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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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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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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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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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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Enzyme-Inspired Coordination Polymers for Selective Oxidization of C(sp³)–H Bonds via Multiphoton Excitation

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(4), С. 2170 - 2182

Опубликована: Янв. 19, 2023

Nature's blueprint provides the fundamental principles for expanding use of abundant metals in catalysis; however, mimicking both structure and function copper enzymes simultaneously one artificial system selective C–H bond oxidation faces marked challenges. Herein, we report a new approach to assembly monooxygenases utilizing binuclear Cu2S2Cl2 cluster duplicate identical catalysis CuA enzyme. The designed monooxygenase Cu-Cl-bpyc facilitates well-defined redox potential that initially activated O2via photoinduced electron transfer, generated an active chlorine radical via ligand-to-metal charge transfer (LMCT) process from consecutive excitation situ formed copper(II) center. abstracts hydrogen atom selectively C(sp3)–H bonds generate intermediate; meanwhile, O2•– species interacted with mimic form mixed-valence species, giving desired oxidization products inherent product selectivity recovering catalyst directly. This enzymatic protocol exhibits excellent recyclability, good functional group tolerance, broad substrate scope, including some biological pharmacologically relevant targets. Mechanistic studies indicate cleavage was rate-determining step cuprous interactions were essential stabilize oxygen species. structural characters fine-modified catalytic properties open avenue develop robust uniform precise sites high performances.

Язык: Английский

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