1
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Wellauer J, Ziereisen F, Sinha N, Prescimone A, Velić A, Meyer F, Wenger OS. Iron(III) Carbene Complexes with Tunable Excited State Energies for Photoredox and Upconversion. J Am Chem Soc 2024; 146. [PMID: 38598280 PMCID: PMC11046485 DOI: 10.1021/jacs.4c00605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/13/2024] [Accepted: 03/19/2024] [Indexed: 04/11/2024]
Abstract
Substituting precious elements in luminophores and photocatalysts by abundant first-row transition metals remains a significant challenge, and iron continues to be particularly attractive owing to its high natural abundance and low cost. Most iron complexes known to date face severe limitations due to undesirably efficient deactivation of luminescent and photoredox-active excited states. Two new iron(III) complexes with structurally simple chelate ligands enable straightforward tuning of ground and excited state properties, contrasting recent examples, in which chemical modification had a minor impact. Crude samples feature two luminescence bands strongly reminiscent of a recent iron(III) complex, in which this observation was attributed to dual luminescence, but in our case, there is clear-cut evidence that the higher-energy luminescence stems from an impurity and only the red photoluminescence from a doublet ligand-to-metal charge transfer (2LMCT) excited state is genuine. Photoinduced oxidative and reductive electron transfer reactions with methyl viologen and 10-methylphenothiazine occur with nearly diffusion-limited kinetics. Photocatalytic reactions not previously reported for this compound class, in particular the C-H arylation of diazonium salts and the aerobic hydroxylation of boronic acids, were achieved with low-energy red light excitation. Doublet-triplet energy transfer (DTET) from the luminescent 2LMCT state to an anthracene annihilator permits the proof of principle for triplet-triplet annihilation upconversion based on a molecular iron photosensitizer. These findings are relevant for the development of iron complexes featuring photophysical and photochemical properties competitive with noble-metal-based compounds.
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Affiliation(s)
- Joël Wellauer
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Fabienne Ziereisen
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Narayan Sinha
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Alessandro Prescimone
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Ajdin Velić
- University
of Göttingen, Institute of Inorganic Chemistry, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Franc Meyer
- University
of Göttingen, Institute of Inorganic Chemistry, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Oliver S. Wenger
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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2
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Azpilcueta-Nicolas CR, Lumb JP. Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters. Beilstein J Org Chem 2024; 20:346-378. [PMID: 38410775 PMCID: PMC10896223 DOI: 10.3762/bjoc.20.35] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 01/29/2024] [Indexed: 02/28/2024] Open
Abstract
Due to their ease of preparation, stability, and diverse reactivity, N-hydroxyphthalimide (NHPI) esters have found many applications as radical precursors. Mechanistically, NHPI esters undergo a reductive decarboxylative fragmentation to provide a substrate radical capable of engaging in diverse transformations. Their reduction via single-electron transfer (SET) can occur under thermal, photochemical, or electrochemical conditions and can be influenced by a number of factors, including the nature of the electron donor, the use of Brønsted and Lewis acids, and the possibility of forming charge-transfer complexes. Such versatility creates many opportunities to influence the reaction conditions, providing a number of parameters with which to control reactivity. In this perspective, we provide an overview of the different mechanisms for radical reactions involving NHPI esters, with an emphasis on recent applications in radical additions, cyclizations and decarboxylative cross-coupling reactions. Within these reaction classes, we discuss the utility of the NHPI esters, with an eye towards their continued development in complexity-generating transformations.
