substituents to be readily assembled. The BODIPY dyes synthesized fluoresce (Φ(f) = 0.56-1.00) in the 560-680 nm region.

Synthesis and Optical Properties of 2-(Benzo[b]thiophene-3-yl)pyrroles and a New BODIPY Fluorophore (BODIPY = 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene)

2-(Benzo[b]thiophene-3-yl)-1-vinylpyrrole has been synthesized directly from 3-acetylbenzo[b]thiophene oxime and acetylene (flow system, KOH-DMSO, 120 degrees C, 5 h) in 68% yield. Devinylation of the synthesized pyrrole (Hg(OAc)(2), NaBH(4), 50 degrees C) led to the corresponding 2-(benzo[b]thiophene-3-yl)pyrrole in 63% yield. Trifluoroacetylation of both the pyrroles with trifluoroacetic anhydride (80 degrees C, 1 h) gave the corresponding 5-trifluoroacetyl pyrroles in 97% and 76% yields, respectively. 2-(Benzo[b]thiophene-3-yl)pyrrole was reacted subsequently with mesityl aldehyde, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and BF(3)OEt(2) to afford 4,4-difluoro-3,5-di(benzo[b]thiophene-3-yl)-8-mesityl-4-bora-3a,4a-diaza-s-indacene, a representative of the novel BODIPY fluorophore family (BODIPY = 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene), in 34% overall yield. The synthesized pyrroles exhibit promising optical properties (absorption and emission spectra, nonlinear optical (NLO) features), superior to existing analogues. The BODIPY fluorophore displays an intense red-shifted fluorescence emission in CH(2)Cl(2) (625 nm, 0.84 fluorescence quantum yield) that is fully preserved in the solid state.

Fluorescence microscopy coupled to electrochemistry : a powerful tool for the controlled electrochemical switch of fluorescent molecules

The first-time coupling of fluorescence microscopy with a three-electrode electrochemical cell is described and applied to the investigation of a controlled-potential redox switch of organic fluorophores such as tetrazine derivatives.

Polypyridyl ruthenium complexes as coating agent for the formation of gold and silver nanocomposites in different media. Preliminary luminescence and electrochemical studies

Three polypyridyl ruthenium complexes, [(phen)2Ru(2,2′-p-phenylene-bis(imidazo[4,5-f][1,10])phenanthroline)](X)2 (1·X2), [(phen)2Ru((4-pyridine)oxazo[4,5-f][1,10]phenanthroline)](X)2 (2·X2) and [(phen)2Ru((3-thiophene)imidazo[4,5-f][1,10]phenanthroline)](X)2 (3·X2), X− = PF6− or Cl−, have been used to functionalize and stabilize gold and silver nanoparticles in aqueous and non aqueous (acetonitrile) media. Direct interaction between the metallic nanoparticles and the ruthenium complexes was ensured by bidentate chelating phenanthroline (1), monodentate pyridine (2) or monodentate thiophene (3) groups. The influence of several parameters was studied in order to control the size, shape and stability of the nanocomposites thus formed: the nature of the metallic nanoparticles, the nature of the coating ruthenium complex, the ratio R = [Mn+]/[Ru2+] (M = Ag or Au) and the solvent. The colloidal solutions have been characterized by UV-Vis spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Preliminary electrochemical and luminescence measurements have shown the influence of the metallic nanoparticle on the properties of the ruthenium complexes.

Incorporation Of Water-Soluble Porphyrins In Sol-Gel Matrices And Application To pH Sensing

Abstract The incorporation of H 2 TPPS 4− into sol–gel materials has been used to determine the pH inside a sol–gel matrix.

Electrochemical, linear optical, and nonlinear optical properties and interpretation by density functional theory calculations of (4-N,N-dimethylaminostyryl)-pyridinium pendant group associated with polypyridinic ligands and respective multifunctional metal complexes (Ru(II) or Zn(II)).

The synthesis, linear optical and nonlinear optical properties, as well as the electrochemical behavior of a series of pro-ligands containing the 4-(4-N,N-dimethylaminostyryl)-1-methyl pyridinium (DASP(+)) group as a push-pull moiety covalently linked to terpyridine or bipyridine as chelating ligands are reported in this full paper. The corresponding multifunctional Ru(II) and Zn(II) complexes were prepared and investigated. The structural, electronic, and optical properties of the pro-ligands and the ruthenium complexes were investigated using density functional theory (DFT) and time-dependent (TD) DFT calculations. A fairly good agreement was observed between the experimental and the calculated electronic spectra of the pro-ligands and their corresponding ruthenium complexes. A quenching of luminescence was evidenced in all ruthenium complexes compared with the free pro-ligands but even the terpyridine-functionalized metal complexes exhibited detectable luminescence at room temperature. Second order nonlinear optical (NLO) measurements were performed by Harmonic Light Scattering and the contribution of the DASP(+) moieties (and their relative ordering) and the metal-polypyridyl core need to be considered to explain the nonlinear optical properties of the metal complexes.

Scanning-less wide-field single-photon counting device for fluorescence intensity, lifetime and time-resolved anisotropy imaging microscopy.

A scanning‐less single‐photon counting system for FLIM and fluorescence anisotropy wide‐field imaging is described and characterized in this paper. The two polarizations of the fluorescence are divided by a Glan prism and acquired at the same time by the QA detector. Fluorescence decay profiles can be reconstructed for any desired area up to each pixel and used to calculate time‐resolved fluorescence anisotropy decays.