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Zhang X, Chen X, Sun Y, Zhao J. Radical enhanced intersystem crossing mechanism, electron spin dynamics of high spin states and their applications in the design of heavy atom-free triplet photosensitizers. Org Biomol Chem 2024; 22:5257-5283. [PMID: 38884590 DOI: 10.1039/d4ob00520a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Heavy atom-free triplet photosensitizers (PSs) can overcome the high cost and biological toxicity of traditional molecular systems containing heavy atoms (such as Pt(II), Ir(III), Ru(II), Pd(II), Lu(III), I, or Br atoms) and, therefore, are developing rapidly. Connecting a stable free radical to the chromophore can promote the intersystem crossing (ISC) process through electron spin exchange interaction to produce the triplet state of the chromophore or the doublet (D) and quartet (Q) states when taking the whole spin system into account. These molecular systems based on the radical enhanced ISC (REISC) mechanism are important in the field of heavy atom-free triplet PSs. The REISC system has a simple molecular structure and good biocompatibility, and it is especially helpful for building high-spin quantum states (D and Q states) that have the potential to be developed as qubits in quantum information science. This review introduces the molecular structure design for the purpose of high-spin states. Time-resolved electron paramagnetic resonance (TREPR) is the most important characterization method to reveal the properties of these molecular systems, generation mechanism and electron spin polarization (ESP) of the high spin states. The spin polarization manipulation of high spin states and potential application in the field of quantum information engineering are also summarized. Moreover, molecular design principles of the REISC system to obtain long absorption wavelength, high triplet state quantum yield and long triplet state lifetime are introduced, as well as applications of the compounds in triplet-triplet annihilation upconversion, photodynamic therapy and bioimaging. This review is useful for the design of heavy atom-free triplet PSs based on the radical-chromophore molecular structure motif and the study of the photophysics of the compounds, as well as the electron spin dynamics of the multi electron system upon photoexcitation.
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Affiliation(s)
- Xue Zhang
- State Key Laboratory of Fine Chemicals, Frontiers Science Centre for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China.
| | - Xi Chen
- State Key Laboratory of Fine Chemicals, Frontiers Science Centre for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China.
| | - Yue Sun
- State Key Laboratory of Fine Chemicals, Frontiers Science Centre for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China.
| | - Jianzhang Zhao
- State Key Laboratory of Fine Chemicals, Frontiers Science Centre for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China.
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2
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Thielert P, El Bitar Nehme M, Mayländer M, Franz M, Zimmermann SL, Fisch F, Gilch P, Vargas Jentzsch A, Rickhaus M, Richert S. Influence of the substitution position on spin communication in photoexcited perylene-nitroxide dyads. Chem Sci 2024; 15:7515-7523. [PMID: 38784753 PMCID: PMC11110163 DOI: 10.1039/d4sc00328d] [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: 01/15/2024] [Accepted: 03/25/2024] [Indexed: 05/25/2024] Open
Abstract
By virtue of the modularity of their structures, their tunable optical and magnetic properties, and versatile applications, photogenerated triplet-radical systems provide an ideal platform for the study of the factors controlling spin communication in molecular frameworks. Typically, these compounds consist of an organic chromophore covalently attached to a stable radical. After formation of the chromophore triplet state by photoexcitation, two spin centres are present in the molecule that will interact. The nature of their interaction is governed by the magnitude of the exchange interaction between them and can be studied by making use of transient electron paramagnetic resonance (EPR) techniques. Here, we investigate three perylene-nitroxide dyads that only differ with respect to the position where the nitroxide radical is attached to the perylene core. The comparison of the results from transient UV-vis and EPR experiments reveals major differences in the excited state properties of the three dyads, notably their triplet state formation yield, excited state deactivation kinetics, and spin coherence times. Spectral simulations and quantum chemical calculations are used to rationalise these findings and demonstrate the importance of considering the structural flexibility and the contribution of rotational conformers for an accurate interpretation of the data.
