A Photorobust Mo(0) Complex Mimicking [Os(2,2′-bipyridine)₃]²⁺ and Its Application in Red-to-Blue Upconversion

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(3), P. 1651 - 1663

Published: Jan. 12, 2021

Osmium(II) polypyridines are a well-known class of complexes with luminescent metal-to-ligand charge-transfer (MLCT) excited states that currently experiencing revival due to their application potential in organic photoredox catalysis, triplet–triplet annihilation upconversion, and phototherapy. At the same time, there is increased interest development photoactive made from Earth-abundant rather than precious metals. Against this background, we present homoleptic Mo(0) complex new diisocyanide ligand exhibiting different bite angles greater extent π-conjugation previously reported related chelates. This design leads deep red emission, which unprecedented for arylisocyanide group 6 With 3MLCT lifetime 56 ns, an emission band maximum at 720 nm, photoluminescence quantum yield 1.5% deaerated toluene room temperature, photophysical properties reminiscent prototypical [Os(2,2′-bipyridine)3]2+ complex. Under 635 nm irradiation cw-laser, sensitizes upconversion 9,10-diphenylanthracene (DPA), resulting delayed blue fluorescence anti-Stokes shift 0.93 eV. The photorobustness high enough generate flux upconverted light can serve as sufficiently potent source blue-light-driven photoisomerization reaction. These findings relevant contexts designing luminophores photosensitizers use red-light-driven photocatalysis, photochemical light-harvesting,

Language: Английский

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A Roadmap Towards Visible Light Mediated Electron Transfer Chemistry with Iridium(III) Complexes

ChemPhotoChem, Journal Year: 2020, Volume and Issue: 5(3), P. 217 - 234

Published: Dec. 12, 2020

Abstract Photo‐induced electron transfer chemistry between molecules is a central theme in several fields including biology, physics and chemistry. Specifically, photoredox catalysis, greater use has been made of iridium(III) complexes as they exhibit ground‐ excited‐state redox potentials that span very large range. Unfortunately, most these suffer from limited visible light absorption properties. This concept article highlights recent developments the synthesis with increased properties their candidates for driven catalysis. Fundamental tools are provided to enable independent tuning HOMO LUMO energy levels. Recent examples given hope this will foster further iridium(III)‐based sensitizers reactivity.

Language: Английский

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Low power threshold photochemical upconversion using a zirconium(iv) LMCT photosensitizer

Chemical Science, Journal Year: 2021, Volume and Issue: 12(26), P. 9069 - 9077

Published: Jan. 1, 2021

The current investigation demonstrates highly efficient photochemical upconversion (UC) where a long-lived Zr(iv) ligand-to-metal charge transfer (LMCT) complex serves as triplet photosensitizer in concert with well-established 9,10-diphenylanthracene (DPA) along newly conceived DPA-carbazole based acceptors/annihilators THF solutions. initial dynamic triplet-triplet energy (TTET) processes (ΔG ∼ -0.19 eV) featured very large Stern-Volmer quenching constants (K SV) approaching or achieving 105 M-1 bimolecular rate between 2 and 3 × 108 s-1 ascertained using static transient spectroscopic techniques. Both the TTET subsequent annihilation (TTA) were verified throughly investigated absorption spectroscopy. metrics support 95% of modest concentrations (0.25 mM) various acceptor/annihilators, no aggregation took place any chromophores THF. Each upconverting formulations operated continuous-wave linear incident power dependence (λ ex = 514.5 nm) down to ultralow excitation densities under optimized experimental conditions. Impressive record-setting η UC values ranging from 31.7% 42.7% achieved conditions (13 mW cm-2) below that solar flux integrated across photosensitizer's band (26.7 cm-2). This study illustrates importance supporting continued development discovery molecular-based photosensitizers on earth-abundant metals.

Language: Английский

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Molecular Triplet Sensitization and Photon Upconversion Using Colloidal Semiconductor Nanocrystals

ACS Energy Letters, Journal Year: 2021, Volume and Issue: 6(9), P. 3151 - 3166

Published: Aug. 23, 2021

Colloidal semiconductor nanocrystals have recently emerged as a novel class of photosensitizers for molecular spin-triplet states. This sensitization strategy combines the advantages strong and readily tunable light absorption with exceptionally long lifetime triplet states, which can find broad range photochemical energy applications. A unique advantage application in triplet–triplet annihilation photon upconversion is that negligible bright-to-dark exciton relaxation loss allows large gain (i.e., anti-Stokes shift). Focus Review highlights recent advances this emerging field, mainly including summary principles mechanisms along factors controlling efficiencies an overview nanocrystal materials been applied to upconversion. We end review our perspectives on remaining challenges field potential applications technology future.

Language: Английский

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Approaching the Spin-Statistical Limit in Visible-to-Ultraviolet Photon Upconversion

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(8), P. 3706 - 3716

Published: Feb. 17, 2022

Triplet–triplet annihilation photon upconversion (TTA-UC) is a process in which triplet excitons combine to form emissive singlets and holds great promise biological applications for improving the spectral match solar energy conversion. While high TTA-UC quantum yields have been reported for, example, red-to-green systems, there are only few examples of visible-to-ultraviolet (UV) transformations yield reaches 10%. In this study, we investigate performance six annihilators when paired with sensitizer 2,3,5,6-tetra(9H-carbazol-9-yl)benzonitrile (4CzBN), purely organic compound that exhibits thermally activated delayed fluorescence. We report record-setting internal (ΦUC,g) 16.8% (out 50% maximum) 1,4-bis((triisopropylsilyl)ethynyl)naphthalene, demonstrating first example visible-to-UV system approaching classical spin-statistical limit 20%. Three other annihilators, 2,5-diphenylfuran has never used previously, also showed impressive performances ΦUC,g above 12%. addition, new method determine rate constant TTA proposed, time-resolved emission measurements needed, circumventing need more challenging transient absorption measurements. The results herein represent an important step toward highly efficient systems hold potential driving high-energy photochemical reactions.

