A Blessing and a Curse: Remote Ligand Functionalization Modulates ³MLCT Relaxation in Group 6 Tricarbonyl Complexes

Inorganic Chemistry, Год журнала: 2025, Номер unknown

Опубликована: Фев. 25, 2025

We recently reported a molecular design for carbonylpyridine molybdenum(0) complexes that unlocks long-lived luminescent and photoactive charge-transfer states. Here, we translate this strategy to chromium(0), tungsten(0) report three fully characterized tricarbonyl metal(0) featuring tripodal ligand with remote n-butyl substituent in the backbone. All show phosphorescence red near-infrared spectral region from metal-to-ligand excited Surprisingly, alkyl chain significantly affects state relaxation: lifetimes are shortened solution but extended solid by one order of magnitude compared complex methyl substituent. Temperature-dependent luminescence NMR spectroscopy combination quantum chemical calculations reveal reasons these disparate effects. The distorts metal coordination geometry. resulting structural flexibility flattens potential energy surfaces solution, which lowers barrier population distorted metal-centered states facilitates nonradiative relaxation. In state, rigidified separates neighboring molecules, reduces self-quenching. Our study sheds light on relationship between structure relaxation inform development based earth-abundant metals.

Язык: Английский

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Molecular Design Principles for Photoactive Transition Metal Complexes: A Guide for “Photo-Motivated” Chemists

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Март 27, 2025

Luminescence and photochemistry involve electronically excited states that are inherently unstable therefore spontaneously decay to electronic ground states, in most cases by nonradiative energy release generates heat. This dissipation can occur on a time scale of 100 fs (∼10–13 s) usually needs be slowed down at least the nanosecond (∼10–9 for luminescence intermolecular occur. is challenging task with many different factors consider. An alternative emerging strategy target dissociative lead metal–ligand bond homolysis subnanosecond access synthetically useful radicals. Based thorough review recent advances field, this article aims provide concise guide obtaining luminescent photochemically coordination compounds d-block elements. We hope encourage "photo-motivated" chemists who have been reluctant apply their synthetic other knowledge photophysics photochemistry, we intend stimulate new approaches control state behavior.

Язык: Английский

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Cyclometallated Co(III) Complexes with Lowest-Energy Charge Transfer Excited States Accessible with Visible Light

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Апрель 10, 2025

The Co(III) complexes, cis-[Co(ppy)2(L)]PF6, where ppy = 2-phenylpyridine and L bpy (2,2'-bipyridine; 1), phen (1,10-phenanthroline; 2), DAP (1,12-diazaperylene; 3), are reported their photophysical properties were investigated to evaluate potential as sensitizers for applications that include solar energy conversion schemes photoredox catalysis. Calculations show cyclometallation in the cis-[Co(ppy)2(L)]PF6 series affords strong Co(dπ)/ppy(π) orbital interactions result a Co/ppy(π*) highest occupied molecular (HOMO) lowest unoccupied (LUMO) localized on diimine ligand, L(π*). Complexes 1-3 exhibit relatively invariant oxidation potentials, whereas reduction event is dependent identity of L, consistent with theoretical predictions. For 3 broad → L(π*) metal/ligand-to-ligand charge transfer (ML-LCT) absorption band observed CH3CN maxima at 507 nm, extending beyond 600 nm. Upon excitation 1ML-LCT transition, transient features population 3ML-LCT excited state lifetimes, τ, 3.0 ps, 4.6 42 ps 1, 2 respectively observed. irradiation 505 able reduce methyl viologen (MV2+), an electron acceptor commonly photocatalytic schemes. To our knowledge, represents first heteroleptic complex combines ligand lowest-lying metal-to-ligand states undergo photoinduced low-energy green light. As such, structural design important step toward d6 photosensitizers based earth abundant metals.

Язык: Английский

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Luminescent and Photoredox‐Active Molybdenum(0) Complexes Competitive with Isoelectronic Ruthenium(II) Polypyridines

Angewandte Chemie International Edition, Год журнала: 2023, Номер 63(10)

Опубликована: Окт. 27, 2023

Ruthenium(II) complexes with chelating polypyridine ligands are among the most frequently investigated compounds in photophysics and photochemistry, owing to their favorable luminescence photoredox properties. Equally good photoluminescence performance attractive photocatalytic behavior is now achievable isoelectronic molybdenum(0) complexes. The zero-valent oxidation state of molybdenum stabilized by carbonyl or isocyanide ligands, metal-to-ligand charge transfer (MLCT) excited states analogous those ruthenium(II) can be established. Microsecond MLCT excited-state lifetimes quantum yields up 0.2 have been achieved solution at room temperature, emission wavelength has become tunable over a large range. stronger photoreductants than polypyridines therefore perform more challenging chemical reductions. triplet nature luminescent allows sensitization photon upconversion via triplet-triplet annihilation, convert low-energy input radiation into higher-energy output fluorescence. This review summarizes current art concerning highlights application potential. Molybdenum roughly 140 times abundant far cheaper ruthenium, hence this research relevant greater context finding sustainable alternatives using precious rare transition metals photochemistry.

Язык: Английский

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Heteroditopic Chelating NHC Ligand-Supported Co^III Complexes: Catalysts for the Reductive Functionalization of Carbon Dioxide under Ambient Conditions

Organometallics, Год журнала: 2023, Номер 42(12), С. 1395 - 1403

Опубликована: Апрель 17, 2023

Synthesis and characterization of heteroditopic chelating NHC ligand-supported air stable CoIII–NHC complexes (1a–d), featuring variable triazole N-substituents thus, being structurally tunable, are reported. These were observed to be very effective catalysts for the reductive functionalization CO2 with aromatic amines using hydrosilane under ambient conditions (1 bar pressure room temperature) yield diverse N-formylated amines, importantly, catalytic activity was found reasonably tuned by N-substituents, which is probably due some electronic modulations, supported electrochemical analysis, rather than any considerable steric alterations as indicated percent buried volume calculation. Notably, corresponding generated in situ also equally effective. It worth mentioning that this first report on N-formylation less nucleophilic primary employing a homogeneous Co complex, best our knowledge. In addition, control experiments suggest protocol proceeds via hydride formoxysilane intermediate formation.

Язык: Английский

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