Chromogranin A preferential interaction with Golgi phosphatidic acid induces membrane deformation and contributes to secretory granule biogenesis.

Chromogranin A (CgA) is a key luminal actor of secretory granule biogenesis at the trans-Golgi network (TGN) level but the molecular mechanisms involved remain obscure. Here, we investigated the possibility that CgA acts synergistically with specific membrane lipids to trigger secretory granule formation. We show that CgA preferentially interacts with the anionic glycerophospholipid phosphatidic acid (PA).

Photochemical Bleaching of an Elaborate Artificial Light-Harvesting Antenna.

The target artificial light-harvesting antenna, comprising 21 discrete chromophores arranged in a logical order, undergoes photochemical bleaching when dispersed in a thin plastic film. The lowest-energy component, which has an absorption maximum at 660 nm, bleaches through first-order kinetics at a relatively fast rate. The other components bleach more slowly, in part, because their excited-state lifetimes are rendered relatively short by virtue of fast intramolecular electronic energy transfer to the terminal acceptor.

Expanding the polymethine paradigm: evidence for the contribution of a bis-dipolar electronic structure.

Although it has been reported in a few instances that the spectroscopic properties of cyanine dyes were strongly dependent on the nature of the chemical substitution of their central carbon atom, there has not been to date any systematic study specifically aimed at rationalizing this behavior. In this article, such a systematic study is carried out on an extended family of 17 polymethine dyes carrying different substituents on their central carbon, some of those being specifically synthesized for this study, some of those similar to previously reported compounds, for the sake of comparison. Their absorption properties, which spread over the whole visible to near-infrared spectral range, are seen to be dramatically dependent on the electron-donating character of this central substituent.

An artificial light-harvesting array constructed from multiple Bodipy dyes.

An artificial light-harvesting array, comprising 21 discrete chromophores arranged in a rational manner, has been synthesized and characterized fully. The design strategy follows a convergent approach that leads to a molecular-scale funnel, having an effective chromophore concentration of 0.6 M condensed into ca.

Carbonyl derivatives of boradiazaindacene via catalytic CO insertion.

A methodological study is presented dealing with carbopalladation reactions on BODIPY dyes bearing aryl-halogen functions. Using this technique, several ester and amide groups were efficiently introduced on the dyes. These changes do not affect the optical properties of the dyes and thus allow the construction of new BODIPY-based functional dyes with carboxylic anchoring groups or peptide links.

New insights into the water-solubilisation of fluorophores by post-synthetic "click" and Sonogashira reactions.

New synthetic methodologies for the efficient chemical conversion of hydrophobic fluorescent dyes into bioconjugable and water-soluble derivatives are described. The combined use of an original sulfonated terminal alkyne and a metal-mediated reaction, namely the copper-catalysed Huisgen 1,3-dipolar cycloaddition ("click" reaction) or the Sonogashira cross-coupling, is the cornerstone of these novel post-synthetic sulfonation approaches.

A general synthetic route to 3,5-substituted boron dipyrromethenes: applications and properties.

An efficient protocol for the direct synthesis of 3-substituted and 3,5-disubstituted BODIPY derivatives via electrophilic attack with NBS was developed. Various substituents like ethers, sugar, hydroxyl, thiophene, sulfur, azide, tertiary amines, alkyne, vinyl, or phosphonate groups were obtained in moderate to excellent yields. The amine-substituted derivatives display unusual spectroscopic and electrochemical properties which were analyzed in solution in the presence of HCl.

Upconversion-powered photoelectrochemistry.

Upconversion photochemistry occurring between palladium(II) octaethylporphyrin (PdOEP, 1) and 9,10-diphenylanthracene (DPA, 2) in toluene successfully sensitizes nanostructured WO(3) photoanodes (E(g) = 2.7 eV) to sub-bandgap non-coherent green photons at low power density.

Boron asymmetry in a BODIPY derivative.

A boradiazaindacene (BODIPY) fluorophore with a chirality held on the central boron has been synthesized and the racemate resolved. Dissymetrization of the BODIPY core was obtained by oxidation of the 3-methyl group to the corresponding carboxaldehyde. A hydrogen bond between the aldehyde proton and the fluorine on the boron atom was evidenced by both (1)H NMR and X-ray diffraction.

Borondipyrromethene dyes with pentane-2,4-dione anchors.

New, acetylacetone-linked borondipyrromethene (BODIPY) dyes were readily obtained from BODIPY cores by various protocols involving direct grafting with acetylacetone or cross-coupling from a preorganized phenylacacH derivative bearing either an iodo or an ethynyl function. Facile anchoring on TiO(2) powder is obtained and scrutinized by FT-IR spectroscopy.

Length dependence for intramolecular energy transfer in three- and four-color donor-spacer-acceptor arrays.

A series of donor-spacer-acceptor triads has been synthesized and fully characterized. Both donor and acceptor units are built from boron dipyrromethene (BODIPY) dyes but they differ in their respective conjugation lengths, and thereby offer quite disparate optical properties. The spacer units comprise an oligomer of 1,4-phenylene-diethynylene repeat units and allow the boron-boron separation distance to be varied progressively from 18 to 38 A.

Boron dipyrromethene chromophores: next generation triplet acceptors/annihilators for low power upconversion schemes.

In the present study, the red-light absorbing platinum(II) tetraphenyltetrabenzoporphyrin (PtTPBP) was used as a triplet sensitizer in conjunction with two distinct iodophenyl-bearing BODIPY derivatives independently serving as triplet acceptors/annihilators poised for photon upconversion based on triplet-triplet annihilation. In deaerated benzene solutions, extremely stable and high quantum efficiency green (Phi(UC) = 0.0313 +/- 0.