Photoactive Metal-to-Ligand Charge Transfer Excited States in 3d⁶ Complexes with Cr⁰, Mn^I, Fe^II, and Co^III

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(9), С. 4903 - 4920

Опубликована: Фев. 21, 2023

Many coordination complexes and organometallic compounds with the 4d6 5d6 valence electron configurations have outstanding photophysical photochemical properties, which stem from metal-to-ligand charge transfer (MLCT) excited states. This substance class makes extensive use of most precious least abundant metal elements, consequently there has been a long-standing interest in first-row transition photoactive MLCT Semiprecious copper(I) its completely filled 3d subshell is relatively straightforward well explored case, but 3d6 partially d-orbitals lead to energetically low-lying metal-centered (MC) states that can cause undesirably fast state deactivation. Herein, we discuss recent advances made isoelectronic Cr0, MnI, FeII, CoIII compounds, for long-lived become accessible over past five years. Furthermore, possible future developments search new subshells next-generation applications photophysics photochemistry.

Язык: Английский

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Visible‐to‐UV Photon Upconversion: Recent Progress in New Materials and Applications

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(25)

Опубликована: Март 8, 2023

Ultraviolet (UV, λ<400 nm) light is essential for various photochemical reactions, but its intensity in the solar spectrum very low, and sources that artificially generate high-energy UV are inefficient environmentally unfriendly. A solution to this problem photon upconversion (UC) from visible (vis, λ>400 light. Among several mechanisms, UC based on triplet-triplet annihilation (TTA-UC) particular has made remarkable progress recent years. The development of new chromophores enabled highly efficient conversion low-intensity into In review, we summarize visible-to-UV TTA-UC, their production films application processes such as catalysis, bond activation polymerization. Finally, challenges opportunities future material applications will be discussed.

Язык: Английский

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Improved transition metal photosensitizers to drive advances in photocatalysis

Chemical Science, Год журнала: 2023, Номер 15(1), С. 77 - 94

Опубликована: Ноя. 24, 2023

To function effectively in a photocatalytic application, photosensitizer's light absorption, excited-state lifetime, and redox potentials, both the ground state excited state, are critically important. The absorption profile is particularly relevant to applications involving solar harvesting, whereas potentials lifetimes determine thermodynamics, kinetics, quantum yields of photoinduced processes. This perspective article focuses on synthetic inorganic organometallic approaches optimize these three characteristics transition-metal based photosensitizers. We include our own work areas, which has focused extensively exceptionally strong cyclometalated iridium photoreductants that enable challenging reductive photoredox transformations organic substrates, more recent led improved harvesting charge-transfer copper(i) chromophores, an emerging class earth-abundant compounds solar-energy applications. also highlight many other complementary strategies for optimizing parameters representative examples from literature. It remains significant challenge simultaneously all at once, since improvements one often come detriment others. These inherent trade-offs obviate or circumvent them discussed throughout.

Язык: Английский

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Triplet–triplet annihilation photon upconversion-mediated photochemical reactions

Nature Reviews Chemistry, Год журнала: 2024, Номер 8(4), С. 238 - 255

Опубликована: Март 21, 2024

Язык: Английский

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Ligand-based modulation of the electronic structure at metal nodes in MOFs to promote the oxygen evolution reaction

Journal of Materials Chemistry A, Год журнала: 2023, Номер 11(13), С. 7239 - 7245

Опубликована: Янв. 1, 2023

Exploring and designing efficacious metal–organic framework (MOF) electrocatalysts may unravel the thorny aspects limiting oxygen evolution reaction (OER) with molecular accuracy.

Язык: Английский

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Direct Observation of Triplet States in the Isomerization of Alkenylboronates by Energy Transfer Catalysis

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(39), С. 21576 - 21586

Опубликована: Сен. 20, 2023

Alkenylboronates are versatile building blocks for stereocontrolled synthesis owing to the traceless nature of boron group that can be leveraged achieve highly selective geometric isomerization. Using thioxanthone as an inexpensive photocatalyst, photoisomerization these species continues provide expansive platform stereodivergent synthesis, particularly in construction bioactive polyenes. Although mechanistic investigations consistent with light-driven energy transfer, direct experimental evidence remains conspicuously absent. Herein, we report a rigorous investigation using two widely used alkenylboronates alongside relevant reference compounds. Through combination irradiation experiments, transient absorption spectroscopic studies, kinetic modeling, and DFT calculations all isomers model compounds, it has been possible unequivocally detect characterize perpendicular triplet generated by transfer. Our results serve not only blueprint studies challenging organic sensitizers, but guidelines delineated have also enabled development more sustainable reaction conditions: first time, efficient organocatalytic isomerization under sunlight become feasible.