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Affiliation(s)
| | - Jean-Philip Lumb
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
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3
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Shee M, Zhang D, Banerjee M, Roy S, Pal B, Anoop A, Yuan Y, Singh NDP. Interrogating bioinspired ESIPT/PCET-based Ir(iii)-complexes as organelle-targeted phototherapeutics: a redox-catalysis under hypoxia to evoke synergistic ferroptosis/apoptosis. Chem Sci 2023; 14:9872-9884. [PMID: 37736623 PMCID: PMC10510766 DOI: 10.1039/d3sc03096b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 08/25/2023] [Indexed: 09/23/2023] Open
Abstract
Installing proton-coupled electron transfer (PCET) in Ir-complexes is indeed a newly explored phenomenon, offering high quantum efficiency and tunable photophysics; however, the prospects for its application in various fields, including interrogating biological systems, are quite open and exciting. Herein, we developed various organelle-targeted Ir(iii)-complexes by leveraging the photoinduced PCET process to see the opportunities in phototherapeutic application and investigate the underlying mechanisms of action (MOAs). We diversified the ligands' nature and also incorporated a H-bonded benzimidazole-phenol (BIP) moiety with π-conjugated ancillary ligands in Ir(iii) to study the excited-state intramolecular proton transfer (ESIPT) process for tuning dual emission bands and to tempt excited-state PCET. These visible or two-photon-NIR light activatable Ir-catalysts generate reactive hydroxyl radicals (˙OH) and simultaneously oxidize electron donating biomolecules (1,4-dihydronicotinamide adenine dinucleotide or glutathione) to disrupt redox homeostasis, downregulate the GPX4 enzyme, and amplify oxidative stress and lipid peroxide (LPO) accumulation. Our homogeneous photocatalytic platform efficiently triggers organelle dysfunction mediated by a Fenton-like pathway with spatiotemporal control upon illumination to evoke ferroptosis poised with the synergistic action of apoptosis in a hypoxic environment leading to cell death. Ir2 is the most efficient photochemotherapy agent among others, which provided profound cytophototoxicity to 4T1 and MCF-7 cancerous cells and inhibited solid hypoxic tumor growth in vitro and in vivo.
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Affiliation(s)
- Maniklal Shee
- Department of Chemistry, Indian Institute of Technology Kharagpur West Bengal-721302 India
| | - Dan Zhang
- School of Biomedical Sciences and Engineering, South China University of Technology, Guangzhou International Campus Guangzhou 511442 PR China
| | - Moumita Banerjee
- Department of Chemistry, Indian Institute of Technology Kharagpur West Bengal-721302 India
| | - Samrat Roy
- Department of Physics, Indian Institute of Science Education and Research Kolkata Mohanpur West Bengal 741246 India
| | - Bipul Pal
- Department of Physics, Indian Institute of Science Education and Research Kolkata Mohanpur West Bengal 741246 India
| | - Anakuthil Anoop
- Department of Chemistry, Indian Institute of Technology Kharagpur West Bengal-721302 India
| | - Youyong Yuan
- School of Biomedical Sciences and Engineering, South China University of Technology, Guangzhou International Campus Guangzhou 511442 PR China
| | - N D Pradeep Singh
- Department of Chemistry, Indian Institute of Technology Kharagpur West Bengal-721302 India
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4
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Wu J, Shu C, Li Z, Noble A, Aggarwal VK. Photoredox-Catalyzed Decarboxylative Bromination, Chlorination and Thiocyanation Using Inorganic Salts. Angew Chem Int Ed Engl 2023; 62:e202309684. [PMID: 37522816 PMCID: PMC10952529 DOI: 10.1002/anie.202309684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 07/28/2023] [Accepted: 07/31/2023] [Indexed: 08/01/2023]
Abstract
Decarboxylative halogenation reactions of alkyl carboxylic acids are highly valuable reactions for the synthesis of structurally diverse alkyl halides. However, many reported protocols rely on stoichiometric strong oxidants or highly electrophilic halogenating agents. Herein, we describe visible-light photoredox-catalyzed decarboxylative halogenation reactions of N-hydroxyphthalimide-activated carboxylic acids that avoid stoichiometric oxidants and use inexpensive inorganic halide salts as the halogenating agents. Bromination with lithium bromide proceeds under simple, transition-metal-free conditions using an organic photoredox catalyst and no other additives, whereas dual photoredox-copper catalysis is required for chlorination with lithium chloride. The mild conditions display excellent functional-group tolerance, which is demonstrated through the transformation of a diverse range of structurally complex carboxylic acid containing natural products into the corresponding alkyl bromides and chlorides. In addition, we show the generality of the dual photoredox-copper-catalyzed decarboxylative functionalization with inorganic salts by extension to thiocyanation with potassium thiocyanide, which was applied to the synthesis of complex alkyl thiocyanates.
