1
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Lyskov I, Anda A, Wong YX, Tilley AJ, Hall CR, Thia J, Russo SP, Wong WWH, Cole JH, Smith TA. Bilirubin analogues as model compounds for exciton coupling. Phys Chem Chem Phys 2020; 22:15567-15572. [PMID: 32613218 DOI: 10.1039/d0cp01421d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A series of phycobilin analogues have been investigated in terms of coupled excitonic systems. These compounds consist of a monomer, a tetrapyrrole structurally similar to bilirubin (bR), and two conjugated bR analogues. Spectroscopic and computational methods have been used to investigate the degree of interchromophore coupling. We find the synthesised bR analogue shows stronger excitonic coupling than bR, owing to a different molecular geometry. The excitonic coupling in the conjugated molecules can be controlled by modifying the bridge side-group. New computed energy levels for bR using the DFT/MRCI method are also presented, which improve on published values and re-assign the character of excited singlet states.
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Affiliation(s)
- Igor Lyskov
- ARC Centre of Excellence in Exciton Science, Australia
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2
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Gao C, Seow JY, Zhang B, Hall CR, Tilley AJ, White JM, Smith TA, Wong WWH. Tetraphenylethene 9,10-Diphenylanthracene Derivatives - Synthesis and Photophysical Properties. Chempluschem 2019; 84:746-753. [PMID: 31944010 DOI: 10.1002/cplu.201900100] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 03/27/2019] [Indexed: 12/20/2022]
Abstract
A series of tetraphenylethene 9,10-diphenylanthracene (TPE-DPA) derivatives have been synthesized, and their photophysical properties studied. Photoluminescence measurements in PMMA, neat films and nanoparticle dispersions reveal that different aggregation states are formed, which leads to different photophysical behavior. The triplet excited state properties were studied using Pt(II) octaethylporphyrin (PtOEP) as triplet sensitizer. Upconverted emission from the DPA moiety is observed in nanoparticle dispersions of each derivative. A higher upconverted emission intensity is observed in aerated (compared to deaerated) solutions of the derivatives following irradiation, which is attributed to oxidation of the TPE moiety. These results provide valuable insight for the design of AIE luminogens for triplet-triplet annihilation upconversion (TTA-UC).
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Affiliation(s)
- Can Gao
- School of Chemistry ARC Centre of Excellence in Exciton Science, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Jia Yi Seow
- School of Chemistry ARC Centre of Excellence in Exciton Science, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Bolong Zhang
- School of Chemistry ARC Centre of Excellence in Exciton Science, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Christopher R Hall
- School of Chemistry ARC Centre of Excellence in Exciton Science, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Andrew J Tilley
- School of Chemistry ARC Centre of Excellence in Exciton Science, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Jonathan M White
- School of Chemistry Bio21 Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Trevor A Smith
- School of Chemistry ARC Centre of Excellence in Exciton Science, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Wallace W H Wong
- School of Chemistry ARC Centre of Excellence in Exciton Science, The University of Melbourne, Parkville, Victoria, 3010, Australia
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3
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Schon TB, An SY, Tilley AJ, Seferos DS. Unusual Capacity Increases with Cycling for Ladder-Type Microporous Polymers. ACS Appl Mater Interfaces 2019; 11:1739-1747. [PMID: 30614678 DOI: 10.1021/acsami.8b18293] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Microporous polymers using triptycene vertices and various ladder-type benzimidazole linkers are synthesized and tested as lithium-ion battery anodes. An unusual increase in performance is observed upon cycling, affording high capacities of 783 and 737 mAh g-1 for a perylene derivative and the pyromellitic derivative after 1000 cycles. The high performance of these materials after cycling is attributed to favorable electrode morphology and high crystallinity for perylene derivative, and the presence of charge carriers for pyromellitic derivative. By studying the effect of various linkers on the electrochemical performance, structure-property relationships are proposed that can be used to guide the development of high-performance materials for lithium-ion batteries.