Язык: Английский

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Shining Fresh Light on Complex Photoredox Mechanisms through Isolation of Intermediate Radical Anions

ACS Catalysis, Год журнала: 2023, Номер 13(14), С. 9392 - 9403

Опубликована: Июнь 30, 2023

Photoredox catalysis (PRC) has gained enormous and wide-ranging interest in recent years but also been subject to significant mechanistic uncertainty, even controversy. To provide a method by which the missing understanding can begin be filled in, we demonstrate herein that it is possible isolate as authentic materials one-electron reduction products of representative PRC catalysts (PCs). Specifically, KC8 both 9,10-dicyanoanthracene naphthalene monoamide derivative presence cryptand provides convenient access corresponding [K(crypt)+][PC·-] salts clean fully characterized techniques including EPR XRD. Because PC·- states are key intermediates reactions, such isolation allows for highly controlled study these anions' specific reactivity hence their roles. As demonstration this principle, show used conveniently interrogate mechanisms recent, high-profile "conPET" "e-PRC" currently acute Using very simple experiments, able striking insights into reactions' underlying observe surprising levels hidden complexity would otherwise have challenging identify emphasize care control needed when interrogating interpreting mechanisms. These studies foundation far broader range questions around conPET, e-PRC, other reaction future, using same strategy isolation.

Язык: Английский

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Organophotocatalytic Mechanisms: Simplicity or Naïvety? Diverting Reactive Pathways by Modifications of Catalyst Structure, Redox States and Substrate Preassemblies

ChemCatChem, Год журнала: 2023, Номер 15(11)

Опубликована: Фев. 21, 2023

Abstract Photocatalysis is a powerful tool to assemble diverse chemical scaffolds, yet bottleneck on its further development the understanding of multitude possible pathways when practitioners rely only oversimplified thermodynamic and optical factors. Recently, there growing number studies in field that exploit, inter alia , kinetic parameters organophotocatalysts are synthetically more programmable terms their redox states opportunities for aggregation with target substrate. Non‐covalent interactions play key role enables access new generation reactivities such as those open‐shell organophotocatalysts. In this review, we discuss how targeted structural modifications influence organophotocatalytic mechanisms together underlying principles. We also highlight benefits strategies preassembly static quenching overcome common reactivity issues (e. g., diffusion rate limits energetic limits).

Язык: Английский

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Applications of red light photoredox catalysis in organic synthesis

Organic & Biomolecular Chemistry, Год журнала: 2023, Номер 21(12), С. 2472 - 2485

Опубликована: Янв. 1, 2023

This review summarizes the current progress in red light-mediated and near-infrared-induced reactions organic synthesis.

Язык: Английский

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Iron(III) Carbene Complexes with Tunable Excited State Energies for Photoredox and Upconversion

Journal of the American Chemical Society, Год журнала: 2024, Номер unknown

Опубликована: Апрель 10, 2024

Substituting precious elements in luminophores and photocatalysts by abundant first-row transition metals remains a significant challenge, iron continues to be particularly attractive owing its high natural abundance low cost. Most complexes known date face severe limitations due undesirably efficient deactivation of luminescent photoredox-active excited states. Two new iron(III) with structurally simple chelate ligands enable straightforward tuning ground state properties, contrasting recent examples, which chemical modification had minor impact. Crude samples feature two luminescence bands strongly reminiscent complex, this observation was attributed dual luminescence, but our case, there is clear-cut evidence that the higher-energy stems from an impurity only red photoluminescence doublet ligand-to-metal charge transfer (2LMCT) genuine. Photoinduced oxidative reductive electron reactions methyl viologen 10-methylphenothiazine occur nearly diffusion-limited kinetics. Photocatalytic not previously reported for compound class, particular C–H arylation diazonium salts aerobic hydroxylation boronic acids, were achieved low-energy light excitation. Doublet–triplet energy (DTET) 2LMCT anthracene annihilator permits proof principle triplet–triplet annihilation upconversion based on molecular photosensitizer. These findings are relevant development featuring photophysical photochemical properties competitive noble-metal-based compounds.

Язык: Английский

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