1
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Kaul N, Asempa E, Valdez-Moreira JA, Smith JM, Jakubikova E, Hammarström L. Enter Mn IV-NHC: A Dark Photooxidant with a Long-Lived Charge-Transfer Excited State. J Am Chem Soc 2024. [PMID: 39106331 DOI: 10.1021/jacs.4c08588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/09/2024]
Abstract
Detailed photophysical investigation of a Mn(IV)-carbene complex has revealed that excitation into its lowest-energy absorption band (∼500 nm) results in the formation of an energetic ligand-to-metal charge-transfer (LMCT) state with a lifetime of 15 ns. To the best of our knowledge, this is the longest lifetime reported for charge-transfer states of first-row-based transition metal complexes in solution, barring those based on Cu, with a d10 configuration. A so-called superoxidant, Mn(IV)-carbene exhibits an excited state potential typically only harnessed via excited states of reactive organic radical species. Furthermore, the long-lived excited state in this case is found to be a dark doublet, with its transition to the quartet ground state being spin-forbidden, a contrast to most first-row literature examples, and a possible cause of the long lifetime. Showcasing excited state properties which in some cases exceed those of complexes based on precious metals, these findings not only advance the library of earth-abundant photosensitizers but also shed general insight into the photophysics of d3 and related Mn complexes.
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Affiliation(s)
- Nidhi Kaul
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
| | - Eyram Asempa
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Juan A Valdez-Moreira
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Jeremy M Smith
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Elena Jakubikova
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Leif Hammarström
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
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2
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Ghosh A, Yarranton JT, McCusker JK. Establishing the origin of Marcus-inverted-region behaviour in the excited-state dynamics of cobalt(III) polypyridyl complexes. Nat Chem 2024:10.1038/s41557-024-01564-3. [PMID: 38965436 DOI: 10.1038/s41557-024-01564-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 05/24/2024] [Indexed: 07/06/2024]
Abstract
Growing interest in the use of first-row transition metal complexes in a number of applied contexts-including but not limited to photoredox catalysis and solar energy conversion-underscores the need for a detailed understanding of their photophysical properties. A recent focus on ligand-field photocatalysis using cobalt(III) polypyridyls in particular has unlocked unprecedented excited-state reactivities. Photophysical studies on Co(III) chromophores in general are relatively uncommon, and so here we carry out a systematic study of a series of Co(III) polypyridyl complexes in order to delineate their excited-state dynamics. Compounds with varying ligand-field strengths were prepared and studied using variable-temperature ultrafast transient absorption spectroscopy. Analysis of the data establishes that the ground-state recovery dynamics are operating in the Marcus inverted region, in stark contrast to what is typically observed in other first-row metal complexes. The analysis has further revealed the underlying reasons driving this excited-state behaviour, thereby enabling potential advancements in the targeted use of the Marcus inverted region for a variety of photolytic applications.
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Affiliation(s)
- Atanu Ghosh
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | | | - James K McCusker
- Department of Chemistry, Michigan State University, East Lansing, MI, USA.
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3
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Venkatraman RK, Tolba AH, Sølling TI, Cibulka R, El-Zohry AM. Ultrafast Events of Photoexcited Iron(III) Chloride for Activation of Benzylic C-H Bonds. J Phys Chem Lett 2024; 15:6202-6208. [PMID: 38836909 DOI: 10.1021/acs.jpclett.4c01116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
The usage of rare-earth-metal catalysts in the synthesis of organic compounds is widespread in chemical industries but is limited owing to its environmental and economic costs. However, recent studies indicate that abundant-earth metals like iron(III) chloride can photocatalyze diverse organic transformations using blue-light LEDs. Still, the underlying mechanism behind such activity is debatable and controversial, especially in the absence of ultrafast spectroscopic results. To address this urgent challenge, we performed femtosecond time-resolved electronic absorption spectroscopy experiments of iron(III) chloride in selected organic solvents relevant to its photocatalytic applications. Our results show that the long-lived species [Fe(II) ← Cl•]* is primarily responsible for both oxidizing the organic substrate and reducing molecular oxygen through the diffusion process, leading to the final product and regenerating the photocatalyst rather than the most widely proposed free chloride radical (Cl•). Our study will guide the rational design of efficient earth-abundant photocatalysts.
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Affiliation(s)
- Ravi Kumar Venkatraman
- Ultrafast Laser Spectroscopy Lab Center for Integrative Petroleum Research, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia
| | - Amal Hassan Tolba
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic
- Chemistry Department, Faculty of Science, Assiut University, Assiut 2074020, Egypt
| | - Theis I Sølling
- Ultrafast Laser Spectroscopy Lab Center for Integrative Petroleum Research, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia
| | - Radek Cibulka
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic
| | - Ahmed M El-Zohry
- Ultrafast Laser Spectroscopy Lab Center for Integrative Petroleum Research, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia
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4
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Goodwin MJ, Dickenson JC, Ripak A, Deetz AM, McCarthy JS, Meyer GJ, Troian-Gautier L. Factors that Impact Photochemical Cage Escape Yields. Chem Rev 2024; 124:7379-7464. [PMID: 38743869 DOI: 10.1021/acs.chemrev.3c00930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The utilization of visible light to mediate chemical reactions in fluid solutions has applications that range from solar fuel production to medicine and organic synthesis. These reactions are typically initiated by electron transfer between a photoexcited dye molecule (a photosensitizer) and a redox-active quencher to yield radical pairs that are intimately associated within a solvent cage. Many of these radicals undergo rapid thermodynamically favored "geminate" recombination and do not diffuse out of the solvent cage that surrounds them. Those that do escape the cage are useful reagents that may undergo subsequent reactions important to the above-mentioned applications. The cage escape process and the factors that determine the yields remain poorly understood despite decades of research motivated by their practical and fundamental importance. Herein, state-of-the-art research on light-induced electron transfer and cage escape that has appeared since the seminal 1972 review by J. P. Lorand entitled "The Cage Effect" is reviewed. This review also provides some background for those new to the field and discusses the cage escape process of both homolytic bond photodissociation and bimolecular light induced electron transfer reactions. The review concludes with some key goals and directions for future research that promise to elevate this very vibrant field to even greater heights.
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Affiliation(s)
- Matthew J Goodwin
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - John C Dickenson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Alexia Ripak
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Alexander M Deetz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jackson S McCarthy
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Gerald J Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Ludovic Troian-Gautier
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
- Wel Research Institute, Avenue Pasteur 6, 1300 Wavre, Belgium
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5
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Trippmacher S, Demeshko S, Prescimone A, Meyer F, Wenger OS, Wang C. Ferromagnetically Coupled Chromium(III) Dimer Shows Luminescence and Sensitizes Photon Upconversion. Chemistry 2024; 30:e202400856. [PMID: 38523568 DOI: 10.1002/chem.202400856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 03/23/2024] [Accepted: 03/25/2024] [Indexed: 03/26/2024]
Abstract
There has been much progress on mononuclear chromium(III) complexes featuring luminescence and photoredox activity, but dinuclear chromium(III) complexes have remained underexplored in these contexts until now. We identified a tridentate chelate ligand able to accommodate both meridional and facial coordination of chromium(III), to either access a mono- or a dinuclear chromium(III) complex depending on reaction conditions. This chelate ligand causes tetragonally distorted primary coordination spheres around chromium(III) in both complexes, entailing comparatively short excited-state lifetimes in the range of 400 to 800 ns in solution at room temperature and making photoluminescence essentially oxygen insensitive. The two chromium(III) ions in the dimer experience ferromagnetic exchange interactions that result in a high spin (S=3) ground state with a coupling constant of +9.3 cm-1. Photoinduced energy transfer from the luminescent ferromagnetically coupled dimer to an anthracene derivative results in sensitized triplet-triplet annihilation upconversion. Based on these proof-of-principle studies, dinuclear chromium(III) complexes seem attractive for the development of fundamentally new types of photophysics and photochemistry enabled by magnetic exchange interactions.
