1
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Kaul N, Asempa E, Valdez-Moreira JA, Smith JM, Jakubikova E, Hammarström L. Enter Mn IV-NHC: A Dark Photooxidant with a Long-Lived Charge-Transfer Excited State. J Am Chem Soc 2024. [PMID: 39106331 DOI: 10.1021/jacs.4c08588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/09/2024]
Abstract
Detailed photophysical investigation of a Mn(IV)-carbene complex has revealed that excitation into its lowest-energy absorption band (∼500 nm) results in the formation of an energetic ligand-to-metal charge-transfer (LMCT) state with a lifetime of 15 ns. To the best of our knowledge, this is the longest lifetime reported for charge-transfer states of first-row-based transition metal complexes in solution, barring those based on Cu, with a d10 configuration. A so-called superoxidant, Mn(IV)-carbene exhibits an excited state potential typically only harnessed via excited states of reactive organic radical species. Furthermore, the long-lived excited state in this case is found to be a dark doublet, with its transition to the quartet ground state being spin-forbidden, a contrast to most first-row literature examples, and a possible cause of the long lifetime. Showcasing excited state properties which in some cases exceed those of complexes based on precious metals, these findings not only advance the library of earth-abundant photosensitizers but also shed general insight into the photophysics of d3 and related Mn complexes.
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Affiliation(s)
- Nidhi Kaul
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
| | - Eyram Asempa
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Juan A Valdez-Moreira
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Jeremy M Smith
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Elena Jakubikova
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Leif Hammarström
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, SE-75120 Uppsala, Sweden
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2
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DiLuzio S, Baumer M, Guzman R, Kagalwala H, Lopato E, Talledo S, Kangas J, Bernhard S. Exploring the Photophysics and Photocatalytic Activity of Heteroleptic Rh(III) Transition-Metal Complexes Using High-Throughput Experimentation. Inorg Chem 2024; 63:14267-14277. [PMID: 39031763 PMCID: PMC11304382 DOI: 10.1021/acs.inorgchem.4c02420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Revised: 07/08/2024] [Accepted: 07/11/2024] [Indexed: 07/22/2024]
Abstract
High-throughput synthesis and screening (HTSS) methods were used to investigate the photophysical properties of 576 heteroleptic Rh(III) transition-metal complexes through measurement of the UV-visible absorption spectra, deaerated excited-state lifetime, and phosphorescent emission spectra. While 4d transition-metal photophysics are often highly influenced by deleterious metal-centered deactivation channels, the HTSS of structurally diverse cyclometalating and ancillary ligands attached to the metal center facilitated the discovery of photoactive complexes exhibiting long-lived charge-transfer phosphorescence (0.15-0.95 μs) spanning a substantial portion of the visible region (546-620 nm) at room temperature. Further photophysical and electrochemical investigations were then carried out on select complexes with favorable photophysics to understand the underlying features controlling these superior properties. Heteroleptic Ir(III) complexes with identical ligand morphology were also synthesized to compare these features to this family of well understood chromophores. A number of these Rh(III) complexes contained the requisite properties for photocatalytic activity and were consequently tested as photocatalysts (PCs) in a water reduction system using a Pd water reduction cocatalyst. Under certain conditions, the activity of the Rh(III) PC actually surpassed that of the Ir(III) PC, uncovering the potential of this often-overlooked class of transition metals as both efficient photoactive chromophores and PCs.
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Affiliation(s)
- Stephen DiLuzio
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Mitchell Baumer
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Rafael Guzman
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Husain Kagalwala
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Eric Lopato
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Savannah Talledo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Joshua Kangas
- 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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3
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Malme JT, Weaver JN, Girolami GS, Vura-Weis J. Picosecond Metal-to-Ligand Charge-Transfer Deactivation in Co(ppy) 3 via Jahn-Teller Distortion. Inorg Chem 2024; 63:13825-13830. [PMID: 39023554 DOI: 10.1021/acs.inorgchem.4c01959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
The excited-state dynamics of fac-Co(ppy)3, where ppy = 2-[2-(pyridyl)phenyl], are measured with femtosecond UV-vis transient absorption spectroscopy. The initial state is confirmed with spectroelectrochemistry to have significant metal-to-ligand charge transfer (MLCT) character, unlike other Co complexes that generally have ligand-to-metal charge transfer or ligand-field transitions in this energy range. Ground-state recovery occurs in 8.65 ps in dichloromethane. Density functional theory calculations show that the MLCT state undergoes Jahn-Teller distortion and converts to a five-coordinate triplet metal-centered state in which one Co-N bond is broken. The results highlight a potential pitfall of heteroleptic bidentate ligands when designing strong-field ligands for transition-metal chromophores.
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Affiliation(s)
- Justin T Malme
- Department of Chemistry, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, United States
| | - Jenelle N Weaver
- Department of Chemistry, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, United States
| | - Gregory S Girolami
- Department of Chemistry, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, United States
| | - Josh Vura-Weis
- Department of Chemistry, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, United States
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4
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Chen T, Ma YJ, Xiao G, Fang X, Liu Y, Li K, Yan D. The trade-off anionic modulation in metal-organic glasses showing color-tunable persistent luminescence. MATERIALS HORIZONS 2024. [PMID: 39045671 DOI: 10.1039/d4mh00771a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
Ultralong room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF) materials provide exciting opportunities for the rational design of persistent luminescence owing to their long-lived excitons. However, conventional rare-earth-based all-inorganic emitters involve high cost and harsh synthesis conditions, and purely organic systems may require complicated synthesis routes and tedious purification. Therefore, it is highly desirable to develop a cost-effective and easily manufacturable method for achieving color-tunable RTP-TADF with a long afterglow. Herein, we demonstrate a rational strategy to introduce different anions (Cl-, Br- and OAc- ions) into a Zn-based metal-organic scaffold, which can improve the crystal rigidity and achieve a well-balanced RTP-TADF. Both theoretical and experimental studies have demonstrated that the adjustment of different anions can effectively modulate the spin-orbit coupling (SOC) and the energy gap of singlet-triplet states (ΔEST) and then tailor the afterglow lifetime. Moreover, we prepared dye-doped metal-organic hybrid glasses with remarkable potential for the color-tunable afterglow. Therefore, this work not only provides a new horizon for modulating crystal and glass states with color/lifetime-tunable persistent luminescence, but also contributes to optical information storage and anti-counterfeiting technology.
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Affiliation(s)
- Tianhong Chen
- Beijing Key Laboratory of Energy Conversion and Storage Materials, and Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
| | - Yu-Juan Ma
- Beijing Key Laboratory of Energy Conversion and Storage Materials, and Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
| | - Guowei Xiao
- Beijing Key Laboratory of Energy Conversion and Storage Materials, and Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
| | - Xiaoyu Fang
- Beijing Key Laboratory of Energy Conversion and Storage Materials, and Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
| | - Yumin Liu
- Beijing Key Laboratory of Energy Conversion and Storage Materials, and Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
| | - Kangjing Li
- Beijing Key Laboratory of Energy Conversion and Storage Materials, and Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
| | - Dongpeng Yan
- Beijing Key Laboratory of Energy Conversion and Storage Materials, and Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
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5
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Ghosh A, Yarranton JT, McCusker JK. Establishing the origin of Marcus-inverted-region behaviour in the excited-state dynamics of cobalt(III) polypyridyl complexes. Nat Chem 2024:10.1038/s41557-024-01564-3. [PMID: 38965436 DOI: 10.1038/s41557-024-01564-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 05/24/2024] [Indexed: 07/06/2024]
Abstract
Growing interest in the use of first-row transition metal complexes in a number of applied contexts-including but not limited to photoredox catalysis and solar energy conversion-underscores the need for a detailed understanding of their photophysical properties. A recent focus on ligand-field photocatalysis using cobalt(III) polypyridyls in particular has unlocked unprecedented excited-state reactivities. Photophysical studies on Co(III) chromophores in general are relatively uncommon, and so here we carry out a systematic study of a series of Co(III) polypyridyl complexes in order to delineate their excited-state dynamics. Compounds with varying ligand-field strengths were prepared and studied using variable-temperature ultrafast transient absorption spectroscopy. Analysis of the data establishes that the ground-state recovery dynamics are operating in the Marcus inverted region, in stark contrast to what is typically observed in other first-row metal complexes. The analysis has further revealed the underlying reasons driving this excited-state behaviour, thereby enabling potential advancements in the targeted use of the Marcus inverted region for a variety of photolytic applications.
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Affiliation(s)
- Atanu Ghosh
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | | | - James K McCusker
- Department of Chemistry, Michigan State University, East Lansing, MI, USA.
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6
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Reinhard ME, Sidhu BK, Lozada IB, Powers-Riggs N, Ortiz RJ, Lim H, Nickel R, Lierop JV, Alonso-Mori R, Chollet M, Gee LB, Kramer PL, Kroll T, Raj SL, van Driel TB, Cordones AA, Sokaras D, Herbert DE, Gaffney KJ. Time-Resolved X-ray Emission Spectroscopy and Synthetic High-Spin Model Complexes Resolve Ambiguities in Excited-State Assignments of Transition-Metal Chromophores: A Case Study of Fe-Amido Complexes. J Am Chem Soc 2024; 146:17908-17916. [PMID: 38889309 DOI: 10.1021/jacs.4c02748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
To fully harness the potential of abundant metal coordination complex photosensitizers, a detailed understanding of the molecular properties that dictate and control the electronic excited-state population dynamics initiated by light absorption is critical. In the absence of detectable luminescence, optical transient absorption (TA) spectroscopy is the most widely employed method for interpreting electron redistribution in such excited states, particularly for those with a charge-transfer character. The assignment of excited-state TA spectral features often relies on spectroelectrochemical measurements, where the transient absorption spectrum generated by a metal-to-ligand charge-transfer (MLCT) electronic excited state, for instance, can be approximated using steady-state spectra generated by electrochemical ligand reduction and metal oxidation and accounting for the loss of absorptions by the electronic ground state. However, the reliability of this approach can be clouded when multiple electronic configurations have similar optical signatures. Using a case study of Fe(II) complexes supported by benzannulated diarylamido ligands, we highlight an example of such an ambiguity and show how time-resolved X-ray emission spectroscopy (XES) measurements can reliably assign excited states from the perspective of the metal, particularly in conjunction with accurate synthetic models of ligand-field electronic excited states, leading to a reinterpretation of the long-lived excited state as a ligand-field metal-centered quintet state. A detailed analysis of the XES data on the long-lived excited state is presented, along with a discussion of the ultrafast dynamics following the photoexcitation of low-spin Fe(II)-Namido complexes using a high-spin ground-state analogue as a spectral model for the 5T2 excited state.