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Affiliation(s)
- Philipp Thielert
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
| | - Mélissa El Bitar Nehme
- Department of Chemistry, University of Zurich Winterthurerstrasse 190 8057 Zurich Switzerland
| | - Maximilian Mayländer
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
| | - Michael Franz
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
| | - Simon L Zimmermann
- Institute of Physical Chemistry, Heinrich Heine University Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
| | - Fabienne Fisch
- Department of Chemistry, University of Zurich Winterthurerstrasse 190 8057 Zurich Switzerland
| | - Peter Gilch
- Institute of Physical Chemistry, Heinrich Heine University Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
| | - Andreas Vargas Jentzsch
- SAMS Research Group, Université de Strasbourg, CNRS, Institut Charles Sadron UPR 22 67000 Strasbourg France
| | - Michel Rickhaus
- Department of Chemistry, University of Zurich Winterthurerstrasse 190 8057 Zurich Switzerland
- Department of Organic Chemistry, University of Geneva 30 Quai Ernest-Ansermet 1211 Geneva 4 Switzerland
| | - Sabine Richert
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
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3
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Chen X, Luo X, Wang K, You X, Xu J, Peng S, Wu D, Xia J. Efficient Intersystem Crossing in Extended Helical Perylene Diimide Dimers with Chalcogen-Annulation. J Phys Chem B 2024; 128:3964-3971. [PMID: 38602495 DOI: 10.1021/acs.jpcb.4c00668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
The properties and formation mechanisms of the triplet state have been widely investigated since they are crucial intermediates in photo functional devices. Specifically, helical PDI dimers, horizontal expanded π-conjugated derivatives of PDI, have shown outstanding performance as electron acceptors in enhancing the performance of photovoltaics. Therefore, the exploration of triplet generation in helical PDI dimers plays a crucial role in understanding the mechanisms and excavating their further application. We make use of Se-annulation to induce intersystem crossing (ISC) in helical PDI dimers and further explore the triplet evolution process systematically as the number of Se atoms increases by transient absorption spectroscopy and the hole-electron analysis method. It shows that the twisted molecular conformation has paved the way for potential ISC in a parent molecule PDI2. The incorporation of Se atoms can result in evident promotion in the efficiency of ISC (ϕTPDI2-2Se = 96.9%) compared to the parent molecule PDI2 (ϕTPDI2 = 26.5%), indicating that chalcogen-annulation is also an efficient strategy in a π-extended system. Our results provide useful insights for understanding the triplet evolution process, which can help broaden the application of the π-extended PDI system into high-performance photovoltaics.
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Affiliation(s)
- Xingyu Chen
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
| | - Xiaoqi Luo
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
| | - Kangwei Wang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
| | - Xiaoxiao You
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
| | - Jingwen Xu
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
| | - Shaoqian Peng
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
| | - Di Wu
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Jianlong Xia
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
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4
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Hudson JM, Evans EW. Radical Spin Polarization and Magnetosensitivity from Reversible Energy Transfer. J Phys Chem Lett 2024; 15:4130-4135. [PMID: 38593182 PMCID: PMC11033935 DOI: 10.1021/acs.jpclett.4c00656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 03/27/2024] [Accepted: 03/29/2024] [Indexed: 04/11/2024]
Abstract
Molecular spins provide potential building units for future quantum information science and spintronic technologies. In particular, doublet (S = 1/2) and triplet (S = 1) molecular spin states have the potential for excellent optical and spin properties for these applications if useful photon-spin mechanisms at room temperature can be devised. Here we explore the potential of exploiting reversible energy transfer between triplet and doublet states to establish magnetosensitive luminescence and spin polarization. We investigate the dependence of the photon-spin mechanism on the magnitude and sign of the exchange interaction between the doublet and triplet spin components in amorphous and crystalline model systems. The design of a magnetic field inclination sensor is proposed from understanding the required "structure" (spin interactions) to "function" (magnetosensitivity).