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Affiliation(s)
- Simon Trippmacher
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Serhiy Demeshko
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstraße 4, 37077, Göttingen, Germany
| | - Alessandro Prescimone
- Department of Chemistry, BPR 1096, University of Basel, Mattenstrasse 24a, 4058, Basel, Switzerland
| | - Franc Meyer
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstraße 4, 37077, Göttingen, Germany
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Cui Wang
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
- Department of Biology and Chemistry, Osnabrück University, Barbarastraße 7, 49076, Osnabrück, Germany
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6
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Ye Q, Cairnie DR, Troya D, Kumar N, Yang X, Morris AJ. Photoinduced Dynamic Ligation in Metal-Organic Frameworks. J Am Chem Soc 2024; 146:101-105. [PMID: 38150536 PMCID: PMC10785796 DOI: 10.1021/jacs.3c12217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 12/29/2023]
Abstract
Metal organic frameworks (MOFs), a class of porous crystalline materials consisting of metal-based nodes and organic linkers, have emerged as a promising platform for photocatalysis due to their ultrahigh functional surface area, customizable topologies, and tunable energetics. While interesting photochemistry has been reported, the related photoinduced structural dynamics of MOFs remains unclear. The consensus is that the coordination bonds between MOF nodes and linkers are considered static during photoexcitation, while the open-metal sites on the nodes are taken as the key active sites for catalysis. In this work, through a complementary time-resolved visible and infrared (IR) spectroscopic investigation, along with computational studies, we report for the first time light-induced structural bond dissociation (COO-M) and reformation in an iron-oxo framework, MIL-101(Fe). The probed excited state displayed ligand-to-metal charge transfer (LMCT) characteristics and exhibited a ca. 30 μs lifetime. The incredibly long excited-state lifetime led us to probe potential structural rearrangements that facilitated charge separation in MIL-101(Fe). By probing the vibrational fingerprints of the carboxylate linker upon LMCT photoexcitation, we observed the reversible transition of the carboxylate-Fe bond from a bidentate bridging mode to a monodentate mode, indicating the partial dissociation of the carboxylate ligand. Importantly, the bidentate configuration is recovered on the same time scale of the excited state lifetimes as probed via visible transient absorption spectroscopy. The elucidated photoinduced configurational dynamics provides a foundation for an in-depth understanding of MOF-based photocatalytic mechanisms.
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Affiliation(s)
- Qingyu Ye
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24060, United States
| | - Daniel R. Cairnie
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24060, United States
| | - Diego Troya
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24060, United States
| | - Naveen Kumar
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24060, United States
| | - Xiaozhou Yang
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24060, United States
| | - Amanda J. Morris
- Department
of Chemistry, Virginia Tech, Blacksburg, Virginia 24060, United States
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7
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Sinha N, Wegeberg C, Häussinger D, Prescimone A, Wenger OS. Photoredox-active Cr(0) luminophores featuring photophysical properties competitive with Ru(II) and Os(II) complexes. Nat Chem 2023; 15:1730-1736. [PMID: 37580444 PMCID: PMC10695827 DOI: 10.1038/s41557-023-01297-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 07/19/2023] [Indexed: 08/16/2023]
Abstract
Coordination complexes of precious metals with the d6 valence electron configuration such as Ru(II), Os(II) and Ir(III) are used for lighting applications, solar energy conversion and photocatalysis. Until now, d6 complexes made from abundant first-row transition metals with competitive photophysical and photochemical properties have been elusive. While previous research efforts focused mostly on Fe(II), we disclose that isoelectronic Cr(0) gives access to higher photoluminescence quantum yields and excited-state lifetimes when compared with any other first-row d6 metal complex reported so far. The luminescence behaviour of the metal-to-ligand charge transfer excited states of these Cr(0) complexes is competitive with Os(II) polypyridines. With these Cr(0) complexes, the metal-to-ligand charge transfer states of first-row d6 metal complexes become exploitable in photoredox catalysis, and benchmark chemical reductions proceed efficiently under low-energy red illumination. Here we demonstrate that appropriate molecular design strategies open up new perspectives for photophysics and photochemistry with abundant first-row d6 metals.
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Affiliation(s)
- Narayan Sinha
- Department of Chemistry, University of Basel, Basel, Switzerland
| | | | | | | | - Oliver S Wenger
- Department of Chemistry, University of Basel, Basel, Switzerland.
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8
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Lee A, Son M, Deegbey M, Woodhouse MD, Hart SM, Beissel HF, Cesana PT, Jakubikova E, McCusker JK, Schlau-Cohen GS. Observation of parallel intersystem crossing and charge transfer-state dynamics in [Fe(bpy) 3] 2+ from ultrafast 2D electronic spectroscopy. Chem Sci 2023; 14:13140-13150. [PMID: 38023502 PMCID: PMC10664481 DOI: 10.1039/d3sc02613b] [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: 05/24/2023] [Accepted: 10/29/2023] [Indexed: 12/01/2023] Open
Abstract
Transition metal-based charge-transfer complexes represent a broad class of inorganic compounds with diverse photochemical applications. Charge-transfer complexes based on earth-abundant elements have been of increasing interest, particularly the canonical [Fe(bpy)3]2+. Photoexcitation into the singlet metal-ligand charge transfer (1MLCT) state is followed by relaxation first to the ligand-field manifold and then to the ground state. While these dynamics have been well-studied, processes within the MLCT manifold that facilitate and/or compete with relaxation have been more elusive. We applied ultrafast two-dimensional electronic spectroscopy (2DES) to disentangle the dynamics immediately following MLCT excitation of this compound. First, dynamics ascribed to relaxation out of the initially formed 1MLCT state was found to correlate with the inertial response time of the solvent. Second, the additional dimension of the 2D spectra revealed a peak consistent with a ∼20 fs 1MLCT → 3MLCT intersystem crossing process. These two observations indicate that the complex simultaneously undergoes intersystem crossing and direct conversion to ligand-field state(s). Resolution of these parallel pathways in this prototypical earth-abundant complex highlights the ability of 2DES to deconvolve the otherwise obscured excited-state dynamics of charge-transfer complexes.
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Affiliation(s)
- Angela Lee
- Department of Chemistry, Massachusetts Institute of Technology Cambridge MA 02139 USA
| | - Minjung Son
- Department of Chemistry, Massachusetts Institute of Technology Cambridge MA 02139 USA
| | - Mawuli Deegbey
- Department of Chemistry, North Carolina State University Raleigh NC 27695 USA
| | - Matthew D Woodhouse
- Department of Chemistry, Michigan State University East Lansing MI 48824 USA
| | - Stephanie M Hart
- Department of Chemistry, Massachusetts Institute of Technology Cambridge MA 02139 USA
| | - Hayden F Beissel
- Department of Chemistry, Michigan State University East Lansing MI 48824 USA
| | - Paul T Cesana
- Department of Chemistry, Massachusetts Institute of Technology Cambridge MA 02139 USA
| | - Elena Jakubikova
- Department of Chemistry, North Carolina State University Raleigh NC 27695 USA
| | - James K McCusker
- Department of Chemistry, Michigan State University East Lansing MI 48824 USA
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9
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Abstract
Cobalt compounds might enable cheaper and more-complex photocatalysis processes.
