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Pal AK, Datta A. First-principles design of heavy-atom-free singlet oxygen photosensitizers for photodynamic therapy. J Chem Phys 2024; 160:164720. [PMID: 38682739 DOI: 10.1063/5.0196557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 04/10/2024] [Indexed: 05/01/2024] Open
Abstract
In photodynamic therapy (PDT) treatment, heavy-atom-free photosensitizers (PSs) are a great source of singlet oxygen photosensitizer. Reactive oxygen species (ROS) are produced by an energy transfer from the lowest energy triplet excited state to the molecular oxygen of cancer cells. To clarify the photophysical characteristics in the excited states of a few experimentally identified thionated (>C=S) molecules and their oxygenated congeners (>C=O), a quantum chemical study is conducted. This study illustrates the properties of the excited states in oxygen congeners that render them unsuitable for PDT treatment. Concurrently, a hierarchy is presented based on the utility of the lowest-energy triplet excitons of thionated compounds. Their non-radiative decay rates are calculated for reverse-ISC and inter-system crossover (ISC) processes. In addition, the vibronic importance of C=O and C=S bonds is clarified by the computation of the Huang-Rhys factor, effective vibrational mode, and reorganization energy inside the Marcus-Levich-Jörtner system. ROS generation in thionated PSs exceeds their oxygen congeners as kf ≪ kISC, where radiative decay rate is designated as kf. As a result, the current work offers a calculated strategy for analyzing the effectiveness of thionated photosensitizers in PDT.
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Affiliation(s)
- Arun K Pal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, West Bengal, India
| | - Ayan Datta
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, West Bengal, India
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Mentzel P, Holzapfel M, Schmiedel A, Günther J, Michel M, Krummenacher I, Wodyński A, Kaupp M, Braunschweig H, Lambert C. Structure and Photophysics of N-Tolanyl-phenochalcogenazines and their Radical Cations. Chemistry 2024; 30:e202303782. [PMID: 38293898 DOI: 10.1002/chem.202303782] [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: 11/14/2023] [Revised: 01/16/2024] [Accepted: 01/26/2024] [Indexed: 02/01/2024]
Abstract
The study focuses on the structural and photophysical characteristics of neutral and oxidized forms of N-tolanyl-phenochalcogenazines PZX-tolan with X=O, S, Se, and Te. X-ray crystal structure analyses show a pseudo-equatorial (pe) structure of the tolan substituent in the O, S, and Se dyads, while the Te dyad possesses a pseudo-axial (pa) structure. DFT calculations suggest the pe structure for O and S, and the pa structure for Se and Te as stable forms. Steady-state and femtosecond-time resolved optical spectroscopy in toluene solution indicate that the O and S dyads emit from a CT state, whereas the Se and Te dyads emit from a tolan-localized state. The T1 state is tolan-localized in all cases, showing phosphorescence at 77 K. The heavy atom effect of chalcogens induces intersystem crossing from S1 to Tx, resulting in a decreasing S1 lifetime from 2.1 ns to 0.42 ps. The T1 states possess potential for singlet oxygen sensitization with a high quantum yield (ca. 40 %) for the O, S, and Se dyads. Radical cations exhibit spin density primarily localized at the heterocycle. EPR measurements and quasirelativistic DFT calculations reveal a very strong g-tensor anisotropy, supporting the pe structure for the S and Se derivatives.
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Affiliation(s)
- Paul Mentzel
- Institut für Organische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Marco Holzapfel
- Institut für Organische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Alexander Schmiedel
- Institut für Organische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Johanna Günther
- Institut für Organische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Maximilian Michel
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Ivo Krummenacher
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Artur Wodyński
- Technische Universität Berlin, Institut für Chemie, Theoretische Chemie/Quantenchemie, Sekr. C7, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Martin Kaupp
- Technische Universität Berlin, Institut für Chemie, Theoretische Chemie/Quantenchemie, Sekr. C7, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Holger Braunschweig
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Christoph Lambert
- Institut für Organische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
- Center for Nanosystems Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
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Upadhyay M, Deka R, Ray D. Carbazole-Benzonitrile-Norbornadiene Conjugates for Photothermally Reversible Ambient Phosphorescence. J Phys Chem Lett 2024; 15:3191-3196. [PMID: 38483186 DOI: 10.1021/acs.jpclett.4c00495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Organic photoswitches have attracted significant attention across various fields, such as sensing, bioimaging, photopharmacology, molecular machines, and solar energy storage. However, as a result of design complexities, achieving photothermally reversible ambient phosphorescence switching in the condensed state remains elusive. Herein, we explore the impact of norbornadiene (NBD)/quadricyclane (QC) substitution at position 5 of the benzonitrile acceptor covalently attached to the carbazole donor on photothermally reversible luminescence switching. Experimental investigations demonstrated that the CzN and TBCzN switches exhibited photothermally reversible fluorescence switching in solution. Moreover, in the condensed state, fluorescence and ambient phosphorescence switching were observed as a result of a low singlet-triplet (ΔEST) gap (CzN ⇆ CzQ, ΔESTCzN/CzQ = 0.05/0.28 eV; TBCzN ⇆ TBCzQ, ΔESTTBCzN/TBCzQ = 0.06/0.09 eV). Reversible ambient phosphorescence switching is primarily influenced by modulation of acceptor conjugation resulting from NBD ⇆ QC switching. This approach may provide important clues for the design of visible-light-absorbing photothermally reversible phosphorescent materials.