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Affiliation(s)
- Tyler B Schon
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , Ontario M5S 2H6 , Canada
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , 200 College Street , Toronto , Ontario M5S 3E5 , Canada
| | - So Young An
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , Ontario M5S 2H6 , Canada
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , 200 College Street , Toronto , Ontario M5S 3E5 , Canada
| | - Andrew J Tilley
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , Ontario M5S 2H6 , Canada
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , 200 College Street , Toronto , Ontario M5S 3E5 , Canada
| | - Dwight S Seferos
- Department of Chemistry , University of Toronto , 80 St. George Street , Toronto , Ontario M5S 2H6 , Canada
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , 200 College Street , Toronto , Ontario M5S 3E5 , Canada
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4
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Gregory MA, Zhang B, Tilley AJ, Scheerlinck T, White JM, Wong WWH. Amine‐Substituted Diazocine Derivatives – Synthesis, Structure, and Photophysical Properties. Helv Chim Acta 2018. [DOI: 10.1002/hlca.201800146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mark A. Gregory
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
| | - Bolong Zhang
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
- ARC Centre of Excellence in Exciton Science School of Chemistry The University of Melbourne Parkville Victoria 3010 Australia
| | - Andrew J. Tilley
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
- ARC Centre of Excellence in Exciton Science School of Chemistry The University of Melbourne Parkville Victoria 3010 Australia
| | - Tamika Scheerlinck
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
| | - Jonathan M. White
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
| | - Wallace W. H. Wong
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
- ARC Centre of Excellence in Exciton Science School of Chemistry The University of Melbourne Parkville Victoria 3010 Australia
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5
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Pensack RD, Tilley AJ, Grieco C, Purdum GE, Ostroumov EE, Granger DB, Oblinsky DG, Dean JC, Doucette GS, Asbury JB, Loo YL, Seferos DS, Anthony JE, Scholes GD. Striking the right balance of intermolecular coupling for high-efficiency singlet fission. Chem Sci 2018; 9:6240-6259. [PMID: 30090312 PMCID: PMC6062843 DOI: 10.1039/c8sc00293b] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 05/31/2018] [Indexed: 12/02/2022] Open
Abstract
Singlet fission is a process that splits collective excitations, or excitons, into two with unity efficiency. This exciton splitting process, unique to molecular photophysics, has the potential to considerably improve the efficiency of optoelectronic devices through more efficient light harvesting. While the first step of singlet fission has been characterized in great detail, subsequent steps critical to achieving overall highly-efficient singlet-to-triplet conversion are only just beginning to become well understood. One of the most elementary suggestions, which has yet to be tested, is that an appropriately balanced coupling is necessary to ensure overall highly efficient singlet fission; that is, the coupling needs to be strong enough so that the first step is fast and efficient, yet weak enough to ensure the independent behavior of the resultant triplets. In this work, we show how high overall singlet-to-triplet conversion efficiencies can be achieved in singlet fission by ensuring that the triplets comprising the triplet pair behave as independently as possible. We show that side chain sterics govern local packing in amorphous pentacene derivative nanoparticles, and that this in turn controls both the rate at which triplet pairs form and the rate at which they decay. We show how compact side chains and stronger couplings promote a triplet pair that effectively couples to the ground state, whereas bulkier side chains promote a triplet pair that appears more like two independent and long-lived triplet excitations. Our results show that the triplet pair is not emissive, that its decay is best viewed as internal conversion rather than triplet-triplet annihilation, and perhaps most critically that, in contrast to a number of recent suggestions, the triplets comprising the initially formed triplet pair cannot be considered independently. This work represents a significant step toward better understanding intermediates in singlet fission, and how molecular packing and couplings govern overall triplet yields.
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Affiliation(s)
- Ryan D Pensack
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , USA .
| | - Andrew J Tilley
- Department of Chemistry , University of Toronto , Toronto , Ontario M5S 3H6 , Canada
| | - Christopher Grieco
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , USA
| | - Geoffrey E Purdum
- Department of Chemical and Biological Engineering , Princeton University , Princeton , New Jersey 08544 , USA
| | - Evgeny E Ostroumov
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , USA .
| | - Devin B Granger
- Department of Chemistry , University of Kentucky , Lexington , Kentucky 40506 , USA .
| | - Daniel G Oblinsky
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , USA .
| | - Jacob C Dean
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , USA .
| | - Grayson S Doucette
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , USA
| | - John B Asbury
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16802 , USA
| | - Yueh-Lin Loo
- Department of Chemical and Biological Engineering , Princeton University , Princeton , New Jersey 08544 , USA
- Andlinger Center for Energy and the Environment , Princeton University , Princeton , New Jersey 08544 , USA
| | - Dwight S Seferos
- Department of Chemistry , University of Toronto , Toronto , Ontario M5S 3H6 , Canada
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , Toronto , Ontario M5S 3E5 , Canada
| | - John E Anthony
- Department of Chemistry , University of Kentucky , Lexington , Kentucky 40506 , USA .
| | - Gregory D Scholes
- Department of Chemistry , Princeton University , Princeton , New Jersey 08544 , USA .