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Affiliation(s)
- Marco E Reinhard
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Baldeep K Sidhu
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Rd, Winnipeg, Manitoba R3T 2N2, Canada
| | - Issiah B Lozada
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Rd, Winnipeg, Manitoba R3T 2N2, Canada
| | - Natalia Powers-Riggs
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Robert J Ortiz
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Rd, Winnipeg, Manitoba R3T 2N2, Canada
| | - Hyeongtaek Lim
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Rachel Nickel
- Department of Physics and Astronomy, University of Manitoba, 31A Sifton Rd, Winnipeg, Manitoba R3T 2N2, Canada
| | - Johan van Lierop
- Department of Physics and Astronomy, University of Manitoba, 31A Sifton Rd, Winnipeg, Manitoba R3T 2N2, Canada
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Matthieu Chollet
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Leland B Gee
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Patrick L Kramer
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Thomas Kroll
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Sumana L Raj
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Tim B van Driel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Amy A Cordones
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Dimosthenis Sokaras
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - David E Herbert
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Rd, Winnipeg, Manitoba R3T 2N2, Canada
| | - Kelly J Gaffney
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
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7
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Gupta R, Negi A, Pal AK. A Bichromophoric Approach to Induce Luminescence - A Blend of Experimental and Theoretical Studies. Chem Asian J 2024; 19:e202400270. [PMID: 38742860 DOI: 10.1002/asia.202400270] [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: 03/09/2024] [Revised: 05/11/2024] [Accepted: 05/14/2024] [Indexed: 05/16/2024]
Abstract
Two homoleptic terpyridyl complexes of Ru(II), 1 and Fe(II), 2 were synthesized using a ligand L1 that contained a phenyl spacer between an anthracenyl (An) and a terpyridyl (tpy) moiety. An equilibrated-bichromophoric strategy was adopted to induce photoluminescence in 1 and 2. A glimpse into the excited state photophysical properties of 1 and 2 revealed that 1 exhibited NIR emission at ~700 nm with an excited state lifetime components of 1.33 and 6.52 ns. On the other hand, 2 was found to be non-luminescent. The origin of emission in case of 1 was attributed to the effect of phenyl spacer which rendered the 3An state to be nearly isoenergetic to the emissive 3MLCT state of 1 facilitating 3MLCT-3An equilibrium. This fact was supported by experimental (photocurrent generation) and theoretical (potential energy diagram) evidences.
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Affiliation(s)
- Rahat Gupta
- Department of Chemistry, Indian Institute of Technology Jammu, Nagrota Bypass Road, Jammu and Kashmir, 181221, India
| | - Anshul Negi
- Department of Chemistry, Indian Institute of Technology Jammu, Nagrota Bypass Road, Jammu and Kashmir, 181221, India
| | - Amlan K Pal
- Department of Chemistry, Indian Institute of Technology Jammu, Nagrota Bypass Road, Jammu and Kashmir, 181221, India
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8
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Alías-Rodríguez M, Huix-Rotllant M. Control of Iron(II)-Tris(2,2'-Bipyridine) Light-Induced Excited-State Trapping via External Electromagnetic Fields. Chemphyschem 2024:e202400471. [PMID: 38797713 DOI: 10.1002/cphc.202400471] [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: 04/24/2024] [Revised: 05/22/2024] [Accepted: 05/22/2024] [Indexed: 05/29/2024]
Abstract
Light-induced excited spin-state trapping reactions in iron pyridinic complexes allow the iron's low-to-high spin transition in a sub-picosecond timescale. Employing a recently developed model for [Fe(2,2'-bipyridine)3]2+ photochemical spin-crossover reaction in conjunction with quantum wavepacket dynamics, we explore the possibility of controlling the reaction through external electromagnetic fields, aiming at stabilizing the initial metal-to-ligand charge transfer states. We show that simple Gaussian-shaped electromagnetic fields have a minor effect on the population kinetics. However, introducing vibrationally excited initial wavepacket representations allows for maintaining the population trapped in the metal-to-ligand charge transfer states. Using optimal control theory, we propose an electromagnetic field shape that increases the lifetime of metal-to-ligand charge transfer states. These results open the route for controlling the iron photochemistry through the action of external electric fields.
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9
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Wellauer J, Ziereisen F, Sinha N, Prescimone A, Velić A, Meyer F, Wenger OS. Iron(III) Carbene Complexes with Tunable Excited State Energies for Photoredox and Upconversion. J Am Chem Soc 2024; 146. [PMID: 38598280 PMCID: PMC11046485 DOI: 10.1021/jacs.4c00605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/13/2024] [Accepted: 03/19/2024] [Indexed: 04/11/2024]
Abstract
Substituting precious elements in luminophores and photocatalysts by abundant first-row transition metals remains a significant challenge, and iron continues to be particularly attractive owing to its high natural abundance and low cost. Most iron complexes known to date face severe limitations due to undesirably efficient deactivation of luminescent and photoredox-active excited states. Two new iron(III) complexes with structurally simple chelate ligands enable straightforward tuning of ground and excited state properties, contrasting recent examples, in which chemical modification had a minor impact. Crude samples feature two luminescence bands strongly reminiscent of a recent iron(III) complex, in which this observation was attributed to dual luminescence, but in our case, there is clear-cut evidence that the higher-energy luminescence stems from an impurity and only the red photoluminescence from a doublet ligand-to-metal charge transfer (2LMCT) excited state is genuine. Photoinduced oxidative and reductive electron transfer reactions with methyl viologen and 10-methylphenothiazine occur with nearly diffusion-limited kinetics. Photocatalytic reactions not previously reported for this compound class, in particular the C-H arylation of diazonium salts and the aerobic hydroxylation of boronic acids, were achieved with low-energy red light excitation. Doublet-triplet energy transfer (DTET) from the luminescent 2LMCT state to an anthracene annihilator permits the proof of principle for triplet-triplet annihilation upconversion based on a molecular iron photosensitizer. These findings are relevant for the development of iron complexes featuring photophysical and photochemical properties competitive with noble-metal-based compounds.
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Affiliation(s)
- Joël Wellauer
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Fabienne Ziereisen
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Narayan Sinha
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Alessandro Prescimone
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Ajdin Velić
- University
of Göttingen, Institute of Inorganic Chemistry, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Franc Meyer
- University
of Göttingen, Institute of Inorganic Chemistry, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Oliver S. Wenger
- Department
of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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10
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Zahn C, Pastore M, Lustres JLP, Gros PC, Haacke S, Heyne K. Femtosecond Infrared Spectroscopy Resolving the Multiplicity of High-Spin Crossover States in Transition Metal Iron Complexes. J Am Chem Soc 2024; 146:9347-9355. [PMID: 38520392 PMCID: PMC10995999 DOI: 10.1021/jacs.4c01637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/09/2024] [Accepted: 03/11/2024] [Indexed: 03/25/2024]
Abstract
Tuning the photophysical properties of iron-based transition-metal complexes is crucial for their employment as photosensitizers in solar energy conversion. For the optimization of these new complexes, a detailed understanding of the excited-state deactivation paths is necessary. Here, we report femtosecond transient mid-IR spectroscopy data on a recently developed octahedral ligand-field enhancing [Fe(dqp)2]2+ (C1) complex with dqp = 2,6-diquinolylpyridine and prototypical [Fe(bpy)3]2+ (C0). By combining mid-IR spectroscopy with quantum chemical DFT calculations, we propose a method for disentangling the 5Q1 and 3T1 multiplicities of the long-lived metal-centered (MC) states, applicable to a variety of metal-organic iron complexes. Our results for C0 align well with the established assignment toward the 5Q1, validating our approach. For C1, we find that deactivation of the initially excited metal-to-ligand charge-transfer state leads to a population of a long-lived MC 5Q1 state. Analysis of transient changes in the mid-IR shows an ultrafast sub 200 fs rearrangement of ligand geometry for both complexes, accompanying the MLCT → MC deactivation. This confirms that the flexibility in the ligand sphere supports the stabilization of high spin states and plays a crucial role in the MLCT lifetime of metal-organic iron complexes.
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Affiliation(s)
- Clark Zahn
- Department
of Physics, Free University Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | | | - J. Luis Perez Lustres
- Department
of Physics, Free University Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | | | - Stefan Haacke
- Université
de Strasbourg—CNRS, IPCMS, 67034 Strasbourg, France
| | - Karsten Heyne
- Department
of Physics, Free University Berlin, Arnimallee 14, D-14195 Berlin, Germany
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11
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Knodel AL, Lozada IB, Ortiz RJ, Williams JAG, Herbert DE. Switching on emission in Zn(II) coordination complexes by tempering N amido character. Chem Commun (Camb) 2024; 60:3515-3518. [PMID: 38323777 DOI: 10.1039/d3cc06227a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
A series of four-coordinate zinc(II) complexes is presented in which the amido vs. imino character of a ligated nitrogen donor correlates to the luminescence intensity. DFT analysis points to a distinct mechanism for this trend wherein emission can be switched on by restricting non-radiative decay pathways through the resonance-induced delocalization of amido ligand lone-pairs.
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Affiliation(s)
- Amy L Knodel
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba, R3T 2N2, Canada.
| | - Issiah B Lozada
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba, R3T 2N2, Canada.
| | - Robert J Ortiz
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba, R3T 2N2, Canada.
| | | | - David E Herbert
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba, R3T 2N2, Canada.
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12
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Prakash O, Chábera P, Kaul N, Hlynsson VF, Rosemann NW, Losada IB, Hoang Hai YT, Huang P, Bendix J, Ericsson T, Häggström L, Gupta AK, Strand D, Yartsev A, Lomoth R, Persson P, Wärnmark K. How Rigidity and Conjugation of Bidentate Ligands Affect the Geometry and Photophysics of Iron N-Heterocyclic Complexes: A Comparative Study. Inorg Chem 2024; 63:4461-4473. [PMID: 38421802 PMCID: PMC10934811 DOI: 10.1021/acs.inorgchem.3c03972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 02/07/2024] [Accepted: 02/08/2024] [Indexed: 03/02/2024]
Abstract
Two iron complexes featuring the bidentate, nonconjugated N-heterocyclic carbene (NHC) 1,1'-methylenebis(3-methylimidazol-2-ylidene) (mbmi) ligand, where the two NHC moieties are separated by a methylene bridge, have been synthesized to exploit the combined influence of geometric and electronic effects on the ground- and excited-state properties of homoleptic FeIII-hexa-NHC [Fe(mbmi)3](PF6)3 and heteroleptic FeII-tetra-NHC [Fe(mbmi)2(bpy)](PF6)2 (bpy = 2,2'-bipyridine) complexes. They are compared to the reported FeIII-hexa-NHC [Fe(btz)3](PF6)3 and FeII-tetra-NHC [Fe(btz)2(bpy)](PF6)2 complexes containing the conjugated, bidentate mesoionic NHC ligand 3,3'-dimethyl-1,1'-bis(p-tolyl)-4,4'-bis(1,2,3-triazol-5-ylidene) (btz). The observed geometries of [Fe(mbmi)3](PF6)3 and [Fe(mbmi)2(bpy)](PF6)2 are evaluated through L-Fe-L bond angles and ligand planarity and compared to those of [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. The FeII/FeIII redox couples of [Fe(mbmi)3](PF6)3 (-0.38 V) and [Fe(mbmi)2(bpy)](PF6)2 (-0.057 V, both vs Fc+/0) are less reducing than [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. The two complexes show intense absorption bands in the visible region: [Fe(mbmi)3](PF6)3 at 502 nm (ligand-to-metal charge transfer, 2LMCT) and [Fe(mbmi)2(bpy)](PF6)2 at 410 and 616 nm (metal-to-ligand charge transfer, 3MLCT). Lifetimes of 57.3 ps (2LMCT) for [Fe(mbmi)3](PF6)3 and 7.6 ps (3MLCT) for [Fe(mbmi)2(bpy)](PF6)2 were probed and are somewhat shorter than those for [Fe(btz)3](PF6)3 and [Fe(btz)2(bpy)](PF6)2. [Fe(mbmi)3](PF6)3 exhibits photoluminescence at 686 nm (2LMCT) in acetonitrile at room temperature with a quantum yield of (1.2 ± 0.1) × 10-4, compared to (3 ± 0.5) × 10-4 for [Fe(btz)3](PF6)3.