Language: 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, Journal Year: 2022, Volume and Issue: 61(27)

Published: March 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)

Language: Английский

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Sensitization-initiated electron transfer via upconversion: mechanism and photocatalytic applications

Chemical Science, Journal Year: 2021, Volume and Issue: 12(29), P. 9922 - 9933

Published: Jan. 1, 2021

A full picture of a new multi-photon excitation mechanism relying on sTTA upconversion is provided, together with selected photocatalytic applications. All mechanistic steps are investigated and the catalytically active species observed directly.

Language: Английский

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High Triplet Energy Iridium(III) Isocyanoborato Complex for Photochemical Upconversion, Photoredox and Energy Transfer Catalysis

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(2), P. 963 - 976

Published: Jan. 5, 2022

Cyclometalated Ir(III) complexes are often chosen as catalysts for challenging photoredox and triplet-triplet-energy-transfer (TTET) catalyzed reactions, they of interest upconversion into the ultraviolet spectral range. However, triplet energies commonly employed photosensitizers typically limited to values around 2.5-2.75 eV. Here, we report on a new luminophore, with an unusually high energy near 3.0 eV owing modification previously reported complex isocyanoborato ligands. Compared nonborylated cyanido precursor complex, introduction B(C6F5)3 units in second coordination sphere results substantially improved photophysical properties, particular luminescence quantum yield (0.87) long excited-state lifetime (13.0 μs), addition energy. These favorable properties (including good long-term photostability) facilitate exceptionally organic photoreactions (sensitized) triplet-triplet annihilation fluorescent singlet excited state beyond 4 eV, deep region. The photocatalyzes sigmatropic shift [2 + 2] cycloaddition reactions that unattainable common transition metal-based photosensitizers. In presence sacrificial electron donor, it furthermore is applicable demanding photoreductions, including dehalogenations, detosylations, degradation lignin model substrate. Our study demonstrates how rational ligand design transition-metal underexplored effects) can be used enhance their thereby broaden application potential solar conversion synthetic photochemistry.

Language: Английский

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Water-Soluble Tris(cyclometalated) Iridium(III) Complexes for Aqueous Electron and Energy Transfer Photochemistry

Accounts of Chemical Research, Journal Year: 2022, Volume and Issue: 55(9), P. 1290 - 1300

Published: April 12, 2022

ConspectusCyclometalated iridium(III) complexes are frequently employed in organic light emitting diodes, and they popular photocatalysts for solar energy conversion synthetic chemistry. They luminesce from redox-active excited states that can have high triplet energies long lifetimes, making them well suited transfer photoredox catalysis. Homoleptic tris(cyclometalated) typically very hydrophobic do not dissolve polar solvents, somewhat limiting their application scope. We developed a family of water-soluble sulfonate-decorated variants with tailored redox potentials excited-state to address several key challenges aqueous photochemistry.First, we aimed at combining enzyme catalysis synthesize enantioenriched products cyclic reaction network. Since the biocatalyst operates best solution, photocatalyst was needed. A new complex provided enough reducing power photochemical reduction imines racemic mixtures amines furthermore compatible monoamine oxidase (MAO-N-9), which deracemized this mixture through kinetic resolution amine via oxidation corresponding imine. This process led accumulation unreactive enantiomer over time. In subsequent studies, discovered same photoionizes under intense irradiation give hydrated electrons as result consecutive two-photon excitation. With visible input, become available catalytic fashion, thereby allowing comparatively mild substrates would only be reactive harsher conditions. Finally, became interested upconversion it desirable obtain compounds energies. goal achieved improved ligand design ultimately enabled sensitized triplet–triplet annihilation unusually far into ultraviolet spectral range.Studies catalysis, rely on use solvents. Water could potentially an attractive alternative many cases, but development lags behind solution compared solvent. The purpose Account is provide overview breadth research perspectives emerged fac-[Ir(ppy)]3 (ppy = 2-phenylpyridine) sulfonated ligands. hope inspire some these or related coordination photochemistry stimulate further conceptual developments interfaces chemistry, photophysics, biocatalysis, sustainable

Language: Английский

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Understanding Ir(III) Photocatalyst Structure–Activity Relationships: A Highly Parallelized Study of Light-Driven Metal Reduction Processes

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(3), P. 1431 - 1444

Published: Jan. 13, 2022

High-throughput synthesis and screening methods were used to measure the photochemical activity of 1440 distinct heteroleptic [Ir(C^N)2(N^N)]+ complexes for photoreduction Sn(II) Zn(II) cations their corresponding neutral metals. Kinetic data collection was carried out using home-built photoreactors measured initial rates, obtained through an automated fitting algorithm, spanned between 0–120 μM/s Sn(0) deposition 0–90 Zn(0) deposition. Photochemical reactivity compared photophysical properties previously such as deaerated excited state lifetime emission spectral these same complexes; however, no clear correlations among features observed. A formal rate law then developed help elucidate observed reactivity. Initial rates found be directly correlated product incident photon flux with three reaction elementary efficiencies: (1) fraction light absorbed by photocatalyst, (2) species that are quenched electron donor, (3) cage escape efficiency. The most active catalysts exhibit high efficiencies all steps, catalyst engineering requirements maximize postulated. kinetic treatment provided mechanistic information needed decipher structure/function trends in high-throughput work.

Language: Английский

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