Cobinamide production of hydrogen in a homogeneous aqueous photochemical system, and assembly and photoreduction in a (βα)8 protein

Robertson, Wesley D.; Bovell, Adonis M.; Warncke, Kurt

doi:10.1007/s00775-013-1015-3

Cited by 12 publications

(3 citation statements)

References 86 publications

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“…where R is the ideal gas constant, T is the temperature, and ΔG is given by eq 3. 26 The free energy term (ΔG ‡ ) accounts for the reorganization energy of (PS*,Q) to (PS + ,Q − ) and the solvent reorganization required for electron transfer (ΔG r ).…”

Section: Photophysical Propertiesmentioning

confidence: 99%

Two-Coordinate Coinage Metal Complexes as Solar Photosensitizers

et al. 2023

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Generating sustainable fuel from sunlight plays an important role in meeting the energy demands of the modern age. Herein, we report two-coordinate carbene-metal-amide (cMa, M = Cu(I) and Au(I)) complexes that can be used as sensitizers to promote the light-driven reduction of water to hydrogen. The cMa complexes studied here absorb visible photons (εvis > 103 M–1 cm–1), maintain long excited-state lifetimes (τ ∼ 0.2–1 μs), and perform stable photoinduced charge transfer to a target substrate with high photoreducing potential (E +/* up to −2.33 V vs Fc+/0 based on a Rehm–Weller analysis). We pair these coinage metal complexes with a cobalt–glyoxime electrocatalyst to photocatalytically generate hydrogen and compare the performance of the copper- and gold-based cMa complexes. We also find that the two-coordinate complexes herein can perform photodriven hydrogen production from water without the addition of the cobalt–glyoxime electrocatalyst. In this “catalyst-free” system, the cMa sensitizer partially decomposes to give metal nanoparticles that catalyze water reduction. This work identifies two-coordinate coinage metal complexes as promising abundant metal, solar fuel photosensitizers that offer exceptional tunability and photoredox properties.

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Section: Photophysical Propertiesmentioning

confidence: 99%

Two-Coordinate Coinage Metal Complexes as Solar Photosensitizers

et al. 2023

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“…115,116 To demonstrate the viability of cMa complexes as solar photosensitizers, hydrogen evolution reactions (HER) were carried out the using a well-established electrocatalyst for water reduction, Co(dmgH)2pyCl (CAT). [117][118][119][120][121] Two reduction events at -1.0 V and -1.7 V vs. Fc +/0 in https://doi.org/10.26434/chemrxiv-2023-6rvrn ORCID: https://orcid.org/0000-0002-7764-4096 Content not peer-reviewed by ChemRxiv. License: CC BY-NC 4.0…”

Section: Cma Complexes As Sensitizers For Photoelectrochemical Reactionsmentioning

confidence: 99%

Two coordinate, monovalent copper complexes as chromophores and luminophores

Schaab,

Djurovich,

Thompson

2023

Preprint

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Two-coordinate Cu(I) complexes have recently emerged as promising luminescent materials for optoelectronic and photocatalytic applications. The complexes have a carbene-metal-amide (cMa) structure where an N-heterocyclic carbene ligand acts as an electron acceptor and the amide ligand serves as an electron donor. The donor-metal-acceptor motif leads to strong interligand charge transfer (ICT) absorption and emission transitions in the cMa complexes. The energy of the ICT transition is determined by the ionization potential of the amide and electron affinity of the carbene and can be varied over the entire visible spectrum by proper choice of the ligands. The highly efficient luminescence is characterized as thermally activated delayed fluorescence (TADF). Emission lifetimes are fast, typically in the 1-2 microsecond range, that are facilitated by strong spin-orbit coupling of the metal center which promotes rapid intersystem crossing between the lowest singlet and triplet states. The complexes have large permanent dipole moments in the ground state that reverse direction in the excited state. This change dipole orientation upon excitation leads to strong negative solvatochromism with increasing solvent polarity in absorption and emission. The radiative rate for the complexes is determined by the extent of overlap between the valence orbitals on the ligands mediated by the small contributions from the metal center. The radiative rate is also correlated to the distance separating the hole and electron in the excited state. The cMa complexes have been employed as luminescent dopants in organic light emitting diodes (OLEDs). OLEDs fabricated using the cMa complexes are highly efficient devices that rival the performance of devices that use precious metal phosphorescent dopants. The cMa complexes have also been used as photosensitizers to catalytically produce H2.

