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, Journal Year: 2023, Volume and Issue: 145(9), P. 4903 - 4920

Published: Feb. 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.

Language: Английский

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Interfacial Mo–S bond modulated S-scheme Mn0.5Cd0.5S/Bi2MoO6 heterojunction for boosted photocatalytic removal of emerging organic contaminants

CHINESE JOURNAL OF CATALYSIS (CHINESE VERSION), Journal Year: 2025, Volume and Issue: 68, P. 259 - 271

Published: Jan. 1, 2025

Language: Английский

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Cage escape governs photoredox reaction rates and quantum yields

Nature Chemistry, Journal Year: 2024, Volume and Issue: 16(7), P. 1151 - 1159

Published: March 18, 2024

Abstract Photoredox catalysis relies on light-induced electron transfer leading to a radical pair comprising an oxidized donor and reduced acceptor in solvent cage. For productive onward reaction occur, the must escape from that cage before they undergo spontaneous reverse transfer. Here we show decisive role plays three benchmark photocatalytic reactions, namely, aerobic hydroxylation, reductive debromination aza-Henry reaction. Using ruthenium(II)- chromium(III)-based photocatalysts, which provide inherently different quantum yields, determined quantitative correlations between rates of photoredox product formation yields. These findings can be largely rationalized within framework Marcus theory for

Language: Английский

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Mechanisms of Photoredox Catalysis Featuring Nickel–Bipyridine Complexes

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(11), P. 9055 - 9076

Published: May 29, 2024

Metallaphotoredox catalysis can unlock useful pathways for transforming organic reactants into desirable products, largely due to the conversion of photon energy chemical potential drive redox and bond transformation processes. Despite importance these processes cross-coupling reactions other transformations, their mechanistic details are only superficially understood. In this review, we have provided a detailed summary various photoredox mechanisms that been proposed date Ni-bipyridine (bpy) complexes, focusing separately on photosensitized direct excitation reaction By highlighting multiple key findings, depict how mechanisms, which ultimately define substrate scope, themselves defined by ground- excited-state geometric electronic structures Ni-based intermediates. We further identify knowledge gaps motivate future studies development synergistic research approaches spanning physical, organic, inorganic chemistry communities.

Language: Английский

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Cobalt(III) Carbene Complex with an Electronic Excited-State Structure Similar to Cyclometalated Iridium(III) Compounds

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(22), P. 9859 - 9873

Published: May 27, 2022

Many organometallic iridium(III) complexes have photoactive excited states with mixed metal-to-ligand and intraligand charge transfer (MLCT/ILCT) character, which form the basis for numerous applications in photophysics photochemistry. Cobalt(III) analogous MLCT excited-state properties seem to be unknown yet, despite fact that cobalt(III) can adopt identical low-spin d6 valence electron configurations due their close chemical relationship. Using a rigid tridentate chelate ligand (LCNC), central amido π-donor is flanked by two σ-donating N-heterocyclic carbene subunits, we obtained robust homoleptic complex [Co(LCNC)2](PF6), featuring state substantial character. Compared vast majority of isoelectronic iron(II) complexes, [Co(LCNC)2](PF6) long-lived because it does not deactivate as efficiently into lower-lying metal-centered states; furthermore, engages directly photoinduced reactions. The comparison [Fe(LCNC)2](PF6), well structural, electrochemical, UV–vis transient absorption studies, provides insight new design principles first-row transition-metal photophysical photochemical reminiscent those known from platinum group metals.

Language: 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, Journal Year: 2022, Volume and Issue: 144(31), P. 14181 - 14194

Published: Aug. 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.

Language: Английский

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Photocatalytic degradation efficiency of Rhodamine-B for CuO/CdO nanosheets attained through simple co-precipitation method

Results in Chemistry, Journal Year: 2023, Volume and Issue: 6, P. 101169 - 101169

Published: Oct. 14, 2023

In the present investigation, growth of CuO/CdO nanosheets by simple coprecipitation method and characterized XRD, SEM with EDX, TEM, UV-visible PL. The incorporation non-ionic surfactant Triton X-100 blend resulted in hexagonal shaped grains a nanoporous structure. pristine CuO CdO display monoclinic cubic phases, respectively, whereas exhibits combination two as proven XRD analysis. According to TEM analysis composite particle size was reduced range between 20 50nm resulting, bandgap value is decreased around 1.26 eV due effect. photocatalytic activity against Rhodamine-B (RhB) showed 94% degradation efficiency compared (71.42%) (77.83%). Furthermore, nanocomposite catalyst dosage increasing found be 97.62%. Although nitration process more efficient at pH 6, for CuO, CdO, 75.74, 85.96%, 99.88% 6. acidic solution, reusability outstanding 95.80% after five successive cycles.

Language: Английский

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Factors that Impact Photochemical Cage Escape Yields

Chemical Reviews, Journal Year: 2024, Volume and Issue: 124(11), P. 7379 - 7464

Published: May 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.

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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Green Light-Triggered Photocatalytic Anticancer Activity of Terpyridine-Based Ru(II) Photocatalysts

Inorganic Chemistry, Journal Year: 2024, Volume and Issue: 63(16), P. 7493 - 7503

Published: April 5, 2024

The relentless increase in drug resistance of platinum-based chemotherapeutics has opened the scope for other new cancer therapies with novel mechanisms action (MoA). Recently, photocatalytic therapy, an intrusive catalytic treatment, is receiving significant interest due to its multitargeting cell death mechanism high selectivity. Here, we report synthesis and characterization three photoresponsive Ru(II) complexes, viz., [Ru(ph-tpy)(bpy)Cl]PF6 (Ru1), [Ru(ph-tpy)(phen)Cl]PF6 (Ru2), [Ru(ph-tpy)(aip)Cl]PF6 (Ru3), where, ph-tpy = 4′-phenyl-2,2′:6′,2″-terpyridine, bpy 2,2′-bipyridine, phen 1,10-phenanthroline, aip 2-(anthracen-9-yl)-1H-imidazo[4,5-f][1,10] phenanthroline, showing anticancer activity. X-ray crystal structures Ru1 Ru2 revealed a distorted octahedral geometry RuN5Cl core. complexes showed intense absorption band 440–600 nm range corresponding metal-to-ligand charge transfer (MLCT) that was further used achieve green light-induced effect. mitochondria-targeting photostable complex Ru3 induced phototoxicity IC50 PI values ca. 0.7 μM 88, respectively, under white light irradiation 1.9 35 against HeLa cells. (Ru1–Ru3) negligible dark cytotoxicity toward normal splenocytes (IC50s > 50 μM). mechanistic study ROS-mediated apoptosis cells via mitochondrial depolarization or exposure. Interestingly, also acted as highly potent catalyst NADH photo-oxidation light. This process contributed photocytotoxicity complexes. Overall, presented synergistic type I II photochemotherapeutic effects.

Language: Английский

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