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Affiliation(s)
- Manoj Upadhyay
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi National Capital Region (NCR), NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Raktim Deka
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi National Capital Region (NCR), NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Debdas Ray
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi National Capital Region (NCR), NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
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Dey S, Deka R, Upadhyay M, Peethambaran S, Ray D. White Light Emission via Dual Thermally Activated Delayed Fluorescence from a Single-Component Phenothiazines-Diphenyl Quinoline Conjugate. J Phys Chem Lett 2024; 15:3135-3141. [PMID: 38477646 DOI: 10.1021/acs.jpclett.4c00185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
White light emission (WLE) via dual thermally activated delayed fluorescence (TADF) from a single-component-based organic system remains challenging as a result of the difficulty in design. Here, we introduce a conformational isomerization approach to achieve WLE from a twisted donor-acceptor (PTzQP1) that comprises two phenothiazines covalently attached to the 6,8-isomeric positions of 2,4-diphenyl quinoline via two C-N single bonds. Spectroscopic studies and quantum chemistry calculations revealed that PTzQP1 shows WLE via simultaneous blue TADF and orange TADF covering the visible range (420-800 nm) with a photoluminescence quantum yield of 45 ± 2% and Commission Internationale de l'Éclairage (CIE) coordinates of 0.30, 0.33. The dual TADF features with high rates of reverse intersystem crossing (kRISC1 = 1.38 × 107 ± 0.24 s-1 and kRISC2 = 5.04 × 106 ± 0.32 s-1) are realized as a result of the low singlet-triplet gaps (S1EQ-T1EQ = 0.04 eV and S1QA-T1QA = 0.05 eV) of the quasi-axial (QA) and quasi-equatorial (QE) conformers. This finding is expected to provide a new direction for designing high-energy-efficient WLE emitters.
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Affiliation(s)
- Suvendu Dey
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi National Capital Region (NCR), NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Raktim Deka
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi National Capital Region (NCR), NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Manoj Upadhyay
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi National Capital Region (NCR), NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Sreerang Peethambaran
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi National Capital Region (NCR), NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Debdas Ray
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi National Capital Region (NCR), NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
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Deka R, Dey S, Upadhyay M, Chawla S, Ray D. Conformational Effect of Catechol-Terephthalonitrile Emitters Leading to Ambient Violet Phosphorescence. J Phys Chem A 2024; 128:581-589. [PMID: 38206828 DOI: 10.1021/acs.jpca.3c06877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
Organic ambient violet phosphorescent (AVP) materials are of great interest due to their involvement of high energy and longer-lived triplet excitons. Here, we show three fused ring functionalized donor-acceptor-donor (D-A-D/D-A-D') emitters (BPT1-BPT3), in which two catechol-based donors (3,4-dihydroxybenzophenone, catechol, or 3,5-ditert-butylcatechol) are covalently fused to the terephthalonitrile acceptor via four O-C single bonds. Spectroscopic analysis revealed that all the molecules show AVP (∼390-394 nm, τAVP = 73-101 μs) with phosphorescence quantum yields (ϕP) of 1.8-27.4% due to low singlet-triplet gaps (0.036-0.046 eV) and conformational effects. BPT3 with bulky tert-butyl groups increases AVP (ϕP = 27.4%). Quantum chemistry calculations reveal flat (F1) and twisted (F2) conformers (ground state) with a low energy difference (∼4-5 kcal/mol) for all molecules; the F1 conformer is responsible for efficient AVP, while weak blue thermally activated delayed fluorescence with longer-lived delayed components is realized from the F2 conformer. This approach may provide important clues for the design of high-energy organic phosphorescent materials.
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Affiliation(s)
- Raktim Deka
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi NCR, NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Suvendu Dey
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi NCR, NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Manoj Upadhyay
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi NCR, NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Sakshi Chawla
- Condensed Phase Dynamics Group, Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab 140306, India
| | - Debdas Ray
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi NCR, NH-91, Tehsil Dadri, Gautam Buddha Nagar, Uttar Pradesh 201314, India
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