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Affiliation(s)
- Polina Yaltseva
- 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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10
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Chan AY, Ghosh A, Yarranton JT, Twilton J, Jin J, Arias-Rotondo DM, Sakai HA, McCusker JK, MacMillan DWC. Exploiting the Marcus inverted region for first-row transition metal-based photoredox catalysis. Science 2023; 382:191-197. [PMID: 37824651 PMCID: PMC10690870 DOI: 10.1126/science.adj0612] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 08/28/2023] [Indexed: 10/14/2023]
Abstract
Second- and third-row transition metal complexes are widely employed in photocatalysis, whereas earth-abundant first-row transition metals have found only limited use because of the prohibitively fast decay of their excited states. We report an unforeseen reactivity mode for productive photocatalysis that uses cobalt polypyridyl complexes as photocatalysts by exploiting Marcus inverted region behavior that couples increases in excited-state energies with increased excited-state lifetimes. These cobalt (III) complexes can engage in bimolecular reactivity by virtue of their strong redox potentials and sufficiently long excited-state lifetimes, catalyzing oxidative C(sp2)-N coupling of aryl amides with challenging sterically hindered aryl boronic acids. More generally, the results imply that chromophores can be designed to increase excited-state lifetimes while simultaneously increasing excited-state energies, providing a pathway for the use of relatively abundant metals as photoredox catalysts.
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Affiliation(s)
- Amy Y. Chan
- Merck Center for Catalysis at Princeton University, Princeton, NJ 08544, USA
| | - Atanu Ghosh
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | | | - Jack Twilton
- Merck Center for Catalysis at Princeton University, Princeton, NJ 08544, USA
| | - Jian Jin
- Merck Center for Catalysis at Princeton University, Princeton, NJ 08544, USA
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | | | - Holt A. Sakai
- Merck Center for Catalysis at Princeton University, Princeton, NJ 08544, USA
| | - James K. McCusker
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
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11
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Alowakennu MM, Ghosh A, McCusker JK. Direct Evidence for Excited Ligand Field State-based Oxidative Photoredox Chemistry of a Cobalt(III) Polypyridyl Photosensitizer. J Am Chem Soc 2023; 145:20786-20791. [PMID: 37703518 DOI: 10.1021/jacs.3c09374] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
Increasing interest in sustainable chemistry coupled with the quest to explore new reactivity has spurred research on first-row transition metal complexes for potential applications in a variety of settings. One of the more active areas of research is photoredox catalysis, where the synthetically tunable nature of their electronic structures provides a rich palette of options for tailoring their reactivity to a desired chemical transformation. Understanding the mechanism of excited-state reactivity is critical for the informed development of next-generation catalysts, which in turn requires information concerning the propensity of their electronic excited states to engage in the desired electron or energy transfer processes. Herein we provide direct evidence of the highly oxidizing nature of the lowest-energy ligand-field (LF) excited state of a first-row d6-low-spin Co(III) photosensitizer [Co(4,4'-Br2bpy)3]3+ (where 4,4'-Br2bpy is 4,4'-dibromo-2,2'-bipyridine). The redox potential associated with the LF excited state of the Co(III) complex was bracketed by performing bimolecular quenching studies by using a series of simple organic electron donors. Time-resolved absorption spectroscopy confirmed a dynamic quenching process attributed to reductive quenching of the lowest-energy ligand-field excited state of the Co(III) chromophore. Analysis of the Stern-Volmer plots for each chromophore-quencher pair revealed a limiting value of Ered* ∼ 1.25 V vs Fc/Fc+ for the metal-centered excited state, which is significantly stronger than that of more commonly employed transition metal-based photoredox agents such as [Ru(bpy)3]2+ (Ered* = 0.32 V vs Fc/Fc+) and [Ir(ppy)2(bpy)]+ (Ered* = 0.27 V vs Fc/Fc+). These results suggest that this class of chromophores could find utility in applications requiring the activation of oxidatively resistant organic substrates for photoredox catalysis.
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Affiliation(s)
- Micheal M Alowakennu
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
| | - Atanu Ghosh
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
| | - James K McCusker
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
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12
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Lepori M, Schmid S, Barham JP. Photoredox catalysis harvesting multiple photon or electrochemical energies. Beilstein J Org Chem 2023; 19:1055-1145. [PMID: 37533877 PMCID: PMC10390843 DOI: 10.3762/bjoc.19.81] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 07/07/2023] [Indexed: 08/04/2023] Open
Abstract
Photoredox catalysis (PRC) is a cutting-edge frontier for single electron-transfer (SET) reactions, enabling the generation of reactive intermediates for both oxidative and reductive processes via photon activation of a catalyst. Although this represents a significant step towards chemoselective and, more generally, sustainable chemistry, its efficacy is limited by the energy of visible light photons. Nowadays, excellent alternative conditions are available to overcome these limitations, harvesting two different but correlated concepts: the use of multi-photon processes such as consecutive photoinduced electron transfer (conPET) and the combination of photo- and electrochemistry in synthetic photoelectrochemistry (PEC). Herein, we review the most recent contributions to these fields in both oxidative and reductive activations of organic functional groups. New opportunities for organic chemists are captured, such as selective reactions employing super-oxidants and super-reductants to engage unactivated chemical feedstocks, and scalability up to gram scales in continuous flow. This review provides comparisons between the two techniques (multi-photon photoredox catalysis and PEC) to help the reader to fully understand their similarities, differences and potential applications and to therefore choose which method is the most appropriate for a given reaction, scale and purpose of a project.
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Affiliation(s)
- Mattia Lepori
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitatsstraße 31, 93040 Regensburg, Germany
| | - Simon Schmid
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitatsstraße 31, 93040 Regensburg, Germany
| | - Joshua P Barham
- Fakultät für Chemie und Pharmazie, Universität Regensburg, Universitatsstraße 31, 93040 Regensburg, Germany
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13
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de Groot LHM, Ilic A, Schwarz J, Wärnmark K. Iron Photoredox Catalysis-Past, Present, and Future. J Am Chem Soc 2023; 145:9369-9388. [PMID: 37079887 PMCID: PMC10161236 DOI: 10.1021/jacs.3c01000] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
Photoredox catalysis of organic reactions driven by iron has attracted substantial attention throughout recent years, due to potential environmental and economic benefits. In this Perspective, three major strategies were identified that have been employed to date to achieve reactivities comparable to the successful noble metal photoredox catalysis: (1) Direct replacement of a noble metal center by iron in archetypal polypyridyl complexes, resulting in a metal-centered photofunctional state. (2) In situ generation of photoactive complexes by substrate coordination where the reactions are driven via intramolecular electron transfer involving charge-transfer states, for example, through visible-light-induced homolysis. (3) Improving the excited-state lifetimes and redox potentials of the charge-transfer states of iron complexes through new ligand design. We seek to give an overview and evaluation of recent developments in this rapidly growing field and, at the same time, provide an outlook on the future of iron-based photoredox catalysis.
