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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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2
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Aderinto SO, John T, Onawole A, Galleh RP, Thomas JA. Iridium(III)-based minor groove binding complexes as DNA photocleavage agents. Dalton Trans 2024; 53:7282-7291. [PMID: 38466178 DOI: 10.1039/d4dt00171k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Transition metal complexes containing the qtpy ligand (2':4,4'':4',4'''-quaterpyridyl) are known to be DNA intercalators or minor groove binders. In this study, new tricationic iridium(III) complexes of qtpy are reported. Both [Ir(bpy)2(qtpy)]3+1 and [Ir(phen)2(qtpy)]3+2 display good water solubility as chloride salts. The complexes possess high-energy excited states, which are quenched in the presence of duplex DNA and even by the mononucleotides guanosine monophosphate and adenosine monophosphate. Further studies reveal that although the complexes bind to quadruplex DNA, they display a preference for duplex structures, which are bound with an order of magnitude higher affinities than their isostructural dicationic RuII-analogues. Detailed molecular dynamics simulations confirm that the complexes are groove binders through the insertion of, predominantly, the qtpy ligand into the minor groove. Photoirradiation of 1 in the presence of plasmid DNA confirms that this class of complexes can function as synthetic photonucleases by cleaving DNA.
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Affiliation(s)
- Stephen O Aderinto
- Department of Chemistry, University of Sheffield, Sheffield, S3 7HF, UK.
| | - Torsten John
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Abdulmujeeb Onawole
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD 4072, Australia
| | | | - Jim A Thomas
- Department of Chemistry, University of Sheffield, Sheffield, S3 7HF, UK.
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3
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Stitch M, Avagliano D, Graczyk D, Clark IP, González L, Towrie M, Quinn SJ. Good Vibrations Report on the DNA Quadruplex Binding of an Excited State Amplified Ruthenium Polypyridyl IR Probe. J Am Chem Soc 2023; 145:21344-21360. [PMID: 37736878 PMCID: PMC10557146 DOI: 10.1021/jacs.3c06099] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Indexed: 09/23/2023]
Abstract
The nitrile containing Ru(II)polypyridyl complex [Ru(phen)2(11,12-dCN-dppz)]2+ (1) is shown to act as a sensitive infrared probe of G-quadruplex (G4) structures. UV-visible absorption spectroscopy reveals enantiomer sensitive binding for the hybrid htel(K) and antiparallel htel(Na) G4s formed by the human telomer sequence d[AG3(TTAG3)3]. Time-resolved infrared (TRIR) of 1 upon 400 nm excitation indicates dominant interactions with the guanine bases in the case of Λ-1/htel(K), Δ-1/htel(K), and Λ-1/htel(Na) binding, whereas Δ-1/htel(Na) binding is associated with interactions with thymine and adenine bases in the loop. The intense nitrile transient at 2232 cm-1 undergoes a linear shift to lower frequency as the solution hydrogen bonding environment decreases in DMSO/water mixtures. This shift is used as a sensitive reporter of the nitrile environment within the binding pocket. The lifetime of 1 in D2O (ca. 100 ps) is found to increase upon DNA binding, and monitoring of the nitrile and ligand transients as well as the diagnostic DNA bleach bands shows that this increase is related to greater protection from the solvent environment. Molecular dynamics simulations together with binding energy calculations identify the most favorable binding site for each system, which are in excellent agreement with the observed TRIR solution study. This study shows the power of combining the environmental sensitivity of an infrared (IR) probe in its excited state with the TRIR DNA "site effect" to gain important information about the binding site of photoactive agents and points to the potential of such amplified IR probes as sensitive reporters of biological environments.