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Affiliation(s)
- Om Prakash
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Pavel Chábera
- Chemical
Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Nidhi Kaul
- Department
of Chemistry − Ångström Laboratory, Uppsala University, Box
523, SE-751 20 Uppsala, Sweden
| | - Valtýr F. Hlynsson
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Nils W. Rosemann
- Chemical
Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Iria Bolaño Losada
- Theoretical
Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Yen Tran Hoang Hai
- Theoretical
Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Ping Huang
- Department
of Chemistry − Ångström Laboratory, Uppsala University, Box
523, SE-751 20 Uppsala, Sweden
| | - Jesper Bendix
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Tore Ericsson
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Lennart Häggström
- Department
of Physics − Ångström Laboratory, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden
| | - Arvind Kumar Gupta
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Daniel Strand
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Arkady Yartsev
- Chemical
Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Reiner Lomoth
- Department
of Chemistry − Ångström Laboratory, Uppsala University, Box
523, SE-751 20 Uppsala, Sweden
| | - Petter Persson
- Theoretical
Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Kenneth Wärnmark
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
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13
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Losada IB, Persson P. Photoredox matching of earth-abundant photosensitizers with hydrogen evolving catalysts by first-principles predictions. J Chem Phys 2024; 160:074302. [PMID: 38375904 DOI: 10.1063/5.0174837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Accepted: 01/09/2024] [Indexed: 02/21/2024] Open
Abstract
Photoredox properties of several earth-abundant light-harvesting transition metal complexes in combination with cobalt-based proton reduction catalysts have been investigated computationally to assess the fundamental viability of different photocatalytic systems of current experimental interest. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations using several GGA (BP86, BLYP), hybrid-GGA (B3LYP, B3LYP*), hybrid meta-GGA (M06, TPSSh), and range-separated hybrid (ωB97X, CAM-B3LYP) functionals were used to calculate relevant ground and excited state reduction potentials for photosensitizers, catalysts, and sacrificial electron donors. Linear energy correction factors for the DFT/TD-DFT results that provide the best agreement with available experimental reference results were determined in order to provide more accurate predictions. Among the selection of functionals, the B3LYP* and TPSSh sets of correction parameters were determined to give the best redox potentials and excited states energies, ΔEexc, with errors of ∼0.2 eV. Linear corrections for both reduction and oxidation processes significantly improve the predictions for all the redox pairs. In particular, for TPSSh and B3LYP*, the calculated errors decrease by more than 0.5 V against experimental values for catalyst reduction potentials, photosensitizer oxidation potentials, and electron donor oxidation potentials. Energy-corrected TPSSh results were finally used to predict the energetics of complete photocatalytic cycles for the light-driven activation of selected proton reduction cobalt catalysts. These predictions demonstrate the broader usefulness of the adopted approach to systematically predict full photocycle behavior for first-row transition metal photosensitizer-catalyst combinations more broadly.
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Affiliation(s)
- Iria Bolaño Losada
- Division of Computational Chemistry, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Petter Persson
- Division of Computational Chemistry, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
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14
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Wegeberg C, Häussinger D, Kupfer S, Wenger OS. Controlling the Photophysical Properties of a Series of Isostructural d 6 Complexes Based on Cr 0, Mn I, and Fe II. J Am Chem Soc 2024; 146:4605-4619. [PMID: 38334415 PMCID: PMC10885143 DOI: 10.1021/jacs.3c11580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Development of first-row transition metal complexes with similar luminescence and photoredox properties as widely used RuII polypyridines is attractive because metals from the first transition series are comparatively abundant and inexpensive. The weaker ligand field experienced by the valence d-electrons of first-row transition metals challenges the installation of the same types of metal-to-ligand charge transfer (MLCT) excited states as in precious metal complexes, due to rapid population of energetically lower-lying metal-centered (MC) states. In a family of isostructural tris(diisocyanide) complexes of the 3d6 metals Cr0, MnI, and FeII, the increasing effective nuclear charge and ligand field strength allow us to control the energetic order between the 3MLCT and 3MC states, whereas pyrene decoration of the isocyanide ligand framework provides control over intraligand (ILPyr) states. The chromium(0) complex shows red 3MLCT phosphorescence because all other excited states are higher in energy. In the manganese(I) complex, a microsecond-lived dark 3ILPyr state, reminiscent of the types of electronic states encountered in many polyaromatic hydrocarbon compounds, is the lowest and becomes photoactive. In the iron(II) complex, the lowest MLCT state has shifted to so much higher energy that 1ILPyr fluorescence occurs, in parallel to other excited-state deactivation pathways. Our combined synthetic-spectroscopic-theoretical study provides unprecedented insights into how effective nuclear charge, ligand field strength, and ligand π-conjugation affect the energetic order between MLCT and ligand-based excited states, and under what circumstances these individual states become luminescent and exploitable in photochemistry. Such insights are the key to further developments of luminescent and photoredox-active first-row transition metal complexes.
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Affiliation(s)
- Christina Wegeberg
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Daniel Häussinger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Stephan Kupfer
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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15
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Shi Y, Zhang G, Xiang C, Liu C, Hu J, Wang J, Ge R, Ma H, Niu Y, Xu Y. Defect-Engineering-Mediated Long-Lived Charge-Transfer Excited-State in Fe-Gallate Complex Improves Iron Cycle and Enables Sustainable Fenton-Like Reaction. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2305162. [PMID: 37708316 DOI: 10.1002/adma.202305162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/18/2023] [Indexed: 09/16/2023]
Abstract
Fenton reactions are inefficient because the Fe(II) catalyst cannot be recycled in time due to the lack of a rapid electron transport pathway. This results in huge H2 O2 wastage in industrial applications. Here, it is shown that a sustainable heterogeneous Fenton system is attainable by enhancing the ligand-to-metal charge-transfer (LMCT) excited-state lifetime in Fe-gallate complex. By engineering oxygen defects in the complex, the lifetime is improved from 10-90 ps. The lengthened lifetime ensures sufficient concentrations of excited-states for an efficient Fe cycle, realizing previously unattainable H2 O2 activation kinetics and hydroxyl radical (• OH) productivity. Spectroscopic and electrochemical studies show the cyclic reaction mechanism involves in situ Fe(II) regeneration and synchronous supply of oxygen atoms from water to recover dissociated Fe─O bonds. Trace amounts of this catalyst effectively destroy two drug-resistant bacteria even after eight reaction cycles. This work reveals the link among LMCT excited-state lifetime, Fe cycle, and catalytic activity and stability, with implications for de novo design of efficient and sustainable Fenton-like processes.
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Affiliation(s)
- Yanfeng Shi
- Institute of Biomedical Engineering, College of Life Sciences, Qingdao University, Qingdao, 266071, China
| | - Gong Zhang
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment, Tsinghua University, Beijing, 100084, China
| | - Chao Xiang
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment, Tsinghua University, Beijing, 100084, China
| | - Chengzhen Liu
- Institute of Biomedical Engineering, College of Life Sciences, Qingdao University, Qingdao, 266071, China
| | - Jun Hu
- School of Chemical Engineering, Northwest University, Xi' an, 710069, China
| | - Junhu Wang
- Center for Advanced Mössbauer Spectroscopy, Mössbauer Effect Data Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116000, China
| | - Rile Ge
- Center for Advanced Mössbauer Spectroscopy, Mössbauer Effect Data Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116000, China
| | - Haixia Ma
- School of Chemical Engineering, Northwest University, Xi' an, 710069, China
| | - Yusheng Niu
- Institute of Biomedical Engineering, College of Life Sciences, Qingdao University, Qingdao, 266071, China
| | - Yuanhong Xu
- Institute of Biomedical Engineering, College of Life Sciences, Qingdao University, Qingdao, 266071, China
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16
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Kim D, Dang VQ, Teets TS. Improved transition metal photosensitizers to drive advances in photocatalysis. Chem Sci 2023; 15:77-94. [PMID: 38131090 PMCID: PMC10732135 DOI: 10.1039/d3sc04580c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 11/22/2023] [Indexed: 12/23/2023] Open
Abstract
To function effectively in a photocatalytic application, a photosensitizer's light absorption, excited-state lifetime, and redox potentials, both in the ground state and excited state, are critically important. The absorption profile is particularly relevant to applications involving solar harvesting, whereas the redox potentials and excited-state lifetimes determine the thermodynamics, kinetics, and quantum yields of photoinduced redox processes. This perspective article focuses on synthetic inorganic and organometallic approaches to optimize these three characteristics of transition-metal based photosensitizers. We include our own work in these areas, which has focused extensively on exceptionally strong cyclometalated iridium photoreductants that enable challenging reductive photoredox transformations on organic substrates, and more recent work which has led to improved solar harvesting in charge-transfer copper(i) chromophores, an emerging class of earth-abundant compounds particularly relevant to solar-energy applications. We also extensively highlight many other complementary strategies for optimizing these parameters and highlight representative examples from the recent literature. It remains a significant challenge to simultaneously optimize all three of these parameters at once, since improvements in one often come at the detriment of the others. These inherent trade-offs and approaches to obviate or circumvent them are discussed throughout.
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Affiliation(s)
- Dooyoung Kim
- University of Houston, Department of Chemistry 3585 Cullen Blvd. Room 112 Houston TX 77204-5003 USA
| | - Vinh Q Dang
- University of Houston, Department of Chemistry 3585 Cullen Blvd. Room 112 Houston TX 77204-5003 USA
| | - Thomas S Teets
- University of Houston, Department of Chemistry 3585 Cullen Blvd. Room 112 Houston TX 77204-5003 USA
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17
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Lindh L, Pascher T, Persson S, Goriya Y, Wärnmark K, Uhlig J, Chábera P, Persson P, Yartsev A. Multifaceted Deactivation Dynamics of Fe(II) N-Heterocyclic Carbene Photosensitizers. J Phys Chem A 2023; 127:10210-10222. [PMID: 38000043 DOI: 10.1021/acs.jpca.3c06983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2023]
Abstract
Excited state dynamics of three iron(II) carbene complexes that serve as prototype Earth-abundant photosensitizers were investigated by ultrafast optical spectroscopy. Significant differences in the dynamics between the investigated complexes down to femtosecond time scales are used to characterize fundamental differences in the depopulation of triplet metal-to-ligand charge-transfer (3MLCT) excited states in the presence of energetically accessible triplet metal-centered (3MC) states. Novel insights into the full deactivation cascades of the investigated complexes include evidence of the need to revise the deactivation model for a prominent iron carbene prototype complex, a refined understanding of complex 3MC dynamics, and a quantitative discrimination between activated and barrierless deactivation steps along the 3MLCT → 3MC → 1GS path. Overall, the study provides an improved understanding of photophysical limitations and opportunities for the use of iron(II)-based photosensitizers in photochemical applications.