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Affiliation(s)
- John M. Hudson
- Department
of Chemistry, Swansea University, Swansea SA2 8PP, United Kingdom
- Centre
for Integrative Semiconductor Materials, Swansea SA1 8EN, United Kingdom
| | - Emrys W. Evans
- Department
of Chemistry, Swansea University, Swansea SA2 8PP, United Kingdom
- Centre
for Integrative Semiconductor Materials, Swansea SA1 8EN, United Kingdom
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5
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Zhang H, Ren G, Hou W, Wang L, Sun Y, Liu J. A Silicon-Rhodamine-Based Heavy-Atom-Free Photosensitizer for Mitochondria-targeted Photodynamic Therapy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 308:123688. [PMID: 38042121 DOI: 10.1016/j.saa.2023.123688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/17/2023] [Accepted: 11/26/2023] [Indexed: 12/04/2023]
Abstract
Silicon-xanthene derivatives (SiXs) have gained popularity in the field of bioimaging due to their advantageous far-red to near-infrared (NIR) absorption and emission wavelengths, notable brightness (ε × Φ), inherent mitochondrial targeting properties and high photo-stability, making them an excellent candidate for photodynamic therapy (PDT). Nevertheless, the utilization of SiXs as photosensitizers (PSs) for PDT in cancer treatment remains largely unexplored, primarily due to their limited capacity to generate cytotoxic reactive oxygen species (ROS). However, the potential of SiXs in PDT warrants further investigation. In this study, utilizing the spin-orbit charge transfer-induced intersystem crossing (SOCT-ISC) mechanism, we reported one novel heavy-atom-free, mitochondria-targeted, silicon-rhodamine-based photosensitizer (SiR-PXZ), which demonstrated excellent biocompatibility, minimal dark toxicity, favorable water-solubility and stability, and considerable singlet oxygen quantum yield under 660 nm light irradiation (ΦΔ = 0.16 in air-saturated PBS). Moreover, SiR-PXZ could be rapidly taken up by the mitochondria and efficiently induced apoptosis of cancer cells with an IC50 value of 1.2 μM. The in vivo studies showed that SiR-PXZ exhibited excellent anti-tumor effects, making it potentially valuable for clinical application. This study offers a source of ideas for the construction of SiXs-based photosensitizers for photodynamic cancer treatment in the future.
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Affiliation(s)
- Hongxing Zhang
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China
| | - Guoxi Ren
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China
| | - Wenhua Hou
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China
| | - Lijuan Wang
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China
| | - Yuanqiang Sun
- College of Chemistry, Zhengzhou University, Zhengzhou 450001, China.
| | - Jing Liu
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, China.
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6
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Qiu Y, Eckvahl HJ, Equbal A, Krzyaniak MD, Wasielewski MR. Enhancing Coherence Times of Chromophore-Radical Molecular Qubits and Qudits by Rational Design. J Am Chem Soc 2023; 145:25903-25909. [PMID: 37963349 DOI: 10.1021/jacs.3c10772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
An important criterion for quantum operations is long qubit coherence times. To elucidate the influence of molecular structure on the coherence times of molecular spin qubits and qudits, a series of molecules featuring perylenediimide (PDI) chromophores covalently linked to stable nitroxide radicals were synthesized and investigated by pulse electron paramagnetic resonance spectroscopy. Photoexcitation of PDI in these systems creates an excited quartet state (Q) followed by a spin-polarized doublet ground state (D0), which hold promise as spin qudits and qubits, respectively. By tailoring the molecular structure of these spin qudit/qubit candidates by selective deuteration and eliminating intramolecular motion, coherence times of Tm = 9.1 ± 0.3 and 4.2 ± 0.3 μs at 85 K for D0 and Q, respectively, are achieved. These coherence times represent a nearly 3-fold enhancement compared to those of the initial molecular design. This approach offers a rational structural design protocol for effectively extending coherence times in molecular spin qudits/qubits.
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Affiliation(s)
- Yunfan Qiu
- Department of Chemistry, Center for Molecular Quantum Transduction, and Paula M. Trienens Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3313, United States
| | - Hannah J Eckvahl
- Department of Chemistry, Center for Molecular Quantum Transduction, and Paula M. Trienens Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3313, United States
| | - Asif Equbal
- Department of Chemistry, Center for Molecular Quantum Transduction, and Paula M. Trienens Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3313, United States
| | - Matthew D Krzyaniak
- Department of Chemistry, Center for Molecular Quantum Transduction, and Paula M. Trienens Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3313, United States
| | - Michael R Wasielewski
- Department of Chemistry, Center for Molecular Quantum Transduction, and Paula M. Trienens Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3313, United States
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7
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Mayländer M, Kopp K, Nolden O, Franz M, Thielert P, Vargas Jentzsch A, Gilch P, Schiemann O, Richert S. PDI-trityl dyads as photogenerated molecular spin qubit candidates. Chem Sci 2023; 14:10727-10735. [PMID: 37829028 PMCID: PMC10566479 DOI: 10.1039/d3sc04375d] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 09/21/2023] [Indexed: 10/14/2023] Open
Abstract
Owing to their potential applications in the field of quantum information science, photogenerated organic triplet-radical conjugates have attracted an increasing amount of attention recently. Typically, these compounds are composed of a chromophore appended to a stable radical. After initialisation of the system by photoexcitation, a highly spin-polarised quartet state may be generated, which serves as a molecular spin qubit candidate. Here, we investigate three perylene diimide (PDI)-based chromophore-radical systems with different phenylene linkers and radical counterparts by both optical spectroscopy and transient electron paramagnetic resonance (EPR) techniques. Femtosecond transient absorption measurements demonstrate chromophore triplet state formation on a picosecond time scale for PDI-trityl dyads, while excited state deactivation is found to be slowed down considerably in a PDI-nitroxide analogue. The subsequent investigation of the coherent spin properties by transient EPR confirms quartet state formation by triplet-doublet spin mixing for all investigated dyads and the suitability of the two studied PDI-trityl dyads as spin qubit candidates. In particular, we show that using tetrathiaryl trityl as the radical counterpart, an intense spin polarisation is observed even at room temperature and quartet state coherence times of 3.0 μs can be achieved at 80 K, which represents a considerable improvement compared to previously studied systems.
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Affiliation(s)
- Maximilian Mayländer
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
| | - Kevin Kopp
- Clausius Institute of Physical and Theoretical Chemistry, University of Bonn Wegelerstraße 12 53115 Bonn Germany
| | - Oliver Nolden
- Institute of Physical Chemistry, Heinrich Heine University Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
| | - Michael Franz
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
| | - Philipp Thielert
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
| | - Andreas Vargas Jentzsch
- SAMS Research Group, Université de Strasbourg, CNRS, Institut Charles Sadron UPR 22 67000 Strasbourg France
| | - Peter Gilch
- Institute of Physical Chemistry, Heinrich Heine University Düsseldorf Universitätsstraße 1 40225 Düsseldorf Germany
| | - Olav Schiemann
- Clausius Institute of Physical and Theoretical Chemistry, University of Bonn Wegelerstraße 12 53115 Bonn Germany
| | - Sabine Richert
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
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8
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Díaz-Norambuena C, Avellanal-Zaballa E, Prieto-Castañeda A, Bañuelos J, de la Moya S, Agarrabeitia AR, Ortiz MJ. Formylation as a Chemical Tool to Modulate the Performance of Photosensitizers Based on Boron Dipyrromethene Dimers. Int J Mol Sci 2023; 24:11837. [PMID: 37511596 PMCID: PMC10380594 DOI: 10.3390/ijms241411837] [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: 06/30/2023] [Revised: 07/19/2023] [Accepted: 07/21/2023] [Indexed: 07/30/2023] Open
Abstract
Heavy-atom-free photosensitizers are envisioned as the next generation of photoactive molecules for photo-theragnosis. In this approach, and after suitable irradiation, a single molecular scaffold is able to visualize and kill tumour cells by fluorescence signalling and photodynamic therapy (PDT), respectively, with minimal side effects. In this regard, BODIPY-based orthogonal dimers have irrupted as suitable candidates for this aim. Herein, we analyse the photophysical properties of a set of formyl-functionalized BODIPY dimers to ascertain their suitability as fluorescent photosensitizers. The conducted computationally aided spectroscopic study determined that the fluorescence/singlet oxygen generation dual performance of these valuable BODIPY dimers not only depends on the BODIPY-BODIPY linkage and the steric hindrance around it, but also can be modulated by proper formyl functionalization at specific chromophoric positions. Thus, we propose regioselective formylation as an effective tool to modulate such a delicate photonic balance in BODIPY-based dimeric photosensitizers. The taming of the excited-state dynamics, in particular intramolecular charge transfer as the key underlying process mediating fluorescence deactivation vs. intersystem crossing increasing, could serve to increase fluorescence for brighter bioimaging, enhance the generation of singlet oxygen for killing activity, or balance both for photo-theragnosis.
