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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Oxidative two-state photoreactivity of a manganese(IV) complex using near-infrared light

Nature Chemistry, Год журнала: 2024, Номер 16(5), С. 827 - 834

Опубликована: Фев. 8, 2024

Язык: Английский

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Factors that Impact Photochemical Cage Escape Yields

Chemical Reviews, Год журнала: 2024, Номер 124(11), С. 7379 - 7464

Опубликована: Май 14, 2024

The utilization of visible light to mediate chemical reactions in fluid solutions has applications that range from solar fuel production medicine and organic synthesis. These are typically initiated by electron transfer between a photoexcited dye molecule (a photosensitizer) redox-active quencher yield radical pairs intimately associated within solvent cage. Many these radicals undergo rapid thermodynamically favored "geminate" recombination do not diffuse out the cage surrounds them. Those escape useful reagents may subsequent important above-mentioned applications. process factors determine yields remain poorly understood despite decades research motivated their practical fundamental importance. Herein, state-of-the-art on light-induced appeared since seminal 1972 review J. P. Lorand entitled "The Cage Effect" is reviewed. This also provides some background for those new field discusses both homolytic bond photodissociation bimolecular induced reactions. concludes with key goals directions future promise elevate this very vibrant even greater heights.

Язык: Английский

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Efficient Triplet‐Triplet Annihilation Upconversion Sensitized by a Chromium(III) Complex via an Underexplored Energy Transfer Mechanism

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(27)

Опубликована: Март 28, 2022

Sensitized triplet-triplet annihilation upconversion (sTTA-UC) mainly relies on precious metal complexes thanks to their high intersystem crossing (ISC) efficiencies, excited state energies, and lifetimes, while of abundant first-row transition metals are only rarely utilized with often moderate UC quantum yields. [Cr(bpmp)

Язык: Английский

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Shedding Light on the Oxidizing Properties of Spin-Flip Excited States in a Cr^III Polypyridine Complex and Their Use in Photoredox Catalysis

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(31), С. 14181 - 14194

Опубликована: Авг. 1, 2022

The photoredox activity of well-known RuII complexes stems from metal-to-ligand charge transfer (MLCT) excited states, in which a ligand-based electron can initiate chemical reductions and metal-centered hole trigger oxidations. CrIII polypyridines show similar properties, although they have fundamentally different electronic structures. Their photoactive state is spin-flip nature, differing the ground merely by change one spin, but with otherwise identical d-orbital occupancy. We find that driving-force dependence for photoinduced 10 donors to complex very polypyridine, thereby validate concept estimating redox potential d3 states analogous manner as MLCT d6 compounds. Building on this insight, we use our photocatalytic reactions not previously explored compound class, including aerobic bromination methoxyaryls, oxygenation 1,1,2,2-tetraphenylethylene, hydroxylation arylboronic acids, vinylation N-phenyl pyrrolidine. This work contributes understanding fundamental photochemical properties first-row transition-metal comparison well-explored precious-metal-based photocatalysts.

Язык: Английский

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Charge‐Transfer and Spin‐Flip States: Thriving as Complements

Angewandte Chemie International Edition, Год журнала: 2022, Номер 62(15)

Опубликована: Окт. 4, 2022

Abstract Transition metal complexes with photoactive charge‐transfer excited states are pervasive throughout the literature. In particular, [Ru(bpy) 3 ] 2+ (bpy=2,2′‐bipyridine), its metal‐to‐ligand emission, has been established as a key complex. Meanwhile, interest in so‐called spin‐flip metal‐centered risen dramatically after molecular ruby [Cr(ddpd) 2 3+ (ddpd= N , ′‐dimethyl‐ ′‐dipyridin‐2‐yl‐pyridine‐2,6‐diamine) led to design principles access strong, long‐lived emission from photostable chromium(III) complexes. This Review contrasts properties of emissive and by using prototypical examples. We discuss relevant states, tunability their energy lifetimes, response external stimuli. Finally, we identify strengths weaknesses applications such photocatalysis circularly polarized luminescence.

Язык: Английский

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Blue‐to‐UVB Upconversion, Solvent Sensitization and Challenging Bond Activation Enabled by a Benzene‐Based Annihilator

Angewandte Chemie International Edition, Год журнала: 2022, Номер 62(8)

Опубликована: Ноя. 18, 2022

Several energy-demanding photoreactions require harsh UV light from inefficient sources. The conversion of low-energy visible to high-energy singlet states via triplet-triplet annihilation upconversion (TTA-UC) could offer a solution for driving such reactions under mild conditions. We present the first annihilator with an emission maximum in UVB region that, combined organic sensitizer, is suitable blue-to-UVB upconversion. was successfully employed as energy donor subsequent FRET activations aliphatic carbonyls. This hitherto unreported UC-FRET reaction sequence directly monitored using laser spectroscopy and applied mechanistic irradiation experiments demonstrating feasibility Norrish chemistry. Our results provide clear evidence novel blue light-driven substrate or solvent activation strategy, which important context developing more sustainable light-to-chemical systems.

Язык: Английский

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Sensitizer-controlled photochemical reactivityviaupconversion of red light

Chemical Science, Год журнала: 2022, Номер 14(1), С. 149 - 161

Опубликована: Дек. 1, 2022

By combining the energy input from two red photons, chemical reactions that would normally require blue or ultraviolet irradiation become accessible. Key advantages of this biphotonic excitation strategy are light usually penetrates deeper into complex reaction mixtures and causes less photo-damage than direct illumination in ultraviolet. Here, we demonstrate primary light-absorber a dual photocatalytic system comprised transition metal-based photosensitizer an organic co-catalyst can completely alter outcome. Photochemical reductions achieved with copper(i) presence sacrificial electron donor, whereas oxidative substrate activation occurs osmium(ii) photosensitizer. Based on time-resolved laser spectroscopy, changeover photochemical reactivity is due to different underlying mechanisms. Following triplet transfer 9,10-dicyanoanthracene (DCA) subsequent triplet-triplet annihilation upconversion, fluorescent singlet excited state DCA triggers activation, which initiates

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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Visible‐Light Induced Fixation of SO₂ into Organic Molecules with Polypyridine Chromium(III) Complexes

ChemCatChem, Год журнала: 2023, Номер 15(6)

Опубликована: Янв. 23, 2023

Abstract Incorporation of sulfur dioxide into organic compounds is achieved by a photocatalytic approach using sensitizers made from earth‐abundant chromium(III) ions and visible light leading to sulfones sulfonamides. We employed three different [Cr(ddpd) 2 ] 3+ , [Cr(bpmp) [Cr(tpe) with long excited state lifetimes ground redox potentials as well varying stability under the reaction conditions (ddpd= N N’ ‐dimethyl‐ ’‐dipyridin‐2‐yl‐pyridine‐2,6‐diamine; bpmp=2,6‐bis(2‐pyridylmethyl)pyridine; tpe=1,1,1‐tris(pyrid‐2‐yl)ethane). Key steps catalytic cycles are identified electrochemical, luminescence quenching, photolysis, laser flash photolysis experiments delivering detailed picture challenges in these transformations. The reactivity reduced chromium complex was key property explain outcomes. Initial cage escape yield determinations revealed that desired photoreactions occur unusually high quantum efficiencies, whereas side reactions almost unproductive.

Язык: Английский

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