1
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Garcia-Orrit S, Vega-Mayoral V, Chen Q, Serra G, Guizzardi M, Romano V, Dal Conte S, Cerullo G, Di Mario L, Kot M, Loi MA, Narita A, Müllen K, Tommasini M, Cabanillas-González J. Visualizing Thermally Activated Conical Intersections Governing Non-Radiative Triplet Decay in a Ni(II) Porphyrin-Nanographene Conjugate with Variable Temperature Transient Absorption Spectroscopy. J Phys Chem Lett 2024; 15:10366-10374. [PMID: 39374120 DOI: 10.1021/acs.jpclett.4c02712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/09/2024]
Abstract
Metalloporphyrins based on open-shell transition metals, such as Ni(II), exhibit typically fast excited-state relaxation. In this work, we shed light into the nonradiative relaxation mechanism in a nanographene-Ni(II) porphyrin conjugate. Variable temperature transient absorption and global fit analysis are combined to produce a picture of the relaxation pathways. At room temperature, photoexcitation of the lowest π-π* transition is followed by vibrational cooling in 1.6 ps, setting a short 20 ps temporal window wherein a small fraction of relaxed singlets radiatively decay to the ground state before intersystem crossing proceeds. Following intersystem crossing, triplets relax rapidly to the ground state (S0) in a few tens of picoseconds. By performing measurements at low temperature, we provide evidence for a competition between two terminal relaxation pathways from the lowest (metal-centered) triplet to the ground state: a slow ground state relaxation process proceeding in time scales beyond 1.6 ns and a faster pathway dictated by a sloped conical intersection, which is thermally accessible at room temperature from the triplet state. The overall triplet decay at a given temperature is dictated by the interplay of these two contributions. This observation bears significance in understanding the underlying fast relaxation processes in Ni-based molecules and related transition metal complexes, opening avenues for potential applications for energy harvesting and optoelectronics.
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Affiliation(s)
- Saül Garcia-Orrit
- Madrid Institute for Advanced Studies, IMDEA Nanociencia, c/Faraday 9, Campus de Cantoblanco, Madrid 28049, Spain
| | - Víctor Vega-Mayoral
- Madrid Institute for Advanced Studies, IMDEA Nanociencia, c/Faraday 9, Campus de Cantoblanco, Madrid 28049, Spain
| | - Qiang Chen
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Gianluca Serra
- Dipartimento di Chimica, Materiali ed Ingegneria Chimica "G.Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)
| | - Michele Guizzardi
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy
| | - Valentino Romano
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy
| | - Stefano Dal Conte
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy
| | - Giulio Cerullo
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano, Italy
| | - Lorenzo Di Mario
- Photophysics and OptoElectronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 3, 9747 AG, Groningen, The Netherlands
| | - Mordechai Kot
- Photophysics and OptoElectronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 3, 9747 AG, Groningen, The Netherlands
| | - Maria Antonietta Loi
- Photophysics and OptoElectronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 3, 9747 AG, Groningen, The Netherlands
| | - Akimitsu Narita
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Organic and Carbon Nanomaterials Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan
| | - Klaus Müllen
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Institute for Physical Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Matteo Tommasini
- Dipartimento di Chimica, Materiali ed Ingegneria Chimica "G.Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)
| | - Juan Cabanillas-González
- Madrid Institute for Advanced Studies, IMDEA Nanociencia, c/Faraday 9, Campus de Cantoblanco, Madrid 28049, Spain
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2
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Li TM, Hu LY, Zou X, Wang JY, Ni S, Liu L, Xiao X, Luo XF. Hybridization of short-range and long-range charge transfer boosts room-temperature phosphorescence performance. RSC Adv 2024; 14:22763-22768. [PMID: 39027035 PMCID: PMC11256979 DOI: 10.1039/d4ra03283g] [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: 05/04/2024] [Accepted: 07/06/2024] [Indexed: 07/20/2024] Open
Abstract
At present, mainstream room-temperature phosphorescence (RTP) emission relies on organic materials with long-range charge-transfer effects; therefore, exploring new forms of charge transfer to generate RTP is worth studying. In this work, indole-carbazole was used as the core to ensure the narrowband fluorescence emission of the material based on its characteristic short-range charge-transfer effect. In addition, halogenated carbazoles were introduced into the periphery to construct long-range charge transfer, resulting in VTCzNL-Cl and VTCzNL-Br. By encapsulating these phosphors into a robust host (TPP), two host-guest crystalline systems were further developed, achieving efficient RTP performance with phosphorescence quantum yields of 26% and phosphorescence lifetimes of 3.2 and 39.2 ms, respectively.