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6
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Pahlavanlu P, Tilley AJ, McAllister BT, Seferos DS. Microwave Synthesis of Thionated Naphthalene Diimide-Based Small Molecules and Polymers. J Org Chem 2017; 82:12337-12345. [DOI: 10.1021/acs.joc.7b02162] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Paniz Pahlavanlu
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Andrew J. Tilley
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Bryony T. McAllister
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Dwight S. Seferos
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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7
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Schon TB, Tilley AJ, Kynaston EL, Seferos DS. Three-Dimensional Arylene Diimide Frameworks for Highly Stable Lithium Ion Batteries. ACS Appl Mater Interfaces 2017; 9:15631-15637. [PMID: 28430407 DOI: 10.1021/acsami.7b02336] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Lithium ion batteries are the best commercial technology to satisfy the energy storage needs of current and emerging applications. However, the use of transition-metal-based cathodes precludes them from being low-cost, sustainable, and environmentally benign, even with recycling programs in place. In this study, we report a highly stable organic material that can be used in place of the transition-metal cathodes. By creating a three-dimensional framework based on triptycene and perylene diimide (PDI), a cathode can be constructed that mitigates stability issues that organic electrodes typically suffer from. When a lithium ion battery is assembled using the PDI-triptycene framework (PDI-Tc) cathode, a capacity of 75.9 mAh g-1 (78.7% of the theoretical value) is obtained. Importantly, the battery retains a near perfect Coulombic efficiency and >80% of its capacity after cycling 500 times, which is the best value reported to date for PDI-based materials.
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Affiliation(s)
- Tyler B Schon
- Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Andrew J Tilley
- Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Emily L Kynaston
- Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Dwight S Seferos
- Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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8
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Liew SK, Holownia A, Tilley AJ, Carrera EI, Seferos DS, Yudin AK. A Study of Boratriazaroles: An Underdeveloped Class of Heterocycles. J Org Chem 2016; 81:10444-10453. [DOI: 10.1021/acs.joc.6b01565] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sean K. Liew
- Davenport and Lash Miller
Chemical Laboratories, Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada
| | - Aleksandra Holownia
- Davenport and Lash Miller
Chemical Laboratories, Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada
| | - Andrew J. Tilley
- Davenport and Lash Miller
Chemical Laboratories, Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada
| | - Elisa I. Carrera
- Davenport and Lash Miller
Chemical Laboratories, Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada
| | - Dwight S. Seferos
- Davenport and Lash Miller
Chemical Laboratories, Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada
| | - Andrei K. Yudin
- Davenport and Lash Miller
Chemical Laboratories, Department of Chemistry, University of Toronto, 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada
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9
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Pensack RD, Ostroumov EE, Tilley AJ, Mazza S, Grieco C, Thorley KJ, Asbury JB, Seferos DS, Anthony JE, Scholes GD. Observation of Two Triplet-Pair Intermediates in Singlet Exciton Fission. J Phys Chem Lett 2016; 7:2370-5. [PMID: 27281713 DOI: 10.1021/acs.jpclett.6b00947] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Singlet fission is an excitation multiplication process in molecular systems that can circumvent energy losses and significantly boost solar cell efficiencies; however, the nature of a critical intermediate that enables singlet fission and details of its evolution into multiple product excitations remain obscure. We resolve the initial sequence of events comprising the fission of a singlet exciton in solids of pentacene derivatives using femtosecond transient absorption spectroscopy. We propose a three-step model of singlet fission that includes two triplet-pair intermediates and show how transient spectroscopy can distinguish initially interacting triplet pairs from those that are spatially separated and noninteracting. We find that the interconversion of these two triplet-pair intermediates is limited by the rate of triplet transfer. These results clearly highlight the classical kinetic model of singlet fission and expose subtle details that promise to aid in resolving problems associated with triplet extraction.
