1
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Jones R, Cowin RA, Ivalo II, Chekulaev D, Roseveare TM, Rice CR, Weinstein JA, Elliott PIP, Scattergood PA. A Near-Infrared Luminescent Cr(III) N-Heterocyclic Carbene Complex. Inorg Chem 2024; 63:8526-8530. [PMID: 38696219 PMCID: PMC11094792 DOI: 10.1021/acs.inorgchem.4c01270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 04/23/2024] [Accepted: 04/26/2024] [Indexed: 05/14/2024]
Abstract
Photoluminescent coordination complexes of Cr(III) are of interest as near-infrared spin-flip emitters. Here, we explore the preparation, electrochemistry, and photophysical properties of the first two examples of homoleptic N-heterocyclic carbene complexes of Cr(III), featuring 2,6-bis(imidazolyl)pyridine (ImPyIm) and 2-imidazolylpyridine (ImPy) ligands. The complex [Cr(ImPy)3]3+ displays luminescence at 803 nm on the microsecond time scale (13.7 μs) from a spin-flip doublet excited state, which transient absorption spectroscopy reveals to be populated within several picoseconds following photoexcitation. Conversely, [Cr(ImPyIm)2]3+ is nonemissive and has a ca. 500 ps excited-state lifetime.
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Affiliation(s)
- Robert
W. Jones
- Department
of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K.
| | - Rory A. Cowin
- Department
of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, U.K.
| | - Iona I. Ivalo
- Department
of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, U.K.
| | - Dimitri Chekulaev
- Department
of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, U.K.
| | - Thomas M. Roseveare
- Department
of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, U.K.
| | - Craig R. Rice
- Department
of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K.
| | - Julia. A. Weinstein
- Department
of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, U.K.
| | - Paul I. P. Elliott
- Department
of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K.
| | - Paul A. Scattergood
- Department
of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K.
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2
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May AM, Dempsey JL. A new era of LMCT: leveraging ligand-to-metal charge transfer excited states for photochemical reactions. Chem Sci 2024; 15:6661-6678. [PMID: 38725519 PMCID: PMC11079626 DOI: 10.1039/d3sc05268k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 04/02/2024] [Indexed: 05/12/2024] Open
Abstract
Ligand-to-metal charge transfer (LMCT) excited states are capable of undergoing a wide array of photochemical reactions, yet receive minimal attention compared to other charge transfer excited states. This work provides general criteria for designing transition metal complexes that exhibit low energy LMCT excited states and routes to drive photochemistry from these excited states. General design principles regarding metal identity, oxidation state, geometry, and ligand sets are summarized. Fundamental photoreactions from these states including visible light-induced homolysis, excited state electron transfer, and other photoinduced chemical transformations are discussed and key design principles for enabling these photochemical reactions are further highlighted. Guided by these fundamentals, this review outlines critical considerations for the future design and application of coordination complexes with LMCT excited states.
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Affiliation(s)
- Ann Marie May
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
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3
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East NR, Naumann R, Förster C, Ramanan C, Diezemann G, Heinze K. Oxidative two-state photoreactivity of a manganese(IV) complex using near-infrared light. Nat Chem 2024; 16:827-834. [PMID: 38332331 DOI: 10.1038/s41557-024-01446-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 01/11/2024] [Indexed: 02/10/2024]
Abstract
Highly reducing or oxidizing photocatalysts are a fundamental challenge in photochemistry. Only a few transition metal complexes with Earth-abundant metal ions have so far advanced to excited state oxidants. All these photocatalysts require high-energy light for excitation, and their oxidizing power has not been fully exploited due to energy dissipation before reaching the photoactive state. Here we demonstrate that the complex [Mn(dgpy)2]4+, based on Earth-abundant manganese and the tridentate 2,6-diguanidylpyridine ligand (dgpy), evolves to a luminescent doublet ligand-to-metal charge transfer (2LMCT) excited state (1,435 nm, 0.86 eV) with a lifetime of 1.6 ns after excitation with low-energy near-infrared light. This 2LMCT state oxidizes naphthalene to its radical cation. Substrates with extremely high oxidation potentials up to 2.4 V enable the [Mn(dgpy)2]4+ photoreduction via a high-energy quartet 4LMCT excited state with a lifetime of 0.78 ps, proceeding via static quenching by the solvent. This process minimizes free energy losses and harnesses the full photooxidizing power, and thus allows oxidation of nitriles and benzene using Earth-abundant elements and low-energy light.
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Affiliation(s)
- Nathan R East
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Robert Naumann
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Christoph Förster
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Charusheela Ramanan
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
- Max-Planck-Institute for Polymer Research, Mainz, Germany
| | - Gregor Diezemann
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Katja Heinze
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany.
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4
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Wellauer J, Ziereisen F, Sinha N, Prescimone A, Velić A, Meyer F, Wenger OS. Iron(III) Carbene Complexes with Tunable Excited State Energies for Photoredox and Upconversion. J Am Chem Soc 2024; 146. [PMID: 38598280 PMCID: PMC11046485 DOI: 10.1021/jacs.4c00605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/13/2024] [Accepted: 03/19/2024] [Indexed: 04/11/2024]
Abstract
Substituting precious elements in luminophores and photocatalysts by abundant first-row transition metals remains a significant challenge, and iron continues to be particularly attractive owing to its high natural abundance and low cost. Most iron complexes known to date face severe limitations due to undesirably efficient deactivation of luminescent and photoredox-active excited states. Two new iron(III) complexes with structurally simple chelate ligands enable straightforward tuning of ground and excited state properties, contrasting recent examples, in which chemical modification had a minor impact. Crude samples feature two luminescence bands strongly reminiscent of a recent iron(III) complex, in which this observation was attributed to dual luminescence, but in our case, there is clear-cut evidence that the higher-energy luminescence stems from an impurity and only the red photoluminescence from a doublet ligand-to-metal charge transfer (2LMCT) excited state is genuine. Photoinduced oxidative and reductive electron transfer reactions with methyl viologen and 10-methylphenothiazine occur with nearly diffusion-limited kinetics. Photocatalytic reactions not previously reported for this compound class, in particular the C-H arylation of diazonium salts and the aerobic hydroxylation of boronic acids, were achieved with low-energy red light excitation. Doublet-triplet energy transfer (DTET) from the luminescent 2LMCT state to an anthracene annihilator permits the proof of principle for triplet-triplet annihilation upconversion based on a molecular iron photosensitizer. These findings are relevant for the development of iron complexes featuring photophysical and photochemical properties competitive with noble-metal-based compounds.
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Affiliation(s)
- Joël Wellauer
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Fabienne Ziereisen
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Narayan Sinha
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Alessandro Prescimone
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Ajdin Velić
- University
of Göttingen, Institute of Inorganic Chemistry, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Franc Meyer
- University
of Göttingen, Institute of Inorganic Chemistry, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Oliver S. Wenger
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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5
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Ogawa T, Wenger OS. Nickel(II) Analogues of Phosphorescent Platinum(II) Complexes with Picosecond Excited-State Decay. Angew Chem Int Ed Engl 2023; 62:e202312851. [PMID: 37732725 DOI: 10.1002/anie.202312851] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/22/2023]
Abstract
Square-planar NiII complexes are interesting as cheaper and more sustainable alternatives to PtII luminophores widely used in lighting and photocatalysis. We investigated the excited-state behavior of two NiII complexes, which are isostructural with two luminescent PtII complexes. The initially excited singlet metal-to-ligand charge transfer (1 MLCT) excited states in the NiII complexes decay to metal-centered (3 MC) excited states within less than 1 picosecond, followed by non-radiative relaxation of the 3 MC states to the electronic ground state within 9-21 ps. This contrasts with the population of an emissive triplet ligand-centered (3 LC) excited state upon excitation of the PtII analogues. Structural distortions of the NiII complexes are responsible for this discrepant behavior and lead to dark 3 MC states far lower in energy than the luminescent 3 LC states of PtII compounds. Our findings suggest that if these structural distortions could be restricted by more rigid coordination environments and stronger ligand fields, the excited-state relaxation in four-coordinate NiII complexes could be decelerated such that luminescent 3 LC or 3 MLCT excited states become accessible. These insights are relevant to make NiII fit for photophysical and photochemical applications that relied on PtII until now.
