1
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Roy R, Brouillac C, Jacques E, Quinton C, Poriel C. π-Conjugated Nanohoops: A New Generation of Curved Materials for Organic Electronics. Angew Chem Int Ed Engl 2024:e202402608. [PMID: 38744668 DOI: 10.1002/anie.202402608] [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: 02/05/2024] [Revised: 05/13/2024] [Accepted: 05/14/2024] [Indexed: 05/16/2024]
Abstract
Nanohoops, cyclic association of π-conjugated systems to form a hoop-shaped molecule, have been widely developed in the last 15 years. Beyond the synthetic challenge, the strong interest towards these molecules arises from their radially oriented π-orbitals, which provide singular properties to these fascinating structures. Thanks to their particular cylindrical arrangement, this new generation of curved molecules have been already used in many applications such as host-guest complexation, biosensing, bioimaging, solid-state emission and catalysis. However, their potential in organic electronics has only started to be explored. From the first incorporation as an emitter in a fluorescent organic light emitting diode (OLED), to the recent first incorporation as a host in phosphorescent OLEDs or as charge transporter in organic field-effect transistors and in organic photovoltaics, this field has shown important breakthroughs in recent years. These findings have revealed that curved materials can play a key role in the future and can even be more efficient than their linear counterparts. This can have important repercussions for the future of electronics. Time has now come to overview the different nanohoops used to date in electronic devices in order to stimulate the future molecular designs of functional materials based on these macrocycles.
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Affiliation(s)
- Rupam Roy
- Univ Rennes, CNRS, ISCR-UMR CNRS 6226, F-35000, Rennes, France
- Department of Chemistry, University of Florida, Gainesville, Florida, United States, 32603
| | | | | | | | - Cyril Poriel
- Univ Rennes, CNRS, ISCR-UMR CNRS 6226, F-35000, Rennes, France
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2
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Alfonso Hernandez L, Freixas VM, Rodriguez-Hernandez B, Tretiak S, Fernandez-Alberti S, Oldani N. Exciton-vibrational dynamics induces efficient self-trapping in a substituted nanoring. Phys Chem Chem Phys 2022; 24:24095-24104. [PMID: 36178044 DOI: 10.1039/d2cp03162k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cycloparaphenylenes, being the smallest segments of carbon nanotubes, have emerged as prototypes of the simplest carbon nanohoops. Their unique structure-dynamics-optical properties relationships have motivated a wide variety of synthesis of new related nanohoop species. Studies of how chemical changes, introduced in these new materials, lead to systems with new structural, dynamics and optical properties, expand their functionalities for optoelectronics applications. Herein, we study the effect that conjugation extension of a cycloparaphenylene through the introduction of a satellite tetraphenyl substitution has on its structural and dynamical properties. Our non-adiabatic excited state molecular dynamics simulations suggest that this substitution accelerates the electronic relaxation from the high-energy band to the lowest excited state. This is partially due to efficient conjugation achieved between specific phenyl units as introduced by the tetraphenyl substitution. We observe a particular exciton redistribution during relaxation, in which the tetraphenyl substitution plays a significant role. As a result, an efficient inter-band energy transfer takes place. Besides, the observed phonon-exciton interplay induces a significant exciton self-trapping. Our results encourage and guide the future studies of new phenyl substitutions in carbon nanorings with desired optoelectronic properties.
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Affiliation(s)
- Laura Alfonso Hernandez
- Departamento de Ciencia Tecnologia, Universidad Nacional de Quilmes/CONICET, B1876BXD Bernal, Argentina.
| | - Victor M Freixas
- Departamento de Ciencia Tecnologia, Universidad Nacional de Quilmes/CONICET, B1876BXD Bernal, Argentina.
| | | | - Sergei Tretiak
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | | | - Nicolas Oldani
- Departamento de Ciencia Tecnologia, Universidad Nacional de Quilmes/CONICET, B1876BXD Bernal, Argentina.