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Affiliation(s)
- Jingjing Wu
- School of ChemistryUniversity of BristolCantock's CloseBS8 1TSBristolUK
- Current address: Frontiers Science Center for Transformative MoleculesSchool of Chemistry and Chemical EngineeringZhangjiang Institute for Advanced StudyShanghai Jiao Tong UniversityNo. 429, Zhangheng Road200213ShanghaiChina
| | - Chao Shu
- School of ChemistryUniversity of BristolCantock's CloseBS8 1TSBristolUK
- Current address: National Key Laboratory of Green PesticideCollege of ChemistryCentral China Normal University (CCNU)152 Luoyu Road430079WuhanHubeiChina
| | - Zhihang Li
- School of ChemistryUniversity of BristolCantock's CloseBS8 1TSBristolUK
| | - Adam Noble
- School of ChemistryUniversity of BristolCantock's CloseBS8 1TSBristolUK
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5
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Bürgin T, Ogawa T, Wenger OS. Better Covalent Connection in a Molecular Triad Enables More Efficient Photochemical Energy Storage. Inorg Chem 2023; 62:13597-13607. [PMID: 37562775 PMCID: PMC10445269 DOI: 10.1021/acs.inorgchem.3c02008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Indexed: 08/12/2023]
Abstract
Numerous studies have explored the kinetics of light-induced charge separation and thermal charge recombination in donor-acceptor compounds, but quantum efficiencies have rarely been investigated. Here, we report on two essentially isomeric molecular triads, both comprising a π-extended tetrathiafulvalene (ExTTF) donor, a ruthenium(II)-based photosensitizer, and a naphthalene diimide (NDI) acceptor. The key difference between the two triads is how the NDI acceptor is connected. Linkage at the NDI core provides stronger electronic coupling to the other molecular components than connection via the nitrogen atoms of NDI. This change in molecular connectivity is expected to accelerate both energy-storing charge separation and energy-wasting charge recombination processes, but it is not a priori clear how this will affect the triad's ability to store photochemical energy; any gain resulting from faster charge separation could potentially be (over)compensated by losses through accelerated charge recombination. The new key insight emerging from our study is that the quantum yield for the formation of a long-lived charge-separated state increases by a factor of 5 when going from nitrogen- to core-connected NDI, providing the important proof of concept that better molecular connectivity indeed enables more efficient photochemical energy storage. The physical origin of this behavior seems to root in different orbital connectivity pathways for charge separation and charge recombination, as well as in differences in the relevant orbital interactions depending on NDI connection. Our work provides guidelines for how to discriminate between energy-storing and energy-wasting electron transfer reactions in order to improve the quantum yields for photochemical energy storage and solar energy conversion.
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Affiliation(s)
- Tobias
H. Bürgin
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, Basel 4056, Switzerland
| | - Tomohiro Ogawa
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, Basel 4056, Switzerland
- Graduate
School of Science and Engineering, University
of Toyama, Toyama 930-8555, Japan
| | - Oliver S. Wenger
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, Basel 4056, Switzerland
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6
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Murray PRD, Leibler INM, Hell SM, Villalona E, Doyle AG, Knowles RR. Radical Redox Annulations: A General Light-Driven Method for the Synthesis of Saturated Heterocycles. ACS Catal 2022; 12:13732-13740. [DOI: 10.1021/acscatal.2c04316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/14/2022] [Indexed: 11/29/2022]
Affiliation(s)
- Philip R. D. Murray
- Department of Chemistry, Princeton University, Princeton, New Jersey08544, United States
| | | | - Sandrine M. Hell
- Department of Chemistry, Princeton University, Princeton, New Jersey08544, United States
| | - Eris Villalona
- Department of Chemistry, Princeton University, Princeton, New Jersey08544, United States
| | - Abigail G. Doyle
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California90095, United States
| | - Robert R. Knowles
- Department of Chemistry, Princeton University, Princeton, New Jersey08544, United States
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7
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Zhang S, Ma L, Ma W, Chen L, Gao K, Yu S, Zhang M, Zhang L, He G. Selenoviologen‐Appendant Metallacycles with Highly Stable Radical Cations and Long‐Lived Charge Separation States for Electrochromism and Photocatalysis. Angew Chem Int Ed Engl 2022; 61:e202209054. [DOI: 10.1002/anie.202209054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Sikun Zhang
- Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education Frontier Institute of Science and Technology Xi'an Jiaotong University Xi'an Shaanxi 710054 China
| | - Lingzhi Ma
- State Key Laboratory for Mechanical Behavior of Materials, Shaanxi International Research Center for Soft Matter, School of Materials Science and Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China
| | - Wenqiang Ma
- Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education Frontier Institute of Science and Technology Xi'an Jiaotong University Xi'an Shaanxi 710054 China
| | - Long Chen
- State Key Laboratory for Mechanical Behavior of Materials, Shaanxi International Research Center for Soft Matter, School of Materials Science and Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China
| | - Kai Gao
- State Key Laboratory for Mechanical Behavior of Materials, Shaanxi International Research Center for Soft Matter, School of Materials Science and Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China
| | - Shi Yu
- School of Materials Science & Engineering Chang'an University Xi'an Shaanxi 710064 China
| | - Mingming Zhang
- State Key Laboratory for Mechanical Behavior of Materials, Shaanxi International Research Center for Soft Matter, School of Materials Science and Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China
| | - Lei Zhang
- School of Optoelectronic Engineering Xidian University Xi'an Shaanxi 710126 China
| | - Gang He
- Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education Frontier Institute of Science and Technology Xi'an Jiaotong University Xi'an Shaanxi 710054 China
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8
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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: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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9
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Zhang S, Ma L, Ma W, Chen L, Gao K, Yu S, Zhang M, Zhang L, He G. Selenoviologen‐Appendant Metallacycles with Highly Stable Radical Cations and Long‐Lived Charge Separation States for Electrochromism and Photocatalysis. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202209054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Sikun Zhang
- Xi'an Jiaotong University Frontier Institute of Science and Technology Xi'an CHINA
| | - Lingzhi Ma
- Xi'an Jiaotong University School of Materials Science and Engineering CHINA
| | - Wenqiang Ma
- Xi'an Jiaotong University Frontier Institute of Science and Technology CHINA
| | - Long Chen
- Xi'an Jiaotong University School of Materials Science and Engineering CHINA
| | - Kai Gao
- Xi'an Jiaotong University School of Materials Science and Engineering CHINA
| | - Shi Yu
- Chang'an University School of Materials Science & Engineering CHINA
| | - Mingming Zhang
- Xi'an Jiaotong University School of Materials Science and Engineering CHINA
| | - Lei Zhang
- Xidian University School of Optoelectronic Engineering CHINA
| | - Gang He
- Xi'an Jiaotong University Frontier Institute of Science and Technology No 99, Yanxiang Road 710054 Xi'an CHINA
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10
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Arsenault EA, Guerra WD, Shee J, Reyes Cruz EA, Yoneda Y, Wadsworth BL, Odella E, Urrutia MN, Kodis G, Moore GF, Head-Gordon M, Moore AL, Moore TA, Fleming GR. Concerted Electron-Nuclear Motion in Proton-Coupled Electron Transfer-Driven Grotthuss-Type Proton Translocation. J Phys Chem Lett 2022; 13:4479-4485. [PMID: 35575065 PMCID: PMC9150097 DOI: 10.1021/acs.jpclett.2c00585] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/02/2022] [Indexed: 06/15/2023]
Abstract
Photoinduced proton-coupled electron transfer and long-range two-proton transport via a Grotthuss-type mechanism are investigated in a biomimetic construct. The ultrafast, nonequilibrium dynamics are assessed via two-dimensional electronic vibrational spectroscopy, in concert with electrochemical and computational techniques. A low-frequency mode is identified experimentally and found to promote double proton and electron transfer, supported by recent theoretical simulations of a similar but abbreviated (non-photoactive) system. Excitation frequency peak evolution and center line slope dynamics show direct evidence of strongly coupled nuclear and electronic degrees of freedom, from which we can conclude that the double proton and electron transfer processes are concerted (up to an uncertainty of 24 fs). The nonequilibrium pathway from the photoexcited Franck-Condon region to the E2PT state is characterized by an ∼110 fs time scale. This study and the tools presented herein constitute a new window into hot charge transfer processes involving an electron and multiple protons.