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“…The change of absorption was measured at 387 and 462 nm. The reaction rates were calculated using the differences of the extinction coefficients, ⌬⑀ 387 nm(MeCbi-Cbi) ϭ Ϫ17,410 M Ϫ1 cm Ϫ1 and ⌬⑀ 465 nm(MeCbi-Cbi) ϭ 7,840 M Ϫ1 cm Ϫ1 , which were calculated from spectra of Robertson et al (58). The reaction was set up inside the glove box as follows: 0.1 M HEPES, pH 7.2, 50 M MeCbi, and 300 M Ti(III)citrate were placed in a screw cap cuvette; the ACS incubation mixture (see ACS reconstitution) was then added to yield a final concentration of 2 M ACS.…”

Section: Analysis Of Complex Formation Behavior Between Acs and Acsf mentioning

confidence: 99%

AcsF Catalyzes the ATP-dependent Insertion of Nickel into the Ni,Ni-[4Fe4S] Cluster of Acetyl-CoA Synthase

Gregg

Goetzl

Jeoung

et al. 2016

Journal of Biological Chemistry

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Acetyl-CoA synthase (ACS) catalyzes the reversible condensation of CO, CoA, and a methyl-cation to form acetyl-CoA at a unique Ni,Ni-[4Fe4S] cluster (the A-cluster). However, it was unknown which proteins support the assembly of the A-cluster. We analyzed the product of a gene from the cluster containing the ACS gene, cooC2 from Carboxydothermus hydrogenoformans, named AcsF Ch , and showed that it acts as a maturation factor of ACS. AcsF Ch and inactive ACS form a stable 2:1 complex that binds two nickel ions with higher affinity than the individual components. The nickel-bound ACS-AcsF Ch complex remains inactive until MgATP is added, thereby converting inactive to active ACS. AcsF Ch is a MinD-type ATPase and belongs to the CooC protein family, which can be divided into homologous subgroups. We propose that proteins of one subgroup are responsible for assembling the Ni,Ni-[4Fe4S] cluster of ACS, whereas proteins of a second subgroup mature the [Ni4Fe4S] cluster of carbon monoxide dehydrogenases.The cellular maturation of metalloenzymes, previously considered a spontaneous process in vivo, typically depends on a machinery of uptake, storage, processing, and delivery factors (1). How metalloenzymes mature has been investigated for some systems, revealing surprisingly complex maturation pathways (2-8). Enzymes containing nickel, although still relatively small in number, play critical roles in archaea, bacteria, and eukarya, through which they impact the global hydrogen (Ni,Fe-hydrogenase), nitrogen (urease), and carbon (acetylCoA synthase, carbon monoxide dehydrogenase, and methylCoM reductase) cycles (9). For most of these enzymes, we now have a good understanding of how nickel is incorporated into the active site (8, 10).The nickel-enzymes acetyl-CoA synthase (ACS) 2 and carbon monoxide dehydrogenase (CODH) are found in a variety of anaerobic microbes, including bacterial sulfate reducers, acetogens, and hydrogenogens, as well as archaeal methanogens and sulfate reducers, where they act as the prime CO 2 and CO converter (11)(12)(13)(14). ACS and CODH can be found as independent monofunctional enzymes in Carboxydothermus hydrogenoformans (15) but are typically found in other microorganisms as protein complexes: in acetogens ACS and CODH form a bifunctional (␣␤) 2 complex, whereas in methanogens they are part of a large (␣␤␥␦⑀) 8 multienzyme complex (11,13,15,16). CODHs catalyze the reversible reduction of CO 2 to CO at the C-cluster, in which a single nickel ion, embedded within a 3Fe-4S scaffold with an additional iron in exo, binds and activates CO and CO 2 for turnover (17)(18)(19). ACS catalyzes the reversible condensation of CO, CoA, and a methyl-cation donated by the methylated corrinoid iron-sulfur protein to form acetyl-CoA (13). ACS depends on a Ni,Ni-[4Fe4S] cluster (also called A-cluster) for activity, in which the two nickel ions have distinct coordinations: the nickel ion distal to the [4Fe4S] cluster (Ni d ) is coordinated by two amide nitrogen atoms and two cysteine thiolates within a Cys-X-Cys ...

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Cobinamide production of hydrogen in a homogeneous aqueous photochemical system, and assembly and photoreduction in a (βα)8 protein

Cited by 12 publications

References 86 publications

Two-Coordinate Coinage Metal Complexes as Solar Photosensitizers

Two-Coordinate Coinage Metal Complexes as Solar Photosensitizers

Two coordinate, monovalent copper complexes as chromophores and luminophores

AcsF Catalyzes the ATP-dependent Insertion of Nickel into the Ni,Ni-[4Fe4S] Cluster of Acetyl-CoA Synthase

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