Mastering the production of solar fuels by artificial photosynthesis would be a considerable feat, either water splitting into hydrogen and oxygen or reduction CO(2) to methanol hydrocarbons: 2H(2)O + 4hnu --> O(2) 2H(2); 8hnu 2O(2) CH(4). It is notable that oxidation dioxygen key half-reaction in both. In principle, these fuel reactions can coupled light absorption molecular assemblies, nanostructured arrays, photoelectrochemical cells (PECs) modular approach. The approach uses absorption,...

Water oxidation is a key reaction in natural photosynthesis and many schemes for artificial photosynthesis. Although metal complexes capable of oxidizing water based on Ru, Mn, Ir are known, significant question whether or not dimeric higher order structures required oxidation. We report here single-site catalytic by the monomeric [Ru(tpy)(bpm)(OH2)]2+ [Ru(tpy)(bpz)(OH2)]2+ (tpy 2,2′:6′,2′′-terpyridine; bpm 2,2′-bipyrimidine; bpz 2,2′-bipyrazine) well-defined mechanism involving RuV═O.

The blue dimer, cis,cis-[(bpy)2(H2O)RuIIIORuIII(H2O)(bpy)2]4+, is the first designed, well-defined molecule known to function as a catalyst for water oxidation. It meets stoichiometric requirements oxidation, 2H2O → −4 e − ,−4 H + O−O, by utilizing proton-coupled electron-transfer (PCET) reactions in which both electrons and protons are transferred. This avoids charge buildup, allowing accumulation of multiple oxidative equivalents at Ru−O−Ru core. PCET pathways involving coupled...

A series of monomeric ruthenium polypyridyl complexes have been synthesized and characterized, their performance as water oxidation catalysts has evaluated. The diversity ligand environments how they influence rates reaction thermodynamics create a platform for catalyst design with controllable reactivity based on variations.

Numerous visible-light absorbing homogeneous photocatalytic compositions are shown to produce copious amounts of hydrogen gas from pure water.

Electrocatalytic water oxidation occurs through the use of phosphonate-derivatized single-site catalyst [Ru(Mebimpy)(4,4'-((HO)(2)OPCH(2))(2)bpy)(OH(2))](2+) [Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; bpy 2,2'-bipyridine] at pH 1 and 5 on fluorine-doped SnO(2) or Sn(IV)-doped In(2)O(3) electrodes nanocrystalline TiO(2). The surface-bound appears to retain mechanism found for [Ru(tpy)(bpm)(OH(2))](2+) [Ru(tpy)(bpz)(OH(2))](2+) (tpy 2,2':6',2''-terpyridine; bpm 2,2'-bipyrimidine;...

Alles in einem bieten die Assoziate aus "Single-Site"-Wasseroxidationskatalysatoren (rot und blau) Redoxvermittlern (grün blau), – sowohl Lösung als auch über Phosphonatlinker an Metalloxidoberflächen gebunden stabile, robuste Katalysatoren für Wasseroxidation wirken. Mehr 28 000 Umsätze wurden mit einer Ladungseffizienz >95 % Sauerstoffproduktion ohne Abnahme der katalytischen Aktivität erreicht.

We report the effects of installing redox-active pyrazines at distinct positions in a series isostructural Co catalysts.

Photocatalytic conversion of CO2 to reduced carbon states using sunlight and an earth-abundant catalyst could provide a critically needed source renewable energy. Very few catalysts have shown CH4 reactivity, significant opportunities exist improve durability. Through the strategic design novel, redox-active bipyridyl- N-heterocyclic carbene macrocyclic ligand complexed with nickel, is converted into energy-rich solar fuel, CH4, photocatalytically photosensitizer in presence water. Up 19 000...

Carbon monoxide (CO) is an emerging gasotransmitter and reactive carbon species with broad anti-inflammatory, cytoprotective, neurotransmitter functions along therapeutic potential for the treatment of cardiovascular diseases. The study CO chemistry in biology medicine relative to other prominent gasotransmitters such as NO H2S remains challenging, large part due limitations available tools direct visualization this transient freely diffusing small molecule complex living systems. Here we...

Light-driven water oxidation occurs in oxygenic photosynthesis photosystem II and provides redox equivalents directed to I, which carbon dioxide is reduced. Water also essential artificial solar fuel-forming reactions, such as splitting into hydrogen oxygen (2 H(2)O + 4 h nu --> O(2) 2 H(2)) or reduction of CO(2) methanol 6 CH(3)OH 3/2 O(2)), hydrocarbons, could provide clean, renewable energy. The "blue ruthenium dimer," cis,cis-[(bpy)(2)(H(2)O)Ru(III)ORu(III)(OH(2))(bpy)(2)](4+), was the...

A structure–activity relationship, revealed through a series of nickel-based CO₂ reduction catalysts, provides insight into the role redox-active macrocycles.

An original series of cobalt complexes bearing redox-active ligands based on bipyridyl-N-heterocyclic carbene donors has been developed for electrocatalytic CO2 reduction in acetonitrile and aqueous solutions. The mechanism was examined by electrochemical methods electronic structure calculations. From controlled potential electrolysis (CPE) CH3CN/2% H2O solutions, 1-Co supported a non-macrocyclic ligand gives Faradaic efficiency (FE) CO2-to-CO conversion 78%, while 2-Co 3-Co tunable...