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Affiliation(s)
- Lisa H M de Groot
- Centre for Analysis and Synthesis, Lund University, Lund SE-22100, Sweden
| | - Aleksandra Ilic
- Centre for Analysis and Synthesis, Lund University, Lund SE-22100, Sweden
| | - Jesper Schwarz
- Centre for Analysis and Synthesis, Lund University, Lund SE-22100, Sweden
| | - Kenneth Wärnmark
- Centre for Analysis and Synthesis, Lund University, Lund SE-22100, Sweden
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14
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Ortiz RJ, Herbert DE. Something new under the sun. Nat Chem 2023; 15:446-447. [PMID: 36941395 DOI: 10.1038/s41557-023-01169-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Affiliation(s)
- Robert J Ortiz
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, Winnipeg, Manitoba, Canada
| | - David E Herbert
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, Winnipeg, Manitoba, Canada.
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15
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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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16
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Liu X, Yang D, Liu Z, Wang Y, Liu Y, Wang S, Wang P, Cong H, Chen YH, Lu L, Qi X, Yi H, Lei A. Unraveling the Structure and Reactivity Patterns of the Indole Radical Cation in Regioselective Electrochemical Oxidative Annulations. J Am Chem Soc 2023; 145:3175-3186. [PMID: 36705997 DOI: 10.1021/jacs.2c12902] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Oxidation-induced strategy for inert chemical bond activation through highly active radical cation intermediate has exhibited unique reactivity. Understanding the structure and reactivity patterns of radical cation intermediates is crucial in the mechanistic study and will be beneficial for developing new reactions. In this work, the structure and properties of indole radical cations have been revealed using time-resolved transient absorption spectroscopy, in situ electrochemical UV-vis, and in situ electrochemical electron paramagnetic resonance (EPR) technique. Density functional theory (DFT) calculations were used to explain and predict the regioselectivity of several electrochemical oxidative indole annulations. Based on the understanding of the inherent properties of several indole radical cations, two different regioselective annulations of indoles have been successfully developed under electrochemical oxidation conditions. Varieties of furo[2,3-b]indolines and furo[3,2-b]indolines were synthesized in good yields with high regioselectivities. Our mechanistic insights into indole radical cations will promote the further development of oxidation-induced indole functionalizations.
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Affiliation(s)
- Xing Liu
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China.,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Dali Yang
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China.,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Zhao Liu
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China.,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Yunkun Wang
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China.,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Yichang Liu
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China.,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Shengchun Wang
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China.,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Pengjie Wang
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China.,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Hengjiang Cong
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China.,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Yi-Hung Chen
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Lijun Lu
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China.,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Xiaotian Qi
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Hong Yi
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China
| | - Aiwen Lei
- The Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, Hubei, P. R. China.,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei, P. R. China.,State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. China
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17
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Ogawa T, Sinha N, Pfund B, Prescimone A, Wenger OS. Molecular Design Principles to Elongate the Metal-to-Ligand Charge Transfer Excited-State Lifetimes of Square-Planar Nickel(II) Complexes. J Am Chem Soc 2022; 144:21948-21960. [DOI: 10.1021/jacs.2c08838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Tomohiro Ogawa
- 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
| | - 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
| | - Oliver S. Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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18
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Schmid L, Chábera P, Rüter I, Prescimone A, Meyer F, Yartsev A, Persson P, Wenger OS. Borylation in the Second Coordination Sphere of Fe II Cyanido Complexes and Its Impact on Their Electronic Structures and Excited-State Dynamics. Inorg Chem 2022; 61:15853-15863. [PMID: 36167335 PMCID: PMC9554916 DOI: 10.1021/acs.inorgchem.2c01667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
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Second coordination sphere interactions
of cyanido complexes with hydrogen-bonding solvents and Lewis acids
are known to influence their electronic structures, whereby the non-labile
attachment of B(C6F5)3 resulted in
several particularly interesting new compounds lately. Here, we investigate
the effects of borylation on the properties of two FeII cyanido complexes in a systematic manner by comparing five different
compounds and using a range of experimental techniques. Electrochemical
measurements indicate that borylation entails a stabilization of the
FeII-based t2g-like orbitals by up to 1.65 eV,
and this finding was confirmed by Mössbauer spectroscopy. This
change in the electronic structure has a profound impact on the UV–vis
absorption properties of the borylated complexes compared to the non-borylated
ones, shifting their metal-to-ligand charge transfer (MLCT) absorption
bands over a wide range. Ultrafast UV–vis transient absorption
spectroscopy provides insight into how borylation affects the excited-state
dynamics. The lowest metal-centered (MC) excited states become shorter-lived
in the borylated complexes compared to their cyanido analogues by
a factor of ∼10, possibly due to changes in outer-sphere reorganization
energies associated with their decay to the electronic ground state
as a result of B(C6F5)3 attachment
at the cyanido N lone pair. Borylation
in the second coordination sphere of two well-known
FeII cyanido complexes leads to isocyanoborato complexes.
The effects of borylation on their electronic structure and photophysical
properties are thoroughly investigated with a range of experimental
techniques.
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Affiliation(s)
- Lucius Schmid
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Pavel Chábera
- Department of Chemical Physics, Lund University, P.O. Box 12 4, 22100 Lund, Sweden
| | - Isabelle Rüter
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Alessandro Prescimone
- Department of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, 4058 Basel, Switzerland
| | - Franc Meyer
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Arkady Yartsev
- Department of Chemical Physics, Lund University, P.O. Box 12 4, 22100 Lund, Sweden
| | - Petter Persson
- Theoretical Chemistry Division, Lund University, P.O. Box 124, 22100 Lund, Sweden
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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19
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Bürgin TH, Glaser F, Wenger OS. Shedding Light on the Oxidizing Properties of Spin-Flip Excited States in a Cr III Polypyridine Complex and Their Use in Photoredox Catalysis. J Am Chem Soc 2022; 144:14181-14194. [PMID: 35913126 PMCID: PMC9376921 DOI: 10.1021/jacs.2c04465] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
The photoredox activity of well-known RuII complexes
stems from metal-to-ligand charge transfer (MLCT) excited states,
in which a ligand-based electron can initiate chemical reductions
and a metal-centered hole can trigger oxidations. CrIII polypyridines show similar photoredox properties, although they
have fundamentally different electronic structures. Their photoactive
excited state is of spin-flip nature, differing from the electronic
ground state merely by a change of one electron spin, but with otherwise
identical d-orbital occupancy. We find that the driving-force dependence
for photoinduced electron transfer from 10 different donors to a spin-flip
excited state of a CrIII complex is very similar to that
for a RuII polypyridine, and thereby validate the concept
of estimating the redox potential of d3 spin-flip excited
states in analogous manner as for the MLCT states of d6 compounds. Building on this insight, we use our CrIII complex for photocatalytic reactions not previously explored with
this compound class, including the aerobic bromination of methoxyaryls,
oxygenation of 1,1,2,2-tetraphenylethylene, aerobic hydroxylation
of arylboronic acids, and the vinylation of N-phenyl
pyrrolidine. This work contributes to understanding the fundamental
photochemical properties of first-row transition-metal complexes in
comparison to well-explored precious-metal-based photocatalysts.