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3
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Kakarlamudi AC, Vennapusa SR. Intersystem crossing pathways in [5]-, [7]-, and [9]cycloparaphenylenes. J Chem Phys 2021; 155:044301. [PMID: 34340401 DOI: 10.1063/5.0056605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We analyze the energetics and internal conversion dynamics of singlet and triplet manifolds to identify the possible intersystem crossing pathways in odd-numbered [n]cycloparaphenylenes ([n]CPPs, n = 5, 7, and 9). Quantum wavepacket propagation calculations within the linear vibronic coupling framework suggest that both [5]- and [7]CPPs rapidly relax to S2 upon populating "bright" higher singlet excited states. The S2-S1 energy decreases with the increase in CPP size, and hence, [9]CPP exhibits a faster S2 → S1 internal conversion decay. Higher triplet states act as receiver states for the intersystem crossing happening either via S1 or S2. The wavepacket evolving on the receiver triplet state would decay to lower states via multiple conical intersections and reach T1. The estimated size-dependent fluorescence and emission energies are in good accord with the experiment.
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Affiliation(s)
- Akhil Chakravarthy Kakarlamudi
- School of Chemistry, Indian Institute of Science Education and Research, Maruthamala PO, Vithura, Thiruvanathapuram 695551, India
| | - Sivaranjana Reddy Vennapusa
- School of Chemistry, Indian Institute of Science Education and Research, Maruthamala PO, Vithura, Thiruvanathapuram 695551, India
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4
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Ayub R, El Bakouri O, Smith JR, Jorner K, Ottosson H. Triplet State Baird Aromaticity in Macrocycles: Scope, Limitations, and Complications. J Phys Chem A 2021; 125:570-584. [PMID: 33427474 PMCID: PMC7884009 DOI: 10.1021/acs.jpca.0c08926] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 12/18/2020] [Indexed: 02/06/2023]
Abstract
The aromaticity of cyclic 4nπ-electron molecules in their first ππ* triplet state (T1), labeled Baird aromaticity, has gained growing attention in the past decade. Here we explore computationally the limitations of T1 state Baird aromaticity in macrocyclic compounds, [n]CM's, which are cyclic oligomers of four different monocycles (M = p-phenylene (PP), 2,5-linked furan (FU), 1,4-linked cyclohexa-1,3-diene (CHD), and 1,4-linked cyclopentadiene (CPD)). We strive for conclusions that are general for various DFT functionals, although for macrocycles with up to 20 π-electrons in their main conjugation paths we find that for their T1 states single-point energies at both canonical UCCSD(T) and approximative DLPNO-UCCSD(T) levels are lowest when based on UB3LYP over UM06-2X and UCAM-B3LYP geometries. This finding is in contrast to what has earlier been observed for the electronic ground state of expanded porphyrins. Yet, irrespective of functional, macrocycles with 2,5-linked furans ([n]CFU's) retain Baird aromaticity until larger n than those composed of the other three monocycles. Also, when based on geometric, electronic and energetic aspects of aromaticity, a 3[n]CFU with a specific n is more strongly Baird-aromatic than the analogous 3[n]CPP while the magnetic indices tell the opposite. To construct large T1 state Baird-aromatic [n]CM's, the design should be such that the T1 state Baird aromaticity of the macrocyclic perimeter dominates over a situation with local closed-shell Hückel aromaticity of one or a few monocycles and semilocalized triplet diradical character. Monomers with lower Hückel aromaticity in S0 than benzene (e.g., furan) that do not impose steric congestion are preferred. Structural confinement imposed by, e.g., methylene bridges is also an approach to larger Baird-aromatic macrocycles. Finally, by using the Zilberg-Haas description of T1 state aromaticity, we reveal the analogy to the Hückel aromaticity of the corresponding closed-shell dications yet observe stronger Hückel aromaticity in the macrocyclic dications than Baird aromaticity in the T1 states of the neutral macrocycles.
