Search results for "electron transfer"
showing 10 items of 282 documents
Interligand Electron Transfer Determines Triplet Excited State Electron Injection in RuN3−Sensitized TiO2 Films
2004
Electron injection from the transition metal complex Ru(dcbpy)(2)(NCS)(2) (dcbpy = 2,2'-bipyridine-4,4'-dicarboxylate) into a titanium dioxide nanoparticle film occurs along two pathways. The dominating part of the electron injection proceeds from the initially excited singlet state of the sensitizer into the conduction band of the semiconductor on the sub-hundred-femtosecond time scale. The slower part of the injection occurs from the thermalized triplet excited state on the picosecond time scale in a nonexponential fashion, as was shown in a previous study (Benko, G.; et al. J. Am. Chem. Soc. 2002, 124, 489). Here we show that the slower channel of injection is the result of the excited s…
Carbene-metal complexes as molecular scaffolds for construction of through-space TADF emitters
2021
Through-space charge transfer (CT) process is observed in Cu(I) carbene-metal-amide complexes, where conventional imidazole or imidazoline N-heterocyclic (NHC) carbene fragments act as inert linkers and CT proceeds between a metal-bound carbazole donor and a distantly situated carbene-bound phenylsulfonyl acceptor. The resulting electron transfer gives a rise to efficient thermally activated delayed fluorescence (TADF), characterized with high photoluminescence quantum yields (ΦPL up to 90 %) and radiative rates (kr) up to 3.32×105 s-1. TADF process is aided by fast reverse intersystem crossing (rISC) rates of up to 2.56×107 s-1. Such emitters can be considered as hybrids of two existing TA…
Unprecedented reactivity of a Schiff base ligand in the co-ordination sphere of copper(I) complex towards β-diketones. Synthesis and X-ray characteri…
2002
International audience; The reactions of the copper(I) derivative [CuL(THF)(CH3CN)]PF6 (1), in which L is the di-imine/pyridine ligand 2,6-bis[1-(2,6-diisopropylphenylimino)ethyl]pyridine, with different β-diketones (2,4-pentanedione (acacH), 1,3-diphenyl-1,3-propanedione (dbm)) yielded the new Cu(I) salt [CuL′2]PF6 (2) (L′: 2-[acetyl]-6-[1-(2,6-diisopropylphenylimino)ethyl]pyridine). These reactions of β-diketones with a di-imine/pyridine ligand co-ordinated to a Cu(I) centre constitute the first example of a partial hydrolysis of such a Schiff base within the inner sphere of a Cu centre. Compound 2·acaH has been characterised by X-ray crystallography. © 2002 Elsevier Science B.V. All righ…
Ship-in-a-bottle synthesis of triphenylamine inside faujasite supercages and generation of the triphenylamminium radical ion
2005
Abstract The ship-in-a-bottle synthesis of triphenylamine encapsulated within basic X zeolite has been accomplished by reacting sodium diphenylamide with bromobenzene in the presence of a bifunctional palladium (Hartwig–Buchwald conditions). The presence of incarcerated triphenylamine was demonstrated by dissolving the zeolite with concentrated HF and analyzing the organic material in the dichloromethane extract. Laser flash photolysis (266 nm) gives rise to the generation of triphenylamminium radical cation detected as a transient species decaying in hundreds of microseconds. Upon repetitive cyclic voltammograms, zeolite encapsulated triphenylamine shows a reversible oxidation–reduction pr…
Grand canonical rate theory for electrochemical and electrocatalytic systems I: General formulation and proton-coupled electron transfer reactions
2020
A generally valid rate theory at fixed potentials is developed to treat electrochemical and electrocatalytic potential-dependent electron, proton, and proton-coupled electron reactions. Both classical and quantum reactions in adiabatic and non-adiabatic limits are treated. The applicability and new information obtained from the theory is demonstrated for the gold catalyzed acidic Volmer reaction.
Tailoring oxide properties: An impact on adsorption characteristics of molecules and metals
2014
Abstract Both density functional theory calculations and numerous experimental studies demonstrate a variety of unique features in metal supported oxide films and transition metal doped simple oxides, which are markedly different from their unmodified counterparts. This review highlights, from the computational perspective, recent literature on the properties of the above mentioned surfaces and how they adsorb and activate different species, support metal aggregates, and even catalyse reactions. The adsorption of Au atoms and clusters on metal-supported MgO films are reviewed together with the cluster׳s theoretically predicted ability to activate and dissociate O 2 at the Au–MgO(100)/Ag(100…
Probing light-induced conformational transitions in bacterial photosynthetic reaction centers embedded in trehalose-water amorphous matrices.
2004
Abstract The coupling between electron transfer and protein dynamics has been studied in photosynthetic reaction centers (RC) from Rhodobacter sphaeroides by embedding the protein into room temperature solid trehalose–water matrices. Electron transfer kinetics from the primary quinone acceptor (Q A − ) to the photoxidized donor (P + ) were measured as a function of the duration of photoexcitation from 20 ns (laser flash) to more than 1 min. Decreasing the water content of the matrix down to ≈5×10 3 water molecules per RC causes a reversible four-times acceleration of P + Q A − recombination after the laser pulse. By comparing the broadly distributed kinetics observed under these conditions …
A Voltammetric Analysis of the Electrochemical Behaviour of Onium Salts at a Mercury Electrode
1980
An analysis of the cyclic voltammograms of the reduction of various onium salt at mercury, produced more detailed information concerning the nature of the reaction pathway, in terms of adsorption, amalgam formation and kinetics of electron transfer, and lead to an interpretation of the characteristic “inverted peak”. An “auto-catalytic” reaction mechanism was indicated, and in conjunction with the preparative experiments [1, 2] a full reduction scheme proposed for the sulphonium salt ([Ph2S+ CH3)]CIO−4) and the phosphonium salt ([Ph2P+ (CH3)2]Br−). Die Analyse der Cyclovoltammogramme der reduktiven Spaltung einiger Phosphonium- und Sulfoniumsaize unterrichtet uber die an der Quecksilberkath…
The Quest for Mononuclear Gold(II) and Its Potential Role in Photocatalysis and Drug Action.
2017
The chemistry of gold strongly focuses on the ubiquitous oxidation states +I and +III. The intermediate oxidation state +II is generally avoided in mononuclear gold species. In recent years, gold(II) has been increasingly suggested as a key intermediate in artificial photosynthesis systems, with gold(III) moieties acting as electron acceptors, as well as in gold-catalyzed photoredox catalysis and radical chemistry. This Minireview provides a concise summary of confirmed and characterized mononuclear open-shell gold(II) complexes. Recent findings on structural motifs and reactivity patterns will be discussed. Exciting developments in the fields of photosynthesis, photocatalysis, and potentia…
Entropy-controlled diastereoselectivity in the photocyclization of rigid derivatives of o-allylaniline.
2002
Two rigid derivatives of o-allylaniline, namely 8-allyl-2-phenyl-1,2,3,4-tetrahydroquinoline (1b) and 7-(trans-2-cinnamyl)-2-methylindoline (1c), have been chosen as suitable systems to study the potential stereoselectivity of the photocyclization process. Photolysis of 1b leads to a mixture of diastereomeric lilolidines 4 (trans/cis), while 1cproduces a mixture of 4 (trans/cis) and the tetrahydropyrrolo[3,2,1-hi]indole derivatives 5 (trans/cis). To disclose whether the diastereoselectivity could be entropy dependent, photolysis of 1b and 1c has been performed at several temperatures. In both cases, linear relationships have been observed when ln(k(t)/k(c)) (the relative reaction rate const…