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Affiliation(s)
- Tobias H Bürgin
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Felix Glaser
- 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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20
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Jang YJ, An H, Choi S, Hong J, Lee SH, Ahn KH, You Y, Kang EJ. Green-Light-Driven Fe(III)(btz) 3 Photocatalysis in the Radical Cationic [4+2] Cycloaddition Reaction. Org Lett 2022; 24:4479-4484. [PMID: 35687841 DOI: 10.1021/acs.orglett.2c01779] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Green-light-driven FeIII(btz)3 photocatalysis for the radical cationic [4+2] cycloaddition of terminal styrenes and nucleophilic dienes has been investigated. The Fe-MIC (mesoionic carbene) complex forms a ligand-to-metal charge-transfer transition state with relatively high excited-state reduction potentials that can selectively oxidize terminal styrene derivatives. Unique multisubstituted cyclohexenes and structurally complex biorelevant cyclohexenes were constructed, highlighting the usefulness of this mild and practical first-row transition metal complex system.
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Affiliation(s)
- Yu Jeong Jang
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
| | - Hyeju An
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
| | - Seunghee Choi
- Division of Chemical Engineering and Materials Science and Graduate Program in System Health Science and Engineering, Ewha Womans University, Seoul 03760, Korea
| | - Jayeon Hong
- Division of Chemical Engineering and Materials Science and Graduate Program in System Health Science and Engineering, Ewha Womans University, Seoul 03760, Korea
| | - Seung Hyun Lee
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
| | - Kwang-Hyun Ahn
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
| | - Youngmin You
- Division of Chemical Engineering and Materials Science and Graduate Program in System Health Science and Engineering, Ewha Womans University, Seoul 03760, Korea
| | - Eun Joo Kang
- Department of Applied Chemistry, Kyung Hee University, Yongin 17104, Korea
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21
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Yarranton JT, McCusker JK. Ligand-Field Spectroscopy of Co(III) Complexes and the Development of a Spectrochemical Series for Low-Spin d 6 Charge-Transfer Chromophores. J Am Chem Soc 2022; 144:12488-12500. [PMID: 35749670 DOI: 10.1021/jacs.2c04945] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A study of a series of six-coordinate Co(III) complexes has been carried out to quantify spectroscopic parameters for a range of ligands that are commonly employed to realize strong charge-transfer absorptions in low-spin, d6 systems. Identification of any three ligand-field transitions allows for the determination of the splitting parameter (10 Dq) as well as the Racah B and C parameters for a given compound. The data revealed a relatively small spread in the magnitude of 10 Dq, ranging from ca. 23 000 cm-1 in the case of [Co(pyrro-bpy)3]3+ (where pyrro-bpy is 4,4'-dipyrrolidinyl-2,2'-bipyridine) to ca. 26 000 cm-1 for [Co(terpy)2]3+ (where terpy is 2,2':6',2″-terpyridine). Significantly, trends across the series suggest that polypyridyl ligands behave as net π-donors when interacting with Co(III), in contrast to the net π-accepting character they exhibit when bound to second- and third-row metals. The influence of strong σ donation associated with carbene-based ligands was evident from the data acquired for [Co(BMeImPy)2]3+ (where BMeImPy is 3,3'-(pyridine-2,6-diyl)bis(1-methyl-1H-3-imidazolium)), where a 10 Dq value of ca. 30 000 cm-1 was determined. Spectroscopic data were also analyzed for [Fe(bpy)3]2+ using the results on [Co(bpy)3]3+ as a reference point. A value for 10 Dq of 21 000 cm-1 was estimated, indicating a reduction in the ligand-field strength of ca. 3000 cm-1 upon replacing Co(III) with Fe(II). We suggest that this approach of taking advantage of the blueshift of the charge-transfer feature in Co(III) complexes to reveal otherwise obscured ligand-field bands can be a useful tool for the development of new ligand systems to expand the photofunctionality of first-row transition-metal-based chromophores.
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Affiliation(s)
- Jonathan T Yarranton
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
| | - James K McCusker
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
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22
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Cotic A, Cerfontaine S, Slep LD, Elias B, Troian-Gautier L, Cadranel A. A photoinduced mixed valence photoswitch. Phys Chem Chem Phys 2022; 24:15121-15128. [PMID: 35699139 DOI: 10.1039/d2cp01791a] [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
The ground state and photoinduced mixed valence states (GSMV and PIMV, respectively) of a dinuclear (Dp4+) ruthenium(II) complex bearing 2,2'-bipyridine ancillary ligands and a 2,2':4',4'':2'',2'''-quaterpyridine (Lp) bridging ligand were investigated using femtosecond and nanosecond transient absorption spectroscopy, electrochemistry and density functional theory. It was shown that the electronic coupling between the transiently light-generated Ru(II) and Ru(III) centers is HDA ∼ 450 cm-1 in the PIMV state, whereas the electrochemically generated GSMV state showed HDA ∼ 0 cm-1, despite virtually identical Ru-Ru distances. This stemmed from the changes in dihedral angles between the two bpy moieties of Lp, estimated at 30° and 4° for the GSMV and PIMV states, respectively, consistent with a through-bond rather than a through-space mechanism. Electronic coupling can be turned on by using visible light excitation, making Dp4+ a competitive candidate for photoswitching applications. A novel strategy to design photoinduced charge transfer molecular switches is proposed.
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Affiliation(s)
- Agustina Cotic
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina. .,CONICET - Universidad de Buenos Aires, Instituto de Química-Física de Materiales, Medio Ambiente y Energía (INQUIMAE), Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Simon Cerfontaine
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium.
| | - Leonardo D Slep
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina. .,CONICET - Universidad de Buenos Aires, Instituto de Química-Física de Materiales, Medio Ambiente y Energía (INQUIMAE), Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Benjamin Elias
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium.
| | - Ludovic Troian-Gautier
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium.