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Affiliation(s)
- Tomohiro Ogawa
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
- Graduate School of Science and Engineering, University of Toyama, Toyama, 930-8555, Japan
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
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6
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Kitzmann WR, Hunger D, Reponen APM, Förster C, Schoch R, Bauer M, Feldmann S, van Slageren J, Heinze K. Electronic Structure and Excited-State Dynamics of the NIR-II Emissive Molybdenum(III) Analogue to the Molecular Ruby. Inorg Chem 2023; 62:15797-15808. [PMID: 37718553 DOI: 10.1021/acs.inorgchem.3c02186] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Photoactive chromium(III) complexes saw a conceptual breakthrough with the discovery of the prototypical molecular ruby mer-[Cr(ddpd)2]3+ (ddpd = N,N'-dimethyl-N,N'-dipyridin-2-ylpyridine-2,6-diamine), which shows intense long-lived near-infrared (NIR) phosphorescence from metal-centered spin-flip states. In contrast to the numerous studies on chromium(III) photophysics, only 10 luminescent molybdenum(III) complexes have been reported so far. Here, we present the synthesis and characterization of mer-MoX3(ddpd) (1, X = Cl; 2, X = Br) and cisfac-[Mo(ddpd)2]3+ (cisfac-[3]3+), an isomeric heavy homologue of the prototypical molecular ruby. For cisfac-[3]3+, we found strong zero-field splitting using magnetic susceptibility measurements and electron paramagnetic resonance spectroscopy. Electronic spectra covering the spin-forbidden transitions show that the spin-flip states in mer-1, mer-2, and cisfac-[3]3+ are much lower in energy than those in comparable chromium(III) compounds. While all three complexes show weak spin-flip phosphorescence in NIR-II, the emission of cisfac-[3]3+ peaking at 1550 nm is particularly low in energy. Femtosecond transient absorption spectroscopy reveals a short excited-state lifetime of 1.4 ns, 6 orders of magnitude shorter than that of mer-[Cr(ddpd)2]3+. Using density functional theory and ab initio multireference calculations, we break down the reasons for this disparity and derive principles for the design of future stable photoactive molybdenum(III) complexes.
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Affiliation(s)
- Winald R Kitzmann
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
- Rowland Institute, Harvard University, 100 Edwin H. Land Boulevard, Cambridge, Massachusetts 02142, United States
| | - David Hunger
- Institute of Physical Chemistry and Center for Integrated Quantum Science and Technology, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Antti-Pekka M Reponen
- Rowland Institute, Harvard University, 100 Edwin H. Land Boulevard, Cambridge, Massachusetts 02142, United States
| | - Christoph Förster
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Roland Schoch
- Faculty of Science, Chemistry Department and Centre for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany
| | - Matthias Bauer
- Faculty of Science, Chemistry Department and Centre for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany
| | - Sascha Feldmann
- Rowland Institute, Harvard University, 100 Edwin H. Land Boulevard, Cambridge, Massachusetts 02142, United States
| | - Joris van Slageren
- Institute of Physical Chemistry and Center for Integrated Quantum Science and Technology, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Katja Heinze
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
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7
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Kitzmann WR, Bertrams MS, Boden P, Fischer AC, Klauer R, Sutter J, Naumann R, Förster C, Niedner-Schatteburg G, Bings NH, Hunger J, Kerzig C, Heinze K. Stable Molybdenum(0) Carbonyl Complex for Upconversion and Photoredox Catalysis. J Am Chem Soc 2023. [PMID: 37478053 DOI: 10.1021/jacs.3c03832] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
Photoactive complexes with earth-abundant metals have attracted increasing interest in the recent years fueled by the promise of sustainable photochemistry. However, sophisticated ligands with complicated syntheses are oftentimes required to enable photoactivity with nonprecious metals. Here, we combine a cheap metal with simple ligands to easily access a photoactive complex. Specifically, we synthesize the molybdenum(0) carbonyl complex Mo(CO)3(tpe) featuring the tripodal ligand 1,1,1-tris(pyrid-2-yl)ethane (tpe) in two steps with a high overall yield. The complex shows intense deep-red phosphorescence with excited state lifetimes of several hundred nanoseconds. Time-resolved infrared spectroscopy and laser flash photolysis reveal a triplet metal-to-ligand charge-transfer (3MLCT) state as the lowest excited state. Temperature-dependent luminescence complemented by density functional theory (DFT) calculations suggest thermal deactivation of the 3MLCT state via higher lying metal-centered states in analogy to the well-known photophysics of [Ru(bpy)3]2+. Importantly, we found that the title compound is very photostable due to the lack of labilized Mo-CO bonds (as caused by trans-coordinated CO) in the facial configuration of the ligands. Finally, we show the versatility of the molybdenum(0) complex in two applications: (1) green-to-blue photon upconversion via a triplet-triplet annihilation mechanism and (2) photoredox catalysis for a green-light-driven dehalogenation reaction. Overall, our results establish tripodal carbonyl complexes as a promising design strategy to access stable photoactive complexes of nonprecious metals avoiding tedious multistep syntheses.
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Affiliation(s)
- Winald R Kitzmann
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Maria-Sophie Bertrams
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Pit Boden
- Department of Chemistry and State Research Center OPTIMAS, RPTU Kaiserslautern, Erwin-Schrödinger-Straße 52, 67663 Kaiserslautern-Landau, Germany
| | - Alexander C Fischer
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - René Klauer
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Johannes Sutter
- Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Robert Naumann
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Christoph Förster
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Gereon Niedner-Schatteburg
- Department of Chemistry and State Research Center OPTIMAS, RPTU Kaiserslautern, Erwin-Schrödinger-Straße 52, 67663 Kaiserslautern-Landau, Germany
| | - Nicolas H Bings
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Johannes Hunger
- Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Christoph Kerzig
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Katja Heinze
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
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8
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Sinha N, Wenger OS. Photoactive Metal-to-Ligand Charge Transfer Excited States in 3d 6 Complexes with Cr 0, Mn I, Fe II, and Co III. J Am Chem Soc 2023; 145:4903-4920. [PMID: 36808978 PMCID: PMC9999427 DOI: 10.1021/jacs.2c13432] [Citation(s) in RCA: 39] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Many coordination complexes and organometallic compounds with the 4d6 and 5d6 valence electron configurations have outstanding photophysical and photochemical properties, which stem from metal-to-ligand charge transfer (MLCT) excited states. This substance class makes extensive use of the most precious and least abundant metal elements, and consequently there has been a long-standing interest in first-row transition metal compounds with photoactive MLCT states. Semiprecious copper(I) with its completely filled 3d subshell is a relatively straightforward and well explored case, but in 3d6 complexes the partially filled d-orbitals lead to energetically low-lying metal-centered (MC) states that can cause undesirably fast MLCT excited state deactivation. Herein, we discuss recent advances made with isoelectronic Cr0, MnI, FeII, and CoIII compounds, for which long-lived MLCT states have become accessible over the past five years. Furthermore, we discuss possible future developments in the search for new first-row transition metal complexes with partially filled 3d subshells and photoactive MLCT states for next-generation applications in photophysics and photochemistry.
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Affiliation(s)
- Narayan Sinha
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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9
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Cheng Y, Yang Q, He J, Zou W, Liao K, Chang X, Zou C, Lu W. The energy gap law for NIR-phosphorescent Cr(III) complexes. Dalton Trans 2023; 52:2561-2565. [PMID: 36354370 DOI: 10.1039/d2dt02872g] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of homoleptic Cr(III) complexes containing substituted anionic 1,3-bis(pyridin-2-ylimino)isoindolin-2-ide ligands are phosphorescent with λmax in the 777-970 nm range in degassed fluid solutions. The energy gap law has been successfully applied to the doublet excited states of Cr(III) complexes.