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Affiliation(s)
- Mark Stitch
- School
of Chemistry, University College Dublin, Dublin, D04 V1W8, Ireland
| | - Davide Avagliano
- Institute
of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währingerstr. 19, 1090 Vienna, Austria
- Department
of Chemistry, Chemical Physics Theory Group, University of Toronto, 80 St. George St., Toronto, Ontario M5S 3H6, Canada
| | - Daniel Graczyk
- School
of Chemistry, University College Dublin, Dublin, D04 V1W8, Ireland
| | - Ian P. Clark
- Central
Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Leticia González
- Institute
of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währingerstr. 19, 1090 Vienna, Austria
- Vienna
Research Platform on Accelerating Photoreaction Discovery, University of Vienna, Währingerstr. 19, 1090 Vienna, Austria
| | - Michael Towrie
- Central
Laser Facility, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Susan J Quinn
- School
of Chemistry, University College Dublin, Dublin, D04 V1W8, Ireland
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Peterková K, Stitch M, Boota RZ, Scattergood PA, Elliott PIP, Towrie M, Podbevšek P, Plavec J, Quinn SJ. G-Quadruplex Binding of an NIR Emitting Osmium Polypyridyl Probe Revealed by Solution NMR and Time-Resolved Infrared Studies. Chemistry 2023; 29:e202203250. [PMID: 36398697 DOI: 10.1002/chem.202203250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/11/2022] [Accepted: 11/17/2022] [Indexed: 11/19/2022]
Abstract
G-quadruplexes are emerging targets in cancer research and understanding how diagnostic probes bind to DNA G-quadruplexes in solution is critical to the development of new molecular tools. In this study the binding of an enantiopure NIR emitting [Os(TAP)2 (dppz)]2+ complex to different G-quadruplex structures formed by human telomer (hTel) and cMYC sequences in solution is reported. The combination of NMR and time-resolved infrared spectroscopic techniques reveals the sensitivity of the emission response to subtle changes in the binding environment of the complex. Similar behaviour is also observed for the related complex [Os(TAP)2 (dppp2)]2+ upon quadruplex binding.
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Affiliation(s)
- Kateřina Peterková
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
- National Centre for Biomolecular Research Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czechia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000, Ljubljana, Slovenia
| | - Mark Stitch
- School of Chemistry, University College Dublin, Dublin, 4, Ireland
| | - Rayhaan Z Boota
- Department of Chemical Sciences, School of Applied Sciences University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, UK
| | - Paul A Scattergood
- Department of Chemical Sciences, School of Applied Sciences University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, UK
| | - Paul I P Elliott
- Department of Chemical Sciences, School of Applied Sciences University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, UK
| | - Michael Towrie
- Rutherford Appleton Laboratory, STFC, Harwell Campus, OX11 0FA, UK
| | - Peter Podbevšek
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
| | - Janez Plavec
- Slovenian NMR Center, National Institute of Chemistry, Hajdrihova 19, 1000, Ljubljana, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000, Ljubljana, Slovenia
- EN-FIST Centre of Excellence Trg OF 13, 1000, Ljubljana, Slovenia
| | - Susan J Quinn
- School of Chemistry, University College Dublin, Dublin, 4, Ireland
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Wang C, Ebel K, Heinze K, Resch-Genger U, Bald I. Quantum Yield of DNA Strand Breaks under Photoexcitation of a Molecular Ruby. Chemistry 2023; 29:e202203719. [PMID: 36734093 DOI: 10.1002/chem.202203719] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/25/2023] [Accepted: 02/02/2023] [Indexed: 02/04/2023]
Abstract
Photodynamic therapy (PDT) used for treating cancer relies on the generation of highly reactive oxygen species, for example, singlet oxygen 1 O2 , by light-induced excitation of a photosensitizer (PS) in the presence of molecular oxygen, inducing DNA damage in close proximity of the PS. Although many precious metal complexes have been explored as PS for PDT and received clinical approval, only recently, the potential of photoactive complexes of non-noble metals as PS has been discovered. Using the DNA origami technology that can absolutely quantify DNA strand break cross sections, we assessed the potential of the luminescent transition metal complex [Cr(ddpd)2 ]3+ (ddpd=N,N'-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine) to damage DNA in an air-saturated aqueous environment upon UV/Vis illumination. The quantum yield for strand breakage, that is, the ratio of DNA strand breaks to the number of absorbed photons, was determined to 1-4 %, indicating efficient transformation of photons into DNA strand breaks by [Cr(ddpd)2 ]3+ .