| | - Alejandro Cadranel
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina. .,CONICET - Universidad de Buenos Aires, Instituto de Química-Física de Materiales, Medio Ambiente y Energía (INQUIMAE), Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.,Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Physical Chemistry I, Egerlandstr. 3, 91058, Erlangen, Germany.,Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Interdisciplinary Center for Molecular Materials, Egerlandstr. 3, 91058, Erlangen, Germany
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23
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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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24
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Herr P, Schwab A, Kupfer S, Wenger OS. Deep‐Red Luminescent Molybdenum(0) Complexes with Bi‐ and Tridentate Isocyanide Chelate Ligands. CHEMPHOTOCHEM 2022. [DOI: 10.1002/cptc.202200052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Patrick Herr
- University of Basel: Universitat Basel Department of Chemistry SWITZERLAND
| | - Alexander Schwab
- Friedrich-Schiller-Universität Jena: Friedrich-Schiller-Universitat Jena Institute of Physical Chemistry GERMANY
| | - Stephan Kupfer
- Friedrich-Schiller-Universität Jena: Friedrich-Schiller-Universitat Jena Institute of Physical Chemistry GERMANY
| | - Oliver S. Wenger
- Universität Basel Departement für Chemie St. Johanns-Ring 19 4056 Basel SWITZERLAND
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25
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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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26
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Mei YK, Min XT, Guo SY, Liu CH, Zhang XX, Ji DW, Wan B, Chen QA. Photo‐Induced Construction of N‐Aryl Amides under Fe Catalysis. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yong-Kang Mei
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Xiang-Ting Min
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Shi-Yu Guo
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Chang-Hui Liu
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Xiang-Xin Zhang
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Ding-Wei Ji
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Boshun Wan
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Qing-An Chen
- Chinese Academy of Sciences Dalian Institute of Chemical Physics 457 Zhongshan Road 116023 Dalian CHINA
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27
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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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28
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DiLuzio S, Connell TU, Mdluli V, Kowalewski JF, Bernhard S. Understanding Ir(III) Photocatalyst Structure-Activity Relationships: A Highly Parallelized Study of Light-Driven Metal Reduction Processes. J Am Chem Soc 2022; 144:1431-1444. [PMID: 35025486 DOI: 10.1021/jacs.1c12059] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
High-throughput synthesis and screening methods were used to measure the photochemical activity of 1440 distinct heteroleptic [Ir(C^N)2(N^N)]+ complexes for the photoreduction of Sn(II) and Zn(II) cations to their corresponding neutral metals. Kinetic data collection was carried out using home-built photoreactors and measured initial rates, obtained through an automated fitting algorithm, spanned between 0-120 μM/s for Sn(0) deposition and 0-90 μM/s for Zn(0) deposition. Photochemical reactivity was compared to photophysical properties previously measured such as deaerated excited state lifetime and emission spectral data for these same complexes; however, no clear correlations among these features were observed. A formal photochemical rate law was then developed to help elucidate the observed reactivity. Initial rates were found to be directly correlated to the product of incident photon flux with three reaction elementary efficiencies: (1) the fraction of light absorbed by the photocatalyst, (2) the fraction of excited state species that are quenched by the electron donor, and (3) the cage escape efficiency. The most active catalysts exhibit high efficiencies for all three steps, and catalyst engineering requirements to maximize these elementary efficiencies were postulated. The kinetic treatment provided the mechanistic information needed to decipher the observed structure/function trends in the high-throughput work.
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Affiliation(s)
- Stephen DiLuzio
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Timothy U Connell
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Velabo Mdluli
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Jakub F Kowalewski
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Stefan Bernhard
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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29
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Genzink MJ, Kidd JB, Swords WB, Yoon TP. Chiral Photocatalyst Structures in Asymmetric Photochemical Synthesis. Chem Rev 2022; 122:1654-1716. [PMID: 34606251 PMCID: PMC8792375 DOI: 10.1021/acs.chemrev.1c00467] [Citation(s) in RCA: 126] [Impact Index Per Article: 63.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Asymmetric catalysis is a major theme of research in contemporary synthetic organic chemistry. The discovery of general strategies for highly enantioselective photochemical reactions, however, has been a relatively recent development, and the variety of photoreactions that can be conducted in a stereocontrolled manner is consequently somewhat limited. Asymmetric photocatalysis is complicated by the short lifetimes and high reactivities characteristic of photogenerated reactive intermediates; the design of catalyst architectures that can provide effective enantiodifferentiating environments for these intermediates while minimizing the participation of uncontrolled racemic background processes has proven to be a key challenge for progress in this field. This review provides a summary of the chiral catalyst structures that have been studied for solution-phase asymmetric photochemistry, including chiral organic sensitizers, inorganic chromophores, and soluble macromolecules. While some of these photocatalysts are derived from privileged catalyst structures that are effective for both ground-state and photochemical transformations, others are structural designs unique to photocatalysis and offer insight into the logic required for highly effective stereocontrolled photocatalysis.
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Affiliation(s)
- Matthew J Genzink
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Jesse B Kidd
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Wesley B Swords
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Tehshik P Yoon
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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30
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Schmid L, Glaser F, Schaer R, Wenger OS. High Triplet Energy Iridium(III) Isocyanoborato Complex for Photochemical Upconversion, Photoredox and Energy Transfer Catalysis. J Am Chem Soc 2022; 144:963-976. [PMID: 34985882 DOI: 10.1021/jacs.1c11667] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cyclometalated Ir(III) complexes are often chosen as catalysts for challenging photoredox and triplet-triplet-energy-transfer (TTET) catalyzed reactions, and they are of interest for upconversion into the ultraviolet spectral range. However, the triplet energies of commonly employed Ir(III) photosensitizers are typically limited to values around 2.5-2.75 eV. Here, we report on a new Ir(III) luminophore, with an unusually high triplet energy near 3.0 eV owing to the modification of a previously reported Ir(III) complex with isocyanoborato ligands. Compared to a nonborylated cyanido precursor complex, the introduction of B(C6F5)3 units in the second coordination sphere results in substantially improved photophysical properties, in particular a high luminescence quantum yield (0.87) and a long excited-state lifetime (13.0 μs), in addition to the high triplet energy. These favorable properties (including good long-term photostability) facilitate exceptionally challenging organic triplet photoreactions and (sensitized) triplet-triplet annihilation upconversion to a fluorescent singlet excited state beyond 4 eV, unusually deep in the ultraviolet region. The new Ir(III) complex photocatalyzes a sigmatropic shift and [2 + 2] cycloaddition reactions that are unattainable with common transition metal-based photosensitizers. In the presence of a sacrificial electron donor, it furthermore is applicable to demanding photoreductions, including dehalogenations, detosylations, and the degradation of a lignin model substrate. Our study demonstrates how rational ligand design of transition-metal complexes (including underexplored second coordination sphere effects) can be used to enhance their photophysical properties and thereby broaden their application potential in solar energy conversion and synthetic photochemistry.
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Affiliation(s)
- Lucius Schmid
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Felix Glaser
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Raoul Schaer
- 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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31
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Ilic A, Schwarz J, Johnson C, de Groot LHM, Kaufhold S, Lomoth R, Wärnmark K. Photoredox Catalysis via Consecutive 2LMCT- and 3MLCT-Excitation of an Fe(III/II)- N-Heterocyclic Carbene Complex. Chem Sci 2022; 13:9165-9175. [PMID: 36093023 PMCID: PMC9383194 DOI: 10.1039/d2sc02122f] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 07/09/2022] [Indexed: 11/21/2022] Open
Abstract
Fe-N-heterocyclic carbene (NHC) complexes attract increasing attention as photosensitisers and photoredox catalysts. Such applications generally rely on sufficiently long excited state lifetimes and efficient bimolecular quenching, which leads to there...
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Affiliation(s)
- Aleksandra Ilic
- Centre for Analysis and Synthesis (CAS), Department of Chemistry, Lund University SE-22100 Lund Sweden
| | - Jesper Schwarz
- Centre for Analysis and Synthesis (CAS), Department of Chemistry, Lund University SE-22100 Lund Sweden
| | - Catherine Johnson
- Department of Chemistry-Ångström Laboratory, Uppsala University SE-75120 Uppsala Sweden
| | - Lisa H M de Groot
- Centre for Analysis and Synthesis (CAS), Department of Chemistry, Lund University SE-22100 Lund Sweden
| | - Simon Kaufhold
- Centre for Analysis and Synthesis (CAS), Department of Chemistry, Lund University SE-22100 Lund Sweden
| | - Reiner Lomoth
- Department of Chemistry-Ångström Laboratory, Uppsala University SE-75120 Uppsala Sweden
| | - Kenneth Wärnmark
- Centre for Analysis and Synthesis (CAS), Department of Chemistry, Lund University SE-22100 Lund Sweden
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32
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Dierks P, Vukadinovic Y, Bauer M. Photoactive iron complexes: more sustainable, but still a challenge. Inorg Chem Front 2022. [DOI: 10.1039/d1qi01112j] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
With the “Criticality Score” used as a benchmark for sustainability – potentials, strategies and challenges are discussed to replace noble metal compounds in photosensitizers by the sustainable alternative iron.