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Affiliation(s)
- Ryan D Pensack
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Evgeny E Ostroumov
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
| | - Andrew J Tilley
- Department of Chemistry, University of Toronto , Toronto, Ontario M5S 3H6, Canada
| | - Samuel Mazza
- Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506, United States
| | - Christopher Grieco
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Karl J Thorley
- Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506, United States
| | - John B Asbury
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Dwight S Seferos
- Department of Chemistry, University of Toronto , Toronto, Ontario M5S 3H6, Canada
| | - John E Anthony
- Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506, United States
| | - Gregory D Scholes
- Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States
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10
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Pensack RD, Tilley AJ, Parkin SR, Lee TS, Payne MM, Gao D, Jahnke AA, Oblinsky DG, Li PF, Anthony JE, Seferos DS, Scholes GD. Exciton Delocalization Drives Rapid Singlet Fission in Nanoparticles of Acene Derivatives. J Am Chem Soc 2015; 137:6790-803. [DOI: 10.1021/ja512668r] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Ryan D. Pensack
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Andrew J. Tilley
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Sean R. Parkin
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Tia S. Lee
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Marcia M. Payne
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Dong Gao
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Ashlee A. Jahnke
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Daniel G. Oblinsky
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Peng-Fei Li
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - John E. Anthony
- Department
of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Dwight S. Seferos
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Gregory D. Scholes
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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11
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Abstract
Time-resolved absorption and emission spectroscopy has been applied to investigate the dynamics of excited state processes in oligomer models for semi-conducting organic materials. Following the photo-excitation of a pentamer oligomer that is a model for the conjugated polymer MEH-PPV, an ultrafast component of a few picoseconds is observed for the decay of the initially formed transient species. Variable temperature absorption and emission spectra combined with X-ray crystallography and calculations support the assignment of this rapid relaxation process to an excited state conformational rearrangement from non-planar to more planar molecular configurations. The implications of the results for the overall photophysics of conjugated polymers are considered.
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Affiliation(s)
- Kenneth P Ghiggino
- School of Chemistry, University of Melbourne, Melbourne, Victoria, Australia.
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12
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Mahrok AK, Carrera EI, Tilley AJ, Ye S, Seferos DS. Synthesis and photophysical properties of platinum-acetylide copolymers with thiophene, selenophene and tellurophene. Chem Commun (Camb) 2015; 51:5475-8. [DOI: 10.1039/c4cc09312g] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of platinum-acetylide copolymers with thiophene, selenophene, and tellurophene have been synthesized and studied.
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Affiliation(s)
| | | | | | - Shuyang Ye
- Department of Chemistry
- University of Toronto
- Toronto
- Canada
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13
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Tilley AJ, Robotham BE, Steer RP, Ghiggino KP. Sensitized non-coherent photon upconversion by intramolecular triplet–triplet annihilation in a diphenylanthracene pendant polymer. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2014.11.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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14
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Kozycz LM, Gao D, Tilley AJ, Seferos DS. One donor-two acceptor (D-A1)-(D-A2) random terpolymers containing perylene diimide, naphthalene diimide, and carbazole units. ACTA ACUST UNITED AC 2014. [DOI: 10.1002/pola.27395] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Lisa M. Kozycz
- Department of Chemistry, Lash Miller Chemical Laboratories; University of Toronto; 80 St. George Street Toronto Ontario M5S 3H6 Canada
| | - Dong Gao
- Department of Chemistry, Lash Miller Chemical Laboratories; University of Toronto; 80 St. George Street Toronto Ontario M5S 3H6 Canada
| | - Andrew J. Tilley
- Department of Chemistry, Lash Miller Chemical Laboratories; University of Toronto; 80 St. George Street Toronto Ontario M5S 3H6 Canada
| | - Dwight S. Seferos
- Department of Chemistry, Lash Miller Chemical Laboratories; University of Toronto; 80 St. George Street Toronto Ontario M5S 3H6 Canada
- Department of Chemical Engineering & Applied Science; University of Toronto; 200 College Street Toronto Ontario M5S 3ES Canada
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15
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Hooley EN, Tilley AJ, White JM, Ghiggino KP, Bell TDM. Energy transfer in PPV-based conjugated polymers: a defocused widefield fluorescence microscopy study. Phys Chem Chem Phys 2014; 16:7108-14. [PMID: 24618928 DOI: 10.1039/c4cp00276h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Both pendant and main chain conjugated MEH-PPV based polymers have been studied at the level of single chains using confocal and widefield fluorescence microscopy techniques. In particular, defocused widefield fluorescence is applied to reveal the extent of energy transfer in these polymers by identifying whether they act as single emitters. For main chain conjugated MEH-PPV, molecular weight and the surrounding matrix play a primary role in determining energy transport processes and whether single emitter behaviour is observed. Surprisingly in polymers with a saturated backbone but containing the same pendant MEH-PPV oligomer on each repeating unit, intra-chain energy transfer to a single emitter is also apparent. The results imply there is chromophore heterogeneity that can facilitate energy funneling to the emitting site. Both main chain conjugated and pendant MEH-PPV polymers exhibit changes in orientation of the emission dipole during a fluorescence trajectory of many seconds, whereas a model MEH-PPV oligomer does not. The results suggest that, in the polymers, the nature of the emitting chromophores can change during the time trajectory.