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Affiliation(s)
- Cui Wang
- Division Biophotonics, Federal Institute for Materials Research and Testing (BAM), Richard-Willstaetter Strasse 11, 12489, Berlin, Germany.,present address: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Kenny Ebel
- Institute of Chemistry, Hybrid Nanostructures, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Katja Heinze
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
| | - Ute Resch-Genger
- Division Biophotonics, Federal Institute for Materials Research and Testing (BAM), Richard-Willstaetter Strasse 11, 12489, Berlin, Germany
| | - Ilko Bald
- Institute of Chemistry, Hybrid Nanostructures, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
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6
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Keane PM, Zehe C, Poynton FE, Bright SA, Estayalo-Adrián S, Devereux SJ, Donaldson PM, Sazanovich IV, Towrie M, Botchway SW, Cardin CJ, Williams DC, Gunnlaugsson T, Long C, Kelly JM, Quinn SJ. Time-resolved infra-red studies of photo-excited porphyrins in the presence of nucleic acids and in HeLa tumour cells: insights into binding site and electron transfer dynamics. Phys Chem Chem Phys 2022; 24:27524-27531. [PMID: 36345709 DOI: 10.1039/d2cp04604k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
Cationic porphyrins based on the 5,10,15,20-meso-(tetrakis-4-N-methylpyridyl) core (TMPyP4) have been studied extensively over many years due to their strong interactions with a variety of nucleic acid structures, and their potential use as photodynamic therapeutic agents and telomerase inhibitors. In this paper, the interactions of metal-free TMPyP4 and Pt(II)TMPyP4 with guanine-containing nucleic acids are studied for the first time using time-resolved infrared spectroscopy (TRIR). In D2O solution (where the metal-free form exists as D2TMPyP4) both compounds yielded similar TRIR spectra (between 1450-1750 cm-1) following pulsed laser excitation in their Soret B-absorption bands. Density functional theory calculations reveal that vibrations centred on the methylpyridinium groups are responsible for the dominant feature at ca. 1640 cm-1. TRIR spectra of D2TMPyP4 or PtTMPyP4 in the presence of guanosine 5'-monophosphate (GMP), double-stranded {d(GC)5}2 or {d(CGCAAATTTGCG)}2 contain negative-going signals, 'bleaches', indicative of binding close to guanine. TRIR signals for D2TMPyP4 or PtTMPyP bound to the quadruplex-forming cMYC sequence {d(TAGGGAGGG)}2T indicate that binding occurs on the stacked guanines. For D2TMPyP4 bound to guanine-containing systems, the TRIR signal at ca. 1640 cm-1 decays on the picosecond timescale, consistent with electron transfer from guanine to the singlet excited state of D2TMPyP4, although IR marker bands for the reduced porphyrin/oxidised guanine were not observed. When PtTMPyP is incorporated into HeLa tumour cells, TRIR studies show protein binding with time-dependent ps/ns changes in the amide absorptions demonstrating TRIR's potential for studying light-activated molecular processes not only with nucleic acids in solution but also in biological cells.
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Affiliation(s)
- Páraic M Keane
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.
- School of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, UK
| | - Clara Zehe
- School of Chemistry, University College Dublin, Dublin 4, Ireland.
| | - Fergus E Poynton
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.
- Trinity Biomedical Sciences Institute, The University of Dublin, Pearse St., Dublin 2, Ireland
| | - Sandra A Bright
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.
- Trinity Biomedical Sciences Institute, The University of Dublin, Pearse St., Dublin 2, Ireland
| | - Sandra Estayalo-Adrián
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.
