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Öner S, Kuila S, Stavrou K, Danos A, Fox MA, Monkman AP, Bryce MR. Exciplex, Not Heavy-Atom Effect, Controls the Triplet Dynamics of a Series of Sulfur-Containing Thermally Activated Delayed Fluorescence Molecules. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2024; 36:7135-7150. [PMID: 39156711 PMCID: PMC11325549 DOI: 10.1021/acs.chemmater.4c00850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 07/18/2024] [Accepted: 07/19/2024] [Indexed: 08/20/2024]
Abstract
The efficiency of thermally activated delayed fluorescence (TADF) in organic materials relies on rapid intersystem crossing rates and fast conversion of triplet (T) excitons into a singlet (S) state. Heavy atoms such as sulfur or selenium are now frequently incorporated into TADF molecular structures to enhance these properties by increased spin-orbit coupling [spin orbit coupling (SOC)] between the T and S states. Here a series of donor-acceptor (D-A) molecules based on 12H-benzo[4,5]thieno[2,3-a]carbazole and dicyanopyridine is compared with their nonsulfur control molecules designed to probe such SOC effects. We reveal that unexpected intermolecular interactions of the D-A molecules with carbazole-containing host materials instead serve as the dominant pathway for triplet decay kinetics in these materials. In-depth photophysical and computational studies combined with organic light emitting diode measurements demonstrate that the anticipated heavy-atom effect from sulfur is overshadowed by exciplex formation. Indeed, even the unsubstituted acceptor fragments exhibit pronounced TADF exciplex emission in appropriate carbazole hosts. The intermolecular charge transfer and TADF in these systems are further confirmed by detailed time-dependent density functional theory studies. This work demonstrates that anticipated heavy-atom effects in TADF emitters do not always control or even impact the photophysical and electroluminescence properties.
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Affiliation(s)
- Saliha Öner
- Department
of Chemistry, Durham University, Stockton Road, Durham DH1 3LE, U.K.
| | - Suman Kuila
- Department
of Chemistry, Durham University, Stockton Road, Durham DH1 3LE, U.K.
- Department
of Physics, Durham University, Stockton Road, Durham DH1 3LE, U.K.
| | - Kleitos Stavrou
- Department
of Physics, Durham University, Stockton Road, Durham DH1 3LE, U.K.
| | - Andrew Danos
- Department
of Physics, Durham University, Stockton Road, Durham DH1 3LE, U.K.
| | - Mark A. Fox
- Department
of Chemistry, Durham University, Stockton Road, Durham DH1 3LE, U.K.
| | - Andrew P. Monkman
- Department
of Physics, Durham University, Stockton Road, Durham DH1 3LE, U.K.
| | - Martin R. Bryce
- Department
of Chemistry, Durham University, Stockton Road, Durham DH1 3LE, U.K.
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2
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Zhang CL, Liu C, Nie SR, Zhang Y, Guo JH, Li XL, Liu C. A Dual Functional Fluorescent Probe Based on Phenothiazine for Detecting Hg 2+ and ClO - and its Applications. J Fluoresc 2023:10.1007/s10895-023-03534-3. [PMID: 38060150 DOI: 10.1007/s10895-023-03534-3] [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: 10/02/2023] [Accepted: 11/28/2023] [Indexed: 12/08/2023]
Abstract
For the efficient detection of Hg2+ and ClO-, a double-analyte-responsive fluorescent probe PTB was successfully synthesized by combining N-butyl-3-formyl phenothiazine with hydrazine benzothiazole, and designing a specific reaction site for recognizing two analytes (Hg2+ and ClO-) in a compound. It was shown that probe PTB successfully formed a stable complex with Hg2+ in the coordination ratio of 2:1 by using the strong sulfur affinity of Hg2+, which resulted in a remarkable "turn-off" effect, with a quenching efficiency of 92.5% and four reversible cycles of Hg2+ fluorescence detection. For the fluorescence detection of Hg2+, the response time is fast (≤ 2 min) and the detection limit is low (7.8 nM), showing extremely high sensitivity, and the performance is obviously better than that of the reported fluorescent probes for detecting Hg2+. In particular, probe PTB has low toxicity and good biocompatibility, and has been successfully used for imaging of Hg2+ in living cells. Moreover, probe PTB uses thioether bond and carbon-nitrogen double bond as reaction sites to detect ClO-, which has large Stokes Shift (149 nm), good selectivity, high quenching efficiency (96.5%) and fast time response (about 10 s), and successfully detects ClO- in actual water samples. The dual functional fluorescent probe PTB is sensitive for Hg2+ and ClO-. It has been successfully used for making pH fluorescent test paper and imaging detection of exogenous Hg2+ in VSMC cells with low toxicity.
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Affiliation(s)
- Cheng-Lu Zhang
- School of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029, China.
| | - Chang Liu
- School of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029, China
| | - Shi-Ru Nie
- School of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029, China
| | - Yang Zhang
- School of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029, China
| | - Jing-Hao Guo
- School of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029, China
| | - Xiang-Ling Li
- School of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029, China
| | - Cui Liu
- School of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian, 116029, China.