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Affiliation(s)
- Yang Cheng
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China.
| | - Qingqing Yang
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China.
| | - Jiang He
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China.
| | - Wenjie Zou
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China.
| | - Keyu Liao
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China.
| | - Xiaoyong Chang
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China.
| | - Chao Zou
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China. .,Functional Coordination Material Group-Frontier Research Center, Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, P. R. China.
| | - Wei Lu
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China.
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10
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Rodriguez TM, Deegbey M, Chen CH, Jakubikova E, Dempsey JL. Isocyanide Ligands Promote Ligand-to-Metal Charge Transfer Excited States in a Rhenium(II) Complex. Inorg Chem 2023; 62:6576-6585. [PMID: 36652699 DOI: 10.1021/acs.inorgchem.2c03193] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A metal-to-ligand charge transfer with mixed intraligand character is observed for the rhenium hexakisarylisocyanide complex [Re(CNAr)6]PF6 (CNAr = 2,6-dimethylphenylisocyanide, λmax = 300 nm). Upon oxidation to [Re(CNAr)6](PF6)2, the dominant low energy optical transition is a ligand-to-metal charge transfer (LMCT) mixed with intraligand transitions (λmax = 650 nm). TD-DFT was used to identify the participating ligand-based orbitals in the LMCT transition, revealing that the majority of the donor orbital is based on the aryl ring (85%) as opposed to the CN bond (14%). For both [Re(CNAr)6]+ and [Re(CNAr)6]2+, structural characterization by X-ray diffraction reveals deviations from Oh geometry at the central Re ion, with larger reduction in symmetry observed for Re(II). For [Re(CNAr)6]+, these structural changes lead to a broadening of the strong ν(C≡N) stretch (2065 cm-1), as the degeneracy of the T1u IR-active mode is broken. Furthermore, a shoulder is observed for this ν(C≡N) stretch, resulting from deviation of the C-N-Ar bond from linearity. By contrast, [Re(CNAr)6]2+ has two weak bands in the ν(C≡N) region (2065 and 2121 cm-1). DFT calculations indicate that reduction of symmetry at the central rhenium ion manifests in the decrease in intensity and the observed split of the ν(C≡N) band. Stability of both complexes are limited by light-induced decomposition where Re(I) dissociates a isocyanide ligand upon irradiation and Re(II) absorbance decays under ambient light. These data provide new insights to the electronic structure of [Re(CNAr)6]2+, enhancing our understanding of LMCT excited states and the versatility of isocyanide ligands.
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Affiliation(s)
- Tayliz M Rodriguez
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Mawuli Deegbey
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Chun-Hsing Chen
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Elena Jakubikova
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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11
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Kübler J, Pfund B, Wenger OS. Zinc(II) Complexes with Triplet Charge-Transfer Excited States Enabling Energy-Transfer Catalysis, Photoinduced Electron Transfer, and Upconversion. JACS AU 2022; 2:2367-2380. [PMID: 36311829 PMCID: PMC9597861 DOI: 10.1021/jacsau.2c00442] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/22/2022] [Accepted: 09/22/2022] [Indexed: 05/28/2023]
Abstract
Many CuI complexes have luminescent triplet charge-transfer excited states with diverse applications in photophysics and photochemistry, but for isoelectronic ZnII compounds, this behavior is much less common, and they typically only show ligand-based fluorescence from singlet π-π* states. We report two closely related tetrahedral ZnII compounds, in which intersystem crossing occurs with appreciable quantum yields and leads to the population of triplet excited states with intraligand charge-transfer (ILCT) character. In addition to showing fluorescence from their initially excited 1ILCT states, these new compounds therefore undergo triplet-triplet energy transfer (TTET) from their 3ILCT states and consequently can act as sensitizers for photo-isomerization reactions and triplet-triplet annihilation upconversion from the blue to the ultraviolet spectral range. The photoactive 3ILCT state furthermore facilitates photoinduced electron transfer. Collectively, our findings demonstrate that mononuclear ZnII compounds with photophysical and photochemical properties reminiscent of well-known CuI complexes are accessible with suitable ligands and that they are potentially amenable to many different applications. Our insights seem relevant in the greater context of obtaining photoactive compounds based on abundant transition metals, complementing well-known precious-metal-based luminophores and photosensitizers.
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12
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East NR, Förster C, Carrella LM, Rentschler E, Heinze K. The Full d 3-d 5 Redox Series of Mononuclear Manganese Complexes: Geometries and Electronic Structures of [Mn(dgpy) 2] n. Inorg Chem 2022; 61:14616-14625. [PMID: 36070611 DOI: 10.1021/acs.inorgchem.2c01680] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Although manganese ions exhibit a rich redox chemistry, redox processes are often accompanied by structural reorganization and a high propensity for ligand substitution, so that no complete structurally characterized manganese(II,III,IV) complex series without significant ligand sphere reorganization akin to the manganese(II,III,IV) oxides exists. We present here the series of pseudo-octahedral homoleptic manganese complexes [Mn(dgpy)2]n+ (n = 2-4) with the adaptable tridentate push-pull ligand 2,6-diguanidylpyridine (dgpy). Mn-N bond lengths and N-Mn-N bond angles change characteristically from n = 2 to n = 4, while the overall [MnN6] coordination sphere is preserved. The manganese(III) complex [Mn(dgpy)2]3+ exhibits a Jahn-Teller elongated octahedron and a negative D = -3.84 cm-1. Concomitantly with the consecutive oxidation of [Mn(dgpy)2]2+ to [Mn(dgpy)2]4+, the optical properties evolve with increasing ligand-to-metal charge transfer character of the absorption bands culminating in the panchromatic absorption of the purple-black manganese(IV) complex [Mn(dgpy)2]4+.