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Affiliation(s)
- Linnea Lindh
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
- Division of Computational Chemistry, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Torbjörn Pascher
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Samuel Persson
- Center for Analysis and Synthesis (CAS), Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Yogesh Goriya
- Center for Analysis and Synthesis (CAS), Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Kenneth Wärnmark
- Center for Analysis and Synthesis (CAS), Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Jens Uhlig
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Pavel Chábera
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Petter Persson
- Division of Computational Chemistry, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
| | - Arkady Yartsev
- Division of Chemical Physics, Department of Chemistry, Lund University, Box 124, SE-22100 Lund, Sweden
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18
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Sinha N, Wegeberg C, Häussinger D, Prescimone A, Wenger OS. Photoredox-active Cr(0) luminophores featuring photophysical properties competitive with Ru(II) and Os(II) complexes. Nat Chem 2023; 15:1730-1736. [PMID: 37580444 PMCID: PMC10695827 DOI: 10.1038/s41557-023-01297-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 07/19/2023] [Indexed: 08/16/2023]
Abstract
Coordination complexes of precious metals with the d6 valence electron configuration such as Ru(II), Os(II) and Ir(III) are used for lighting applications, solar energy conversion and photocatalysis. Until now, d6 complexes made from abundant first-row transition metals with competitive photophysical and photochemical properties have been elusive. While previous research efforts focused mostly on Fe(II), we disclose that isoelectronic Cr(0) gives access to higher photoluminescence quantum yields and excited-state lifetimes when compared with any other first-row d6 metal complex reported so far. The luminescence behaviour of the metal-to-ligand charge transfer excited states of these Cr(0) complexes is competitive with Os(II) polypyridines. With these Cr(0) complexes, the metal-to-ligand charge transfer states of first-row d6 metal complexes become exploitable in photoredox catalysis, and benchmark chemical reductions proceed efficiently under low-energy red illumination. Here we demonstrate that appropriate molecular design strategies open up new perspectives for photophysics and photochemistry with abundant first-row d6 metals.
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Affiliation(s)
- Narayan Sinha
- Department of Chemistry, University of Basel, Basel, Switzerland
| | | | | | | | - Oliver S Wenger
- Department of Chemistry, University of Basel, Basel, Switzerland.
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19
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Wang C, Wegeberg C, Wenger OS. First-Row d 6 Metal Complex Enables Photon Upconversion and Initiates Blue Light-Dependent Polymerization with Red Light. Angew Chem Int Ed Engl 2023; 62:e202311470. [PMID: 37681516 DOI: 10.1002/anie.202311470] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/07/2023] [Accepted: 09/08/2023] [Indexed: 09/09/2023]
Abstract
Photosensitizers for sensitized triplet-triplet annihilation upconversion (sTTA-UC) often rely on precious heavy metals, whereas coordination complexes based on abundant first-row transition metals are less common. This is mainly because long-lived triplet excited states are more difficult to obtain for 3d metals, particularly when the d-subshell is only partially filled. Here, we report the first example of sTTA-UC based on a 3d6 metal photosensitizer yielding an upconversion performance competitive with precious metal-based analogues. Using a newly developed Cr0 photosensitizer featuring equally good photophysical properties as an OsII benchmark complex in combination with an acetylene-decorated anthracene annihilator, red-to-blue upconversion is achievable. The upconversion efficiency under optimized conditions is 1.8 %, and the excitation power density threshold to reach the strong annihilation limit is 5.9 W/cm2 . These performance factors, along with high photostability, permit the initiation of acrylamide polymerization by red light, based on radiative energy transfer between delayed annihilator fluorescence and a blue light absorbing photo-initiator. Our study provides the proof-of-concept for photon upconversion with elusive first-row analogues of widely employed precious d6 metal photosensitizers, and for their application in photochemical reactions triggered by excitation wavelengths close to near-infrared.
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Affiliation(s)
- Cui Wang
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
- Current address: Department of Biology and Chemistry, Osnabrück University, Barbarastraße 7, 49076, Osnabrück, Germany
| | - Christina Wegeberg
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
- Current address: Division of Chemical Physics, Department of Chemistry, Lund University Box 124, 22100, Lund, Sweden
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
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20
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Chan AY, Ghosh A, Yarranton JT, Twilton J, Jin J, Arias-Rotondo DM, Sakai HA, McCusker JK, MacMillan DWC. Exploiting the Marcus inverted region for first-row transition metal-based photoredox catalysis. Science 2023; 382:191-197. [PMID: 37824651 PMCID: PMC10690870 DOI: 10.1126/science.adj0612] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 08/28/2023] [Indexed: 10/14/2023]
Abstract
Second- and third-row transition metal complexes are widely employed in photocatalysis, whereas earth-abundant first-row transition metals have found only limited use because of the prohibitively fast decay of their excited states. We report an unforeseen reactivity mode for productive photocatalysis that uses cobalt polypyridyl complexes as photocatalysts by exploiting Marcus inverted region behavior that couples increases in excited-state energies with increased excited-state lifetimes. These cobalt (III) complexes can engage in bimolecular reactivity by virtue of their strong redox potentials and sufficiently long excited-state lifetimes, catalyzing oxidative C(sp2)-N coupling of aryl amides with challenging sterically hindered aryl boronic acids. More generally, the results imply that chromophores can be designed to increase excited-state lifetimes while simultaneously increasing excited-state energies, providing a pathway for the use of relatively abundant metals as photoredox catalysts.
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Affiliation(s)
- Amy Y. Chan
- Merck Center for Catalysis at Princeton University, Princeton, NJ 08544, USA
| | - Atanu Ghosh
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | | | - Jack Twilton
- Merck Center for Catalysis at Princeton University, Princeton, NJ 08544, USA
| | - Jian Jin
- Merck Center for Catalysis at Princeton University, Princeton, NJ 08544, USA
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | | | - Holt A. Sakai
- Merck Center for Catalysis at Princeton University, Princeton, NJ 08544, USA
| | - James K. McCusker
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
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21
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Alowakennu MM, Ghosh A, McCusker JK. Direct Evidence for Excited Ligand Field State-based Oxidative Photoredox Chemistry of a Cobalt(III) Polypyridyl Photosensitizer. J Am Chem Soc 2023; 145:20786-20791. [PMID: 37703518 DOI: 10.1021/jacs.3c09374] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
Increasing interest in sustainable chemistry coupled with the quest to explore new reactivity has spurred research on first-row transition metal complexes for potential applications in a variety of settings. One of the more active areas of research is photoredox catalysis, where the synthetically tunable nature of their electronic structures provides a rich palette of options for tailoring their reactivity to a desired chemical transformation. Understanding the mechanism of excited-state reactivity is critical for the informed development of next-generation catalysts, which in turn requires information concerning the propensity of their electronic excited states to engage in the desired electron or energy transfer processes. Herein we provide direct evidence of the highly oxidizing nature of the lowest-energy ligand-field (LF) excited state of a first-row d6-low-spin Co(III) photosensitizer [Co(4,4'-Br2bpy)3]3+ (where 4,4'-Br2bpy is 4,4'-dibromo-2,2'-bipyridine). The redox potential associated with the LF excited state of the Co(III) complex was bracketed by performing bimolecular quenching studies by using a series of simple organic electron donors. Time-resolved absorption spectroscopy confirmed a dynamic quenching process attributed to reductive quenching of the lowest-energy ligand-field excited state of the Co(III) chromophore. Analysis of the Stern-Volmer plots for each chromophore-quencher pair revealed a limiting value of Ered* ∼ 1.25 V vs Fc/Fc+ for the metal-centered excited state, which is significantly stronger than that of more commonly employed transition metal-based photoredox agents such as [Ru(bpy)3]2+ (Ered* = 0.32 V vs Fc/Fc+) and [Ir(ppy)2(bpy)]+ (Ered* = 0.27 V vs Fc/Fc+). These results suggest that this class of chromophores could find utility in applications requiring the activation of oxidatively resistant organic substrates for photoredox catalysis.
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Affiliation(s)
- Micheal M Alowakennu
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
| | - Atanu Ghosh
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
| | - James K McCusker
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
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22
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Reinhard M, Skoien D, Spies JA, Garcia-Esparza AT, Matson BD, Corbett J, Tian K, Safranek J, Granados E, Strader M, Gaffney KJ, Alonso-Mori R, Kroll T, Sokaras D. Solution phase high repetition rate laser pump x-ray probe picosecond hard x-ray spectroscopy at the Stanford Synchrotron Radiation Lightsource. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2023; 10:054304. [PMID: 37901682 PMCID: PMC10613086 DOI: 10.1063/4.0000207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 10/11/2023] [Indexed: 10/31/2023]
Abstract
We present a dedicated end-station for solution phase high repetition rate (MHz) picosecond hard x-ray spectroscopy at beamline 15-2 of the Stanford Synchrotron Radiation Lightsource. A high-power ultrafast ytterbium-doped fiber laser is used to photoexcite the samples at a repetition rate of 640 kHz, while the data acquisition operates at the 1.28 MHz repetition rate of the storage ring recording data in an alternating on-off mode. The time-resolved x-ray measurements are enabled via gating the x-ray detectors with the 20 mA/70 ps camshaft bunch of SPEAR3, a mode available during the routine operations of the Stanford Synchrotron Radiation Lightsource. As a benchmark study, aiming to demonstrate the advantageous capabilities of this end-station, we have conducted picosecond Fe K-edge x-ray absorption spectroscopy on aqueous [FeII(phen)3]2+, a prototypical spin crossover complex that undergoes light-induced excited spin state trapping forming an electronic excited state with a 0.6-0.7 ns lifetime. In addition, we report transient Fe Kβ main line and valence-to-core x-ray emission spectra, showing a unique detection sensitivity and an excellent agreement with model spectra and density functional theory calculations, respectively. Notably, the achieved signal-to-noise ratio, the overall performance, and the routine availability of the developed end-station have enabled a systematic time-resolved science program using the monochromatic beam at the Stanford Synchrotron Radiation Lightsource.