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Affiliation(s)
- Tian-Miao Li
- College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology Shijiazhuang 050018 China
- College of Material Science and Chemical Engineering, Ningbo University of Technology Ningbo 315211 P. R. China
| | - Li-Yuan Hu
- College of Material Science and Chemical Engineering, Ningbo University of Technology Ningbo 315211 P. R. China
| | - Xin Zou
- Frontiers Science Center for Flexible Electronics (FSCFE), Northwestern Polytechnical University Xi'an 710072 P. R. China
| | - Jun-Yi Wang
- College of Material Science and Chemical Engineering, Ningbo University of Technology Ningbo 315211 P. R. China
| | - Sheng Ni
- College of Material Science and Chemical Engineering, Ningbo University of Technology Ningbo 315211 P. R. China
| | - Lei Liu
- College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology Shijiazhuang 050018 China
| | - Xunwen Xiao
- College of Material Science and Chemical Engineering, Ningbo University of Technology Ningbo 315211 P. R. China
- State Key Laboratory of Applied Organic Chemistry (Lanzhou University) Lanzhou 730000 China
| | - Xu-Feng Luo
- College of Material Science and Chemical Engineering, Ningbo University of Technology Ningbo 315211 P. R. China
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3
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Wallick R, Chakrabarti S, Burke JH, Gnewkow R, Chae JB, Rossi TC, Mantouvalou I, Kanngießer B, Fondell M, Eckert S, Dykstra C, Smith LE, Vura-Weis J, Mirica LM, van der Veen RM. Excited-State Identification of a Nickel-Bipyridine Photocatalyst by Time-Resolved X-ray Absorption Spectroscopy. J Phys Chem Lett 2024; 15:4976-4982. [PMID: 38691639 PMCID: PMC11089568 DOI: 10.1021/acs.jpclett.4c00226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/18/2024] [Accepted: 04/16/2024] [Indexed: 05/03/2024]
Abstract
Photoassisted catalysis using Ni complexes is an emerging field for cross-coupling reactions in organic synthesis. However, the mechanism by which light enables and enhances the reactivity of these complexes often remains elusive. Although optical techniques have been widely used to study the ground and excited states of photocatalysts, they lack the specificity to interrogate the electronic and structural changes at specific atoms. Herein, we report metal-specific studies using transient Ni L- and K-edge X-ray absorption spectroscopy of a prototypical Ni photocatalyst, (dtbbpy)Ni(o-tol)Cl (dtb = 4,4'-di-tert-butyl, bpy = bipyridine, o-tol = ortho-tolyl), in solution. We unambiguously confirm via direct experimental evidence that the long-lived (∼5 ns) excited state is a tetrahedral metal-centered triplet state. These results demonstrate the power of ultrafast X-ray spectroscopies to unambiguously elucidate the nature of excited states in important transition-metal-based photocatalytic systems.
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Affiliation(s)
- Rachel
F. Wallick
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Sagnik Chakrabarti
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, Urbana, Illinois 61801, United States
| | - John H. Burke
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Richard Gnewkow
- Department
of Atomic-Scale Dynamics in Light-Energy Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin 14109, Germany
- Institute
of Optics and Atomic Physics, Technische
Universität Berlin, Berlin 10623, Germany
| | - Ju Byeong Chae
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Thomas C. Rossi
- Department
of Atomic-Scale Dynamics in Light-Energy Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin 14109, Germany
| | - Ioanna Mantouvalou
- Department
of Atomic-Scale Dynamics in Light-Energy Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin 14109, Germany
- Institute
of Optics and Atomic Physics, Technische
Universität Berlin, Berlin 10623, Germany
| | - Birgit Kanngießer
- Department
of Atomic-Scale Dynamics in Light-Energy Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin 14109, Germany
- Institute
of Optics and Atomic Physics, Technische
Universität Berlin, Berlin 10623, Germany
| | - Mattis Fondell
- Department
of Atomic-Scale Dynamics in Light-Energy Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin 14109, Germany
| | - Sebastian Eckert
- Department
of Atomic-Scale Dynamics in Light-Energy Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin 14109, Germany
| | - Conner Dykstra
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Laura E. Smith
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Josh Vura-Weis
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Liviu M. Mirica
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Renske M. van der Veen
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, Urbana, Illinois 61801, United States
- Department
of Atomic-Scale Dynamics in Light-Energy Conversion, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin 14109, Germany
- Institute
of Optics and Atomic Physics, Technische
Universität Berlin, Berlin 10623, Germany
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4
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Hung TC, Godinez-Loyola Y, Steinbrecher M, Kiraly B, Khajetoorians AA, Doltsinis NL, Strassert CA, Wegner D. Activating the Fluorescence of a Ni(II) Complex by Energy Transfer. J Am Chem Soc 2024; 146:8858-8864. [PMID: 38513215 PMCID: PMC10996004 DOI: 10.1021/jacs.3c07716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 03/07/2024] [Accepted: 03/07/2024] [Indexed: 03/23/2024]
Abstract
Luminescence of open-shell 3d metal complexes is often quenched due to ultrafast intersystem crossing (ISC) and cooling into a dark metal-centered excited state. We demonstrate successful activation of fluorescence from individual nickel phthalocyanine (NiPc) molecules in the junction of a scanning tunneling microscope (STM) by resonant energy transfer from other metal phthalocyanines at low temperature. By combining STM, scanning tunneling spectroscopy, STM-induced luminescence, and photoluminescence experiments as well as time-dependent density functional theory, we provide evidence that there is an activation barrier for the ISC, which, in most experimental conditions, is overcome. We show that this is also the case in an electroluminescent tunnel junction where individual NiPc molecules adsorbed on an ultrathin NaCl decoupling film on a Ag(111) substrate are probed. However, when an MPc (M = Zn, Pd, Pt) molecule is placed close to NiPc by means of STM atomic manipulation, resonant energy transfer can excite NiPc without overcoming the ISC activation barrier, leading to Q-band fluorescence. This work demonstrates that the thermally activated population of dark metal-centered states can be avoided by a designed local environment at low temperatures paired with directed molecular excitation into vibrationally cold electronic states. Thus, we can envisage the use of luminophores based on more abundant transition metal complexes that do not rely on Pt or Ir by restricting vibration-induced ISC.