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Affiliation(s)
- Eric A. Arsenault
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli
Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, United States
| | - Walter D. Guerra
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - James Shee
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Edgar A. Reyes Cruz
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- The Biodesign
Institute Center for Applied Structural Discovery (CASD), Tempe, Arizona 85287, United States
| | - Yusuke Yoneda
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli
Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, United States
| | - Brian L. Wadsworth
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- The Biodesign
Institute Center for Applied Structural Discovery (CASD), Tempe, Arizona 85287, United States
| | - Emmanuel Odella
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Maria N. Urrutia
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Gerdenis Kodis
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- The Biodesign
Institute Center for Applied Structural Discovery (CASD), Tempe, Arizona 85287, United States
| | - Gary F. Moore
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- The Biodesign
Institute Center for Applied Structural Discovery (CASD), Tempe, Arizona 85287, United States
| | - Martin Head-Gordon
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Ana L. Moore
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Thomas A. Moore
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
| | - Graham R. Fleming
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Molecular
Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli
Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, United States
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12
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Millet A, Cesana PT, Sedillo K, Bird MJ, Schlau-Cohen GS, Doyle AG, MacMillan DWC, Scholes GD. Bioinspired Supercharging of Photoredox Catalysis for Applications in Energy and Chemical Manufacturing. Acc Chem Res 2022; 55:1423-1434. [PMID: 35471814 DOI: 10.1021/acs.accounts.2c00083] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
ConspectusFor more than a decade, photoredox catalysis has been demonstrating that when photoactive catalysts are irradiated with visible light, reactions occur under milder, cheaper, and environmentally friendlier conditions. Furthermore, this methodology allows for the activation of abundant chemicals into valuable products through novel mechanisms that are otherwise inaccessible. The photoredox approach, however, has been primarily used for pharmaceutical applications, where its implementation has been highly effective, but typically with a more rudimentary understanding of the mechanisms involved in these transformations. From a global perspective, the manufacture of everyday chemicals by the chemical industry as a whole currently accounts for 10% of total global energy consumption and generates 7% of the world's greenhouse gases annually. In this context, the Bio-Inspired Light-Escalated Chemistry (BioLEC) Energy Frontier Research Center (EFRC) was founded to supercharge the photoredox approach for applications in chemical manufacturing aimed at reducing its energy consumption and emissions burden, by using bioinspired schemes to harvest multiple electrons to drive endothermically uphill chemical reactions. The Center comprises a diverse group of researchers with expertise that includes synthetic chemistry, biophysics, physical chemistry, and engineering. The team works together to gain a deeper understanding of the mechanistic details of photoredox reactions while amplifying the applications of these light-driven methodologies.In this Account, we review some of the major advances in understanding, approach, and applicability made possible by this collaborative Center. Combining sophisticated spectroscopic tools and photophysics tactics with enhanced photoredox reactions has led to the development of novel techniques and reactivities that greatly expand the field and its capabilities. The Account is intended to highlight how the interplay between disciplines can have a major impact and facilitate the advance of the field. For example, techniques such as time-resolved dielectric loss (TRDL) and pulse radiolysis are providing mechanistic insights not previously available. Hypothesis-driven photocatalyst design thus led to broadening of the scope of several existing transformations. Moreover, bioconjugation approaches and the implementation of triplet-triplet annihilation mechanisms created new avenues for the exploration of reactivities. Lastly, our multidisciplinary approach to tackling real-world problems has inspired the development of efficient methods for the depolymerization of lignin and artificial polymers.