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Affiliation(s)
- Marco Reinhard
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Dean Skoien
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | | | | | | | - Jeff Corbett
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Kai Tian
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - James Safranek
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Eduardo Granados
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Matthew Strader
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Kelly J. Gaffney
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | | | - Thomas Kroll
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
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23
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Reinhard M, Gallo A, Guo M, Garcia-Esparza AT, Biasin E, Qureshi M, Britz A, Ledbetter K, Kunnus K, Weninger C, van Driel T, Robinson J, Glownia JM, Gaffney KJ, Kroll T, Weng TC, Alonso-Mori R, Sokaras D. Ferricyanide photo-aquation pathway revealed by combined femtosecond Kβ main line and valence-to-core x-ray emission spectroscopy. Nat Commun 2023; 14:2443. [PMID: 37147295 PMCID: PMC10163258 DOI: 10.1038/s41467-023-37922-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 03/30/2023] [Indexed: 05/07/2023] Open
Abstract
Reliably identifying short-lived chemical reaction intermediates is crucial to elucidate reaction mechanisms but becomes particularly challenging when multiple transient species occur simultaneously. Here, we report a femtosecond x-ray emission spectroscopy and scattering study of the aqueous ferricyanide photochemistry, utilizing the combined Fe Kβ main and valence-to-core emission lines. Following UV-excitation, we observe a ligand-to-metal charge transfer excited state that decays within 0.5 ps. On this timescale, we also detect a hitherto unobserved short-lived species that we assign to a ferric penta-coordinate intermediate of the photo-aquation reaction. We provide evidence that bond photolysis occurs from reactive metal-centered excited states that are populated through relaxation of the charge transfer excited state. Beyond illuminating the elusive ferricyanide photochemistry, these results show how current limitations of Kβ main line analysis in assigning ultrafast reaction intermediates can be circumvented by simultaneously using the valence-to-core spectral range.
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Affiliation(s)
- Marco Reinhard
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA.
| | | | - Meiyuan Guo
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | | | - Elisa Biasin
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | | | | | - Kathryn Ledbetter
- Department of Physics, Stanford University, Stanford, CA, USA
- Department of Physics, Harvard University, Cambridge, MA, USA
| | | | - Clemens Weninger
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- MAX IV Laboratory, Lund University, Lund, Sweden
| | - Tim van Driel
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | | | | | | | - Thomas Kroll
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
| | - Tsu-Chien Weng
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
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24
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Steube J, Kruse A, Bokareva OS, Reuter T, Demeshko S, Schoch R, Argüello Cordero MA, Krishna A, Hohloch S, Meyer F, Heinze K, Kühn O, Lochbrunner S, Bauer M. Janus-type emission from a cyclometalated iron(III) complex. Nat Chem 2023; 15:468-474. [PMID: 36849804 PMCID: PMC10070185 DOI: 10.1038/s41557-023-01137-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 01/19/2023] [Indexed: 03/01/2023]
Abstract
Although iron is a dream candidate to substitute noble metals in photoactive complexes, realization of emissive and photoactive iron compounds is demanding due to the fast deactivation of their charge-transfer states. Emissive iron compounds are scarce and dual emission has not been observed before. Here we report the FeIII complex [Fe(ImP)2][PF6] (HImP = 1,1'-(1,3-phenylene)bis(3-methyl-1-imidazol-2-ylidene)), showing a Janus-type dual emission from ligand-to-metal charge transfer (LMCT)- and metal-to-ligand charge transfer (MLCT)-dominated states. This behaviour is achieved by a ligand design that combines four N-heterocyclic carbenes with two cyclometalating aryl units. The low-lying π* levels of the cyclometalating units lead to energetically accessible MLCT states that cannot evolve into LMCT states. With a lifetime of 4.6 ns, the strongly reducing and oxidizing MLCT-dominated state can initiate electron transfer reactions, which could constitute a basis for future applications of iron in photoredox catalysis.
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Affiliation(s)
- Jakob Steube
- Institute of Inorganic Chemistry, Paderborn University, Paderborn, Germany
- Center for Sustainable Systems Design, Paderborn University, Paderborn, Germany
| | - Ayla Kruse
- Department of Life, Light and Matter, University of Rostock, Rostock, Germany
- Institute for Physics, University of Rostock, Rostock, Germany
| | - Olga S Bokareva
- Institute for Physics, University of Rostock, Rostock, Germany
- Institute of Physics, University of Kassel, Kassel, Germany
| | - Thomas Reuter
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Serhiy Demeshko
- Institute of Inorganic Chemistry, University of Göttingen, Göttingen, Germany
| | - Roland Schoch
- Institute of Inorganic Chemistry, Paderborn University, Paderborn, Germany
- Center for Sustainable Systems Design, Paderborn University, Paderborn, Germany
| | - Miguel A Argüello Cordero
- Department of Life, Light and Matter, University of Rostock, Rostock, Germany
- Institute for Physics, University of Rostock, Rostock, Germany
| | - Athul Krishna
- Institute of Inorganic Chemistry, Paderborn University, Paderborn, Germany
- Center for Sustainable Systems Design, Paderborn University, Paderborn, Germany
| | - Stephan Hohloch
- Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Austria
| | - Franc Meyer
- Institute of Inorganic Chemistry, University of Göttingen, Göttingen, Germany
| | - Katja Heinze
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Oliver Kühn
- Department of Life, Light and Matter, University of Rostock, Rostock, Germany
- Institute for Physics, University of Rostock, Rostock, Germany
| | - Stefan Lochbrunner
- Department of Life, Light and Matter, University of Rostock, Rostock, Germany
- Institute for Physics, University of Rostock, Rostock, Germany
| | - Matthias Bauer
- Institute of Inorganic Chemistry, Paderborn University, Paderborn, Germany.
- Center for Sustainable Systems Design, Paderborn University, Paderborn, Germany.
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25
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Malme JT, Clendening RA, Ash R, Curry T, Ren T, Vura-Weis J. Nanosecond Metal-to-Ligand Charge-Transfer State in an Fe(II) Chromophore: Lifetime Enhancement via Nested Potentials. J Am Chem Soc 2023; 145:6029-6034. [PMID: 36913625 DOI: 10.1021/jacs.2c13532] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
Examples of Fe complexes with long-lived (≥1 ns) charge-transfer states are limited to pseudo-octahedral geometries with strong σ-donor chelates. Alternative strategies based on varying both coordination motifs and ligand donicity are highly desirable. Reported herein is an air-stable, tetragonal FeII complex, Fe(HMTI)(CN)2 (HMTI = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene), with a 1.25 ns metal-to-ligand charge-transfer (MLCT) lifetime. The structure has been determined, and the photophysical properties have been examined in a variety of solvents. The HMTI ligand is highly π-acidic due to low-lying π*(C═N), which enhances ΔFe via stabilizing t2g orbitals. The inflexible geometry of the macrocycle results in short Fe-N bonds, and density functional theory calculations show that this rigidity results in an unusual set of nested potential energy surfaces. Moreover, the lifetime and energy of the MLCT state depends strongly on the solvent environment. This dependence is caused by modulation of the axial ligand-field strength by Lewis acid-base interactions between the solvent and the cyano ligands. This work represents the first example of a long-lived charge transfer state in an FeII macrocyclic species.
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Affiliation(s)
- Justin T Malme
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Reese A Clendening
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ryan Ash
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Taylor Curry
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Tong Ren
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Josh Vura-Weis
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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26
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Huss T, Dixon IM. Electronic Structure and Geometry of the Lowest 2LMCT State of Fe(III) Potential Fluorescent Emitters†. Inorg Chem 2023; 62:4284-4290. [PMID: 36852931 DOI: 10.1021/acs.inorgchem.2c04407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Metal complexes with a 3d6 electron count are emerging as an alternative to 4d6-based photosensitizers, emitters, or photoredox catalysts. In recent years, several Fe(II) potential emitters have been proposed, based on strongly donating ligand sets. Those tend to facilitate oxidation to their 3d5 species, whose photophysics is based on low-lying ligand-to-metal charge-transfer (LMCT) states. The geometry and electronic structure of 2LMCT states are unveiled in this work.
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Affiliation(s)
- Tabea Huss
- Laboratoire de Chimie et Physique Quantiques, Universite de Toulouse, CNRS, Universite Toulouse III - Paul Sabatier, F-31062 Toulouse, France
| | - Isabelle M Dixon
- Laboratoire de Chimie et Physique Quantiques, Universite de Toulouse, CNRS, Universite Toulouse III - Paul Sabatier, F-31062 Toulouse, France
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27
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Sinha N, Wenger OS. Photoactive Metal-to-Ligand Charge Transfer Excited States in 3d 6 Complexes with Cr 0, Mn I, Fe II, and Co III. J Am Chem Soc 2023; 145:4903-4920. [PMID: 36808978 PMCID: PMC9999427 DOI: 10.1021/jacs.2c13432] [Citation(s) in RCA: 39] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Many coordination complexes and organometallic compounds with the 4d6 and 5d6 valence electron configurations have outstanding photophysical and photochemical properties, which stem from metal-to-ligand charge transfer (MLCT) excited states. This substance class makes extensive use of the most precious and least abundant metal elements, and consequently there has been a long-standing interest in first-row transition metal compounds with photoactive MLCT states. Semiprecious copper(I) with its completely filled 3d subshell is a relatively straightforward and well explored case, but in 3d6 complexes the partially filled d-orbitals lead to energetically low-lying metal-centered (MC) states that can cause undesirably fast MLCT excited state deactivation. Herein, we discuss recent advances made with isoelectronic Cr0, MnI, FeII, and CoIII compounds, for which long-lived MLCT states have become accessible over the past five years. Furthermore, we discuss possible future developments in the search for new first-row transition metal complexes with partially filled 3d subshells and photoactive MLCT states for next-generation applications in photophysics and photochemistry.
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Affiliation(s)
- Narayan Sinha
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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28
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Duan C, Nandy A, Terrones GG, Kastner DW, Kulik HJ. Active Learning Exploration of Transition-Metal Complexes to Discover Method-Insensitive and Synthetically Accessible Chromophores. JACS AU 2023; 3:391-401. [PMID: 36873700 PMCID: PMC9976347 DOI: 10.1021/jacsau.2c00547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 06/18/2023]
Abstract
Transition-metal chromophores with earth-abundant transition metals are an important design target for their applications in lighting and nontoxic bioimaging, but their design is challenged by the scarcity of complexes that simultaneously have well-defined ground states and optimal target absorption energies in the visible region. Machine learning (ML) accelerated discovery could overcome such challenges by enabling the screening of a larger space but is limited by the fidelity of the data used in ML model training, which is typically from a single approximate density functional. To address this limitation, we search for consensus in predictions among 23 density functional approximations across multiple rungs of "Jacob's ladder". To accelerate the discovery of complexes with absorption energies in the visible region while minimizing the effect of low-lying excited states, we use two-dimensional (2D)efficient global optimization to sample candidate low-spin chromophores from multimillion complex spaces. Despite the scarcity (i.e., ∼0.01%) of potential chromophores in this large chemical space, we identify candidates with high likelihood (i.e., >10%) of computational validation as the ML models improve during active learning, representing a 1000-fold acceleration in discovery. Absorption spectra of promising chromophores from time-dependent density functional theory verify that 2/3 of candidates have the desired excited-state properties. The observation that constituent ligands from our leads have demonstrated interesting optical properties in the literature exemplifies the effectiveness of our construction of a realistic design space and active learning approach.