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Affiliation(s)
- Nathan R East
- Department of Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Christoph Förster
- Department of Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Luca M Carrella
- Department of Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Eva Rentschler
- Department of Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Katja Heinze
- Department of Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany
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13
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Cadranel A, Gravogl L, Munz D, Meyer K. Intense Photoinduced Intervalence Charge Transfer in High‐Valent Iron Mixed Phenolate/Carbene Complexes. Chemistry 2022; 28:e202200269. [PMID: 35302682 PMCID: PMC9401866 DOI: 10.1002/chem.202200269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Alejandro Cadranel
- Department Chemie und Pharmazie Physikalische Chemie Friedrich-Alexander-Universität Erlangen–Nürnberg Egerlandstraße 3 91058 Erlangen Germany
- Departamento de Química Inorgánica Analítica y Química Física Universidad de Buenos Aires Facultad de Ciencias Exactas y Naturales Pabellón 2, Ciudad Universitaria C1428EHA Buenos Aires Argentina
- Instituto de Química Física de Materiales Medio Ambiente y Energía (INQUIMAE) CONICET–Universidad de Buenos Aires Pabellón 2, Ciudad Universitaria C1428EHA Buenos Aires Argentina
| | - Lisa Gravogl
- Department Chemie und Pharmazie Anorganische Chemie Friedrich-Alexander-Universität Erlangen–Nürnberg Egerlandstraße 1 91058 Erlangen Germany
| | - Dominik Munz
- Department Chemie und Pharmazie Anorganische Chemie Friedrich-Alexander-Universität Erlangen–Nürnberg Egerlandstraße 1 91058 Erlangen Germany
- Anorganische Chemie: Koordinationschemie Universität des Saarlandes Campus C4.1 66123 Saarbrücken Germany
| | - Karsten Meyer
- Department Chemie und Pharmazie Anorganische Chemie Friedrich-Alexander-Universität Erlangen–Nürnberg Egerlandstraße 1 91058 Erlangen Germany
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14
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Ossinger S, Prescimone A, Häussinger D, Wenger OS. Manganese(I) Complex with Monodentate Arylisocyanide Ligands Shows Photodissociation Instead of Luminescence. Inorg Chem 2022; 61:10533-10547. [PMID: 35768069 PMCID: PMC9377510 DOI: 10.1021/acs.inorgchem.2c01438] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Recently reported
manganese(I) complexes with chelating arylisocyanide
ligands exhibit luminescent metal-to-ligand charge-transfer (MLCT)
excited states, similar to ruthenium(II) polypyridine complexes with
the same d6 valence electron configuration used for many
different applications in photophysics and photochemistry. However,
chelating arylisocyanide ligands require substantial synthetic effort,
and therefore it seemed attractive to explore the possibility of using
more readily accessible monodentate arylisocyanides instead. Here,
we synthesized the new Mn(I) complex [Mn(CNdippPhOMe2)6]PF6 with the known ligand CNdippPhOMe2 = 4-(3,5-dimethoxyphenyl)-2,6-diisopropylphenylisocyanide. This
complex was investigated by NMR spectroscopy, single-crystal structure
analysis, high-resolution electrospray ionization mass spectrometry
(HR-ESI-MS) measurements, IR spectroscopy supported by density functional
theory (DFT) calculations, cyclic voltammetry, and time-resolved as
well as steady-state UV–vis absorption spectroscopy. The key
finding is that the new Mn(I) complex is nonluminescent and instead
undergoes arylisocyanide ligand loss during continuous visible laser
irradiation into ligand-centered and charge-transfer absorption bands,
presumably owed to the population of dissociative d–d excited
states. Thus, it seems that chelating bi- or tridentate binding motifs
are essential for obtaining emissive MLCT excited states in manganese(I)
arylisocyanides. Our work contributes to understanding the basic properties
of photoactive first-row transition metal complexes and could help
advance the search for alternatives to precious metal-based luminophores,
photocatalysts, and sensors. We
report the synthesis, characterization, and X-ray crystal
structure of an octahedral manganese(I) complex with six monodentate
arylisocyanide ligands that undergoes photoinduced ligand loss.
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Affiliation(s)
- Sascha Ossinger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Alessandro Prescimone
- Department of Chemistry, University of Basel, Mattenstrasse 24a, 4058 Basel, Switzerland
| | - Daniel Häussinger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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15
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Luminescent Metal Complexes for Bioassays in the Near-Infrared (NIR) Region. Top Curr Chem (Cham) 2022; 380:31. [PMID: 35715540 DOI: 10.1007/s41061-022-00386-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/14/2022] [Indexed: 10/18/2022]
Abstract
Near-infrared (NIR, 700-1700 nm) luminescent imaging is an emerging bioimaging technology with low photon scattering, minimal autofluorescence, deep tissue penetration, and high spatiotemporal resolution that has shown fascinating promise for NIR imaging-guided theranostics. In recent progress, NIR luminescent metal complexes have attracted substantially increased research attention owing to their intrinsic merits, including small size, anti-photobleaching, long lifetime, and metal-centered NIR emission. In the past decade, scientists have contributed to the advancement of NIR metal complexes involving efforts to improve photophysical properties, biocompatibility, specificity, pharmacokinetics, in vivo visualization, and attempts to exploit new ligand platforms. Herein, we summarize recent progress and provide future perspectives for NIR metal complexes, including d-block transition metals and f-block lanthanides (Ln) as NIR optical molecular probes for bioassays.
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16
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Sinha N, Pfund B, Wegeberg C, Prescimone A, Wenger OS. Cobalt(III) Carbene Complex with an Electronic Excited-State Structure Similar to Cyclometalated Iridium(III) Compounds. J Am Chem Soc 2022; 144:9859-9873. [PMID: 35623627 PMCID: PMC9490849 DOI: 10.1021/jacs.2c02592] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
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 and photochemistry. Cobalt(III) complexes with analogous
MLCT excited-state properties seem to be unknown yet, despite the
fact that iridium(III) and cobalt(III) can adopt identical low-spin
d6 valence electron configurations due to their close chemical
relationship. Using a rigid tridentate chelate ligand (LCNC), in which a central amido π-donor is flanked by two σ-donating
N-heterocyclic carbene subunits, we obtained a robust homoleptic complex
[Co(LCNC)2](PF6), featuring a photoactive
excited state with substantial MLCT character. Compared to the vast
majority of isoelectronic iron(II) complexes, the MLCT state of [Co(LCNC)2](PF6) is long-lived because it
does not deactivate as efficiently into lower-lying metal-centered
excited states; furthermore, it engages directly in photoinduced electron
transfer reactions. The comparison with [Fe(LCNC)2](PF6), as well as structural, electrochemical, and UV–vis
transient absorption studies, provides insight into new ligand design
principles for first-row transition-metal complexes with photophysical
and photochemical properties reminiscent of those known from the platinum
group metals.
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Affiliation(s)
- Narayan Sinha
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Björn Pfund
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Christina Wegeberg
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Alessandro Prescimone
- Department of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, 4058 Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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17
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Joyce JP, Portillo RI, Rappé AK, Shores MP. Doublet Ground State in a Vanadium(II) Complex: Redox and Coordinative Noninnocence of Tripodal Ligand Architecture. Inorg Chem 2022; 61:6376-6391. [DOI: 10.1021/acs.inorgchem.1c03418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Justin P. Joyce
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Romeo I. Portillo
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Anthony K. Rappé
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Matthew P. Shores
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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18
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Abstract
In molecular photochemistry, charge-transfer emission is well understood and widely exploited. In contrast, luminescent metal-centered transitions only came into focus in recent years. This gave rise to strongly phosphorescent CrIII complexes with a d3 electronic configuration featuring luminescent metal-centered excited states which are characterized by the flip of a single spin. These so-called spin-flip emitters possess unique properties and require different design strategies than traditional charge-transfer phosphors. In this review, we give a brief introduction to ligand field theory as a framework to understand this phenomenon and outline prerequisites for efficient spin-flip emission including ligand field strength, symmetry, intersystem crossing and common deactivation pathways using CrIII complexes as instructive examples. The recent progress and associated challenges of tuning the energies of emissive excited states and of emerging applications of the unique photophysical properties of spin-flip emitters are discussed. Finally, we summarize the current state-of-the-art and challenges of spin-flip emitters beyond CrIII with d2, d3, d4 and d8 electronic configuration, where we mainly cover pseudooctahedral molecular complexes of V, Mo, W, Mn, Re and Ni, and highlight possible future research opportunities.
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19
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Mohanty S, Kaczmarek AM. Unravelling the benefits of transition-metal-co-doping in lanthanide upconversion nanoparticles. Chem Soc Rev 2022; 51:6893-6908. [DOI: 10.1039/d2cs00495j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this review we provide an overview of the current knowledge on lanthanide upconversion materials co-doped with transition metals. We focus on how the co-dopants affect the host lattice and the energy transfer processes.
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Affiliation(s)
- Sonali Mohanty
- NanoSensing Group, Department of Chemistry, Ghent University, Krijgslaan 281-S3, B-9000, Ghent, Belgium
| | - Anna M. Kaczmarek
- NanoSensing Group, Department of Chemistry, Ghent University, Krijgslaan 281-S3, B-9000, Ghent, Belgium
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20
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Abstract
In this Frontier article, recently discovered chromium(0) and manganese(i) complexes emitting from metal-to-ligand charge transfer (MLCT) excited states are highlighted. Chelating isocyanide ligands give access to this new class of 3d6 emitters with MLCT lifetimes in (or close to) the nanosecond regime in solution at room temperature. Although the so far achievable luminescence quantum yields in these open-shell complexes are yet comparatively low, the photophysical properties of the new chromium(0) and manganese(i) isocyanides are reminiscent of those of well-known ruthenium(ii) polypyridines. Our findings provide insight into how undesired nonradiative MLCT deactivation in 3d6 complexes can be counteracted, and they seem therefore relevant for the further development of new luminescent first-row transition metal complexes based on iron(ii) and cobalt(iii) in addition to chromium(0) and manganese(i). In this Frontier article, recently discovered chromium(0) and manganese(i) complexes emitting from metal-to-ligand charge transfer (MLCT) excited states are highlighted.![]()
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Affiliation(s)
- Christina Wegeberg
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.