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3
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Wright IA, Etherington MK, Batsanov AS, Monkman AP, Bryce MR. Oxidation State Tuning of Room Temperature Phosphorescence and Delayed Fluorescence in Phenothiazine and Phenothiazine-5,5-dioxide Dimers. Chemistry 2023; 29:e202300428. [PMID: 36916635 PMCID: PMC10946842 DOI: 10.1002/chem.202300428] [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: 02/09/2023] [Revised: 03/10/2023] [Accepted: 03/13/2023] [Indexed: 03/16/2023]
Abstract
Heterocyclic dimers consisting of combinations of butterfly-shaped phenothiazine (PTZ) and its chemically oxidized form phenothiazine-5,5-dioxide (PTZ(SO2 )) have been synthesized. A twist is imposed across the dimers by ortho-substituents including methyl ethers, sulfides and sulfones. X-ray crystallography, cyclic voltammetry and optical spectroscopy, underpinned by computational studies, have been employed to study the interplay between the oxidation state, conformational restriction, and emission mechanisms including thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP). While the PTZ(SO2 ) dimers are simple fluorophores, the presence of PTZ induces triplet-mediated emission with a mixed PTZ-PTZ(SO2 ) dimer displaying concentration dependent hallmarks of both TADF and RTP.
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Affiliation(s)
- Iain A. Wright
- Department of ChemistryDurham UniversitySouth RoadDurhamDH1 3LEUK
- School of ChemistryUniversity of EdinburghDavid Brewster RoadEdinburghEH9 3FJUK
| | - Marc K. Etherington
- Department of PhysicsDurham UniversitySouth RoadDurhamDH1 3LEUK
- Department of Mathematics, Physics and Electrical EngineeringNorthumbria UniversityEllison PlaceNewcastle upon TyneNE1 8STUK
| | | | | | - Martin R. Bryce
- Department of ChemistryDurham UniversitySouth RoadDurhamDH1 3LEUK
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4
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Ding X, Jin JL, Yang JF, Ou LH, Gao Y, Wu Y. Theoretical studies on spiro[acridine-fluorene]-based emitters with efficient thermally activated delayed fluorescence. J Mol Struct 2023. [DOI: 10.1016/j.molstruc.2023.135431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
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5
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Hempe M, Kukhta NA, Danos A, Batsanov AS, Monkman AP, Bryce MR. Intramolecular Hydrogen Bonding in Thermally Activated Delayed Fluorescence Emitters: Is There Evidence Beyond Reasonable Doubt? J Phys Chem Lett 2022; 13:8221-8227. [PMID: 36007139 PMCID: PMC9465681 DOI: 10.1021/acs.jpclett.2c00907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Intramolecular hydrogen bonding between donor and acceptor segments in thermally activated delayed fluorescence (TADF) materials is now frequently employed to─purportedly─rigidify the structure and improve the emission performance of these materials. However, direct evidence for these intramolecular interactions is often lacking or ambiguous, leading to assertions that are largely speculative. Here we investigate a series of TADF-active materials incorporating pyridine, which bestows the potential ability to form intramolecular H-bonding interactions. Despite possible indications of H-bonding from an X-ray analysis, an array of other experimental investigations proved largely inconclusive. Instead, after examining computational potential energy surfaces of the donor-acceptor torsion angle we conclude that the pyridine group primarily alleviates steric congestion in our case, rather than enabling an H-bond interaction as elsewhere assumed. We suggest that many previously reported "H-bonding" TADF materials featuring similar chemical motifs may instead operate similarly and that investigation of potential energy surfaces should become a key feature of future studies.
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Affiliation(s)
- Matthias Hempe
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Nadzeya A. Kukhta
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
- Materials
Science and Engineering Department, University
of Washington, Seattle, Washington 98195, United States
| | - Andrew Danos
- Physics
Department, Durham University, South Road, Durham, DH1 3LE, U.K.
| | - Andrei S. Batsanov
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Andrew P. Monkman
- Physics
Department, Durham University, South Road, Durham, DH1 3LE, U.K.
| | - Martin R. Bryce
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
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Roy I, David AHG, Das PJ, Pe DJ, Stoddart JF. Fluorescent cyclophanes and their applications. Chem Soc Rev 2022; 51:5557-5605. [PMID: 35704949 DOI: 10.1039/d0cs00352b] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
With the serendipitous discovery of crown ethers by Pedersen more than half a century ago and the subsequent introduction of host-guest chemistry and supramolecular chemistry by Cram and Lehn, respectively, followed by the design and synthesis of wholly synthetic cyclophanes-in particular, fluorescent cyclophanes, having rich structural characteristics and functions-have been the focus of considerable research activity during the past few decades. Cyclophanes with remarkable emissive properties have been investigated continuously over the years and employed in numerous applications across the field of science and technology. In this Review, we feature the recent developments in the chemistry of fluorescent cyclophanes, along with their design and synthesis. Their host-guest chemistry and applications related to their structure and properties are highlighted.
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Affiliation(s)
- Indranil Roy
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
| | - Arthur H G David
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
| | - Partha Jyoti Das
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
| | - David J Pe
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
| | - J Fraser Stoddart
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA. .,School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia.,Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310021, China.,ZJU-Hangzhou Global Scientific and Technological Innovation Center Hangzhou, 311215, China
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Mayer L, Müller TJJ. 3,10‐Diaryl Phenothiazines – One‐pot Synthesis and Conformational Tuning of Ground and Excited State Electronics. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100659] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Laura Mayer
- Institut für Organische Chemie und Makromolekulare Chemie Heinrich-Heine-Universität Düsseldorf Universitätsstrasse 1 40225 Düsseldorf Germany
| | - Thomas J. J. Müller
- Institut für Organische Chemie und Makromolekulare Chemie Heinrich-Heine-Universität Düsseldorf Universitätsstrasse 1 40225 Düsseldorf Germany
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