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Affiliation(s)
- Chenru Duan
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139, United States
| | - Aditya Nandy
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139, United States
| | - Gianmarco G. Terrones
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
| | - David W. Kastner
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
- Department
of Biological Engineering, Massachusetts
Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather J. Kulik
- Department
of Chemical Engineering, Massachusetts Institute
of Technology, Cambridge, Massachusetts 02139, United States
- Department
of Chemistry, Massachusetts Institute of
Technology, Cambridge, Massachusetts 02139, United States
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29
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Wu X, Yu F, Han Y, Jiang L, Li Z, Zhu J, Xu Q, Tedesco AC, Zhang J, Bi H. Enhanced chemodynamic and photoluminescence efficiencies of Fe-O 4 coordinated carbon dots via the core-shell synergistic effect. NANOSCALE 2022; 15:376-386. [PMID: 36511884 DOI: 10.1039/d2nr05281d] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
In natural systems like photosynthetic organisms and photo-active enzymes, the spatial organization of chromophores is critical for efficient light harvesting and bio-catalysis. Inspired by nature, a novel modular nanoplatform with both biological imaging and therapeutic functions is constructed by taking advantage of the intrinsic core-shell structure of Fe-decorated carbon dots. Light-harvesting chromophores with deep-red photoluminescence are densely packed into the carbon core. Simultaneously, the atomically dispersed Fe3+ catalytic sites accounting for efficient conversion of H2O2 to ˙OH are discretely distributed on the shell. Precise control over their spatial distribution leads to the elegant integration and exciting interplay of the functional moieties. On the one hand, incorporating a catalysis shell enhances the emission of chromophores via synergistic shielding and rigidifying effects. On the other hand, visible light excitation of the chromophores significantly increases the catalytic activity and cytotoxicity against cancer cells, ascribed to the promotion of the charge transfer process. This nanoplatform exhibits excellent biocompatibility, bright red fluorescence, and light-regulated cytotoxicity for anti-cancer treatment, promising its applications in smart nanocatalytic medicines and efficient chemodynamic therapy.
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Affiliation(s)
- Xiaoyan Wu
- School of Materials Science and Engineering, Anhui University, Hefei 230601, China.
| | - Feng Yu
- School of Chemistry and Chemical Engineering, Anhui University, Hefei 230601, China
| | - Yifei Han
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Anhui 230026, China
| | - Lei Jiang
- School of Chemistry and Chemical Engineering, Anhui University, Hefei 230601, China
| | - Zijian Li
- School of Materials Science and Engineering, Anhui University, Hefei 230601, China.
| | - Junfa Zhu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, China.
| | - Qian Xu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, China.
| | - Antonio Claudio Tedesco
- School of Chemistry and Chemical Engineering, Anhui University, Hefei 230601, China
- Department of Chemistry, Center of Nanotechnology and Tissue Engineering-Photobiology and Photomedicine Re-search Group, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, Ri-beirão Preto, São Paulo 14040-901, Brazil
| | - Jiangwei Zhang
- College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
| | - Hong Bi
- School of Materials Science and Engineering, Anhui University, Hefei 230601, China.
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30
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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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31
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Curtin GM, Jakubikova E. Extended π-Conjugated Ligands Tune Excited-State Energies of Iron(II) Polypyridine Dyes. Inorg Chem 2022; 61:18850-18860. [DOI: 10.1021/acs.inorgchem.2c02362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Gregory M. Curtin
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Elena Jakubikova
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
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32
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Lozada IB, Braun JD, Williams JAG, Herbert DE. Yellow-Emitting, Pseudo-Octahedral Zinc Complexes of Benzannulated N^N^O Pincer-Type Ligands. Inorg Chem 2022; 61:17568-17578. [DOI: 10.1021/acs.inorgchem.2c02585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Issiah B. Lozada
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, ManitobaR3T 2N2, Canada
| | - Jason D. Braun
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, ManitobaR3T 2N2, Canada
| | | | - David E. Herbert
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, ManitobaR3T 2N2, Canada
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33
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Prakash O, Lindh L, Kaul N, Rosemann NW, Losada IB, Johnson C, Chábera P, Ilic A, Schwarz J, Gupta AK, Uhlig J, Ericsson T, Häggström L, Huang P, Bendix J, Strand D, Yartsev A, Lomoth R, Persson P, Wärnmark K. Photophysical Integrity of the Iron(III) Scorpionate Framework in Iron(III)–NHC Complexes with Long-Lived 2LMCT Excited States. Inorg Chem 2022; 61:17515-17526. [DOI: 10.1021/acs.inorgchem.2c02410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Om Prakash
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Linnea Lindh
- Chemical Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
- Theoretical Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Nidhi Kaul
- Department of Chemistry − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Nils W. Rosemann
- Chemical Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Iria Bolaño Losada
- Theoretical Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Catherine Johnson
- Department of Chemistry − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Pavel Chábera
- Chemical Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Aleksandra Ilic
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Jesper Schwarz
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Arvind Kumar Gupta
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Jens Uhlig
- Chemical Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Tore Ericsson
- Department of Physics − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Lennart Häggström
- Department of Physics − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Ping Huang
- Department of Chemistry − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Jesper Bendix
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100Copenhagen, Denmark
| | - Daniel Strand
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Arkady Yartsev
- Chemical Physics Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Reiner Lomoth
- Department of Chemistry − Ångström Laboratory, Uppsala University, Box 523, SE-75120Uppsala, Sweden
| | - Petter Persson
- Theoretical Chemistry Division, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
| | - Kenneth Wärnmark
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, Box 124, SE-22100Lund, Sweden
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34
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Kübler J, Pfund B, Wenger OS. Zinc(II) Complexes with Triplet Charge-Transfer Excited States Enabling Energy-Transfer Catalysis, Photoinduced Electron Transfer, and Upconversion. JACS AU 2022; 2:2367-2380. [PMID: 36311829 PMCID: PMC9597861 DOI: 10.1021/jacsau.2c00442] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/22/2022] [Accepted: 09/22/2022] [Indexed: 05/28/2023]
Abstract
Many CuI complexes have luminescent triplet charge-transfer excited states with diverse applications in photophysics and photochemistry, but for isoelectronic ZnII compounds, this behavior is much less common, and they typically only show ligand-based fluorescence from singlet π-π* states. We report two closely related tetrahedral ZnII compounds, in which intersystem crossing occurs with appreciable quantum yields and leads to the population of triplet excited states with intraligand charge-transfer (ILCT) character. In addition to showing fluorescence from their initially excited 1ILCT states, these new compounds therefore undergo triplet-triplet energy transfer (TTET) from their 3ILCT states and consequently can act as sensitizers for photo-isomerization reactions and triplet-triplet annihilation upconversion from the blue to the ultraviolet spectral range. The photoactive 3ILCT state furthermore facilitates photoinduced electron transfer. Collectively, our findings demonstrate that mononuclear ZnII compounds with photophysical and photochemical properties reminiscent of well-known CuI complexes are accessible with suitable ligands and that they are potentially amenable to many different applications. Our insights seem relevant in the greater context of obtaining photoactive compounds based on abundant transition metals, complementing well-known precious-metal-based luminophores and photosensitizers.
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35
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Moll J, Naumann R, Sorge L, Förster C, Gessner N, Burkhardt L, Ugur N, Nuernberger P, Seidel W, Ramanan C, Bauer M, Heinze K. Pseudo-Octahedral Iron(II) Complexes with Near-Degenerate Charge Transfer and Ligand Field States at the Franck-Condon Geometry. Chemistry 2022; 28:e202201858. [PMID: 35862259 DOI: 10.1002/chem.202201858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Indexed: 01/07/2023]
Abstract
Increasing the metal-to-ligand charge transfer (MLCT) excited state lifetime of polypyridine iron(II) complexes can be achieved by lowering the ligand's π* orbital energy and by increasing the ligand field splitting. In the homo- and heteroleptic complexes [Fe(cpmp)2 ]2+ (12+ ) and [Fe(cpmp)(ddpd)]2+ (22+ ) with the tridentate ligands 6,2''-carboxypyridyl-2,2'-methylamine-pyridyl-pyridine (cpmp) and N,N'-dimethyl-N,N'-di-pyridin-2-ylpyridine-2,6-diamine (ddpd) two or one dipyridyl ketone moieties provide low energy π* acceptor orbitals. A good metal-ligand orbital overlap to increase the ligand field splitting is achieved by optimizing the octahedricity through CO and NMe units between the coordinating pyridines which enable the formation of six-membered chelate rings. The push-pull ligand cpmp provides intra-ligand and ligand-to-ligand charge transfer (ILCT, LL'CT) excited states in addition to MLCT excited states. Ground and excited state properties of 12+ and 22+ were accessed by X-ray diffraction analyses, resonance Raman spectroscopy, (spectro)electrochemistry, EPR spectroscopy, X-ray emission spectroscopy, static and time-resolved IR and UV/Vis/NIR absorption spectroscopy as well as quantum chemical calculations.
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Affiliation(s)
- Johannes Moll
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
| | - Robert Naumann
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
| | - Lukas Sorge
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
| | - Christoph Förster
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
| | - Niklas Gessner
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Lukas Burkhardt
- Department of Chemistry, University of Paderborn, Warburger Str. 100, 33098, Paderborn, Germany
| | - Naz Ugur
- Max-Planck-Institute for Polymer Research, Mainz, Germany
| | - Patrick Nuernberger
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Wolfram Seidel
- Institute of Chemistry, University of Rostock, Albert-Einstein-Straße 3a, 18059, Rostock, Germany
| | - Charusheela Ramanan
- Max-Planck-Institute for Polymer Research, Mainz, Germany
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Matthias Bauer
- Department of Chemistry, University of Paderborn, Warburger Str. 100, 33098, Paderborn, Germany
| | - Katja Heinze
- Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128, Mainz, Germany
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Saravanakumar K, Sathiyaseelan A, Manivasagan P, Jeong MS, Choi M, Jang ES, Priya VV, Wang MH. Photothermally responsive chitosan-coated iron oxide nanoparticles for enhanced eradication of bacterial biofilms. BIOMATERIALS ADVANCES 2022; 141:213129. [PMID: 36191538 DOI: 10.1016/j.bioadv.2022.213129] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 09/09/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
This work developed a pH/NIR responsive antibacterial agent (CS-FeNPs) composed of chitosan (CS) and Fe3O4 nanoparticles (FeNPs). CS triggers bacterial attraction through surface charge, while Fe acts as a photothermal agent (PTA). The CS-Fe NPs exhibited antibacterial and antibiofilm activity against both bacteria (G+/G-). However, higher activity was observed against bacteria (G-) due to electrostatic interactions. The CS-FeNPs bind with the bacterial membrane through electrostatic interactions and disturb bacterial cells. Later, in an acidic environment, CS-FeNPs bind with bacterial membrane, and NIR irradiation leads the antibacterial activity. CS-FeNPs exhibited a potential photothermal conversion efficiency (η) of 21.53 %. Thus, it converts NIR irradiation into heat to kill the bacterial pathogen. The CS-FeNPs were found to be less cytotoxic with great antibacterial efficiency on planktonic bacteria and their biofilm, which indicates that they deserve to develop potential and safe treatment strategies for the treatment of bacterial infections.