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21
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Wegeberg C, Wenger OS. Luminescent First-Row Transition Metal Complexes. JACS AU 2021; 1:1860-1876. [PMID: 34841405 PMCID: PMC8611671 DOI: 10.1021/jacsau.1c00353] [Citation(s) in RCA: 101] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Indexed: 05/25/2023]
Abstract
Precious and rare elements have traditionally dominated inorganic photophysics and photochemistry, but now we are witnessing a paradigm shift toward cheaper and more abundant metals. Even though emissive complexes based on selected first-row transition metals have long been known, recent conceptual breakthroughs revealed that a much broader range of elements in different oxidation states are useable for this purpose. Coordination compounds of V, Cr, Mn, Fe, Co, Ni, and Cu now show electronically excited states with unexpected reactivity and photoluminescence behavior. Aside from providing a compact survey of the recent conceptual key advances in this dynamic field, our Perspective identifies the main design strategies that enabled the discovery of fundamentally new types of 3d-metal-based luminophores and photosensitizers operating in solution at room temperature.
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22
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Sinha N, Jiménez J, Pfund B, Prescimone A, Piguet C, Wenger OS. A Near-Infrared-II Emissive Chromium(III) Complex. Angew Chem Int Ed Engl 2021; 60:23722-23728. [PMID: 34125469 PMCID: PMC8597102 DOI: 10.1002/anie.202106398] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Indexed: 12/25/2022]
Abstract
The combination of π-donating amido with π-accepting pyridine coordination units in a tridentate chelate ligand causes a strong nephelauxetic effect in a homoleptic CrIII complex, which shifts its luminescence to the NIR-II spectral range. Previously explored CrIII polypyridine complexes typically emit between 727 and 778 nm (in the red to NIR-I spectral region), and ligand design strategies have so far concentrated on optimizing the ligand field strength. The present work takes a fundamentally different approach and focusses on increasing metal-ligand bond covalence to shift the ruby-like 2 E emission of CrIII to 1067 nm at 77 K.
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Affiliation(s)
- Narayan Sinha
- Department of ChemistryUniversity of BaselSt. Johanns-Ring 194056BaselSwitzerland
| | - Juan‐Ramón Jiménez
- Department of Inorganic and Analytical ChemistryUniversity of Geneva30 quai E. Ansermet1211Geneva 4Switzerland
| | - Björn Pfund
- Department of ChemistryUniversity of BaselSt. Johanns-Ring 194056BaselSwitzerland
| | - Alessandro Prescimone
- Department of ChemistryUniversity of Basel, BPR 1096Mattenstrasse 24a4058BaselSwitzerland
| | - Claude Piguet
- Department of Inorganic and Analytical ChemistryUniversity of Geneva30 quai E. Ansermet1211Geneva 4Switzerland
| | - Oliver S. Wenger
- Department of ChemistryUniversity of BaselSt. Johanns-Ring 194056BaselSwitzerland
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23
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Chang L, An Q, Duan L, Feng K, Zuo Z. Alkoxy Radicals See the Light: New Paradigms of Photochemical Synthesis. Chem Rev 2021; 122:2429-2486. [PMID: 34613698 DOI: 10.1021/acs.chemrev.1c00256] [Citation(s) in RCA: 121] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Alkoxy radicals are highly reactive species that have long been recognized as versatile intermediates in organic synthesis. However, their development has long been impeded due to a lack of convenient methods for their generation. Thanks to advances in photoredox catalysis, enabling facile access to alkoxy radicals from bench-stable precursors and free alcohols under mild conditions, research interest in this field has been renewed. This review comprehensively summarizes the recent progress in alkoxy radical-mediated transformations under visible light irradiation. Elementary steps for alkoxy radical generation from either radical precursors or free alcohols are central to reaction development; thus, each section is categorized and discussed accordingly. Throughout this review, we have focused on the different mechanisms of alkoxy radical generation as well as their impact on synthetic utilizations. Notably, the catalytic generation of alkoxy radicals from abundant alcohols is still in the early stage, providing intriguing opportunities to exploit alkoxy radicals for diverse synthetic paradigms.
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Affiliation(s)
- Liang Chang
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 200032 Shanghai, China.,School of Pharmacy, Nanjing University of Chinese Medicine, 210023 Nanjing, China
| | - Qing An
- School of Physical Science and Technology, ShanghaiTech University, 201210 Shanghai, China
| | - Lingfei Duan
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 200032 Shanghai, China
| | - Kaixuan Feng
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 200032 Shanghai, China
| | - Zhiwei Zuo
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 200032 Shanghai, China
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24
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Herr P, Kerzig C, Larsen CB, Häussinger D, Wenger OS. Manganese(I) complexes with metal-to-ligand charge transfer luminescence and photoreactivity. Nat Chem 2021; 13:956-962. [PMID: 34341527 DOI: 10.1038/s41557-021-00744-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 06/04/2021] [Indexed: 11/09/2022]
Abstract
Precious metal complexes with the d6 valence electron configuration often exhibit luminescent metal-to-ligand charge transfer (MLCT) excited states, which form the basis for many applications in lighting, sensing, solar cells and synthetic photochemistry. Iron(II) has received much attention as a possible Earth-abundant alternative, but to date no iron(II) complex has been reported to show MLCT emission upon continuous-wave excitation. Manganese(I) has the same electron configuration as that of iron(II), but until now has typically been overlooked in the search for cheap MLCT luminophores. Here we report that isocyanide chelate ligands give access to air-stable manganese(I) complexes that exhibit MLCT luminescence in solution at room temperature. These compounds were successfully used as photosensitizers for energy- and electron-transfer reactions and were shown to promote the photoisomerization of trans-stilbene. The observable electron transfer photoreactivity occurred from the emissive MLCT state, whereas the triplet energy transfer photoreactivity originated from a ligand-centred 3π-π* state.
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Affiliation(s)
- Patrick Herr
- Department of Chemistry, University of Basel, Basel, Switzerland
| | - Christoph Kerzig
- Department of Chemistry, University of Basel, Basel, Switzerland
| | | | | | - Oliver S Wenger
- Department of Chemistry, University of Basel, Basel, Switzerland.
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25
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Sinha N, Jiménez J, Pfund B, Prescimone A, Piguet C, Wenger OS. A Near‐Infrared‐II Emissive Chromium(III) Complex. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202106398] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Narayan Sinha
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Juan‐Ramón Jiménez
- Department of Inorganic and Analytical Chemistry University of Geneva 30 quai E. Ansermet 1211 Geneva 4 Switzerland
| | - Björn Pfund
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
| | - Alessandro Prescimone
- Department of Chemistry University of Basel, BPR 1096 Mattenstrasse 24a 4058 Basel Switzerland
| | - Claude Piguet
- Department of Inorganic and Analytical Chemistry University of Geneva 30 quai E. Ansermet 1211 Geneva 4 Switzerland
| | - Oliver S. Wenger
- Department of Chemistry University of Basel St. Johanns-Ring 19 4056 Basel Switzerland
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26
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DeJesus JF, Kerr RWF, Penchoff DA, Carroll XB, Peterson CC, Arnold PL, Jenkins DM. Actinide tetra-N-heterocyclic carbene 'sandwiches'. Chem Sci 2021; 12:7882-7887. [PMID: 34168841 PMCID: PMC8188502 DOI: 10.1039/d1sc01007g] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 04/15/2021] [Indexed: 11/21/2022] Open
Abstract
Highly-symmetrical, thorium and uranium octakis-carbene 'sandwich' complexes have been prepared by 'sandwiching' the An(iv) cations between two anionic macrocyclic tetra-NHC ligands, one with sixteen atoms and the other with eighteen atoms. The complexes were characterized by a range of experimental methods and DFT calculations. X-ray crystallography confirms the geometry at the metal centre can be set by the size of the macrocyclic ring, leading to either square prismatic or square anti-prismatic shapes; the geometry of the latter is retained in solution, which also undergoes reversible, electrochemical one-electron oxidation or reduction for the uranium variant. DFT calculations reveal a frontier orbital picture that is similar to thorocene and uranocene, in which the NHC ligands show almost exclusively σ-donation to the metal without π-backbonding.