- Trinity Biomedical Sciences Institute, The University of Dublin, Pearse St., Dublin 2, Ireland
| | | | - Paul M Donaldson
- STFC Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Igor V Sazanovich
- STFC Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Michael Towrie
- STFC Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Stanley W Botchway
- STFC Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0QX, UK
| | - Christine J Cardin
- School of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, UK
| | - D Clive Williams
- Trinity Biomedical Sciences Institute, The University of Dublin, Pearse St., Dublin 2, Ireland
| | - Thorfinnur Gunnlaugsson
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.
- Trinity Biomedical Sciences Institute, The University of Dublin, Pearse St., Dublin 2, Ireland
| | - Conor Long
- School of Chemical Sciences, Dublin City University, Dublin 9, Ireland.
| | - John M Kelly
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.
| | - Susan J Quinn
- School of Chemistry, University College Dublin, Dublin 4, Ireland.
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7
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Stitch M, Boota RZ, Chalkley AS, Keene TD, Simpson JC, Scattergood PA, Elliott PIP, Quinn SJ. Photophysical Properties and DNA Binding of Two Intercalating Osmium Polypyridyl Complexes Showing Light-Switch Effects. Inorg Chem 2022; 61:14947-14961. [PMID: 36094851 PMCID: PMC9516684 DOI: 10.1021/acs.inorgchem.2c01231] [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: 11/29/2022]
Abstract
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The synthesis and
photophysical characterization of two osmium(II)
polypyridyl complexes, [Os(TAP)2dppz]2+ (1) and [Os(TAP)2dppp2]2+ (2) containing dppz (dipyrido[3,2-a:2′,3′-c]phenazine) and dppp2 (pyrido[2′,3′:5,6]pyrazino[2,3-f][1,10]phenanthroline) intercalating ligands and TAP (1,4,5,8-tetraazaphenanthrene)
ancillary ligands, are reported. The complexes exhibit complex electrochemistry
with five distinct reductive redox couples, the first of which is
assigned to a TAP-based process. The complexes emit in the near-IR
(1 at 761 nm and 2 at 740 nm) with lifetimes
of >35 ns with a low quantum yield of luminescence in aqueous solution
(∼0.25%). The Δ and Λ enantiomers of 1 and 2 are found to bind to natural DNA and with AT
and GC oligodeoxynucleotides with high affinities. In the presence
of natural DNA, the visible absorption spectra are found to display
significant hypochromic shifts, which is strongly evident for the
ligand-centered π–π* dppp2 transition at 355 nm,
which undergoes 46% hypochromism. The emission of both complexes increases
upon DNA binding, which is observed to be sensitive to the Δ
or Λ enantiomer and the DNA composition. A striking result is
the sensitivity of Λ-2 to the presence of AT DNA,
where a 6-fold enhancement of luminescence is observed and reflects
the nature of the binding for the enantiomer and the protection from
solution. Thermal denaturation studies show that both complexes are
found to stabilize natural DNA. Finally, cellular studies show that
the complexes are internalized by cultured mammalian cells and localize
in the nucleus. Osmium(II)
polypyridyl complexes comprising extended dipyrido[3,2-a:2′,3′-c]phenazine (1) and pyrido[2′,3′:5,6]pyrazino[2,3-f][1,10]phenanthroline (2) intercalating ligands
are shown to be effective DNA binders accompanied by enhanced near-IR
emission. The emission response to B-DNA is found to be sensitive
to the enantiomer and the composition of DNA, with greater emission
observed for AT-rich sequences. Thermal denaturation studies show
that both complexes stabilize natural DNA. Cellular studies show that
the complexes are internalized by cultured mammalian cells and localize
in the nucleus.