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Affiliation(s)
- Kandasamy Saravanakumar
- Department of Bio-Health Convergence, Kangwon National University, Chuncheon 200-701, Republic of Korea.
| | - Anbazhagan Sathiyaseelan
- Department of Bio-Health Convergence, Kangwon National University, Chuncheon 200-701, Republic of Korea.
| | - Panchanathan Manivasagan
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi, Gyeongbuk 730-701, Republic of Korea.
| | - Myeong Seon Jeong
- Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon, South Korea; Chuncheon Center, Korea Basic Science Institute, Chuncheon, South Korea.
| | - Miri Choi
- Chuncheon Center, Korea Basic Science Institute, Chuncheon, South Korea.
| | - Eue-Soon Jang
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi, Gyeongbuk 730-701, Republic of Korea.
| | - Veeraraghavan Vishnu Priya
- Department of Biochemistry, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai 600077, India.
| | - Myeong-Hyeon Wang
- Department of Bio-Health Convergence, Kangwon National University, Chuncheon 200-701, Republic of Korea.
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Carrillo U, Francés-Monerris A, Marri AR, Cebrián C, Gros PC. Substituent-Induced Control of fac/ mer Isomerism in Azine-NHC Fe(II) Complexes. ACS ORGANIC & INORGANIC AU 2022; 2:525-536. [PMID: 36855530 PMCID: PMC9955161 DOI: 10.1021/acsorginorgau.2c00038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 09/12/2022] [Accepted: 09/13/2022] [Indexed: 11/29/2022]
Abstract
The stereoselective synthesis of geometrical iron(II) complexes bearing azine-NHC ligands is described. Facial and meridional selectivity is achieved as a function of the steric demand of the azine unit, with no remarkable influence of the carbene nature. More specifically, meridional complexes are obtained upon selecting bulky 5-mesityl-substituted pyridyl coordinating units. Unexpectedly, increase of the steric hindrance in the α position with respect to the N coordinating atom results in an exclusive facial configuration, which is in stark contrast to the meridional selectivity induced by other reported α-substituted bidentate ligands. Investigation of the structure and the optical and electrochemical properties of the here-described complexes has revealed the non-negligible effect of the fac/mer ligand configuration around the metal center.
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38
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Schmid L, Chábera P, Rüter I, Prescimone A, Meyer F, Yartsev A, Persson P, Wenger OS. Borylation in the Second Coordination Sphere of Fe II Cyanido Complexes and Its Impact on Their Electronic Structures and Excited-State Dynamics. Inorg Chem 2022; 61:15853-15863. [PMID: 36167335 PMCID: PMC9554916 DOI: 10.1021/acs.inorgchem.2c01667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
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Second coordination sphere interactions
of cyanido complexes with hydrogen-bonding solvents and Lewis acids
are known to influence their electronic structures, whereby the non-labile
attachment of B(C6F5)3 resulted in
several particularly interesting new compounds lately. Here, we investigate
the effects of borylation on the properties of two FeII cyanido complexes in a systematic manner by comparing five different
compounds and using a range of experimental techniques. Electrochemical
measurements indicate that borylation entails a stabilization of the
FeII-based t2g-like orbitals by up to 1.65 eV,
and this finding was confirmed by Mössbauer spectroscopy. This
change in the electronic structure has a profound impact on the UV–vis
absorption properties of the borylated complexes compared to the non-borylated
ones, shifting their metal-to-ligand charge transfer (MLCT) absorption
bands over a wide range. Ultrafast UV–vis transient absorption
spectroscopy provides insight into how borylation affects the excited-state
dynamics. The lowest metal-centered (MC) excited states become shorter-lived
in the borylated complexes compared to their cyanido analogues by
a factor of ∼10, possibly due to changes in outer-sphere reorganization
energies associated with their decay to the electronic ground state
as a result of B(C6F5)3 attachment
at the cyanido N lone pair. Borylation
in the second coordination sphere of two well-known
FeII cyanido complexes leads to isocyanoborato complexes.
The effects of borylation on their electronic structure and photophysical
properties are thoroughly investigated with a range of experimental
techniques.
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Affiliation(s)
- Lucius Schmid
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Pavel Chábera
- Department of Chemical Physics, Lund University, P.O. Box 12 4, 22100 Lund, Sweden
| | - Isabelle Rüter
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Alessandro Prescimone
- Department of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, 4058 Basel, Switzerland
| | - Franc Meyer
- Institute of Inorganic Chemistry, University of Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Arkady Yartsev
- Department of Chemical Physics, Lund University, P.O. Box 12 4, 22100 Lund, Sweden
| | - Petter Persson
- Theoretical Chemistry Division, Lund University, P.O. Box 124, 22100 Lund, Sweden
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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Nemez DB, Lozada IB, Braun JD, Williams JAG, Herbert DE. Synthesis and Coordination Chemistry of a Benzannulated Bipyridine: 6,6'-Biphenanthridine. Inorg Chem 2022; 61:13386-13398. [PMID: 35972335 DOI: 10.1021/acs.inorgchem.2c01514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The synthesis, characterization, and coordination chemistry of a doubly π-extended bipyridine analogue, 6,6'-biphenanthridine (biphe), is presented. The structure of the molecule has been determined in the solid state by X-ray diffraction, showing an angle of 72.6° between the phenanthridine planes. The free, uncoordinated organic molecule displays blue fluorescence in solution. It can be singly protonated with strong acids, and the protonated form displays more intense yellow emission. The effect of acid on the excited states is interpreted with the aid of TDDFT calculations. Two Ru(II) coordination complexes, tris(6,6'-biphenanthridine)ruthenium(II) dichloride, [Ru(biphe)3]Cl2, and bis(2,2'-bipyridine)(6,6'-biphenanthridine)ruthenium(II) tetraphenylborate, [Ru(bpy)2(biphe)](BPh4)2, are also reported and their structures determined in the solid state by X-ray diffraction. Both complexes display emission at 77 K that is strongly bathochromically shifted by almost 200 nm compared to that of the archetypal 3MLCT emitter [Ru(bpy)3]2+. Such a red shift is consistent with the more extended conjugation and lower-energy π* orbitals associated with the biphe ligand, lowering the energy of the 3MLCT excited state, as revealed by TDDFT calculations. The efficient non-radiative decay that is typical of such low-energy emitters renders the phosphorescence extremely weak and short-lived at ambient temperature, and rapid ligand photodissociation also competes with radiative decay, especially in the heteroleptic complex. Electrochemical analysis illustrates the effect of biphe's stabilized vacant π* manifold, with multiple reversible reductions evident at much less negative potentials than those observed for [Ru(bpy)3]2+.
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Affiliation(s)
- Dion B Nemez
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
| | - Issiah B Lozada
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
| | - Jason D Braun
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
| | | | - David E Herbert
- Department of Chemistry and the Manitoba Institute for Materials, University of Manitoba, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada
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Cadranel A, Gravogl L, Munz D, Meyer K. Intense Photoinduced Intervalence Charge Transfer in High‐Valent Iron Mixed Phenolate/Carbene Complexes. Chemistry 2022; 28:e202200269. [PMID: 35302682 PMCID: PMC9401866 DOI: 10.1002/chem.202200269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Alejandro Cadranel
- Department Chemie und Pharmazie Physikalische Chemie Friedrich-Alexander-Universität Erlangen–Nürnberg Egerlandstraße 3 91058 Erlangen Germany
- Departamento de Química Inorgánica Analítica y Química Física Universidad de Buenos Aires Facultad de Ciencias Exactas y Naturales Pabellón 2, Ciudad Universitaria C1428EHA Buenos Aires Argentina
- Instituto de Química Física de Materiales Medio Ambiente y Energía (INQUIMAE) CONICET–Universidad de Buenos Aires Pabellón 2, Ciudad Universitaria C1428EHA Buenos Aires Argentina
| | - Lisa Gravogl
- Department Chemie und Pharmazie Anorganische Chemie Friedrich-Alexander-Universität Erlangen–Nürnberg Egerlandstraße 1 91058 Erlangen Germany
| | - Dominik Munz
- Department Chemie und Pharmazie Anorganische Chemie Friedrich-Alexander-Universität Erlangen–Nürnberg Egerlandstraße 1 91058 Erlangen Germany
- Anorganische Chemie: Koordinationschemie Universität des Saarlandes Campus C4.1 66123 Saarbrücken Germany
| | - Karsten Meyer
- Department Chemie und Pharmazie Anorganische Chemie Friedrich-Alexander-Universität Erlangen–Nürnberg Egerlandstraße 1 91058 Erlangen Germany
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41
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Ossinger S, Prescimone A, Häussinger D, Wenger OS. Manganese(I) Complex with Monodentate Arylisocyanide Ligands Shows Photodissociation Instead of Luminescence. Inorg Chem 2022; 61:10533-10547. [PMID: 35768069 PMCID: PMC9377510 DOI: 10.1021/acs.inorgchem.2c01438] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Recently reported
manganese(I) complexes with chelating arylisocyanide
ligands exhibit luminescent metal-to-ligand charge-transfer (MLCT)
excited states, similar to ruthenium(II) polypyridine complexes with
the same d6 valence electron configuration used for many
different applications in photophysics and photochemistry. However,
chelating arylisocyanide ligands require substantial synthetic effort,
and therefore it seemed attractive to explore the possibility of using
more readily accessible monodentate arylisocyanides instead. Here,
we synthesized the new Mn(I) complex [Mn(CNdippPhOMe2)6]PF6 with the known ligand CNdippPhOMe2 = 4-(3,5-dimethoxyphenyl)-2,6-diisopropylphenylisocyanide. This
complex was investigated by NMR spectroscopy, single-crystal structure
analysis, high-resolution electrospray ionization mass spectrometry
(HR-ESI-MS) measurements, IR spectroscopy supported by density functional
theory (DFT) calculations, cyclic voltammetry, and time-resolved as
well as steady-state UV–vis absorption spectroscopy. The key
finding is that the new Mn(I) complex is nonluminescent and instead
undergoes arylisocyanide ligand loss during continuous visible laser
irradiation into ligand-centered and charge-transfer absorption bands,
presumably owed to the population of dissociative d–d excited
states. Thus, it seems that chelating bi- or tridentate binding motifs
are essential for obtaining emissive MLCT excited states in manganese(I)
arylisocyanides. Our work contributes to understanding the basic properties
of photoactive first-row transition metal complexes and could help
advance the search for alternatives to precious metal-based luminophores,
photocatalysts, and sensors. We
report the synthesis, characterization, and X-ray crystal
structure of an octahedral manganese(I) complex with six monodentate
arylisocyanide ligands that undergoes photoinduced ligand loss.