A series of four electron-deficient-substituted Re(I) pyridyl N-heterocyclic carbene (pyNHC) complexes have been synthesized, and their electrocatalytic reduction CO2 has evaluated by cyclic voltammetry controlled potential electrolysis experiments. All the catalysts were under inert atmosphere compared to known benchmark catalyst Re(bpy)(CO)3Br. Among Re-NHC catalysts, Re(pyNHC-PhCF3)(CO)3Br (2) demonstrated highest catalytic rate (icat/ip)(2) at first second events with a value 4 (TOF =...

A series of rhenium(I) fac-tricarbonyl complexes containing pendent arylamine functionality in the second coordination sphere have been developed and studied as electrocatalysts for carbon dioxide (CO2) reduction. Aniline moieties were appended at 6 position a 2,2′-bipyridine (bpy) donor which primary amine was positioned ortho- (1-Re), meta- (2-Re), para- (3-Re) sites aniline substituent to generate family isomers. The relationship between catalyst structure activity explored across series,...

Abstract Nanosecond laser flash photolysis has been used to investigate injection and back electron transfer from the complex [(Ru(bpy) 2 (4,4′‐(PO 3 H ) bpy)] 2+ surface‐bound TiO ( ‐Ru II ). The measurements were conducted under conditions appropriate for water oxidation catalysis by known single‐site catalysts. Systematic variations in average lifetimes transfer, < τ bet >, observed with changes pH, surface coverage, incident excitation intensity, applied bias. results qualitatively...

Single-electron activation of multielectron catalysis has been shown to be viable in catalytic water oxidation with stepwise proton-coupled electron transfer, leading high-energy precursors. For the blue dimer, cis,cis-[(bpy)2(H2O)RuIIIORuIII(H2O)(bpy)2]4+, first well-defined molecular catalyst for oxidation, 4e−/4H+ occurs give reactive precursor [(O)RuVORuV(O)]4+. This key intermediate is kinetically inaccessible at an unmodified metal oxide surface, where only available redox pathway...

Catalytic O(2) evolution with cis,cis-[(bpy)(2)(H(2)O)Ru(III)ORu(III)(OH(2))(bpy)(2)](4+) (bpy is 2,2-bipyridine), the so-called blue dimer, first designed water oxidation catalyst, was monitored by UV-vis, EPR, and X-ray absorption spectroscopy (XAS) ms time resolution. Two processes were identified, one of which occurs on a scale 100 to few seconds results in catalyst formation an intermediate, here termed [3,4]'. A slower process occurring minutes decay this intermediate evolution....

Anthracene-bridged dinuclear rhenium complexes are reported for electrocatalytic carbon dioxide (CO2) reduction to monoxide (CO). Related by hindered rotation of each active site either side the anthracene bridge, cis and trans conformers have been isolated characterized. Electrochemical studies reveal distinct mechanisms, whereby conformer operates via cooperative bimetallic CO2 activation conversion reduces through well-established single-site bimolecular pathways analogous Re(bpy)(CO)3Cl....

In single site water or hydrocarbon oxidation catalysis with polypyridyl Ru complexes such as [Ru II (Mebimpy)(bpy)(H 2 O)] 2+ [where bpy is 2,2′-bipyridine, and Mebimpy 2,6-bis(1-methylbenzimidazol-2-yl)pyridine] , its surface-bound analog (Mebimpy)(4,4 ′ -bis-methlylenephosphonato-2,2 -bipyridine)(OH )] - PO 3 H accessing the reactive states, V = O 3+ /Ru IV at electrode interface typically rate limiting. The higher states are accessible by proton-coupled electron transfer of aqua...

Nanosecond laser flash photolysis and photocurrent measurements have been used to investigate use of [(Ru(bpy)2(4,4′-(PO3H2)2bpy)]2+ attached TiO2 nanoparticle films, TiO2−RuII, in a dye-sensitized photoelectrosynthesis cell (DSPEC) configuration for H2 production. In these experiments, excitation TiO2−RuII rapid injection lead TiO2(e−)−RuIII with subsequent → back electron transfer monitored on the nsec time scale without added triethanolamine (TEOA) deprotonated ethylenediaminetetraacetic...

L(2,3)-edge X-ray absorption spectroscopy (XAS) has demonstrated unique capabilities for the analysis of electronic structure di-Ru complexes such as blue dimer cis,cis-[Ru(III)(2)O(H(2)O)(2)(bpy)(4)](4+) water oxidation catalyst. Spectra and monomeric [Ru(NH(3))(6)](3+) model complex show considerably different splitting Ru L(2,3) edge, which reflects changes in relative energies 4d orbitals caused by hybridization with a bridging ligand spin-orbit coupling effects. To aid interpretation...

The first designed molecular catalyst for water oxidation is the "blue dimer", cis,cis-[(bpy)(2)(H(2)O)Ru(III)ORu(III)(OH(2))(bpy)(2)](4+). Although there experimental evidence extensive electronic coupling across μ-oxo bridge, results of earlier DFT and CASSCF calculations provide a model with magnetic interactions weak to moderately coupled Ru(III) ions bridge. We present comprehensive investigation, combined calculations. experiments demonstrate both that strong in blue dimer its effects...

Well-defined dinuclear rhenium photocatalysts featuring an anthracene chromophore are significantly faster and more durable than their mononuclear counterparts.

Abstract A series of molecular Mn catalysts featuring aniline groups in the second‐coordination sphere has been developed for electrochemical and photochemical CO 2 reduction. The arylamine moieties were installed at 6 position 2,2’‐bipyridine (bpy) to generate a family isomers which primary amine is located ortho‐ ( 1‐Mn ), meta‐ 2‐Mn or para‐ site 3‐Mn ) ring. proximity second‐sphere functionality active critical factor determining catalytic performance. Catalyst , possessing shortest...