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Affiliation(s)
- E N Hooley
- School of Chemistry and Bio21 Institute, The University of Melbourne, Parkville, Vic. 3010, Australia.
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17
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Tilley AJ, Zanatta SD, Qin CX, Kim IK, Seok YM, Stewart A, Woodman OL, Williams SJ. 2-Morpholinoisoflav-3-enes as flexible intermediates in the synthesis of phenoxodiol, isophenoxodiol, equol and analogues: vasorelaxant properties, estrogen receptor binding and Rho/RhoA kinase pathway inhibition. Bioorg Med Chem 2012; 20:2353-61. [PMID: 22377671 DOI: 10.1016/j.bmc.2012.02.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 01/26/2012] [Accepted: 02/02/2012] [Indexed: 12/17/2022]
Abstract
Isoflavone consumption correlates with reduced rates of cardiovascular disease. Epidemiological studies and clinical data provide evidence that isoflavone metabolites, such as the isoflavan equol, contribute to these beneficial effects. In this study we developed a new route to isoflavans and isoflavenes via 2-morpholinoisoflavenes derived from a condensation reaction of phenylacetaldehydes, salicylaldehydes and morpholine. We report the synthesis of the isoflavans equol and deoxygenated analogues, and the isoflavenes 7,4'-dihydroxyisoflav-3-ene (phenoxodiol, haganin E) and 7,4'-dihydroxyisoflav-2-ene (isophenoxodiol). Vascular pharmacology studies reveal that all oxygenated isoflavans and isoflavenes can attenuate phenylephrine-induced vasoconstriction, which was unaffected by the estrogen receptor antagonist ICI 182,780. Furthermore, the compounds inhibited U46619 (a thromboxane A(2) analogue) induced vasoconstriction in endothelium-denuded rat aortae, and reduced the formation of GTP RhoA, with the effects being greatest for equol and phenoxodiol. Ligand displacement studies of rat uterine cytosol estrogen receptor revealed the compounds to be generally weak binders. These data are consistent with the vasorelaxation activity of equol and phenoxodiol deriving at least in part by inhibition of the RhoA/Rho-kinase pathway, and along with the limited estrogen receptor affinity supports a role for equol and phenoxodiol as useful agents for maintaining cardiovascular function with limited estrogenic effects.