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Affiliation(s)
- Sascha Ossinger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Alessandro Prescimone
- Department of Chemistry, University of Basel, Mattenstrasse 24a, 4058 Basel, Switzerland
| | - Daniel Häussinger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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42
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Yarranton JT, McCusker JK. Ligand-Field Spectroscopy of Co(III) Complexes and the Development of a Spectrochemical Series for Low-Spin d 6 Charge-Transfer Chromophores. J Am Chem Soc 2022; 144:12488-12500. [PMID: 35749670 DOI: 10.1021/jacs.2c04945] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A study of a series of six-coordinate Co(III) complexes has been carried out to quantify spectroscopic parameters for a range of ligands that are commonly employed to realize strong charge-transfer absorptions in low-spin, d6 systems. Identification of any three ligand-field transitions allows for the determination of the splitting parameter (10 Dq) as well as the Racah B and C parameters for a given compound. The data revealed a relatively small spread in the magnitude of 10 Dq, ranging from ca. 23 000 cm-1 in the case of [Co(pyrro-bpy)3]3+ (where pyrro-bpy is 4,4'-dipyrrolidinyl-2,2'-bipyridine) to ca. 26 000 cm-1 for [Co(terpy)2]3+ (where terpy is 2,2':6',2″-terpyridine). Significantly, trends across the series suggest that polypyridyl ligands behave as net π-donors when interacting with Co(III), in contrast to the net π-accepting character they exhibit when bound to second- and third-row metals. The influence of strong σ donation associated with carbene-based ligands was evident from the data acquired for [Co(BMeImPy)2]3+ (where BMeImPy is 3,3'-(pyridine-2,6-diyl)bis(1-methyl-1H-3-imidazolium)), where a 10 Dq value of ca. 30 000 cm-1 was determined. Spectroscopic data were also analyzed for [Fe(bpy)3]2+ using the results on [Co(bpy)3]3+ as a reference point. A value for 10 Dq of 21 000 cm-1 was estimated, indicating a reduction in the ligand-field strength of ca. 3000 cm-1 upon replacing Co(III) with Fe(II). We suggest that this approach of taking advantage of the blueshift of the charge-transfer feature in Co(III) complexes to reveal otherwise obscured ligand-field bands can be a useful tool for the development of new ligand systems to expand the photofunctionality of first-row transition-metal-based chromophores.
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Affiliation(s)
- Jonathan T Yarranton
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
| | - James K McCusker
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States
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43
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Sinha N, Pfund B, Wegeberg C, Prescimone A, Wenger OS. Cobalt(III) Carbene Complex with an Electronic Excited-State Structure Similar to Cyclometalated Iridium(III) Compounds. J Am Chem Soc 2022; 144:9859-9873. [PMID: 35623627 PMCID: PMC9490849 DOI: 10.1021/jacs.2c02592] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Many organometallic
iridium(III) complexes have photoactive excited
states with mixed metal-to-ligand and intraligand charge transfer
(MLCT/ILCT) character, which form the basis for numerous applications
in photophysics and photochemistry. Cobalt(III) complexes with analogous
MLCT excited-state properties seem to be unknown yet, despite the
fact that iridium(III) and cobalt(III) can adopt identical low-spin
d6 valence electron configurations due to their close chemical
relationship. Using a rigid tridentate chelate ligand (LCNC), in which a central amido π-donor is flanked by two σ-donating
N-heterocyclic carbene subunits, we obtained a robust homoleptic complex
[Co(LCNC)2](PF6), featuring a photoactive
excited state with substantial MLCT character. Compared to the vast
majority of isoelectronic iron(II) complexes, the MLCT state of [Co(LCNC)2](PF6) is long-lived because it
does not deactivate as efficiently into lower-lying metal-centered
excited states; furthermore, it engages directly in photoinduced electron
transfer reactions. The comparison with [Fe(LCNC)2](PF6), as well as structural, electrochemical, and UV–vis
transient absorption studies, provides insight into new ligand design
principles for first-row transition-metal complexes with photophysical
and photochemical properties reminiscent of those known from the platinum
group metals.
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Affiliation(s)
- Narayan Sinha
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Björn Pfund
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Christina Wegeberg
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Alessandro Prescimone
- Department of Chemistry, University of Basel, BPR 1096, Mattenstrasse 24a, 4058 Basel, Switzerland
| | - Oliver S Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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44
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Herr P, Schwab A, Kupfer S, Wenger OS. Deep‐Red Luminescent Molybdenum(0) Complexes with Bi‐ and Tridentate Isocyanide Chelate Ligands. CHEMPHOTOCHEM 2022. [DOI: 10.1002/cptc.202200052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Patrick Herr
- University of Basel: Universitat Basel Department of Chemistry SWITZERLAND
| | - Alexander Schwab
- Friedrich-Schiller-Universität Jena: Friedrich-Schiller-Universitat Jena Institute of Physical Chemistry GERMANY
| | - Stephan Kupfer
- Friedrich-Schiller-Universität Jena: Friedrich-Schiller-Universitat Jena Institute of Physical Chemistry GERMANY
| | - Oliver S. Wenger
- Universität Basel Departement für Chemie St. Johanns-Ring 19 4056 Basel SWITZERLAND
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45
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Dimitriev OP. Dynamics of Excitons in Conjugated Molecules and Organic Semiconductor Systems. Chem Rev 2022; 122:8487-8593. [PMID: 35298145 DOI: 10.1021/acs.chemrev.1c00648] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The exciton, an excited electron-hole pair bound by Coulomb attraction, plays a key role in photophysics of organic molecules and drives practically important phenomena such as photoinduced mechanical motions of a molecule, photochemical conversions, energy transfer, generation of free charge carriers, etc. Its behavior in extended π-conjugated molecules and disordered organic films is very different and very rich compared with exciton behavior in inorganic semiconductor crystals. Due to the high degree of variability of organic systems themselves, the exciton not only exerts changes on molecules that carry it but undergoes its own changes during all phases of its lifetime, that is, birth, conversion and transport, and decay. The goal of this review is to give a systematic and comprehensive view on exciton behavior in π-conjugated molecules and molecular assemblies at all phases of exciton evolution with emphasis on rates typical for this dynamic picture and various consequences of the above dynamics. To uncover the rich variety of exciton behavior, details of exciton formation, exciton transport, exciton energy conversion, direct and reverse intersystem crossing, and radiative and nonradiative decay are considered in different systems, where these processes lead to or are influenced by static and dynamic disorder, charge distribution symmetry breaking, photoinduced reactions, electron and proton transfer, structural rearrangements, exciton coupling with vibrations and intermediate particles, and exciton dissociation and annihilation as well.
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Affiliation(s)
- Oleg P Dimitriev
- V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, pr. Nauki 41, Kyiv 03028, Ukraine
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46
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Mei YK, Min XT, Guo SY, Liu CH, Zhang XX, Ji DW, Wan B, Chen QA. Photo‐Induced Construction of N‐Aryl Amides under Fe Catalysis. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Yong-Kang Mei
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Xiang-Ting Min
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Shi-Yu Guo
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Chang-Hui Liu
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Xiang-Xin Zhang
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Ding-Wei Ji
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Boshun Wan
- Chinese Academy of Sciences Dalian Institute of Chemical Physics CHINA
| | - Qing-An Chen
- Chinese Academy of Sciences Dalian Institute of Chemical Physics 457 Zhongshan Road 116023 Dalian CHINA
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47
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Abstract
In molecular photochemistry, charge-transfer emission is well understood and widely exploited. In contrast, luminescent metal-centered transitions only came into focus in recent years. This gave rise to strongly phosphorescent CrIII complexes with a d3 electronic configuration featuring luminescent metal-centered excited states which are characterized by the flip of a single spin. These so-called spin-flip emitters possess unique properties and require different design strategies than traditional charge-transfer phosphors. In this review, we give a brief introduction to ligand field theory as a framework to understand this phenomenon and outline prerequisites for efficient spin-flip emission including ligand field strength, symmetry, intersystem crossing and common deactivation pathways using CrIII complexes as instructive examples. The recent progress and associated challenges of tuning the energies of emissive excited states and of emerging applications of the unique photophysical properties of spin-flip emitters are discussed. Finally, we summarize the current state-of-the-art and challenges of spin-flip emitters beyond CrIII with d2, d3, d4 and d8 electronic configuration, where we mainly cover pseudooctahedral molecular complexes of V, Mo, W, Mn, Re and Ni, and highlight possible future research opportunities.
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48
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Law KC, Tang Z, Wu L, Wan Q, To WP, Chang X, Low KH, Liu Y, Che CM. Cyclometalated Iron and Ruthenium Complexes Supported by a Tetradentate Ligand Scaffold with Mixed O, N, and C Donor Atoms: Synthesis, Structures, and Excited-State Properties. Organometallics 2022. [DOI: 10.1021/acs.organomet.1c00677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kwok-Chung Law
- State Key Laboratory of Synthetic Chemistry and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Zhou Tang
- State Key Laboratory of Synthetic Chemistry and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Liangliang Wu
- State Key Laboratory of Synthetic Chemistry and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Qingyun Wan
- State Key Laboratory of Synthetic Chemistry and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Wai-Pong To
- State Key Laboratory of Synthetic Chemistry and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Xiaoyong Chang
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Kam-Hung Low
- State Key Laboratory of Synthetic Chemistry and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Yungen Liu
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Chi-Ming Che
- State Key Laboratory of Synthetic Chemistry and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
- HKU Shenzhen Institute of Research & Innovation, Shenzhen, Guangdong 518057, China
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49
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Cebrían C, Pastore M, Monari A, Assfeld X, Gros PC, Haacke S. Ultrafast Spectroscopy of Fe(II) Complexes Designed for Solar Energy Conversion: Current Status and Open Questions. Chemphyschem 2022; 23:e202100659. [DOI: 10.1002/cphc.202100659] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 01/22/2022] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | | | - Stefan Haacke
- University of Strasbourg: Universite de Strasbourg IPCMS 23, rue du Loess 67034 Strasbourg FRANCE
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50
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Leis W, Argüello Cordero MA, Lochbrunner S, Schubert H, Berkefeld A. A Photoreactive Iron(II) Complex Luminophore. J Am Chem Soc 2022; 144:1169-1173. [PMID: 35025493 DOI: 10.1021/jacs.1c13083] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Controlling the order and lifetimes of electronically excited states is essential to effective light-to-potential energy conversion by molecular chromophores. This work reports a luminescent and photoreactive iron(II) complex, the first performant group homologue of prototypical sensitizers of ruthenium. Double cyclometalation of a phenylphenanthroline framework at iron(II) favors the population of a triplet metal-to-ligand charge transfer (3MLCT) state as the lowest energy excited state. Near-infrared (NIR) luminescence exhibits a monoexponential decay with τ = 2.4 ns in the solid state and 1 ns in liquid phase. Lifetimes of 14 ns at 77 K are in line with a narrowing of the NIR emission band at λem,max = 1170-1230 nm. Featuring a 3MLCT excited-state redox potential of -2 V vs the ferrocene/ferrocenium couple, the use of the Fe(II) chromophore as a sensitizer for light-driven synthesis is exemplified by the radical cross-coupling of 4-chlorobromobenzene and benzene.
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Affiliation(s)
- Wolfgang Leis
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
| | - Miguel A Argüello Cordero
- Institute for Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany
| | - Stefan Lochbrunner
- Institute for Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany
| | - Hartmut Schubert
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
| | - Andreas Berkefeld
- Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany
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