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Affiliation(s)
- Joseph F DeJesus
- Department of Chemistry, The University of Tennessee Knoxville Tennessee 37996 USA
| | - Ryan W F Kerr
- School of Chemistry, University of Edinburgh West Mains Road Edinburgh EH9 3JJ UK
| | - Deborah A Penchoff
- Howard H. Baker Jr. Center for Public Policy, The University of Tennessee Knoxville Tennessee 37996 USA
| | - Xian B Carroll
- Department of Chemistry, The University of Tennessee Knoxville Tennessee 37996 USA
| | - Charles C Peterson
- Howard H. Baker Jr. Center for Public Policy, The University of Tennessee Knoxville Tennessee 37996 USA
- Research IT Services, University of North Texas Denton Texas 76201 USA
| | - Polly L Arnold
- School of Chemistry, University of Edinburgh West Mains Road Edinburgh EH9 3JJ UK
| | - David M Jenkins
- Department of Chemistry, The University of Tennessee Knoxville Tennessee 37996 USA
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27
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Kaufhold S, Rosemann NW, Chábera P, Lindh L, Bolaño Losada I, Uhlig J, Pascher T, Strand D, Wärnmark K, Yartsev A, Persson P. Microsecond Photoluminescence and Photoreactivity of a Metal-Centered Excited State in a Hexacarbene-Co(III) Complex. J Am Chem Soc 2021; 143:1307-1312. [PMID: 33449685 PMCID: PMC7877722 DOI: 10.1021/jacs.0c12151] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
![]()
The
photofunctionality of the cobalt–hexacarbene complex
[Co(III)(PhB(MeIm)3)2]+ (PhB(MeIm)3 = tris(3-methylimidazolin-2-ylidene)(phenyl)borate)
has been investigated by time-resolved optical spectroscopy. The complex
displays a weak (Φ ∼ 10–4) but remarkably
long-lived (τ ∼ 1 μs) orange photoluminescence
at 690 nm in solution at room temperature following excitation with
wavelengths shorter than 350 nm. The strongly red-shifted emission
is assigned from the spectroscopic evidence and quantum chemical calculations
as a rare case of luminescence from a metal-centered state in a 3d6 complex. Singlet oxygen quenching supports the assignment
of the emitting state as a triplet metal-centered state and underlines
its capability of driving excitation energy transfer processes.
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Affiliation(s)
- Simon Kaufhold
- Center for Analysis and Synthesis (CAS), Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden.,Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Nils W Rosemann
- Center for Analysis and Synthesis (CAS), Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden.,Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Pavel Chábera
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Linnea Lindh
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden.,Division of Theoretical Chemistry, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Iria Bolaño Losada
- Division of Theoretical Chemistry, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Jens Uhlig
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Torbjörn Pascher
- Pascher Instruments AB, Stora Råby Byaväg 24, S-22480 Lund, Sweden
| | - Daniel Strand
- Center for Analysis and Synthesis (CAS), Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Kenneth Wärnmark
- Center for Analysis and Synthesis (CAS), Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Arkady Yartsev
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Petter Persson
- Division of Theoretical Chemistry, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
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28
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Bilger JB, Kerzig C, Larsen CB, Wenger OS. A Photorobust Mo(0) Complex Mimicking [Os(2,2'-bipyridine) 3] 2+ and Its Application in Red-to-Blue Upconversion. J Am Chem Soc 2021; 143:1651-1663. [PMID: 33434435 DOI: 10.1021/jacs.0c12805] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Osmium(II) polypyridines are a well-known class of complexes with luminescent metal-to-ligand charge-transfer (MLCT) excited states that are currently experiencing a revival due to their application potential in organic photoredox catalysis, triplet-triplet annihilation upconversion, and phototherapy. At the same time, there is increased interest in the development of photoactive complexes made from Earth-abundant rather than precious metals. Against this background, we present a homoleptic Mo(0) complex with a new diisocyanide ligand exhibiting different bite angles and a greater extent of π-conjugation than previously reported related chelates. This new design leads to deep red emission, which is unprecedented for homoleptic arylisocyanide complexes of group 6 metals. With a 3MLCT lifetime of 56 ns, an emission band maximum at 720 nm, and a photoluminescence quantum yield of 1.5% in deaerated toluene at room temperature, the photophysical properties are reminiscent of the prototypical [Os(2,2'-bipyridine)3]2+ complex. Under 635 nm irradiation with a cw-laser, the new Mo(0) complex sensitizes triplet-triplet annihilation upconversion of 9,10-diphenylanthracene (DPA), resulting in delayed blue fluorescence with an anti-Stokes shift of 0.93 eV. The photorobustness of the Mo(0) complex and the upconversion quantum yield are high enough to generate a flux of upconverted light that can serve as a sufficiently potent irradiation source for a blue-light-driven photoisomerization reaction. These findings are relevant in the greater contexts of designing new luminophores and photosensitizers for use in red-light-driven photocatalysis, photochemical upconversion, light-harvesting, and phototherapy.
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Affiliation(s)
- Jakob B Bilger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Christoph Kerzig
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Christopher B Larsen
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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Chábera P, Lindh L, Rosemann NW, Prakash O, Uhlig J, Yartsev A, Wärnmark K, Sundström V, Persson P. Photofunctionality of iron(III) N-heterocyclic carbenes and related d transition metal complexes. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2020.213517] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Braun JD, Lozada IB, Herbert DE. In Pursuit of Panchromatic Absorption in Metal Coordination Complexes: Experimental Delineation of the HOMO Inversion Model Using Pseudo-Octahedral Complexes of Diarylamido Ligands. Inorg Chem 2020; 59:17746-17757. [PMID: 33225695 DOI: 10.1021/acs.inorgchem.0c02973] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ability of a compound to broadly absorb light across the incident solar spectrum is an important design target in the development of molecular photosensitizers. The 'HOMO inversion' model predicts that for [(tpy)2Fe]2+ (tpy = 2,2':6',2″-terpyridine) compounds, adjusting the character of the highest occupied molecular orbital (HOMO) from metal-centered to ligand-centered can drastically improve photophysical properties by broadening absorption in the visible and increasing molar extinction coefficients. In an effort to experimentally realize strong, panchromatic absorption, a tridentate N^N-^N diarylamido ligand bearing flanking benzannulated N-heterocyclic donors (tBuL) was used to prepare deeply colored, pseudo-octahedral coordination complexes of a range of first-row transition and main-group metals [(tBuL)2M0/+; M = Fe, Co, Ni, Zn, Ga]. While the Fe(II) congener exhibits the sought-after broad absorption, isostructural and isoelectronic complexes of other first-row transition and main-group metals show vastly different absorption and redox properties. Density functional theory (DFT) calculations point toward the relative energies of the metal d orbitals and ligand orbitals as the source of major changes in electronic structure, confirming aspects and limitations of the predictive 'HOMO inversion' model in experimentally realized systems with implications for the design of abundant transition-metal sensitizers with broad, panchromatic absorptive properties.
