Not only surprisingly facile, a hydrosilylation of pyridines under the catalysis [Cp(iPr3P)Ru(NCCH3)2]+ has advantages that it is 1,4-regioselective and reversible. The products can be transformed in variety ways (see scheme). related complex [CpRu(NCCH3)3]+ catalyzes two-hydrogen-atom reduction phenanthroline by HSiMe2Ph/water.

Reduction of the cationic Ge(II) complex [dimpyrGeCl][GeCl3] (dimpyr=2,6-(ArN=CMe)2NC5H3, Ar=2,6-iPr2C6H3) with potassium graphite in benzene affords an air sensitive, dark green compound Ge(0), [dimpyrGe], which is stabilized by a bis(imino)pyridine platform. This first example zero-valent Group 14 element that does not contain carbene or carbenoid ligand. species has singlet ground state. DFT studies revealed partial delocalization one Ge lone pairs over π*(C=N) orbitals imines. results...

The most severe problems for adoption of LiMn2O4 (LMO) as a low-cost and sustainable cathode in lithium-ion batteries are manganese dissolution structural degradation, especially at an elevated temperature. Developing large single crystals (SCs) LMO could be feasible solution since it significantly reduces electrode/electrolyte interfaces where degradation can occur, while exceptionally high ionic diffusivity its spinel structure guarantee decent kinetics. In this work, we discovered unique...

Unsymmetrical POC(H)N-type pincer ligands react with NiBr2(NCMe)x to give the complexes (POCN)NiIIBr (POCN= κP,κC,κN-{2-(i-Pr2PO),6-(NR2CH2)-C6H3}; NR2= 3-morpholino (3a), NMe2 (3b), and NEt2 (3c)). The presence of an added base such as NEt3 in these metalation reactions maximizes yields target by suppressing formation side-products arising from protonation ligand situ-generated HBr. cyclic voltammograms 3 exhibit a quasi-reversible, one-electron oxidation at ca. +1.0 V, addition...

The directionality of electron transfer in Photosystem I (PS I) is investigated using site-directed mutations the phylloquinone (QK) and FX binding regions Synnechocystis sp. PCC 6803. kinetics forward from secondary acceptor A1 (phylloquinone) were measured mutants time-resolved optical difference spectroscopy transient EPR spectroscopy. In whole cells PS complexes wild-type both techniques reveal a major, slow kinetic component τ ≈ 300 ns while data resolve an additional minor 10 ns. Whole...

The X-ray crystal structure of photosystem I (PS I) depicts six chlorophyll a molecules (in three pairs), two phylloquinones, and [4Fe-4S] cluster arranged in pseudo C2-symmetric branches that diverge at the P700 special pair reconverge interpolypeptide FX cluster. At present, there is agreement light-induced electron transfer proceeds via PsaA branch, but conflicting evidence whether, to what extent, PsaB branch active. This problem addressed cyanobacterial PS by changing Met688PsaA...

Photosystem I has two branches of cofactors down which light-driven electron transfer (ET) could potentially proceed, each consisting a pair chlorophylls (Chls) and phylloquinone (PhQ). Forward ET from PhQ to the next cofactor (F X ) is described by kinetic components with decay times ≈20 ≈200 ns, have been proposed represent B A , respectively. Immediately preceding quinone Chl (ec3), receives H-bond nearby tyrosine. To decrease reduction potential these Chls, thus modify relative yield...

Light-induced electron transfer is investigated in a ferrocene-aluminum(III) porphyrin-fullerene supramolecular triad (FcAlPorC(60)) and the constituent dyads (AlPorC(60) FcAlPorPh). The fullerene unit (C(60)) bound axially to aluminum(III) porphyrin (AlPor) via benzoate spacer, ferrocene (Fc) attached an amide linkage one of four phenyl groups meso positions ring. absorption spectra voltammetry data complexes suggest that ground state electronic structures Fc, AlPor, C(60) entities are not...

Abstract Reduction of the cationic Ge II complex [dimpyrGeCl][GeCl 3 ] (dimpyr=2,6‐(ArN=CMe) 2 NC 5 H 3, Ar=2,6‐ i Pr C 6 ) with potassium graphite in benzene affords an air sensitive, dark green compound 0 , [dimpyrGe], which is stabilized by a bis(imino)pyridine platform. This first example zero‐valent Group 14 element that does not contain carbene or carbenoid ligand. species has singlet ground state. DFT studies revealed partial delocalization one lone pairs over π*(CN) orbitals imines....

Abstract Two self‐assembled supramolecular donor–acceptor triads consisting of Al III porphyrin (AlPor) with axially bound naphthalenediimide (NDI) as an acceptor and tetrathiafulvalene (TTF) a secondary donor are reported. In the triads, NDI TTF units attached to on opposite faces porphyrin, through covalent coordination bonds, respectively. Fluorescence studies show that lowest excited singlet state is quenched electron transfer hole TTF. dichloromethane dominates, whereas in benzonitrile...

In supramolecular reaction center models, the lifetime of charge-separated state depends on many factors. However, little attention has been paid to redox potential species that lie between donor and acceptor in final charge separated state. Here, we report a series self-assembled aluminum porphyrin-based triads provide unique opportunity study influence porphyrin independently other The triads, BTMPA-Im→AlPorFn-Ph-C60 (n = 0, 3, 5), were constructed by linking fullerene (C60)...

