Improved transition metal photosensitizers to drive advances in photocatalysis

Chemical Science, Journal Year: 2023, Volume and Issue: 15(1), P. 77 - 94

Published: Nov. 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.

Language: Английский

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

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: unknown

Published: April 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.

Language: Английский

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First‐Row d⁶ Metal Complex Enables Photon Upconversion and Initiates Blue Light‐Dependent Polymerization with Red Light

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(43)

Published: Sept. 8, 2023

Photosensitizers for sensitized triplet-triplet annihilation upconversion (sTTA-UC) often rely on precious heavy metals, whereas coordination complexes based abundant first-row transition metals are less common. This is mainly because long-lived triplet excited states more difficult to obtain 3d particularly when the d-subshell only partially filled. Here, we report first example of sTTA-UC a 3d6 metal photosensitizer yielding an performance competitive with metal-based analogues. Using newly developed Cr0 featuring equally good photophysical properties as OsII benchmark complex in combination acetylene-decorated anthracene annihilator, red-to-blue achievable. The efficiency under optimized conditions 1.8 %, and excitation power density threshold reach strong limit 5.9 W/cm2 . These factors, along high photostability, permit initiation acrylamide polymerization by red light, radiative energy transfer between delayed annihilator fluorescence blue light absorbing photo-initiator. Our study provides proof-of-concept photon elusive analogues widely employed d6 photosensitizers, their application photochemical reactions triggered wavelengths close near-infrared.

Language: Английский

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Long Excited-State Lifetimes in Three-Coordinate Copper(I) Complexes via Triplet–Triplet Energy Transfer to Pyrene-Decorated Isocyanides

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(28), P. 19193 - 19204

Published: July 2, 2024

There has been much effort to improve excited-state lifetimes in photosensitizers based on earth-abundant first-row transition metals. Copper(I) complexes have gained significant attention this field, and most cases, sterically driven approaches are used optimize their lifetimes. This study presents a series of three-coordinate copper(I) (Cu1–Cu3) where the lifetime is extended by triplet–triplet energy transfer. The heteroleptic compounds feature cyclohexyl-substituted β-diketiminate (CyNacNacMe) paired with aryl isocyanide ligands, giving general formula Cu(CyNacNacMe)(CN-Ar) (CN-dmp = 2,6-dimethylphenyl for Cu1; CN-pyr 1-pyrenyl Cu2; CN-dmp-pyr 2,6-dimethyl-4-(1-pyrenyl)phenyl Cu3). nature, energies, dynamics low-energy triplet excited states assessed combination photoluminescence measurements at room temperature 77 K, ultrafast transient absorption (UFTA) spectroscopy, DFT calculations. pyrene-decorated isocyanides (Cu2 Cu3) exhibit resulting from transfer (TTET) between short-lived charge-transfer state (3CT) long-lived pyrene-centered (3pyr). TTET process irreversible Cu3, producing exclusively 3pyr state, Cu2, 3CT nearly isoenergetic, enabling reversible luminescence. improved photophysical properties Cu2 Cu3 result improvements activity both photocatalytic stilbene E/Z isomerization via photoredox transformations involving hydrodebromination C–O bond activation. These results illustrate that achieved through newly conceived photosynthetically relevant metal complexes.

Language: Английский

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Low-power, non-coherent light-triggered two-photon absorption via extending the lifetime of the transition state

Coordination Chemistry Reviews, Journal Year: 2024, Volume and Issue: 511, P. 215868 - 215868

Published: April 22, 2024

Language: Английский

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Photocyclization by a triplet–triplet annihilation upconversion pair in water – avoiding UV-light and oxygen removal

Chemical Science, Journal Year: 2023, Volume and Issue: 14(40), P. 11040 - 11044

Published: Jan. 1, 2023

We present a formal [2 + 2]-cycloaddition of unsaturated ketones enabled by green-to-ultraviolet triplet-triplet annihilation upconversion (TTA-UC) pair, using commercially available Ru(bpy)32+ and pyrene as sensitizer annihilator, respectively. In the developed protocol, visible light irradiation at λmax = 520 nm allows for reaction to proceed without need UV-light aqueous medium eliminates oxygen removing protocols. Through this study, application readily pair is broadened include cyclization reactions. showcase utility system generating bicyclo[2.1.1]hexanes that are valuable bioisosteres ortho-substituted benzenes, promising motif pharmaceuticals.