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Affiliation(s)
- Rabia Ayub
- Department
of Chemistry - Ångström Laboratory, Uppsala University, Box 523, SE-751 20, Uppsala, Sweden
| | - Ouissam El Bakouri
- Department
of Chemistry - Ångström Laboratory, Uppsala University, Box 523, SE-751 20, Uppsala, Sweden
| | - Joshua R. Smith
- Department
of Chemistry - Ångström Laboratory, Uppsala University, Box 523, SE-751 20, Uppsala, Sweden
- Department
of Chemistry, Humboldt State University, One Harpst Street, Arcata, California 95521, United States
| | - Kjell Jorner
- Department
of Chemistry - Ångström Laboratory, Uppsala University, Box 523, SE-751 20, Uppsala, Sweden
| | - Henrik Ottosson
- Department
of Chemistry - Ångström Laboratory, Uppsala University, Box 523, SE-751 20, Uppsala, Sweden
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5
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Pérez‐Jiménez ÁJ, Sancho‐García JC. Theoretical Insights for Materials Properties of Cyclic Organic Nanorings. ADVANCED THEORY AND SIMULATIONS 2020. [DOI: 10.1002/adts.202000110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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6
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Pérez-Guardiola A, Ortiz-Cano R, Sandoval-Salinas ME, Fernández-Rossier J, Casanova D, Pérez-Jiménez AJ, Sancho-García JC. From cyclic nanorings to single-walled carbon nanotubes: disclosing the evolution of their electronic structure with the help of theoretical methods. Phys Chem Chem Phys 2019; 21:2547-2557. [PMID: 30656301 DOI: 10.1039/c8cp06615a] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We systematically investigate the relationships between structural and electronic effects of finite size zigzag or armchair carbon nanotubes of various diameters and lengths, starting from a molecular template of varying shape and diameter, i.e. cyclic oligoacene or oligophenacene molecules, and disclosing how adding layers and/or end-caps (i.e. hemifullerenes) can modify their (poly)radicaloid nature. We mostly used tight-binding and finite-temperature density-based methods, the former providing a simple but intuitive picture about their electronic structure, and the latter dealing effectively with strong correlation effects by relying on a fractional occupation number weighted electron density (ρFOD), with additional RAS-SF calculations backing up the latter results. We also explore how minor structural modifications of nanotube end-caps might influence the results, showing that topology, together with the chemical nature of the systems, is pivotal for the understanding of the electronic properties of these and other related systems.
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Affiliation(s)
- A Pérez-Guardiola
- Department of Physical Chemistry, University of Alicante, E-03080 Alicante, Spain.
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7
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Lin Z, Van Voorhis T. Triplet Tuning: A Novel Family of Non-Empirical Exchange–Correlation Functionals. J Chem Theory Comput 2019; 15:1226-1241. [DOI: 10.1021/acs.jctc.8b00853] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Zhou Lin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Troy Van Voorhis
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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8
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Daengngern R, Camacho C, Kungwan N, Irle S. Theoretical Prediction and Analysis of the UV/Visible Absorption and Emission Spectra of Chiral Carbon Nanorings. J Phys Chem A 2018; 122:7284-7292. [PMID: 30160478 DOI: 10.1021/acs.jpca.8b07270] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
UV/vis absorption and emission spectra of recently synthesized chiral carbon nanorings were simulated using first-principles-based molecular dynamics and time-dependent density functional theory (TD-DFT). The chiral carbon nanorings are derivatives of the [ n]cycloparaphenylene ([ n]CPP) macrocycles, containing an acene unit such as naphthalene, ([ n]CPPN), anthracene ([ n]CPPA), and tetracene ([ n]CPPT), in addition to n paraphenylene units. In order to study the effect of increasing molecular size on absorption and emission spectra, we investigated the cases where n = 6 and 8. Frontier molecular orbital analysis was carried out to give insight into the degree of excitation delocalization and its relationship to the predicted absorption spectra. The lowest excited singlet state S1 corresponds to a HOMO-LUMO π-π* transition, which is allowed in all chiral carbon nanorings due to lack of molecular symmetry, in contrast to the forbidden HOMO-LUMO transition in the symmetric [ n]CPP molecules. The S1 absorption peak exhibits a blue-shift with increasing number of paraphenylene units in particular for [ n]CPPN and [ n]CPPA and less so in the case of [ n]CPPT. In the case of CPPN and CPPA, the transition density is mainly localized over a semicircle of the macrocycle with the acene unit in its center but is strongly localized on the tetracene unit in the case of CPPT. Molecular dynamics simulations performed on the excited state potential energy surfaces reveal red-shifted emission of these chiral carbon nanorings when the size of the π-conjugated acene units is increased, although the characteristic [ n]CPP blue-shift with increasing paraphenylene unit number n remains apparent. The anomalous emission blue-shift is caused by the excited state bending and torsional motions that stabilize the π HOMO and destabilize the π* LUMO, resulting in an increasing HOMO-LUMO gap.
