1
|
Ammenhäuser R, Klein P, Schmid E, Streicher S, Vogelsang J, Lehmann CW, Lupton JM, Meskers SCJ, Scherf U. Circularly Polarized Light Probes Excited-State Delocalization in Rectangular Ladder-type Pentaphenyl Helices. Angew Chem Int Ed Engl 2023; 62:e202211946. [PMID: 36345828 PMCID: PMC10107742 DOI: 10.1002/anie.202211946] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Indexed: 11/09/2022]
Abstract
Ladder-type pentaphenyl chromophores have a rigid, planar π-system and show bright fluorescence featuring pronounced vibrational structure. Such moieties are ideal for studying interchromophoric interactions and delocalization of electronic excitations. We report the synthesis of helical polymers with a rigid square structure based on spiro-linked ladder-type pentaphenyl units. The variation of circular dichroism with increasing chain length provides direct evidence for delocalization of electronic excitations over at least 10 monomeric units. The change in the degree of circular polarization of the fluorescence across the vibronic side bands shows that vibrational motion can localize the excitation dynamically to almost one single unit through breakdown of the Born-Oppenheimer approximation. The dynamic conversion between delocalized and localized excited states provides a new paradigm for interpreting circular dichroism in helical polymers such as proteins and polynucleic acids.
Collapse
Affiliation(s)
- Robin Ammenhäuser
- Department of Chemistry, Macromolecular Chemistry group (BUWmakro), and Wuppertal Institute for Smart Materials and Systems (CM@S), Bergische Universität Wuppertal, Gauss-Str. 20, 42119, Wuppertal, Germany
| | - Patrick Klein
- Department of Chemistry, Macromolecular Chemistry group (BUWmakro), and Wuppertal Institute for Smart Materials and Systems (CM@S), Bergische Universität Wuppertal, Gauss-Str. 20, 42119, Wuppertal, Germany
| | - Eva Schmid
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Sabrina Streicher
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Jan Vogelsang
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Christian W Lehmann
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - John M Lupton
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Stefan C J Meskers
- Molecular Materials and Nanosystems and Institute of Complex Molecular Systems, Technische Universiteit Eindhoven, PO Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Ullrich Scherf
- Department of Chemistry, Macromolecular Chemistry group (BUWmakro), and Wuppertal Institute for Smart Materials and Systems (CM@S), Bergische Universität Wuppertal, Gauss-Str. 20, 42119, Wuppertal, Germany
| |
Collapse
|
2
|
Eder T, Kraus D, Höger S, Vogelsang J, Lupton JM. Vibrations Responsible for Luminescence from HJ-Aggregates of Conjugated Polymers Identified by Cryogenic Spectroscopy of Single Nanoparticles. ACS NANO 2022; 16:6382-6393. [PMID: 35394735 DOI: 10.1021/acsnano.2c00472] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A single polymer chain can be thought of as a covalently bound J-aggregate, where the microscopic transition-dipole moments line up to emit in phase. Packing polymer chains into a bulk film can result in the opposite effect, inducing H-type coupling between chains. Cofacial transition-dipole moments oscillate out of phase, canceling each other out, so that the lowest-energy excited state turns dark. H-aggregates of conjugated polymers can, in principle, be coaxed into emitting light by mixing purely electronic and vibronic transitions. However, it is challenging to characterize this electron-phonon coupling experimentally. In a bulk film, many different conformations exist with varying degrees of intrachain J-type and interchain H-type coupling strengths, giving rise to broad and featureless aggregate absorption and emission spectra. Even if single nanoparticles consisting of only a few single chains are grown in a controlled fashion, the luminescence spectra remain broad, owing to the underlying molecular dynamics and structural heterogeneity at room temperature. At cryogenic temperatures, emission from H-type aggregates should be suppressed because, in the absence of thermal energy, internal conversion drives the aggregate to the lowest-energy dark state. At the same time, electronic and vibronic transitions narrow substantially, facilitating the attribution of spectral signatures to distinct vibrational modes. We demonstrate how to distinguish signatures of interchain H-type aggregate species from those of intramolecular J-type coupling. Whereas all dominant vibronic modes revealed in the photoluminescence (PL) and surface-enhanced resonance Raman scattering spectra of a single chromophore within a single polymer chain are identified in the J-type aggregate luminescence spectra, they are not all present at once in the H-type spectra. Universal spectral features are found for the luminescence from strongly HJ-coupled chains, clearly resolving the vibrations responsible for the nonadiabatic excited-state molecular dynamics that enable light emission. We discuss the possible combinations of vibrational modes responsible for H-type aggregate PL and demonstrate that only one, mainly the lowest energy one, of the three dominant vibrational modes contributes to the 0-1 transition, whereas combinations of all three are found in the 0-2 transition. From this analysis, we can distinguish between energy shifts due to either J-type intrachain coupling or H-type interchain interactions, offering a means to directly discriminate between structural and energetic disorder.