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Affiliation(s)
- Andrew J Tilley
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
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19
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20
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21
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Tilley AJ, Danczak SM, Browne C, Young T, Tan T, Ghiggino KP, Smith TA, White J. Synthesis and Fluorescence Characterization of MEHPPV Oligomers. J Org Chem 2011; 76:3372-80. [DOI: 10.1021/jo200336m] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andrew J. Tilley
- School of Chemistry and Bio 21 Institute, University of Melbourne, Victoria, Australia 3010
| | - Stephen M. Danczak
- School of Chemistry and Bio 21 Institute, University of Melbourne, Victoria, Australia 3010
| | - Christine Browne
- School of Chemistry and Bio 21 Institute, University of Melbourne, Victoria, Australia 3010
| | - Timothy Young
- School of Chemistry and Bio 21 Institute, University of Melbourne, Victoria, Australia 3010
| | - Tina Tan
- School of Chemistry and Bio 21 Institute, University of Melbourne, Victoria, Australia 3010
| | - Kenneth P. Ghiggino
- School of Chemistry and Bio 21 Institute, University of Melbourne, Victoria, Australia 3010
| | - Trevor A. Smith
- School of Chemistry and Bio 21 Institute, University of Melbourne, Victoria, Australia 3010
| | - Jonathan White
- School of Chemistry and Bio 21 Institute, University of Melbourne, Victoria, Australia 3010
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Ngo TT, Liu GB, Tilley AJ, Pettigrew JD, Miller SM. The changing face of perceptual rivalry. Brain Res Bull 2008; 75:610-8. [DOI: 10.1016/j.brainresbull.2007.10.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 09/03/2007] [Accepted: 10/17/2007] [Indexed: 11/28/2022]
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Ngo TT, Liu GB, Tilley AJ, Pettigrew JD, Miller SM. Caloric vestibular stimulation reveals discrete neural mechanisms for coherence rivalry and eye rivalry: A meta-rivalry model. Vision Res 2007; 47:2685-99. [PMID: 17719618 DOI: 10.1016/j.visres.2007.03.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2006] [Revised: 02/27/2007] [Accepted: 03/26/2007] [Indexed: 11/19/2022]
Abstract
Binocular rivalry is an extraordinary visual phenomenon that has engaged investigators for centuries. Since its first report, there has been vigorous debate over how the brain achieves the perceptual alternations that occur when conflicting images are presented simultaneously, one to each eye. Opposing high-level/stimulus-representation models and low-level/eye-based models have been proposed to explain the phenomenon, recently merging into an amalgam view. Here, we provide evidence that during viewing of Díaz-Caneja stimuli, coherence rivalry -- in which aspects of each eye's presented image are perceptually regrouped into rivalling coherent images -- and eye rivalry operate via discrete neural mechanisms. We demonstrate that high-level brain activation by unilateral caloric vestibular stimulation shifts the predominance of perceived coherent images (coherence rivalry) but not half-field images (eye rivalry). This finding suggests that coherence rivalry (like conventional rivalry according to our previous studies) is mediated by interhemispheric switching at a high level, while eye rivalry is mediated by intrahemispheric mechanisms, most likely at a low level. Based on the present data, we further propose that Díaz-Caneja stimuli induce 'meta-rivalry' whereby the discrete high- and low-level competitive processes themselves rival for visual consciousness.
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Affiliation(s)
- Trung T Ngo
- Vision Touch and Hearing Research Centre, Research Road, School of Biomedical Sciences, University of Queensland, Brisbane, QLD, Australia.
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Abstract
This paper examines the psychometric quality of the Early/Late Preferences Scale (PS) relative to that of the Composite Morningness Scale (CS). Questionnaires were completed by 670 undergraduate students aged 16-37 years (mean 22.5), of whom 64% were female. Both scales displayed satisfactory inter-item correlations and similar total mean scores to those reported previously, although the CS had higher variability. Principal axis factor analysis produced single-factor solutions for both scales, although loadings for Items 7 and 9 on the PS were low. Internal consistencies for both scales were good (PS = 0.86, CS = 0.90) with only a small improvement achieved by deleting Items 7 and 9 from the PS. Test-retest reliability over 11 weeks was good for both scales (PS = 0.92, CS = 0.89). Differences between morning, evening and intermediate groups in self-rated alertness at different times of day, and significant correlations with other indices of morning-evening orientation, provided evidence of validity for both scales. These results indicate that PS is psychometrically comparable with CS. In view of its simpler format and lower cultural specificity, PS may be considered a preferable measure for most applications.
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Affiliation(s)
- P Bohle
- University of New South Wales, Sydney, Australia.
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Abstract
This study examined the impact of night shift on six dimensions of mood. The efficacy of a range of personality, behavioural, and social/organizational predictors of these responses was also examined. Thirty-five female student nurses were studied during their first period of night work. ANOVAs indicated that only fatigue-inertia and vigour-activity were significantly affected by night work. Multivariate profile analyses revealed that significant changes were predominantly confined to the interval between the preceding rest day (B) and the first night (N1), although vigour-activity dropped significantly between N1 and N2 and rose significantly by N5 for one group of subjects. Multiple regression analyses revealed that morningness, neuroticism, work-non-work conflict, and sleep quality between shifts predicted fatigue-inertia. Extroversion and social support from both co-workers and family predicted vigour-activity. Extroversion and social support from co-workers appeared to predict the positive affect component of vigour-activity, rather than the vigour and energy component.