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Affiliation(s)
- Rathawat Daengngern
- Department of Chemistry, Faculty of Science , King Mongkut's Institute of Technology Ladkrabang , Bangkok 10520 , Thailand.,Institute of Transformative Bio-Molecules (WPI-ITbM) and Department of Chemistry, Graduate School of Science , Nagoya University , Nagoya 464-8601 , Japan
| | - Cristopher Camacho
- Institute of Transformative Bio-Molecules (WPI-ITbM) and Department of Chemistry, Graduate School of Science , Nagoya University , Nagoya 464-8601 , Japan.,School of Chemistry , University of Costa Rica , San José 11501-2060 , Costa Rica
| | - Nawee Kungwan
- Department of Chemistry, Faculty of Science , Chiang Mai University , Chiang Mai 50200 , Thailand.,Center of Excellence in Materials Science and Technology , Chiang Mai University , Chiang Mai 50200 , Thailand
| | - Stephan Irle
- Institute of Transformative Bio-Molecules (WPI-ITbM) and Department of Chemistry, Graduate School of Science , Nagoya University , Nagoya 464-8601 , Japan.,Computational Sciences and Engineering Division and Chemical Sciences Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
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9
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Nelson TR, Ondarse-Alvarez D, Oldani N, Rodriguez-Hernandez B, Alfonso-Hernandez L, Galindo JF, Kleiman VD, Fernandez-Alberti S, Roitberg AE, Tretiak S. Coherent exciton-vibrational dynamics and energy transfer in conjugated organics. Nat Commun 2018; 9:2316. [PMID: 29899334 PMCID: PMC5998141 DOI: 10.1038/s41467-018-04694-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 04/27/2018] [Indexed: 11/09/2022] Open
Abstract
Coherence, signifying concurrent electron-vibrational dynamics in complex natural and man-made systems, is currently a subject of intense study. Understanding this phenomenon is important when designing carrier transport in optoelectronic materials. Here, excited state dynamics simulations reveal a ubiquitous pattern in the evolution of photoexcitations for a broad range of molecular systems. Symmetries of the wavefunctions define a specific form of the non-adiabatic coupling that drives quantum transitions between excited states, leading to a collective asymmetric vibrational excitation coupled to the electronic system. This promotes periodic oscillatory evolution of the wavefunctions, preserving specific phase and amplitude relations across the ensemble of trajectories. The simple model proposed here explains the appearance of coherent exciton-vibrational dynamics due to non-adiabatic transitions, which is universal across multiple molecular systems. The observed relationships between electronic wavefunctions and the resulting functionalities allows us to understand, and potentially manipulate, excited state dynamics and energy transfer in molecular materials.
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Affiliation(s)
- Tammie R Nelson
- Theoretical Division, Center for Nonlinear studies and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 81545, USA
| | | | - Nicolas Oldani
- Universidad Nacional de Quilmes/CONICET, Roque Saenz Peña 352, B1876BXD, Bernal, Argentina
| | | | | | - Johan F Galindo
- Department of Chemistry, Universidad Nacional de Colombia, Av. Cra 30 # 45-03, Bogotá, 111321, Colombia
| | - Valeria D Kleiman
- Department of Chemistry, University of Florida, Gainesville, FL, 32611, USA
| | | | - Adrian E Roitberg
- Department of Chemistry, University of Florida, Gainesville, FL, 32611, USA
| | - Sergei Tretiak
- Theoretical Division, Center for Nonlinear studies and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 81545, USA.
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10
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Oldani N, Doorn SK, Tretiak S, Fernandez-Alberti S. Photoinduced dynamics in cycloparaphenylenes: planarization, electron–phonon coupling, localization and intra-ring migration of the electronic excitation. Phys Chem Chem Phys 2017; 19:30914-30924. [DOI: 10.1039/c7cp06426h] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Cycloparaphenylenes represent the smallest possible fragments of armchair carbon nanotubes.