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Affiliation(s)
- Tzu-Chao Hung
- Institute
for Molecules and Materials, Radboud University, 6500 GL Nijmegen, The Netherlands
- Institute
for Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
| | - Yokari Godinez-Loyola
- Institut
für Anorganische und Analytische Chemie, University of Münster, 48149 Münster, Germany
- Center
for Nanotechnology (CeNTech), University
of Münster, 48149 Münster, Germany
| | - Manuel Steinbrecher
- Institute
for Molecules and Materials, Radboud University, 6500 GL Nijmegen, The Netherlands
| | - Brian Kiraly
- Institute
for Molecules and Materials, Radboud University, 6500 GL Nijmegen, The Netherlands
| | | | - Nikos L. Doltsinis
- Institut
für Festkörpertheorie and Center for Multiscale Theory
and Computation, University of Münster, 48149 Münster, Germany
| | - Cristian A. Strassert
- Institut
für Anorganische und Analytische Chemie, University of Münster, 48149 Münster, Germany
- Center
for Nanotechnology (CeNTech), University
of Münster, 48149 Münster, Germany
- Cells in
Motion Interfaculty Centre (CiMIC) and Center for Soft Nanoscience
(SoN), University of Münster, 48149 Münster, Germany
| | - Daniel Wegner
- Institute
for Molecules and Materials, Radboud University, 6500 GL Nijmegen, The Netherlands
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5
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Karpova L, Daniel M, Kancherla R, Muralirajan K, Maity B, Rueping M. Excited-State Nickel-Catalyzed Amination of Aryl Bromides: Synthesis of Diphenylamines and Primary Anilines. Org Lett 2024; 26:1657-1661. [PMID: 38381879 DOI: 10.1021/acs.orglett.4c00147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Excited-state nickel-catalyzed C-N cross-coupling of aryl bromides with sodium azide enables the synthesis of diarylamines and primary anilines under mild reaction conditions. The oxidative addition of electron-rich aryl bromides with low-valent Ni under the photochemical conditions is endothermic. Herein, we demonstrate a light-mediated nickel-catalyzed reaction of electronically rich aryl bromides that yields diarylamines, while the reaction with electron-deficient aryl bromides gives access to anilines at room temperature.
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Affiliation(s)
- Lidia Karpova
- Kaust Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Matěj Daniel
- Kaust Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Rajesh Kancherla
- Kaust Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Krishnamoorthy Muralirajan
- Kaust Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Bholanath Maity
- Kaust Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Magnus Rueping
- Kaust Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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6
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Ogawa T, Wenger OS. Nickel(II) Analogues of Phosphorescent Platinum(II) Complexes with Picosecond Excited-State Decay. Angew Chem Int Ed Engl 2023; 62:e202312851. [PMID: 37732725 DOI: 10.1002/anie.202312851] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/22/2023]
Abstract
Square-planar NiII complexes are interesting as cheaper and more sustainable alternatives to PtII luminophores widely used in lighting and photocatalysis. We investigated the excited-state behavior of two NiII complexes, which are isostructural with two luminescent PtII complexes. The initially excited singlet metal-to-ligand charge transfer (1 MLCT) excited states in the NiII complexes decay to metal-centered (3 MC) excited states within less than 1 picosecond, followed by non-radiative relaxation of the 3 MC states to the electronic ground state within 9-21 ps. This contrasts with the population of an emissive triplet ligand-centered (3 LC) excited state upon excitation of the PtII analogues. Structural distortions of the NiII complexes are responsible for this discrepant behavior and lead to dark 3 MC states far lower in energy than the luminescent 3 LC states of PtII compounds. Our findings suggest that if these structural distortions could be restricted by more rigid coordination environments and stronger ligand fields, the excited-state relaxation in four-coordinate NiII complexes could be decelerated such that luminescent 3 LC or 3 MLCT excited states become accessible. These insights are relevant to make NiII fit for photophysical and photochemical applications that relied on PtII until now.
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Affiliation(s)
- Tomohiro Ogawa
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
- Graduate School of Science and Engineering, University of Toyama, Toyama, 930-8555, Japan
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
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7
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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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8
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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: 21] [Impact Index Per Article: 10.5] [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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