Language: Английский

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Steric and Electronic Influence of Excited-State Decay in Cu(I) MLCT Chromophores

Accounts of Chemical Research, Journal Year: 2024, Volume and Issue: 57(19), P. 2872 - 2886

Published: Sept. 11, 2024

ConspectusFor the past 11 years, a dedicated effort in our research group focused on fundamentally advancing photophysical properties of cuprous

Language: Английский

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Sensitization-Initiated Electron Transfer Mechanism in Photoredox Catalysis Using a Ru-Py Dyad as a Dual Sensitizer and Reductant

The Journal of Physical Chemistry C, Journal Year: 2025, Volume and Issue: 129(9), P. 4398 - 4406

Published: Feb. 24, 2025

The sensitization-initiated electron transfer (SenI-ET) mechanism is a well-established concept in photoredox catalysis, yet its kinetic intricacies remain to be fully elucidated. In this study, we have successfully designed and synthesized dyad, Ru(bpy)32+–pyrene (Ru-Py), which functions dually as sensitizer reductant. By the use of rapid intramolecular triplet singlet energy Ru-Py, complex decay pathway SenI-ET process was effectively simplified. Notably, demonstrated that direct from 3Ru*-Py diisopropyl ethylamine generates Ru(I)-Py, further drives catalytic process, rather than reaction being driven by formation Ru-Py•- through Ru-3Py* ethylamine. Furthermore, employed Ru-Py catalyst for C–H oxidation an activated aryl bromide, demonstrating superior efficiency compared conventional Ru(bpy)32+/pyrene system.

Language: Английский

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Multichromatic Anti-Stokes Photon Upconversion through BNOSe Sensitization

The Journal of Physical Chemistry Letters, Journal Year: 2025, Volume and Issue: unknown, P. 4270 - 4276

Published: April 22, 2025

Triplet-triplet annihilation upconversion (TTA-UC) has become an important sensing technique due to its ability eliminate tissue autofluorescence interference. However, quantitative application in oxygen within complex systems remains fundamentally constrained. To overcome this limitation and explore synergistic anti-Stokes mechanisms, we developed a heavy-metal-free photosensitizer (BNOSe) via multiresonance architecture engineering. This innovation enables the creation of first integrated platform capable simultaneous TTA-UC oxygen-resistant single-photon absorption (SPA-UC). The optimized system exhibits remarkable performance: it converts deep-red light (640 nm) into dual emissions at 617 nm (orange) 412 (blue), achieving record quantum yield 19.3% with 1.07 eV shift, largest value reported for visible-to-blue using metal-free sensitizers. Importantly, oxygen-dependent SPA-UC channels establish self-calibrating paradigm, showcasing multimodal capabilities oxygen-probing bioimaging multicolor analyte detection.

Language: Английский

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Bulky Substituents Promote Triplet–Triplet Annihilation Over Triplet Excimer Formation in Naphthalene Derivatives

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(40), P. 22168 - 22175

Published: Sept. 28, 2023

Visible-to-ultraviolet (UV) triplet-triplet annihilation photochemical upconversion (TTA-UC) has gained a lot of attention recently due to its potential for driving demanding high-energy photoreactions using low-intensity visible light. The efficiency this process rapidly improved in the past few years, part thanks discovered annihilator compound 1,4-bis((triisopropylsilyl)ethynyl)naphthalene (N-2TIPS). Despite beneficial TTA-UC characteristics, success N-2TIPS context is not yet fully understood. In work, we seek elucidate what role specific type and number substituents naphthalene compounds play achieve characteristics sought after TTA-UC. We show that substituent attached core crucial performance as an annihilator. More specifically, argue choice dictates degree sensitized triplets form excimer complexes with ground state annihilators same type, which competing TTA. addition more bulky positively impacts upconverting ability by impeding formation on triplet surface, effect enhanced substituents. presence excimers confirmed from transient absorption measurements, rate quantified, showing several orders magnitude differences between different derivatives. These insights will aid further development solar energy applications behavior at low incident powers particular significance.

Language: Английский

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