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Affiliation(s)
- Agustin Millet
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul T. Cesana
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Kassandra Sedillo
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Matthew J. Bird
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Gabriela S. Schlau-Cohen
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Abigail G. Doyle
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - David W. C. MacMillan
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Gregory D. Scholes
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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Guerra WD, Sayre HJ, Ripberger HH, Odella E, Scholes GD, Moore TA, Knowles RR, Moore AL. Ir(III)-Naphthoquinone complex as a platform for photocatalytic activity. Journal of Photochemistry and Photobiology 2022; 9:100098. [DOI: 10.1016/j.jpap.2021.100098] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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14
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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15
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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: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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16
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Shen GB, Qian BC, Zhang GS, Luo GZ, Fu YH, Zhu XQ. Thermodynamics regulated organic hydride/acid pairs as novel organic hydrogen reductants. Org Chem Front 2022. [DOI: 10.1039/d2qo01605b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Organic hydride/acid pairs could realize transformation of N-substituted organic hydrides from hydride reductants to thermodynamics regulated hydrogen reductants on conveniently choosing suitable organic hydrides and acids with various acidities.
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Affiliation(s)
- Guang-Bin Shen
- School of Medical Engineering, Jining Medical University, Jining, Shandong, 272000, P. R. China
| | - Bao-Chen Qian
- School of Medical Engineering, Jining Medical University, Jining, Shandong, 272000, P. R. China
| | - Gao-Shuai Zhang
- School of Medical Engineering, Jining Medical University, Jining, Shandong, 272000, P. R. China
| | - Guang-Ze Luo
- School of Medical Engineering, Jining Medical University, Jining, Shandong, 272000, P. R. China
| | - Yan-Hua Fu
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology, Anyang, Henan, 455000, China
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Tianjin 300071, China
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17
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Kim S, Choi J, Cho DW, Ahn M, Eom S, Kim J, Wee KR, Ihee H. Solvent-modulated proton-coupled electron transfer in an iridium complex with an ESIPT ligand. Chem Sci 2022; 13:3809-3818. [PMID: 35432886 PMCID: PMC8966730 DOI: 10.1039/d1sc07250a] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 03/03/2022] [Indexed: 11/21/2022] Open
Abstract
Proton-coupled electron transfer (PCET), an essential process in nature with a well-known example of photosynthesis, has recently been employed in metal complexes to improve the energy conversion efficiency; however, a profound understanding of the mechanism of PCET in metal complexes is still lacking. In this study, we synthesized cyclometalated Ir complexes strategically designed to exploit the excited-state intramolecular proton transfer (ESIPT) of the ancillary ligand and studied their photoinduced PCET in both aprotic and protic solvent environments using femtosecond transient absorption spectroscopy and density functional theory (DFT) and time-dependent DFT calculations. The data reveal solvent-modulated PCET, where charge transfer follows proton transfer in an aprotic solvent and the temporal order of charge transfer and proton transfer is reversed in a protic solvent. In the former case, ESIPT from the enol form to the keto form, which precedes the charge transfer from Ir to the ESIPT ligand, improves the efficiency of metal-to-ligand charge transfer. This finding demonstrates the potential to control the PCET reaction in the desired direction and the efficiency of charge transfer by simply perturbing the external hydrogen-bonding network with the solvent. The iridium complex with an ESIPT ligand shows solvent-modulated proton-coupled electron transfer, in which the temporal order of proton transfer and charge transfer is altered by the solvent environment.![]()
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Affiliation(s)
- Siin Kim
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science Daejeon 34141 Republic of Korea
| | - Jungkweon Choi
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science Daejeon 34141 Republic of Korea
| | - Dae Won Cho
- Department of Advanced Materials Chemistry, Korea University, Sejong Campus Sejong 30019 Korea
| | - Mina Ahn
- Department of Chemistry and Institute of Natural Science, Daegu University Gyeongsan 38453 Republic of Korea
| | - Seunghwan Eom
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science Daejeon 34141 Republic of Korea
| | - Jungmin Kim
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science Daejeon 34141 Republic of Korea
| | - Kyung-Ryang Wee
- Department of Chemistry and Institute of Natural Science, Daegu University Gyeongsan 38453 Republic of Korea
| | - Hyotcherl Ihee
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science Daejeon 34141 Republic of Korea
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