Photoactive Copper Complexes: Properties and Applications

Chemical Reviews, Год журнала: 2022, Номер 122(22), С. 16365 - 16609

Опубликована: Ноя. 9, 2022

Photocatalyzed and photosensitized chemical processes have seen growing interest recently become among the most active areas of research, notably due to their applications in fields such as medicine, synthesis, material science or environmental chemistry. Among all homogeneous catalytic systems reported date, photoactive copper(I) complexes been shown be especially attractive, not only alternative noble metal complexes, extensively studied utilized recently. They are at core this review article which is divided into two main sections. The first one focuses on an exhaustive comprehensive overview structural, photophysical electrochemical properties mononuclear typical examples highlighting critical structural parameters impact being presented enlighten future design complexes. second section devoted application (photoredox catalysis organic reactions polymerization, hydrogen production, photoreduction carbon dioxide dye-sensitized solar cells), illustrating progression from early current state-of-the-art showcasing how some limitations can overcome with high versatility.

Язык: Английский

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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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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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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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Excited Organic Radicals in Photoredox Catalysis

JACS Au, Год журнала: 2025, Номер 5(2), С. 426 - 447

Опубликована: Янв. 29, 2025

Many important synthetic-oriented works have proposed excited organic radicals as photoactive species, yet mechanistic studies raised doubts about whether they can truly function photocatalysts. This skepticism originates from the formation of (photo)redox-active degradation products and picosecond decay electronically radicals, which is considered too short for diffusion-based photoinduced electron transfer reactions. From this perspective, we analyze synthetic transformations where been photocatalysts, comparing their theoretical maximum state potentials with required observed photocatalytic reactivity. We summarize structurally similar photocatalysts indicating different reaction pathways some catalytic systems, addressing cases radical exceed Additionally, perform a kinetic analysis to explain in on subpicosecond time scales. further rationalize potential anti-Kasha reactivity higher states femtosecond lifetimes, highlighting how future photocatalysis advancements could unlock new photochemical pathways.

Язык: Английский

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Red light excitation: illuminating photocatalysis in a new spectrum

Beilstein Journal of Organic Chemistry, Год журнала: 2025, Номер 21, С. 296 - 326

Опубликована: Фев. 7, 2025

Red-light-activated photocatalysis has become a powerful approach for achieving sustainable chemical transformations, combining high efficiency with energy-saving, mild conditions. By harnessing the deeper penetration and selectivity of red near-infrared light, this method minimizes side reactions typical higher-energy sources, making it particularly suited large-scale applications. Recent advances highlight unique advantages both metal-based metal-free catalysts under red-light irradiation, broadening range possible reactions, from selective oxidations to complex polymerizations. In biological contexts, enables innovative applications in phototherapy controlled drug release, exploiting its tissue low cytotoxicity. Together, these developments underscore versatility impact photocatalysis, positioning as cornerstone green organic chemistry significant potential synthetic biomedical fields.

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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Molecular Design Principles to Elongate the Metal-to-Ligand Charge Transfer Excited-State Lifetimes of Square-Planar Nickel(II) Complexes

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(48), С. 21948 - 21960

Опубликована: Ноя. 23, 2022

Square-planar NiII complexes and their electronically excited states play key roles in cross-coupling catalysis could offer new opportunities to complement well-known isoelectronic PtII luminophores. Metal-to-ligand charge transfer (MLCT) deactivation pathways are particularly relevant these contexts. We sought extend the lifetimes of 3MLCT square-planar by creating coordination environments that seemed well adapted 3d8 valence electron configuration. Using a rigid tridentate chelate ligand, which central cyclometalated phenyl unit is flanked two coordinating N-heterocyclic carbenes, along with monodentate isocyanide very strong ligand field created. Bulky substituents at backbone furthermore protect center from nucleophilic attack axial directions. UV-Vis transient absorption spectroscopies reveal upon excitation into 1MLCT bands ultrafast intersystem crossing state, latter relaxes onward metal-centered triplet state (3MC). A torsional motion NiII-carbon bond elongation facilitate relaxation 3MC state. The lifetime gets longer increasing strength improved steric protection, thereby revealing clear design guidelines for enhanced photophysical properties. longest reached solution room temperature 48 ps, factor 5-10 compared previously investigated complexes. Our study contributes making first-row transition metal partially filled d-orbitals more amenable applications photophysics photochemistry.

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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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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