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Affiliation(s)
- N. Oldani
- Universidad Nacional de Quilmes
- B1876BXD Bernal
- Argentina
| | - S. K. Doorn
- Theoretical Division
- Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT)
- Los Alamos National Laboratory
- Los Alamos
- USA
| | - S. Tretiak
- Theoretical Division
- Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT)
- Los Alamos National Laboratory
- Los Alamos
- USA
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11
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Franklin-Mergarejo R, Alvarez DO, Tretiak S, Fernandez-Alberti S. Carbon nanorings with inserted acenes: breaking symmetry in excited state dynamics. Sci Rep 2016; 6:31253. [PMID: 27507429 PMCID: PMC4978956 DOI: 10.1038/srep31253] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 07/13/2016] [Indexed: 12/25/2022] Open
Abstract
Conjugated cycloparaphenylene rings have unique electronic properties being the smallest segments of carbon nanotubes. Their conjugated backbones support delocalized electronic excitations, which dynamics is strongly influenced by cyclic geometry. Here we present a comparative theoretical study of the electronic and vibrational energy relaxation and redistribution in photoexcited cycloparaphenylene carbon nanorings with inserted naphthalene, anthracene, and tetracene units using non-adiabatic excited-state molecular dynamics simulations. Calculated excited state structures reflect modifications of optical selection rules and appearance of low-energy electronic states localized on the acenes due to gradual departure from a perfect circular symmetry. After photoexcitation, an ultrafast electronic energy relaxation to the lowest excited state is observed on the time scale of hundreds of femtoseconds in all molecules studied. Concomitantly, the efficiency of the exciton trapping in the acene raises when moving from naphthalene to anthracene and to tetracene, being negligible in naphthalene, and ~60% and 70% in anthracene and tetracene within the first 500 fs after photoexcitation. Observed photoinduced dynamics is further analyzed in details using induced molecular distortions, delocatization properties of participating electronic states and non-adiabatic coupling strengths. Our results provide a number of insights into design of cyclic molecular systems for electronic and light-harvesting applications.
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Affiliation(s)
- R Franklin-Mergarejo
- Universidad Nacional de Quilmes/CONICET, Roque Saenz Peña 352, B1876BXD Bernal, Argentina
| | - D Ondarse Alvarez
- Universidad Nacional de Quilmes/CONICET, Roque Saenz Peña 352, B1876BXD Bernal, Argentina
| | - S Tretiak
- Theoretical Division, Center for Nonlinear Studies (CNLS), and Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - S Fernandez-Alberti
- Universidad Nacional de Quilmes/CONICET, Roque Saenz Peña 352, B1876BXD Bernal, Argentina
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12
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Parkinson P, Kamonsutthipaijit N, Anderson HL, Herz LM. Size-Independent Energy Transfer in Biomimetic Nanoring Complexes. ACS NANO 2016; 10:5933-5940. [PMID: 27176553 PMCID: PMC4928140 DOI: 10.1021/acsnano.6b01265] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 05/13/2016] [Indexed: 06/05/2023]
Abstract
Supramolecular antenna-ring complexes are of great interest due to their presence in natural light-harvesting complexes. While such systems are known to provide benefits through robust and efficient energy funneling, the relationship between molecular structure, strain (governed by nuclear coordinates and motion), and energy dynamics (arising from electronic behavior) is highly complex. We present a synthetic antenna-nanoring system based on a series of conjugated porphyrin chromophores ideally suited to explore such effects. By systematically varying the size of the acceptor nanoring, we reveal the interplay between antenna-nanoring binding, local strain, and energy dynamics on the picosecond time scale. Binding of the antenna unit creates a local strain in the nanoring, and this strain was measured as a function of the size of the nanoring, by UV-vis-NIR titration, providing information on the conformational flexibility of the system. Strikingly, the energy-transfer rate is independent of nanoring size, indicating the existence of strain-localized acceptor states, spread over about six porphyrin units, arising from the noncovalent antenna-nanoring association.