A change in the sign of ground-state electron spin polarization (ESP) is reported complexes where an organic radical (nitronylnitroxide, NN) covalently attached to a donor-acceptor chromophore via two different meta-phenylene bridges (bpy)Pt(CAT-m-Ph-NN) (mPh-Pt) and (bpy)Pt(CAT-6-Me-m-Ph-NN) (6-Me-mPh-Pt) (bpy = 5,5'-di-tert-butyl-2,2'-bipyridine, CAT 3-tert-butylcatecholate, m-Ph meta-phenylene). These molecules represent new class chromophores that can be photoexcited with visible light...

Photoinduced electron spin polarization (ESP) is reported in the electronic ground states of three Pt(II) complexes comprised two S = 1/2 nitronyl nitroxide (NN) radicals attached through different length para-phenylethynyl bridges to 3,6 positions a catecholate (CAT, donor) and 4,4′-di-tert-butyl-2,2′-bipyridine (bpy, acceptor). Complexes 1–3 have from 17 41 bonds separating NN display cw-EPR spectra consistent with |JNN-NN| ≫ |aN|, ≥ < respectively, where JNN-NN magnetic exchange coupling...

Light-induced spin polarization can be produced in chromophore-radical conjugates by reversible transitions between the excited trip-doublet and trip-quartet states. The precise origin of this is often difficult to elucidate because different transition pathways, promoted interactions, occur depending on nature conjugate. Moreover, complexity expressions describing evolution state populations generated these makes it estimate dependence factors such as exchange interaction spin–orbit...

Transient electron paramagnetic resonance (TREPR) spectroscopy has been used to probe photoinduced spin polarization in the recovered ground states of four radical-elaborated (CAT)Pt(bpy) donor-acceptor complexes (CAT = catechol; bpy 4,4′-di-tert-butyl-2,2′-bipyridine). These are comprised one or two S 1/2 nitronyl nitroxide radicals attached through different phenylethynyl bridges 3- 3,6 positions CAT donor. In this study, we demonstrate effects substitution patterns on magnitude TREPR...

The time dependence of the light-induced spin polarization a series porphyrins is reported. contain central elements from three distinct groups in Periodic Table with different oxidation states, types, and numbers axial ligands, as well peripheral substituents on porphyrin ring. Shortly after photoexcitation, all cases, primary multiplet triplet state evolves into long-lived net whose lifetime determined by state. zero-field splitting parameters sign vary significantly among porphyrins, but...

Interruption of the <i>menA</i>or <i>menB</i> gene in <i>Synechocystis</i> sp. PCC 6803 results incorporation a foreign quinone, termed Q, into A₁ site photosystem I with number experimental indicators identifying Q as plastoquinone-9. A global multiexponential analysis time-resolved optical spectra blue region shows following three kinetic components: 1) 3-ms lifetime absence methyl viologen that represents charge recombination between P700⁺ and an FeS⁻...

The Photosystem I (PS I) reaction center contains two branches of nearly symmetric cofactors bound to the PsaA and PsaB heterodimer. From x-ray crystal structure it is known that Trp697PsaA Trp677PsaB are π-stacked with head group phylloquinones H-bonded Ser692PsaA Ser672PsaB, whereas Arg694PsaA Arg674PsaB involved in a network side groups connects binding environments FX. mutants W697FPsaA, W677FPsaB, S692CPsaA, S672CPsaB, R694APsaA, R674APsaB were constructed characterized. All grew...

Electron paramagnetic resonance (EPR) and electron-nuclear double studies of the photosystem (PS) I quinone acceptor, A₁, in phylloquinone biosynthetic pathway mutants are described. Room temperature continuous wave EPR measurements at X-band whole cells <i>menA</i> and<i>menB</i> interruption show a transient reduction oxidation an organic radical with <i>g</i>-value anisotropy characteristic quinone. In PS complexes, spectrum photoaccumulated Q⁻radical, measured...

Nicht nur überraschend einfach, sondern zudem 1,4-regioselektiv und reversibel verläuft die Hydrosilylierung von Pyridinen mit [Cp(iPr3P)Ru(NCCH3)2]+ (Cp=Cyclopentadienyl) als Katalysator. Die Produkte können auf vielfältige Art weiter umgesetzt werden (siehe Schema). Der verwandte Komplex [CpRu(NCCH3)3]+ katalysiert Reduktion Phenanthrolin durch HSiMe2Ph/Wasser, bei der zwei H-Atome übertragen werden.

The electrolytic and chemical oxidation of the dimeric pincer complex [κP,κC,κN,μN-(2,6-(i-Pr2POC6H3CH2NBn)Ni]2 (1; Bn = CH2Ph) has been investigated by various analytic techniques. Cyclic voltammetry measurements have shown that 1 undergoes a quasi-reversible, one electron, Ni-based redox process (ΔE01/2 −0.07 V vs Cp2Fe/[Cp2Fe]+), spectroelectrochemical conducted on product oxidation, [1]+•, multiple low-energy electronic transitions in range 10000−15000 cm−1. Computational studies using...

The ability of PPors to photo-oxidize Ir(III)Cp* Ir(IV)Cp* indicates that they are promising photoanode components.