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Affiliation(s)
- P Bohle
- Griffith University, Nathan, Australia
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Abstract
8 subjects performed an unprepared simple reaction time task for 20 min. every 2 hr. while taking part in an all night disco dancing marathon (continuous exercise) and during a control (no exercise) night. Mean reaction times were significantly faster and less variable during the dance marathon. It was suggested that the effects of continuous exercise in the form of disco dancing may be to reduce drowsiness which in turn assists performance.
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Affiliation(s)
- A J Tilley
- Department of Psychology, University of Queensland, St. Lucia, Australia
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Abstract
The sleep of 8 women was restricted to the first half of the night for 1 night on two separate occasions. On each occasion, heavy loss of REM (64%) and stage 2 (60%) with only a relatively light loss (20%) of slow wave sleep resulted. The purpose of the present study was to investigate whether or not the circadian timing of recovery sleep, particularly the second 4 h, would affect the response of the sleep system to the differential loss of the sleep stages. Recovery sleep commenced at 2000 h (i.e., after a normal daily span of 16 h of wakefulness) and was either continuous or interrupted after 4 h with 4 h of enforced wakefulness. Thus, the second 4 h of recovery sleep occurred between either 0000-0400 h or 0400-0800 h, two periods of the night normally associated with low and high levels of REM, respectively. The composition of recovery sleep, particularly the level of REM sleep, was found to be relatively unaffected by circadian factors. Instead, the response of the sleep system was mainly determined by stage 4 debt. It was suggested that obtaining a daily stage 4 quota acts as the primary drive mechanism of the sleep system.
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Abstract
The sleep and performance of 12 male shift workers, operating a discontinuous, weekly alternating, three-shift system, were monitored over the course of one complete shift cycle. Compared with nocturnal sleep, day sleep was shorter in duration and was degraded in quality, and its sleep stages were temporally disrupted. Simple unprepared reaction time and four-choice reaction time were impaired at night, and simple reaction time deteriorated as a function of the number of days into the shift and the time on task. Sleep and performance changes can be primarily attributed to circadian factors; however, the deterioration in performance from night to night and with time on task is probably due to an accumulative sleep deficit. As far as sleep and performance are concerned, the best shift system is probably one having a short rotation cycle, with afternoon shifts or rest days preceding and following the night shift.
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Abstract
Pairs of subjects were presented with a 20-item picture series at bedtime. In the latter part of the night, a tape-recorded series of 10 words, the verbal equivalent of half the original series of pictures, was repeated 10 times during either Stage 2 or REM sleep. Morning recall and recognition for repeated words was found to be facilitated following repetition during Stage 2 sleep, but relatively unaffected following repetition during REM sleep. However, adjusting for recall, the number of additional words elicited through recognition was found to be significantly greater for REM repeated words than for Stage 2 repeated words. It was suggested that retrieval limitations, perhaps as a result of REM state dependency, rather than storage inhibition may be the main locus of the initial recall failure. By comparison, Stage 2 sleep would seem to present both a lower barrier to memory storage and retrieval compatibility with wakefulness.
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Barwood TJ, Empson JA, Lister SG, Tilley AJ. Auditory evoked potentials and transcendental meditation. Electroencephalogr Clin Neurophysiol 1978; 45:671-3. [PMID: 81770 DOI: 10.1016/0013-4694(78)90168-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Auditory evoked potentials to tone stimuli were recorded from 8 practised meditators before, during, and after meditation, and also during light sleep. No consistent changes were noted between baseline and meditating AEPs, or between meditating and sleep AEPs.
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Abstract
One proposal referring to a specific function of REM sleep has been that it is necessary for, or at least conductive to, the progress of memory consolidation. This hypothesis was tested by comparing the effects on story retention of REM deprivation against an S4 deprived control. It was found that recall accuracy following REM deprivation was significantly poorer than following S4 deprivation. Furthermore, the degree of deterioration in recall accuracy during REM recovery sleep was less than during S4 recovery sleep. These findings were interpreted as evidence for active REM facilitation of memory consolidation. However, alternative explanations based upon proactive influences need to be investigated.
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