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Affiliation(s)
- Jason D Braun
- Department of Chemistry and the Manitoba Institute of Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
| | - Issiah B Lozada
- Department of Chemistry and the Manitoba Institute of Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
| | - David E Herbert
- Department of Chemistry and the Manitoba Institute of Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
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Dill RD, Portillo RI, Shepard SG, Shores MP, Rappé AK, Damrauer NH. Long-Lived Mixed 2MLCT/MC States in Antiferromagnetically Coupled d 3 Vanadium(II) Bipyridine and Phenanthroline Complexes. Inorg Chem 2020; 59:14706-14715. [PMID: 32886504 DOI: 10.1021/acs.inorgchem.0c01950] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Exploration of [V(bpy)3]2+ and [V(phen)3]2+ (bpy = 2,2'-bipyridine; phen = 1,10-phenanthroline) using electronic spectroscopy reveals an ultrafast excited-state decay process and implicates a pair of low-lying doublets with mixed metal-to-ligand charge-transfer (MLCT) and metal-centered (MC) character. Transient absorption (TA) studies of the vanadium(II) species probing in the visible and near-IR, in combination with spectroelectrochemical techniques and computational chemistry, lead to the conclusion that after excitation into the intense and broad visible 4MLCT ← 4GS (ground-state) absorption band (ε400-700 nm = 900-8000 M-1 cm-1), the 4MLCT state rapidly (τisc < 200 fs) relaxes to the upper of two doublet states with mixed MLCT/MC character. Electronic interconversion (τ ∼ 2.5-3 ps) to the long-lived excited state follows, which we attribute to formation of the lower mixed state. Following these initial dynamics, GS recovery ensues with τ = 430 ps and 1.6 ns for [V(bpy)3]2+ and [V(phen)3]2+, respectively. This stands in stark contrast with isoelectronic [Cr(bpy)3]3+, which rapidly forms a long-lived doublet metal-centered (2MC) state following photoexcitation and lacks strong visible GS absorption character. 2MLCT character in the long-lived states of the vanadium(II) species produces geometric distortion and energetic stabilization, both of which accelerate nonradiative decay to the GS compared to [Cr(bpy)3]3+, where the GS and 2MC are well nested. These conclusions are significant because (i) long-lived states with MLCT character are rare in first-row transition-metal complexes and (ii) the presence of a 2MLCT state at lower energy than the 4MLCT state has not been previously considered. The spin assignment of charge-transfer states in open-shell transition-metal complexes is not trivial; when metal-ligand interaction is strong, low-spin states must be carefully considered when assessing reactivity and decay from electronic excited states.
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Affiliation(s)
- Ryan D Dill
- Department of Chemistry and Renewable and Sustainable Energy Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - Romeo I Portillo
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Samuel G Shepard
- Department of Chemistry and Renewable and Sustainable Energy Institute, University of Colorado, Boulder, Colorado 80309, United States
| | - Matthew P Shores
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Anthony K Rappé
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Niels H Damrauer
- Department of Chemistry and Renewable and Sustainable Energy Institute, University of Colorado, Boulder, Colorado 80309, United States
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Photophysics and Photochemistry of Iron Carbene Complexes for Solar Energy Conversion and Photocatalysis. Catalysts 2020. [DOI: 10.3390/catal10030315] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Earth-abundant first row transition metal complexes are important for the development of large-scale photocatalytic and solar energy conversion applications. Coordination compounds based on iron are especially interesting, as iron is the most common transition metal element in the Earth’s crust. Unfortunately, iron-polypyridyl and related traditional iron-based complexes generally suffer from poor excited state properties, including short excited-state lifetimes, that make them unsuitable for most light-driven applications. Iron carbene complexes have emerged in the last decade as a new class of coordination compounds with significantly improved photophysical and photochemical properties, that make them attractive candidates for a range of light-driven applications. Specific aspects of the photophysics and photochemistry of these iron carbenes discussed here include long-lived excited state lifetimes of charge transfer excited states, capabilities to act as photosensitizers in solar energy conversion applications like dye-sensitized solar cells, as well as recent demonstrations of promising progress towards driving photoredox and photocatalytic processes. Complementary advances towards photofunctional systems with both Fe(II) complexes featuring metal-to-ligand charge transfer excited states, and Fe(III) complexes displaying ligand-to-metal charge transfer excited states are discussed. Finally, we outline emerging opportunities to utilize the improved photochemical properties of iron carbenes and related complexes for photovoltaic, photoelectrochemical and photocatalytic applications.
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Treiling S, Wang C, Förster C, Reichenauer F, Kalmbach J, Boden P, Harris JP, Carrella LM, Rentschler E, Resch‐Genger U, Reber C, Seitz M, Gerhards M, Heinze K. Luminescence and Light-Driven Energy and Electron Transfer from an Exceptionally Long-Lived Excited State of a Non-Innocent Chromium(III) Complex. Angew Chem Int Ed Engl 2019; 58:18075-18085. [PMID: 31600421 PMCID: PMC6916301 DOI: 10.1002/anie.201909325] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/01/2019] [Indexed: 01/10/2023]
Abstract
Photoactive metal complexes employing Earth-abundant metal ions are a key to sustainable photophysical and photochemical applications. We exploit the effects of an inversion center and ligand non-innocence to tune the luminescence and photochemistry of the excited state of the [CrN6 ] chromophore [Cr(tpe)2 ]3+ with close to octahedral symmetry (tpe=1,1,1-tris(pyrid-2-yl)ethane). [Cr(tpe)2 ]3+ exhibits the longest luminescence lifetime (τ=4500 μs) reported up to date for a molecular polypyridyl chromium(III) complex together with a very high luminescence quantum yield of Φ=8.2 % at room temperature in fluid solution. Furthermore, the tpe ligands in [Cr(tpe)2 ]3+ are redox non-innocent, leading to reversible reductive chemistry. The excited state redox potential and lifetime of [Cr(tpe)2 ]3+ surpass those of the classical photosensitizer [Ru(bpy)3 ]2+ (bpy=2,2'-bipyridine) enabling energy transfer (to oxygen) and photoredox processes (with azulene and tri(n-butyl)amine).
