Heteroleptic diimine copper(i) complexes with large extinction coefficients: synthesis, quantum chemistry calculations and physico-chemical properties.

International audience: Using the HETPHEN approach, five new heteroleptic copper(i) complexes composed of a push-pull 4,4'-styryl-6,6'-dimethyl-2,2'-bipyridine ligand and a bulky bis[(2-diphenylphosphino)phenyl]-ether (DPEphos) or a bis2,9-mesityl phenanthroline (Mes2Phen) were prepared and characterized by electronic absorption spectroscopy, electrochemistry, and TD-DFT calculations. These complexes exhibit very intense absorption bands in the visible region with extinction coefficient in the range of 5-7 × 10(4) M(-1) cm(-1). The analysis of the position, intensity and band shape indicates a strong contribution from an intra-ligand charge-transfer transition centered on the styrylbipyridine ligand along with MLCT transitions. These new complexes experimentally demonstrate that good light harvesting properties with bis-diimine copper(i) complexes are a reality if one chooses suitable ligands in the coordination sphere. This constitutes a milestone towards using bis-diimine copper(i) complexes for solar energy conversion (artificial photosynthesis and solar cells)

Comparative ultrafast spectroscopy and structural analysis of OCP1 and OCP2 from Tolypothrix.

The orange carotenoid protein (OCP) is a structurally and functionally modular photoactive protein involved in cyanobacterial photoprotection. Recently, based on bioinformatic analysis and phylogenetic relationships, new families of OCP have been described, OCP2 and OCPx. The first characterization of the OCP2 showed both faster photoconversion and back-conversion, and lower fluorescence quenching of phycobilisomes relative to the well-characterized OCP1. Moreover, OCP2 is not regulated by the fluorescence recovery protein (FRP). In this work, we present a comprehensive study combining ultrafast spectroscopy and structural analysis to compare the photoactivation mechanisms of OCP1 and OCP2 from Tolypothrix PCC 7601. We show that despite significant differences in their functional characteristics, the spectroscopic properties of OCP1 and OCP2 are comparable. This indicates that the OCP functionality is not directly related to the spectroscopic properties of the bound carotenoid. In addition, the structural analysis by X-ray footprinting reveals that, overall, OCP1 and OCP2 have grossly the same photoactivation mechanism. However, the OCP2 is less reactive to radiolytic labeling, suggesting that the protein is less flexible than OCP1. This observation could explain fast photoconversion of OCP2

Photoreactions of a Ru(II)complex in presence of amino acids anchored to DNA

info:eu-repo/semantics/nonPublishe

New metal complexes as promising materials for electronic and optoelectronic applications

info:eu-repo/semantics/nonPublishe

Photo-electron transfer between a Ru(II)-TAP complex and trytophan: a DNA duplex assisted photoreaction

info:eu-repo/semantics/nonPublishe

Synthesis and photophysical studies of mononuclear complexes based on Rh(III) and Ir(III) Metal Centers incorporating a dipyrromethene derivative

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Mechanism and application of the photoaddition reaction of two tryptophan residues on a Ru-TAP complex

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Study of photoreactions between a Ru(II)-TAP complex and tryptophan by using a duplex template

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Broadband femtosecond spectroscopic ellipsometry

We present a setup for time-resolved spectroscopic ellipsometry in a pump–probe scheme using femtosecond laser pulses. As a probe, the system deploys supercontinuum white light pulses that are delayed with respect to single-wavelength pump pulses. A polarizer–sample–compensator–analyzer configuration allows ellipsometric measurements by scanning the compensator azimuthal angle. The transient ellipsometric parameters are obtained from a series of reflectance-difference spectra that are measured for various pump–probe delays and polarization (compensator) settings. The setup is capable of performing time-resolved spectroscopic ellipsometry from the near-infrared through the visible to the near-ultraviolet spectral range at 1.3 eV–3.6 eV. The temporal resolution is on the order of 100 fs within a delay range of more than 5 ns. We analyze and discuss critical aspects such as fluctuations of the probe pulses and imperfections of the polarization optics and present strategies deployed for circumventing related issues. Funding: project "Advanced research using high intensity laser produced photons and particles" (ADONIS) from the European Regional Development Fund [CZ.02.1.01/0.0/0.0/16_019/0000789]; project "Structural dynamics of biomolecular systems" (ELIBIO) from the Europea</p

Photoinduced electron transfer from tryptophan to Ru(II)TAP complexes: the primary process for photo-cross-linking with oligopeptides.

The photoreaction mechanism of [Ru(TAP)(2)(phen)](2+) and [Ru(TAP)(3)](2+) (TAP = 1,4,5,8-tetraazaphenanthrene) with tryptophan (Trp), N-acetyl-Trp, and Lys-Trp-Lys is examined. The existence of a photoelectron-transfer process from the amino acid unit is demonstrated by laser flash photolysis experiments. The back electron transfer (BET) from the reduced complex to the oxidized amino acid, occurring at the microsecond time scale, corresponds approximately to an equimolecular-bimolecular process; however, it is disturbed by another reaction, originating from the oxidized Trp. Moreover, in competition with the BET, the reduced and oxidized intermediates give rise to an adduct. The latter is clearly detected by gel electrophoresis experiments in denaturing conditions, with a system composed of an oligonucleotide derivatized at the 3' end by the Ru(II)TAP complex and hybridized with the complementary sequence functionalized at the 5' end by the tripeptide Lys-Trp-Lys. Thus, upon illumination, a cross-linking between the two strands is observed, which originates from the presence of a Trp residue.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe