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Auty AJ, Scattergood PA, Keane T, Cheng T, Wu G, Carson H, Shipp J, Sadler A, Roseveare T, Sazanovich IV, Meijer AJHM, Chekulaev D, Elliot PIP, Towrie M, Weinstein JA. A stronger acceptor decreases the rates of charge transfer: ultrafast dynamics and on/off switching of charge separation in organometallic donor-bridge-acceptor systems. Chem Sci 2023; 14:11417-11428. [PMID: 37886100 PMCID: PMC10599469 DOI: 10.1039/d2sc06409j] [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: 11/21/2022] [Accepted: 09/23/2023] [Indexed: 10/28/2023] Open
Abstract
To unravel the role of driving force and structural changes in directing the photoinduced pathways in donor-bridge-acceptor (DBA) systems, we compared the ultrafast dynamics in novel DBAs which share a phenothiazine (PTZ) electron donor and a Pt(ii) trans-acetylide bridge (-C[triple bond, length as m-dash]C-Pt-C[triple bond, length as m-dash]C-), but bear different acceptors conjugated into the bridge (naphthalene-diimide, NDI; or naphthalene-monoimide, NAP). The excited state dynamics were elucidated by transient absorption, time-resolved infrared (TRIR, directly following electron density changes on the bridge/acceptor), and broadband fluorescence-upconversion (FLUP, directly following sub-picosecond intersystem crossing) spectroscopies, supported by TDDFT calculations. Direct conjugation of a strong acceptor into the bridge leads to switching of the lowest excited state from the intraligand 3IL state to the desired charge-separated 3CSS state. We observe two surprising effects of an increased strength of the acceptor in NDI vs. NAP: a ca. 70-fold slow-down of the 3CSS formation-(971 ps)-1vs. (14 ps)-1, and a longer lifetime of the 3CSS (5.9 vs. 1 ns); these are attributed to differences in the driving force ΔGet, and to distance dependence. The 100-fold increase in the rate of intersystem crossing-to sub-500 fs-by the stronger acceptor highlights the role of delocalisation across the heavy-atom containing bridge in this process. The close proximity of several excited states allows one to control the yield of 3CSS from ∼100% to 0% by solvent polarity. The new DBAs offer a versatile platform for investigating the role of bridge vibrations as a tool to control excited state dynamics.
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Affiliation(s)
- Alexander J Auty
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | | | - Theo Keane
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Tao Cheng
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Guanzhi Wu
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Heather Carson
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - James Shipp
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Andrew Sadler
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Thomas Roseveare
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Igor V Sazanovich
- Laser for Science Facility, Rutherford Appleton Laboratory, RCaH, STFC OX11 0QX UK
| | | | - Dimitri Chekulaev
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
| | - Paul I P Elliot
- Department of Chemical Sciences, University of Huddersfield HD1 3DH UK
| | - Mike Towrie
- Laser for Science Facility, Rutherford Appleton Laboratory, RCaH, STFC OX11 0QX UK
| | - Julia A Weinstein
- Department of Chemistry, The University of Sheffield Sheffield S3 7HF UK ,
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Ishikawa H, Demise A, Kitagawa Y, Shinozaki Y, Kinoshita Y, Tamiaki H. Difluoroboron complexes of peripheral β-diketonates in cyclopheophorbides: Their syntheses and optical properties. Tetrahedron 2022. [DOI: 10.1016/j.tet.2021.132596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Covalent heterodyads of synthetic chlorophyll derivatives linked with linear rigid substituents at the 20-positions constructing photoexcited energy transfer systems. Tetrahedron 2020. [DOI: 10.1016/j.tet.2020.131130] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Tamiaki H, Tatebe T, Kitagawa Y. Covalently linked dimer of chlorophyll-a derivative with an amide bond and its folded conformer. Tetrahedron Lett 2018. [DOI: 10.1016/j.tetlet.2018.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Tamiaki H, Tanaka T, Wang XF. Photophysical properties of synthetic monomer, dimer, trimer, and tetramer of chlorophyll derivatives and their application to organic solar cells. J Photochem Photobiol A Chem 2015. [DOI: 10.1016/j.jphotochem.2015.05.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Yamamoto Y, Tamiaki H. Synthesis of chlorophyll derivatives possessing a mono/bi/terpyridinyl group at the C3-ethynyl terminal and optical properties of the π-conjugates. Tetrahedron 2014. [DOI: 10.1016/j.tet.2014.02.090] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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