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Affiliation(s)
- Steffen Treiling
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of MainzDuesbergweg 10–1455128MainzGermany
| | - Cui Wang
- Division BiophotonicsFederal Institute for Materials Research and Testing (BAM)Richard-Willstätter-Straße 1112489BerlinGermany
- Institute of Chemistry and BiochemistryFreie Universität BerlinTakustraße 314195BerlinGermany
| | - Christoph Förster
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of MainzDuesbergweg 10–1455128MainzGermany
| | - Florian Reichenauer
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of MainzDuesbergweg 10–1455128MainzGermany
| | - Jens Kalmbach
- Institute of Inorganic ChemistryUniversity of TübingenAuf der Morgenstelle 1872076TübingenGermany
| | - Pit Boden
- Department of Chemistry and Research Center OptimasTU KaiserslauternErwin-Schrödinger-Straße67663KaiserslauternGermany
| | - Joe P. Harris
- Département de chimieUniversité de MontréalMontréalQuébecH3C 3J7Canada
| | - Luca M. Carrella
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of MainzDuesbergweg 10–1455128MainzGermany
| | - Eva Rentschler
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of MainzDuesbergweg 10–1455128MainzGermany
| | - Ute Resch‐Genger
- Division BiophotonicsFederal Institute for Materials Research and Testing (BAM)Richard-Willstätter-Straße 1112489BerlinGermany
| | - Christian Reber
- Département de chimieUniversité de MontréalMontréalQuébecH3C 3J7Canada
| | - Michael Seitz
- Institute of Inorganic ChemistryUniversity of TübingenAuf der Morgenstelle 1872076TübingenGermany
| | - Markus Gerhards
- Department of Chemistry and Research Center OptimasTU KaiserslauternErwin-Schrödinger-Straße67663KaiserslauternGermany
| | - Katja Heinze
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of MainzDuesbergweg 10–1455128MainzGermany
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Treiling S, Wang C, Förster C, Reichenauer F, Kalmbach J, Boden P, Harris JP, Carrella LM, Rentschler E, Resch‐Genger U, Reber C, Seitz M, Gerhards M, Heinze K. Luminescence and Light‐Driven Energy and Electron Transfer from an Exceptionally Long‐Lived Excited State of a Non‐Innocent Chromium(III) Complex. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201909325] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Steffen Treiling
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of Mainz Duesbergweg 10–14 55128 Mainz Germany
| | - Cui Wang
- Division BiophotonicsFederal Institute for Materials Research and Testing (BAM) Richard-Willstätter-Straße 11 12489 Berlin Germany
- Institute of Chemistry and BiochemistryFreie Universität Berlin Takustraße 3 14195 Berlin Germany
| | - Christoph Förster
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of Mainz Duesbergweg 10–14 55128 Mainz Germany
| | - Florian Reichenauer
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of Mainz Duesbergweg 10–14 55128 Mainz Germany
| | - Jens Kalmbach
- Institute of Inorganic ChemistryUniversity of Tübingen Auf der Morgenstelle 18 72076 Tübingen Germany
| | - Pit Boden
- Department of Chemistry and Research Center OptimasTU Kaiserslautern Erwin-Schrödinger-Straße 67663 Kaiserslautern Germany
| | - Joe P. Harris
- Département de chimieUniversité de Montréal Montréal Québec H3C 3J7 Canada
| | - Luca M. Carrella
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of Mainz Duesbergweg 10–14 55128 Mainz Germany
| | - Eva Rentschler
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of Mainz Duesbergweg 10–14 55128 Mainz Germany
| | - Ute Resch‐Genger
- Division BiophotonicsFederal Institute for Materials Research and Testing (BAM) Richard-Willstätter-Straße 11 12489 Berlin Germany
| | - Christian Reber
- Département de chimieUniversité de Montréal Montréal Québec H3C 3J7 Canada
| | - Michael Seitz
- Institute of Inorganic ChemistryUniversity of Tübingen Auf der Morgenstelle 18 72076 Tübingen Germany
| | - Markus Gerhards
- Department of Chemistry and Research Center OptimasTU Kaiserslautern Erwin-Schrödinger-Straße 67663 Kaiserslautern Germany
| | - Katja Heinze
- Institute of Inorganic Chemistry and Analytical ChemistryJohannes Gutenberg University of Mainz Duesbergweg 10–14 55128 Mainz Germany
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McKearney D, Zhou W, Zellman C, Williams VE, Leznoff DB. Facile tuning of strong near-IR absorption wavelengths in manganese(iii) phthalocyanines via axial ligand exchange. Chem Commun (Camb) 2019; 55:6696-6699. [PMID: 31062005 DOI: 10.1039/c9cc02151e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The facile tuning of near-infrared absorption of manganese(iii) phthalocyanines was accomplished by changing the nature and number of bound axial ligands. For a series of axial ligands on manganese α-octabutoxyphthalocyanine and α-octakis-(isopropylthio)phthalocyanine, the electron density on the metal and its displacement from the Pc-ring plane both control the position of the complex's Q-band. For these two macrocycles, this strong absorption band could be tuned over a λmax range of 815-948 nm by axial ligand exchange.
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Affiliation(s)
- Declan McKearney
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A1S6.
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Vinogradova KA, Shekhovtsov NA, Berezin AS, Sukhikh TS, Krivopalov VP, Nikolaenkova EB, Plokhikh IV, Bushuev MB. A near-infra-red emitting manganese(II) complex with a pyrimidine-based ligand. INORG CHEM COMMUN 2019. [DOI: 10.1016/j.inoche.2018.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Harris JP, Sonneville C, Villain O, Calas G, Reber C. Analytical fitting of temperature-dependent spin-flip transitions in absorption spectra of Cr3+-doped silicate glasses. Chem Phys Lett 2019. [DOI: 10.1016/j.cpletx.2018.100003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kjær KS, Kaul N, Prakash O, Chábera P, Rosemann NW, Honarfar A, Gordivska O, Fredin LA, Bergquist KE, Häggström L, Ericsson T, Lindh L, Yartsev A, Styring S, Huang P, Uhlig J, Bendix J, Strand D, Sundström V, Persson P, Lomoth R, Wärnmark K. Luminescence and reactivity of a charge-transfer excited iron complex with nanosecond lifetime. Science 2018; 363:249-253. [DOI: 10.1126/science.aau7160] [Citation(s) in RCA: 167] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 11/14/2018] [Indexed: 01/04/2023]
Abstract
Iron’s abundance and rich coordination chemistry are potentially appealing features for photochemical applications. However, the photoexcitable charge-transfer states of most iron complexes are limited by picosecond or subpicosecond deactivation through low-lying metal-centered states, resulting in inefficient electron-transfer reactivity and complete lack of photoluminescence. In this study, we show that octahedral coordination of iron(III) by two mono-anionic facialtris-carbene ligands can markedly suppress such deactivation. The resulting complex [Fe(phtmeimb)2]+, where phtmeimb is {phenyl[tris(3-methylimidazol-1-ylidene)]borate}−, exhibits strong, visible, room temperature photoluminescence with a 2.0-nanosecond lifetime and 2% quantum yield via spin-allowed transition from a doublet ligand-to-metal charge-transfer (2LMCT) state to the doublet ground state. Reductive and oxidative electron-transfer reactions were observed for the2LMCT state of [Fe(phtmeimb)2]+in bimolecular quenching studies with methylviologen and diphenylamine.
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Abstract
In this invited Perspective, recent developments and possible future directions of research on photoactive coordination compounds made from nonprecious transition metal elements will be discussed. The focus is on conceptually new, structurally well-characterized complexes with excited-state lifetimes between 10 ps and 1 ms in fluid solution for possible applications in photosensitizing, light-harvesting, luminescence and catalysis. The key metal elements considered herein are Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, W and Ce in various oxidation states equipped with diverse ligands, giving access to long-lived excited states via a range of fundamentally different types of electronic transitions. Research performed in this area over the past five years demonstrated that a much broader spectrum of metal complexes than what was long considered relevant exhibits useful photophysics and photochemistry.
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Affiliation(s)
- Oliver S Wenger
- Department of Chemistry , University of Basel , St. Johanns-Ring 19 , 4056 Basel , Switzerland
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Büldt LA, Wenger OS. Chromium complexes for luminescence, solar cells, photoredox catalysis, upconversion, and phototriggered NO release. Chem Sci 2017; 8:7359-7367. [PMID: 29163886 PMCID: PMC5672834 DOI: 10.1039/c7sc03372a] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 09/04/2017] [Indexed: 12/15/2022] Open
Abstract
Cr(iii) and Cr(0) complexes are earth-abundant alternatives to photosensitizers that are commonly made from precious metals.
Some complexes of Cr(iii) and Cr(0) have long been known to exhibit interesting photophysical and photochemical properties, but in the past few years important conceptual progress was made. This Perspective focuses on the recent developments of Cr(iii) complexes as luminophores and dyes for solar cells, their application in photoredox catalysis, their use as sensitizers in upconversion processes, and their performance as photochemical nitric oxide sources. The example of a luminescent Cr(0) isocyanide complex illustrates the possibility of obtaining photoactive analogues of d6 metal complexes that are commonly made from precious metals such as Ru(ii) or Ir(iii). The studies highlighted herein illustrate the favorable excited-state properties of robust first-row transition metal complexes with broad application potential.
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Affiliation(s)
- Laura A Büldt
- Department of Chemistry , University of Basel , St. Johanns-Ring 19 , 4056 Basel , Switzerland .
| | - Oliver S Wenger
- Department of Chemistry , University of Basel , St. Johanns-Ring 19 , 4056 Basel , Switzerland .
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