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Affiliation(s)
- Carolina Díaz-Norambuena
- Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco-EHU, Apartado 644, 48080 Bilbao, Spain
- Departamento Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
| | - Edurne Avellanal-Zaballa
- Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco-EHU, Apartado 644, 48080 Bilbao, Spain
| | - Alejandro Prieto-Castañeda
- Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco-EHU, Apartado 644, 48080 Bilbao, Spain
- Departamento Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
| | - Jorge Bañuelos
- Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco-EHU, Apartado 644, 48080 Bilbao, Spain
| | - Santiago de la Moya
- Departamento Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
| | - Antonia R Agarrabeitia
- Departamento Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
- Sección Departamental de Química Orgánica, Facultad de Óptica y Optometría, Universidad Complutense de Madrid, Arcos de Jalón 118, 28037 Madrid, Spain
| | - María J Ortiz
- Departamento Química Orgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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9
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Mayländer M, Thielert P, Quintes T, Vargas Jentzsch A, Richert S. Room Temperature Electron Spin Coherence in Photogenerated Molecular Spin Qubit Candidates. J Am Chem Soc 2023. [PMID: 37337625 DOI: 10.1021/jacs.3c04021] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
One of the main challenges in the emerging field of molecular spintronics is the identification of new spin qubit materials for quantum information applications. In this regard, recent work has shown that photoexcited chromophore-radical systems are promising candidates to expand our repertoire of suitable candidate molecules. Here, we investigate a series of three chromophore-radical compounds composed of a perylene diimide (PDI) chromophore and a stable 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) radical by transient electron paramagnetic resonance (EPR) techniques. We explore the influence of isotope labeling of the TEMPO moiety on the EPR spectra and electron spin coherence times of the molecular quartet states generated upon photoexcitation and illustrate that (i) a coherent manipulation of the spin state is possible in these systems even at room temperature and that (ii) a spin coherence time of 0.7 μs can be achieved under these conditions. This demonstration of electron spin coherence at ambient temperatures paves the way for practical applications of such systems in functional molecular devices.
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Affiliation(s)
- Maximilian Mayländer
- Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104 Freiburg, Germany
| | - Philipp Thielert
- Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104 Freiburg, Germany
| | - Theresia Quintes
- Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104 Freiburg, Germany
| | - Andreas Vargas Jentzsch
- SAMS Research Group, Université de Strasbourg, CNRS, Institut Charles Sadron UPR 22, 67000 Strasbourg, France
| | - Sabine Richert
- Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104 Freiburg, Germany
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10
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Mayländer M, Quintes T, Franz M, Allonas X, Vargas Jentzsch A, Richert S. Distance dependence of enhanced intersystem crossing in BODIPY-nitroxide dyads. Chem Sci 2023; 14:5361-5368. [PMID: 37234885 PMCID: PMC10207891 DOI: 10.1039/d3sc00589e] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 04/28/2023] [Indexed: 05/28/2023] Open
Abstract
Photogenerated organic triplet-doublet systems have attracted an increasing amount of attention in recent years due to their versatility and suitability for a range of technological applications in the emerging field of molecular spintronics. Such systems are typically generated by enhanced intersystem crossing (EISC) preceded by photoexcitation of an organic chromophore covalently linked to a stable radical. After formation of the chromophore triplet state by EISC, triplet state and stable radical may interact, whereby the nature of the interaction depends on the exchange interaction JTR between them. If JTR surpasses all other magnetic interactions in the system, molecular quartet states may be formed by spin mixing. For the design of new spintronic materials based on photogenerated triplet-doublet systems, it is crucial to gain further knowledge about the factors influencing the EISC process and the yield of the subsequent quartet state formation. Here we investigate a series of three BODIPY-nitroxide dyads characterised by different separation distances and different relative orientations of the two spin centres. Our combined results from optical spectroscopy, transient electron paramagnetic resonance, and quantum chemical calculations suggest that the chromophore triplet formation by EISC is mediated by dipolar interactions and depends primarily on the distance between the chromophore and radical electrons, while the yield of the subsequent quartet state formation by triplet-doublet spin mixing is influenced by the absolute magnitude of JTR.