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Affiliation(s)
- Mark Stitch
- School of Chemistry, University College Dublin, Dublin 4 D04 V1W8, Ireland
| | - Rayhaan Z Boota
- Department of Chemical Sciences, School of Applied Sciences University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
| | - Alannah S Chalkley
- Cell Screening Laboratory, School of Biology and Environmental Science, University College Dublin, Dublin 4 D04 V1W8, Ireland
| | - Tony D Keene
- School of Chemistry, University College Dublin, Dublin 4 D04 V1W8, Ireland
| | - Jeremy C Simpson
- Cell Screening Laboratory, School of Biology and Environmental Science, University College Dublin, Dublin 4 D04 V1W8, Ireland
| | - Paul A Scattergood
- Department of Chemical Sciences, School of Applied Sciences University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
| | - Paul I P Elliott
- Department of Chemical Sciences, School of Applied Sciences University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
| | - Susan J Quinn
- School of Chemistry, University College Dublin, Dublin 4 D04 V1W8, Ireland
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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] [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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Sittel S, Naumann R, Heinze K. Molecular Rubies in Photoredox Catalysis. Front Chem 2022; 10:887439. [PMID: 35464204 PMCID: PMC9021569 DOI: 10.3389/fchem.2022.887439] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 03/17/2022] [Indexed: 01/22/2023] Open
Abstract
The molecular ruby [Cr(tpe) 2 ] 3+ and the tris(bipyridine) chromium(III) complex [Cr(dmcbpy) 3 ] 3+ as well as the tris(bipyrazine)ruthenium(II) complex [Ru(bpz) 3 ] 2+ were employed in the visible light-induced radical cation [4+2] cycloaddition (tpe = 1,1,1-tris(pyrid-2-yl)ethane, dmcbpy = 4,4'-dimethoxycarbonyl-2,2'-bipyridine, bpz = 2,2'-bipyrazine), while [Cr(ddpd) 2 ] 3+ serves as a control system (ddpd = N,N'-dimethyl-N,N'-dipyridin-2-ylpyridine-2,6-diamine). Along with an updated mechanistic proposal for the CrIII driven catalytic cycle based on redox chemistry, Stern-Volmer analyses, UV/Vis/NIR spectroscopic and nanosecond laser flash photolysis studies, we demonstrate that the very weakly absorbing photocatalyst [Cr(tpe) 2 ] 3+ outcompetes [Cr(dmcbpy) 3 ] 3+ and even [Ru(bpz) 3 ] 2+ in particular at low catalyst loadings, which appears contradictory at first sight. The high photostability, the reversible redoxchemistry and the very long excited state lifetime account for the exceptional performance and even reusability of [Cr(tpe) 2 ] 3+ in this photoredox catalytic system.
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Affiliation(s)
- Steven Sittel
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Robert Naumann
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Katja Heinze
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
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10
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Stein L, Boden P, Naumann R, Förster C, Niedner-Schatteburg G, Heinze K. The overlooked NIR luminescence of Cr(ppy) 3. Chem Commun (Camb) 2022; 58:3701-3704. [PMID: 35226026 DOI: 10.1039/d2cc00680d] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cr(ppy)3, a structural analog of the green phosphorescent Ir(ppy)3, emits even in solution at room temperature from a weakly distorted spin-flip state at 910 nm (Hppy = 2-phenylpyridine). The low energy arises from an enhanced covalence of the Cr-C bonds as compared to Cr-N bonds. Lower temperature reduces thermally activated decay increasing the emission intensity.
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Affiliation(s)
- Laura Stein
- Johannes Gutenberg-University, Department of Chemistry, Duesbergweg 10-14, Mainz, Germany.
| | - Pit Boden
- Department of Chemistry and Research Center Optimas, TU Kaiserslautern, Erwin-Schrödinger-Straße 52, 67663 Kaiserslautern, Germany
| | - Robert Naumann
- Johannes Gutenberg-University, Department of Chemistry, Duesbergweg 10-14, Mainz, Germany.
| | - Christoph Förster
- Johannes Gutenberg-University, Department of Chemistry, Duesbergweg 10-14, Mainz, Germany.
| | - Gereon Niedner-Schatteburg
- Department of Chemistry and Research Center Optimas, TU Kaiserslautern, Erwin-Schrödinger-Straße 52, 67663 Kaiserslautern, Germany
| | - Katja Heinze
- Johannes Gutenberg-University, Department of Chemistry, Duesbergweg 10-14, Mainz, Germany.
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