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Affiliation(s)
- Patrick Parkinson
- Department
of Physics, Clarendon Laboratory, University
of Oxford, Oxford OX1 3PU, United Kingdom
| | - Nuntaporn Kamonsutthipaijit
- Department
of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Harry L. Anderson
- Department
of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Laura M. Herz
- Department
of Physics, Clarendon Laboratory, University
of Oxford, Oxford OX1 3PU, United Kingdom
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13
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Park KH, Cho JW, Kim TW, Shimizu H, Nakao K, Iyoda M, Kim D. Defining Cyclic-Acyclic Exciton Transition at the Single-Molecule Level: Size-Dependent Conformational Heterogeneity and Exciton Delocalization in Ethynylene-Bridged Cyclic Oligothiophenes. J Phys Chem Lett 2016; 7:1260-1266. [PMID: 26983838 DOI: 10.1021/acs.jpclett.6b00360] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Conformational disorder in π-conjugated cyclic systems plays a crucial role in controlling the extent of exciton delocalization in much the same way as that in linear counterparts. However, to date, there have been no detailed spectroscopic investigations on the nature of excitons in π-conjugated cyclic systems at the single-molecule level. Herein, we studied the effect of conformational disorder on the excitonic behaviors of cyclic oligothiophenes composed of 6, 8, 10, and 12 subunits (C-6T, C-8T, C-10T, and C-12T, respectively) by employing single-molecule fluorescence spectroscopy. We found that, due to the cyclic symmetry constraint which suppresses S1-S0 transition, small and rigid C-6T and C-8T exhibit extremely long fluorescence lifetimes, while short lifetimes typical of linear systems are dominant in large, flexible C-10T and C-12T. Two-dimensional correlation maps between fluorescence lifetimes and spectral positions show that, by torsional defects created through continued photoexcitation, fully delocalized cyclic excitons shrink to form acyclic excitons in the case of C-10T, while localized acyclic excitons from initial states are maintained in the case of C-12T. The distribution of linear dichroism values from C-6T to C-10T gradually broadens but narrows in C-12T, suggesting a cyclic-to-acyclic transition in excitonic nature between C-10T and C-12T.
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Affiliation(s)
- Kyu Hyung Park
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University , Seoul 03722, Korea
| | - Jae-Won Cho
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University , Seoul 03722, Korea
| | - Tae-Woo Kim
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University , Seoul 03722, Korea
| | - Hideyuki Shimizu
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University , Hachioji, Tokyo 192-0397, Japan
| | - Kazumi Nakao
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University , Hachioji, Tokyo 192-0397, Japan
| | - Masahiko Iyoda
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University , Hachioji, Tokyo 192-0397, Japan
| | - Dongho Kim
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University , Seoul 03722, Korea
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14
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Describing excited states of [n]cycloparaphenylenes by hybrid and double-hybrid density functionals: from isolated to weakly interacting molecules. Theor Chem Acc 2016. [DOI: 10.1007/s00214-015-1778-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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15
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Talipov MR, Jasti R, Rathore R. A Circle Has No End: Role of Cyclic Topology and Accompanying Structural Reorganization on the Hole Distribution in Cyclic and Linear Poly-p-phenylene Molecular Wires. J Am Chem Soc 2015; 137:14999-5006. [DOI: 10.1021/jacs.5b09596] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marat R. Talipov
- Department
of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, Wisconsin 53201-1881, United States
| | - Ramesh Jasti
- Department of Chemistry & Biochemistry and Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States
| | - Rajendra Rathore
- Department
of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, Wisconsin 53201-1881, United States
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16
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Adamska L, Nazin GV, Doorn SK, Tretiak S. Self-Trapping of Charge Carriers in Semiconducting Carbon Nanotubes: Structural Analysis. J Phys Chem Lett 2015; 6:3873-3879. [PMID: 26722885 DOI: 10.1021/acs.jpclett.5b01729] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The spatial extent of charged electronic states in semiconducting carbon nanotubes with indices (6,5) and (7,6) was evaluated using density functional theory. It was observed that electrons and holes self-trap along the nanotube axis on length scales of about 4 and 8 nm, respectively, which localize cations and anions on comparable length scales. Self-trapping is accompanied by local structural distortions showing periodic bond-length alternation. The average lengthening (shortening) of the bonds for anions (cations) is expected to shift the G-mode frequency to lower (higher) values. The smaller-diameter nanotube has reduced structural relaxation due to higher carbon-carbon bond strain. The reorganization energy due to charge-induced deformations in both nanotubes is found to be in the 30-60 meV range. Our results represent the first theoretical simulation of self-trapping of charge carriers in semiconducting nanotubes, and agree with available experimental data.
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Affiliation(s)
- Lyudmyla Adamska
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - George V Nazin
- Department of Chemistry and Biochemistry, University of Oregon , 1253 University of Oregon, Eugene, Oregon 97403, United States
| | - Stephen K Doorn
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Sergei Tretiak
- Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
- Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
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