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Affiliation(s)
- Philipp Dierks
- Faculty of Science, Chemistry Department and Center for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany
| | - Yannik Vukadinovic
- Faculty of Science, Chemistry Department and Center for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany
| | - Matthias Bauer
- Faculty of Science, Chemistry Department and Center for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany
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33
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Magra K, Francés‐Monerris A, Cebrián C, Monari A, Haacke S, Gros PC. Bidentate Pyridyl‐NHC Ligands: Synthesis, Ground and Excited State Properties of Their Iron(II) Complexes and the Role of the fac/mer Isomerism. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100818] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Kévin Magra
- Université de Lorraine, CNRS, L2CM 57000 Metz France
| | | | | | - Antonio Monari
- Université de Lorraine, CNRS, LPCT 54000 Nancy France
- Université de de Paris and CNRS, Itodys 75006 Paris France
| | - Stefan Haacke
- Université de Strasbourg, CNRS, IPCMS 67000 Strasbourg France
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34
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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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35
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Affiliation(s)
- Katja Heinze
- Department of Chemistry, Johannes Gutenberg University of Mainz, Mainz, Germany.
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36
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Aydogan A, Bangle RE, Cadranel A, Turlington MD, Conroy DT, Cauët E, Singleton ML, Meyer GJ, Sampaio RN, Elias B, Troian-Gautier L. Accessing Photoredox Transformations with an Iron(III) Photosensitizer and Green Light. J Am Chem Soc 2021; 143:15661-15673. [PMID: 34529421 DOI: 10.1021/jacs.1c06081] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Efficient excited-state electron transfer between an iron(III) photosensitizer and organic electron donors was realized with green light irradiation. This advance was enabled by the use of the previously reported iron photosensitizer, [Fe(phtmeimb)2]+ (phtmeimb = {phenyl[tris(3-methyl-imidazolin-2-ylidene)]borate}, that exhibited long-lived and luminescent ligand-to-metal charge-transfer (LMCT) excited states. A benchmark dehalogenation reaction was investigated with yields that exceed 90% and an enhanced stability relative to the prototypical photosensitizer [Ru(bpy)3]2+. The initial catalytic step is electron transfer from an amine to the photoexcited iron sensitizer, which is shown to occur with a large cage-escape yield. For LMCT excited states, this reductive electron transfer is vectorial and may be a general advantage of Fe(III) photosensitizers. In-depth time-resolved spectroscopic methods, including transient absorption characterization from the ultraviolet to the infrared regions, provided a quantitative description of the catalytic mechanism with associated rate constants and yields.
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Affiliation(s)
- Akin Aydogan
- Université Catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Rachel E Bangle
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Alejandro Cadranel
- Department of Chemistry and Pharmacy, Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany.,Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina.,CONICET - Universidad de Buenos Aires. Instituto de Química Física de Materiales, Medio Ambiente y Energía (INQUIMAE), Pabellón 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Michael D Turlington
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Daniel T Conroy
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Emilie Cauët
- Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing (CP 160/09), Université Libre de Bruxelles, 50 av. F. D. Roosevelt, B-1050 Brussels, Belgium
| | - Michael L Singleton
- Université Catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Gerald J Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Renato N Sampaio
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Benjamin Elias
- Université Catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Ludovic Troian-Gautier
- Université Catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium.,Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States.,Laboratoire de Chimie Organique, Université Libre de Bruxelles (ULB), CP 160/06, 50 avenue F.D. Roosevelt, 1050 Brussels, Belgium
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37
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Wu C, Bian Q, Ding T, Tang M, Zhang W, Xu Y, Liu B, Xu H, Li HB, Fu H. Photoinduced Iron-Catalyzed ipso-Nitration of Aryl Halides via Single-Electron Transfer. ACS Catal 2021. [DOI: 10.1021/acscatal.1c02272] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Cunluo Wu
- Institute of Functional Organic Molecular Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Qilong Bian
- Institute of Functional Organic Molecular Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | | | - Mingming Tang
- Institute of Functional Organic Molecular Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Wenkai Zhang
- Institute of Functional Organic Molecular Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Yuanqing Xu
- Institute of Functional Organic Molecular Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Baoying Liu
- Institute of Functional Organic Molecular Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
| | - Hao Xu
- Institute of Functional Organic Molecular Engineering, College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China
- Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Hai-Bei Li
- School of Ocean, Shandong University, Weihai 264209, China
| | - Hua Fu
- Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China
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38
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Qin Y, Zhu Q, Sun R, Ganley JM, Knowles RR, Nocera DG. Mechanistic Investigation and Optimization of Photoredox Anti-Markovnikov Hydroamination. J Am Chem Soc 2021; 143:10232-10242. [PMID: 34191486 PMCID: PMC8600941 DOI: 10.1021/jacs.1c03644] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The reaction mechanism and the origin of the selectivity for the photocatalytic intermolecular anti-Markovnikov hydroamination of unactivated alkenes with primary amines to furnish secondary amines have been revealed by time-resolved laser kinetics measurements of the key reaction intermediates. We show that back-electron transfer (BET) between the photogenerated aminium radical cation (ARC) and reduced photocatalyst complex (Ir(II)) is nearly absent due to rapid deprotonation of the ARC on the sub-100 ns time scale. The selectivity for primary amine alkylation is derived from the faster addition of the primary ARCs (as compared to secondary ARCs) to alkenes. The turnover of the photocatalyst occurs via the reaction between Ir(II) and a thiyl radical; the in situ formation of an off-cycle disulfide from thiyl radicals suppresses this turnover, diminishing the efficiency of the reaction. With these detailed mechanistic insights, the turnover of the photocatalyst has been optimized, resulting in a >10-fold improvement in the quantum yield. These improvements enabled the development of a scalable flow protocol, demonstrating a potential strategy for practical applications with improved energy efficiency and cost-effectiveness.
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Affiliation(s)
- Yangzhong Qin
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Qilei Zhu
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Rui Sun
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Jacob M Ganley
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Robert R Knowles
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Daniel G Nocera
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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39
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Dierks P, Kruse A, Bokareva OS, Al-Marri MJ, Kalmbach J, Baltrun M, Neuba A, Schoch R, Hohloch S, Heinze K, Seitz M, Kühn O, Lochbrunner S, Bauer M. Distinct photodynamics of κ-N and κ-C pseudoisomeric iron(II) complexes. Chem Commun (Camb) 2021; 57:6640-6643. [PMID: 34126627 DOI: 10.1039/d1cc01716k] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Two closely related FeII complexes with 2,6-bis(1-ethyl-1H-1,2,3-triazol-4yl)pyridine and 2,6-bis(1,2,3-triazol-5-ylidene)pyridine ligands are presented to gain new insights into the photophysics of bis(tridentate) iron(ii) complexes. The [Fe(N^N^N)2]2+ pseudoisomer sensitizes singlet oxygen through a MC state with nanosecond lifetime after MLCT excitation, while the bis(tridentate) [Fe(C^N^C)2]2+ pseudoisomer possesses a similar 3MLCT lifetime as the tris(bidentate) [Fe(C^C)2(N^N)]2+ complexes with four mesoionic carbenes.