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Affiliation(s)
- Maximilian Mayländer
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
| | - Theresia Quintes
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
| | - Michael Franz
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
| | - Xavier Allonas
- Laboratoire de Photochimie et d'Ingénierie Macromoléculaires, Institut Jean Baptiste Donnet 3b rue Alfred Werner 68093 Mulhouse Cedex France
| | - Andreas Vargas Jentzsch
- SAMS Research Group, Université de Strasbourg, CNRS, Institut Charles Sadron UPR 22 67000 Strasbourg France
| | - Sabine Richert
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
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11
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Dou L, Li Y, Dong L, Zhang S, Wu Y, Gong Y, Yang W, Lu H, Zhu S, Zhou X. Panchromatic Light-Absorbing [70]Fullerene-Perylene-BODIPY Triad with Cascade of Energy Transfer as an Efficient Singlet Oxygen Sensitizer. Molecules 2023; 28:molecules28083534. [PMID: 37110773 PMCID: PMC10144093 DOI: 10.3390/molecules28083534] [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: 03/19/2023] [Revised: 04/06/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
A panchromatic light-absorbing [70]fullerene-perylene-BODIPY triad (C70-P-B) was synthesized and applied as a heavy atom-free organic triplet photosensitizer for photooxidation. The photophysical processes were comprehensively investigated by the methods of steady-state spectroscopy, time-resolved spectroscopy, as well as theoretical calculations. C70-P-B shows a strong absorption ability from 300-620 nm. Efficient cascading intramolecular singlet-singlet energy transfer in C70-P-B was confirmed by the luminescence study. The backward triplet excited state energy transfer from C70 moiety to perylene then occurs to populate 3perylene*. Thus, the triplet excited states of C70-P-B are distributed on both C70 and perylene moiety with lifetimes of 23 ± 1 μs and 175 ± 17 μs, respectively. C70-P-B exhibits excellent photooxidation capacity, and its yield of singlet oxygen reaches 0.82. The photooxidation rate constant of C70-P-B is 3.70 times that of C70-Boc and 1.58 times that of MB, respectively. The results in this paper are useful for designing efficient heavy atom-free organic triplet photosensitizers for practical application in photovoltaics, photodynamic therapy, etc.
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Affiliation(s)
- Lifeng Dou
- School of Energy, Materials and Chemical Engineering, Hefei University, Hefei 230601, China
| | - Yuanming Li
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Lei Dong
- School of Energy, Materials and Chemical Engineering, Hefei University, Hefei 230601, China
| | - Shuao Zhang
- School of Energy, Materials and Chemical Engineering, Hefei University, Hefei 230601, China
| | - Yuanqi Wu
- School of Energy, Materials and Chemical Engineering, Hefei University, Hefei 230601, China
| | - Yu Gong
- School of Energy, Materials and Chemical Engineering, Hefei University, Hefei 230601, China
| | - Wei Yang
- School of Energy, Materials and Chemical Engineering, Hefei University, Hefei 230601, China
| | - Hongdian Lu
- School of Energy, Materials and Chemical Engineering, Hefei University, Hefei 230601, China
| | - Sane Zhu
- School of Energy, Materials and Chemical Engineering, Hefei University, Hefei 230601, China
- State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, China
| | - Xiaoguo Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
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12
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Properties and applications of photoexcited chromophore–radical systems. Nat Rev Chem 2023; 7:75-90. [PMID: 37117913 DOI: 10.1038/s41570-022-00453-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2022] [Indexed: 02/11/2023]
Abstract
Photoexcited organic chromophore-radical systems hold great promise for a range of technological applications in molecular spintronics, including quantum information technology and artificial photosynthesis. However, further development of such systems will depend on the ability to control the magnetic properties of these materials, which requires a profound understanding of the underlying excited-state dynamics. In this Review, we discuss photogenerated triplet-doublet systems and their potential to be used for applications in molecular spintronics. We outline the theoretical description of the spin system in the different coupling regimes and the invoked excited-state mechanisms governing the generation and transfer of spin polarization. The main characterization techniques used to evaluate the optical and magnetic properties of chromophore-radical systems are discussed. We conclude by giving an overview of previously investigated covalently linked triplet-radical systems, and highlight the need for further systematic investigations to improve our understanding of the magnetic interactions in such systems.
