Search results for "transfer"

The first example of cofacial bis(dipyrrins)

2016

International audience; Two series of cofacial bis(dipyrrins) were prepared and their photophysical properties as well as their bimolecular fluorescence quenching with C-60 were investigated. DFT and TDDFT computations were also performed as a modeling tool to address the nature of the fluorescence state and the possible inter-chromophore interactions. Clearly, there is no evidence for such interactions and the bimolecular quenching of fluorescence, in comparison with mono-dipyrrins, indicates that C-60-bis(dipyrrin) contacts occur from the outside of the "mouth" of the cofacial structure.

Gold(II) Porphyrins in Photoinduced Electron Transfer Reactions

2019

Chemistry - a European journal 25(23), 5940 - 5949 (2019). doi:10.1002/chem.201900050

Cover Picture: Dynamic Chemical Devices: Photoinduced Electron Transfer and Its Ion-Triggered Switching in Nanomechanical Butterfly-Type Bis(porphyri…

2006

Synthesis of an Acceptor–Donor–Acceptor Multichromophore Consisting of Terrylene and Perylene Diimides for Multistep Energy Transfer Studies

2016

Motivated by the results obtained from the investigation of singlet–singlet annihilation in a linear multichromophore comprising terrylene diimides (TDI) and perylene diimide (PDI) in 2010, we report the detailed process toward the successful synthesis of a TDI–PDI–TDI dyad. Ineffective synthetic pathways, which were necessary for the understanding of the step-by-step construction of the complex multichromophore, are described, leading toward a universal synthetic plan for multicomponent systems containing rylene diimides separated by rigid oligophenylene spacers.

TiO2 Nanoparticles Functionalized with Non-innocent Ligands Allow Oxidative Photocyanation of Amines with Visible/Near-Infrared Photons

2018

Photosynthesis is an efficient mechanism for converting solar light energy into chemical energy. We report on a strategy for the aerobic photocyanation of tertiary amines with visible and near-infrared (NIR) light. Panchromatic sensitization was achieved by functionalizing TiO2 with a 2-methylisoquinolinium chromophore, which captures essential features of the extended π-system of 2,7-diazapyrenium (DAP2+) dications or graphitic carbon nitride. Two phenolic hydroxy groups make this ligand highly redox-active and allow for efficient surface binding and enhanced electron transfer to the TiO2 surface. Non-innocent ligands have energetically accessible levels that allow redox reactions to chang…

Cis- and trans molybdenum oxo complexes of a prochiral tetradentate aminophenolate ligand : Synthesis, characterization and oxotransfer activity

2020

Abstract Reaction of [MoO2Cl2(dmso)2] with the tetradentate O2N2 donor ligand papy [H2papy = N-(2-hydroxybenzyl)-N-(2-picolyl)glycine] leads to formation of the dioxomolybdenum(VI) complex [MoO2(papy)] (1) as a mixture of cis and trans isomers. Recrystallization from methanol furnishes solid cis-1, whereas the use of a dichloromethane-hexane mixture allows for the isolation of the trans-1 isomer. Both isomers have been structurally characterized by X-ray crystallography and the energy difference between the isomeric pair has been investigated by electronic structure calculations. Optimization of two configurational isomers in the gas phase predicts the trans isomer to lie 2.5 kcal/mol lower…

Fluorescence Quenching in BODIPYs Having Ir‐ and Rh‐Tethered Complexes

2016

The effect of Rh- and Ir-centers on the optical properties of the BODIPY core has been studied. To this end, novel metal complexes tethered to BODIPY have been prepared through an easy and versatile procedure using N-directed C–H activation reactions. The organometallic moiety has a tremendous influence on the emissive properties of the BODIPY fragment. A photoinduced electron transfer (PET) mechanism is suggested to be the main mechanism responsible for the suppression of the BODIPY fluorescence emission in the newly formed dyads. The efficiency of the PET depends on both the distance between the chromophores in the dyad and the nature of the transition metal (Rh vs. Ir).

The photochemistry of mono- and dinuclear cyclometalated bis(tridentate)ruthenium(ii) complexes: dual excited state deactivation and dual emission

2016

The synthesis and characterization of a series of weakly emissive mononuclear cyclometalated [Ru(dpb-R)(tpy)](+) complexes with functional groups R of varying electron-donating characters at the dpb ligand are described (dpbH = 1,3-di(2-pyridyl)benzene, tpy = 2,2';6',2''-terpyridine, 1(+): R = NHCOMe, 2(+): R = NH2, 3(+): R = COOEt, 4(+): R = COOH). Steady-state emission spectroscopy in the temperature range between 298 K and 77 K revealed a previously unrecognized excited state deactivation pathway via low-lying triplet ligand-to-ligand ((3)LL'CT) charge transfer states in addition to the well-known pathway via(3)MC states. Thermal activation barriers for depopulation of the emissive metal…

How Many Phosphoric Acid Units Are Required to Ensure Uniform Occlusion of Sterically Stabilized Nanoparticles within Calcite?

2019

Polymerization-induced self-assembly (PISA) mediated by reversible addition-fragmentation chain transfer (RAFT) polymerization offers a platform technology for the efficient and versatile synthesis of well-defined sterically stabilized block copolymer nanoparticles. Herein we synthesize a series of such nanoparticles with tunable anionic charge density within the stabilizer chains, which are prepared via statistical copolymerization of anionic 2-(phosphonooxy)ethyl methacrylate (P) with non-ionic glycerol monomethacrylate (G). Systematic variation of the P/G molar ratio enables elucidation of the minimum number of phosphate groups per copolymer chain required to promote nanoparticle occlusi…

Cobaltocenium substituents as electron acceptors in photosynthetic model dyads

2017

Abstract Cobaltocenium carboxylic acid hexafluorophosphate has been attached to a zinc(II) meso-tetraphenyl porphyrin chromophore via an amide linkage. Optical and electrochemical studies reveal that the metallocene and the porphyrin interact only negligibly in the ground state of the dyad. Photoinduced charge-shift from the zinc porphyrin to the cobaltocenium substituent to give the zinc porphyrin radical cation and the cobaltocene occurs upon exciting the porphyrin with light. Steady state emission, time-resolved fluorescence and transient absorption pump–probe spectroscopy in addition to density functional theory calculations suggest that the charge shift to the cobaltocenium substituent…