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Affiliation(s)
- Philipp Dierks
- Faculty of Science, Chemistry Department and Centre for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany.
| | - Ayla Kruse
- Institute of Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany
| | - Olga S Bokareva
- Institute of Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany and Department of Physical Chemistry, Kazan Federal University, 420008 Kazan, Russia
| | - Mohammed J Al-Marri
- Institute of Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany and College of Engineering, Qatar University, P.O. Box 2713, Doha, Qatar
| | - Jens Kalmbach
- Institute of Inorganic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Marc Baltrun
- Faculty of Science, Chemistry Department and Centre for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany.
| | - Adam Neuba
- Faculty of Science, Chemistry Department and Centre for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany.
| | - Roland Schoch
- Faculty of Science, Chemistry Department and Centre for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany.
| | - Stephan Hohloch
- University of Innsbruck, Faculty of Chemistry and Pharmacy, Institute for General, Inorganic and Theoretical Chemistry, Innrain 80-82, Innsbruck 6020, Austria
| | - Katja Heinze
- Department of Chemistry, Johannes Gutenberg, University of Mainz, 55128 Mainz, Germany
| | - Michael Seitz
- Institute of Inorganic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Oliver Kühn
- Institute of Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany
| | - Stefan Lochbrunner
- Institute of Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany
| | - Matthias Bauer
- Faculty of Science, Chemistry Department and Centre for Sustainable Systems Design, Paderborn University, 33098 Paderborn, Germany.
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40
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Paulus BC, Nielsen KC, Tichnell CR, Carey MC, McCusker JK. A Modular Approach to Light Capture and Synthetic Tuning of the Excited-State Properties of Fe(II)-Based Chromophores. J Am Chem Soc 2021; 143:8086-8098. [PMID: 34014077 DOI: 10.1021/jacs.1c02451] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The development of chromophores based on earth-abundant transition metals whose photophysical properties are dominated by their charge-transfer excited states has inspired considerable research over the past decade. One challenge associated with this effort is satisfying the dual requirements of a strong ligand field and chemical tunability of the compound's absorptive cross-section. Herein we explore one possible approach using a heteroleptic compositional motif that combines both of these attributes into a single compound. With the parent complex [Fe(phen)3]2+ (1; where phen is 1,10-phenanthroline) as the starting material, replacement of one of the phen ligands for two cyanides to obtain Fe(phen)2(CN)2 (2) allows for conversion to [Fe(phen)2(C4H10N4)]2+ (3), a six-coordinate Fe(II) complex whose coordination sphere consists of two chelating polypyridyl ligands and one bidentate carbene-based donor. Ground-state absorption spectra of all three compounds exhibit 1A1 → 1MLCT transition(s) associated with the phen ligands that are relatively insensitive to the identity of the third counterligand(s). Ultrafast time-resolved electronic absorption measurements revealed lifetimes for the MLCT excited states of compounds 1 and 2 of 180 ± 30 and 250 ± 90 fs, respectively, values that are typical for iron(II)-based polypyridyl complexes. The corresponding kinetics for compound 3 were substantially slower at 7.4 ± 0.9 ps; the spectral evolution associated with these dynamics confirms that these kinetics are tracking the MLCT excited state and, more importantly, are coupled to ground-state recovery from this excited state. The data are interpreted in terms of a modulation of the relative energies of the MLCT and ligand-field states across the series, leading to a systematic destabilization of metal-localized ligand-field excited states such that the low-energy portions of the charge-transfer and ligand-field manifolds are at or near an energetic inversion point in compound 3. We believe these results illustrate the potential for a modular, orthogonal approach to chromophore design in which part of the coordination sphere can be targeted for light absorption while another can be used to tune electronic-state energetics.
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Affiliation(s)
- Bryan C Paulus
- Department of Chemistry, Michigan State University 578 South Shaw Lane, East Lansing, Michigan 48824, United States
| | - Karl C Nielsen
- Department of Chemistry, Michigan State University 578 South Shaw Lane, East Lansing, Michigan 48824, United States
| | - Christopher R Tichnell
- Department of Chemistry, Michigan State University 578 South Shaw Lane, East Lansing, Michigan 48824, United States
| | - Monica C Carey
- Department of Chemistry, Michigan State University 578 South Shaw Lane, East Lansing, Michigan 48824, United States
| | - James K McCusker
- Department of Chemistry, Michigan State University 578 South Shaw Lane, East Lansing, Michigan 48824, United States
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41
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Vela J, Weiss EA. Periodic TableTalks: The Elements Never Go Out of Style. Inorg Chem 2021; 60:6957-6963. [PMID: 33899476 DOI: 10.1021/acs.inorgchem.1c01094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Javier Vela
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.,Ames Laboratory, Ames, Iowa 50011, United States
| | - Emily A Weiss
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
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42
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De Bonfils P, Péault L, Nun P, Coeffard V. State of the Art of Bodipy‐Based Photocatalysts in Organic Synthesis. European J Org Chem 2021. [DOI: 10.1002/ejoc.202001446] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Paul De Bonfils
- CEISAM UMR CNRS 6230 Université de Nantes 44000 Nantes France
| | - Louis Péault
- CEISAM UMR CNRS 6230 Université de Nantes 44000 Nantes France
| | - Pierrick Nun
- CEISAM UMR CNRS 6230 Université de Nantes 44000 Nantes France
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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
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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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Aydogan A, Bangle RE, De Kreijger S, Dickenson JC, Singleton ML, Cauët E, Cadranel A, Meyer GJ, Elias B, Sampaio RN, Troian-Gautier L. Mechanistic investigation of a visible light mediated dehalogenation/cyclisation reaction using iron( iii), iridium( iii) and ruthenium( ii) photosensitizers. Catal Sci Technol 2021. [DOI: 10.1039/d1cy01771c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The identification of reaction mechanisms unique to the iron, ruthenium, and iridium PS represents progress towards the long-sought goal of utilizing earth-abundant, first-row transition metals for emerging energy and environmental applications.
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Affiliation(s)
- Akin Aydogan
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Rachel E. Bangle
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA
| | - Simon De Kreijger
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - John C. Dickenson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA
| | - Michael L. Singleton
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Emilie Cauët
- Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing (CP 160/09), Université libre de Bruxelles, 50 av. F. D. Roosevelt, B-1050 Brussels, Belgium
| | - Alejandro Cadranel
- Department of Chemistry and Pharmacy, Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
- CONICET – Universidad de Buenos Aires. Instituto de Química Física de Materiales, Medio Ambiente y Energía (INQUIMAE), Pabellón 2, Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Gerald J. Meyer
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA
| | - Benjamin Elias
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
| | - Renato N. Sampaio
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA
- Chemistry Division, Brookhaven National Laboratory, Upton, NY 11973-5000, USA
| | - Ludovic Troian-Gautier
- Université catholique de Louvain (UCLouvain), Institut de la Matière Condensée et des Nanosciences (IMCN), Molecular Chemistry, Materials and Catalysis (MOST), Place Louis Pasteur 1, bte L4.01.02, 1348 Louvain-la-Neuve, Belgium
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