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13
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Mao H, Young RM, Krzyaniak MD, Wasielewski MR. Optical Initialization of Molecular Qubit Spin States Using Weak Exchange Coupling to Photogenerated Fullerene Triplet States. J Phys Chem B 2022; 126:10519-10527. [DOI: 10.1021/acs.jpcb.2c07096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Affiliation(s)
- Haochuan Mao
- Department of Chemistry, Center for Molecular Quantum Transduction, and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Ryan M. Young
- Department of Chemistry, Center for Molecular Quantum Transduction, and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Matthew D. Krzyaniak
- Department of Chemistry, Center for Molecular Quantum Transduction, and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Michael R. Wasielewski
- Department of Chemistry, Center for Molecular Quantum Transduction, and Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208-3113, United States
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14
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Franz M, Neese F, Richert S. Calculation of exchange couplings in the electronically excited state of molecular three-spin systems. Chem Sci 2022; 13:12358-12366. [PMID: 36382276 PMCID: PMC9629084 DOI: 10.1039/d2sc04701b] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 09/17/2022] [Indexed: 09/19/2023] Open
Abstract
Photogenerated molecular three-spin systems, composed of a chromophore and a covalently bound stable radical, are promising candidates for applications in the field of molecular spintronics. Through excitation with light, an excited doublet state and a quartet state are generated, whereby their energy difference depends on the exchange interaction J TR between the chromophore triplet state (T) and the stable radical (R). In order to establish design rules for new materials to be used in molecular spintronics devices, it is of great importance to gain knowledge on the magnitude of J TR as well as the factors influencing J TR on a molecular level. Here, we present a robust and reliable computational method to determine excited state exchange couplings in three-electron-three-centre systems based on a CASSCF/QD-NEVPT2 approach. The methodology is benchmarked and then applied to a series of molecules composed of a perylene chromophore covalently linked to various stable radicals. We calculate the phenomenological exchange interaction J TR between chromophore and radical, which can be compared directly to the experiment, but also illustrate how the individual exchange interactions J ij can be extracted using an effective Hamiltonian that corresponds to the Heisenberg-Dirac-Van-Vleck Hamiltonian. The latter procedure enables a more detailed analysis of the contributions to the exchange interaction J TR and yields additional insight that will be invaluable for future design optimisation.
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Affiliation(s)
- Michael Franz
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung Kaiser-Wilhelm-Platz 1 45470 Mülheim an der Ruhr Germany
| | - Sabine Richert
- Institute of Physical Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
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15
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Lu Y, Zhao R, Zhang J, Liu M, Gao J. Minimal Active Space: NOSCF and NOSI in Multistate Density Functional Theory. J Chem Theory Comput 2022; 18:6407-6420. [DOI: 10.1021/acs.jctc.2c00908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yangyi Lu
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen518055, China
| | - Ruoqi Zhao
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen518055, China
- Institute of Theoretical Chemistry, Jilin University, Changchun, Jilin Province130023, China
| | - Jun Zhang
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen518055, China
| | - Meiyi Liu
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen518055, China
| | - Jiali Gao
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen518055, China
- Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota55455, United States
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