Collapse
Affiliation(s)
- Theresa Eder
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
| | - Daniel Kraus
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
| | - Sigurd Höger
- Kekulé-Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
| | - Jan Vogelsang
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
| | - John M Lupton
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany
| |
Collapse
|
3
|
Bai L, Han Y, Wei Q, Sun L, Sun N, Wei C, An X, Ni M, Cai J, Zhuo Z, Zheng Y, Wang S, He L, Yang J, Liu B, Lin Z, Xu M, Lin J, Huang W. A Molecular Design Principle for Pure-Blue Light-Emitting Polydiarylfluorene with Suppressed Defect Emission by the Side-Chain Steric Hindrance Effect. Macromolecules 2022. [DOI: 10.1021/acs.macromol.1c02310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Lubing Bai
- Frontiers Science Center for Flexible Electronics & Institute of Flexible Electronics (IFE), Northwestern Polytechnical University (NPU), Xi’an 710072, China
| | - Yamin Han
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Qi Wei
- Frontiers Science Center for Flexible Electronics & Institute of Flexible Electronics (IFE), Northwestern Polytechnical University (NPU), Xi’an 710072, China
| | - Lili Sun
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Ning Sun
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Chuanxin Wei
- State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, Nanjing 210023, China
| | - Xiang An
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Mingjian Ni
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Jiangli Cai
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Zhiqiang Zhuo
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Yingying Zheng
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Shengjie Wang
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Liangliang He
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Jinghao Yang
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Bin Liu
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Zongqiong Lin
- Frontiers Science Center for Flexible Electronics & Institute of Flexible Electronics (IFE), Northwestern Polytechnical University (NPU), Xi’an 710072, China
| | - Man Xu
- State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, Nanjing 210023, China
| | - Jinyi Lin
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
| | - Wei Huang
- Frontiers Science Center for Flexible Electronics & Institute of Flexible Electronics (IFE), Northwestern Polytechnical University (NPU), Xi’an 710072, China
- Key Laboratory of Flexible Electronics (KLoFE) and Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing 211816, China
- State Key Laboratory of Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, Nanjing 210023, China
| |
Collapse
|
4
|
Wang L, Rothberg L. Complications in the Interpretation of F8T2 Spectra in Terms of Morphology. J Phys Chem B 2021; 125:5660-5666. [PMID: 34008981 DOI: 10.1021/acs.jpcb.1c02701] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photophysical properties of conjugated polymers strongly correlate with chain morphology and interactions between chains. Here, we observed two characteristic types of spectra of poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(bithiophene)] (F8T2) in both single-chain and bulk cases. Despite the similarities in emission spectra, fluorescence dynamics and intensities corresponding to each type of spectrum are radically different in these cases. We hypothesize that the origin of the spectrum with a suppressed 0-0 vibronic band in photoluminescence is chain bending in the single-chain experiments, while the same phenomenon is caused by interchain aggregation in bulk samples. We propose a microscopic interpretation of the single-chain result in terms of bending that we expect to be characteristic of flexible conjugated polymers with five-membered rings. Caution must be exercised in drawing inferences about the meaning of single-chain spectra by analogy with bulk data.
Collapse
Affiliation(s)
- Liwei Wang
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Lewis Rothberg
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| |
Collapse
|
5
|
Wilhelm P, Blank D, Lupton JM, Vogelsang J. Control of Intrachain Morphology in the Formation of Polyfluorene Aggregates on the Single-Molecule Level. Chemphyschem 2020; 21:961-965. [PMID: 32255242 PMCID: PMC7317353 DOI: 10.1002/cphc.202000118] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/18/2020] [Indexed: 12/13/2022]
Abstract
Controlling the morphology of π-conjugated polymers for organic optoelectronic devices has long been a goal in the field of materials science. Since the morphology of a polymer chain is closely intertwined with its photophysical properties, it is desirable to be able to change the arrangement of the polymers at will. We investigate the π-conjugated polymer poly(9,9-dioctylfluorene) (PFO), which can exist in three distinctly different structural phases: the α-, β-, and γ-phase. Every phase has a different chain structure and a unique photoluminescence (PL) spectrum. Due to its unique properties and the pronounced spectral structure-property relations, PFO can be used as a model system to study the morphology of π-conjugated polymers. To avoid ensemble averaging, we examine the PL spectrum of single PFO chains embedded in a non-fluorescent matrix. With single-molecule spectroscopy the structural phase of every single chain can be determined, and changes can be monitored very easily. To manipulate the morphology, solvent vapor annealing (SVA) was applied, which leads to a diffusion of the polymer chains in the matrix. The β- and γ-phases appear during the self-assembly of single α-phase PFO chains into mesoscopic aggregates. The extent of β- and γ-phase formation is directed by the solvent-swelling protocol used for aggregation. Aggregation unequivocally promotes formation of the more planar β- and γ-phases. Once these lower-energy more ordered structural phases are formed, SVA cannot return the polymer chain to the less ordered phase by aggregate swelling.
Collapse
Affiliation(s)
- Philipp Wilhelm
- Institut für Experimentelle und Angewandte PhysikUniversität RegensburgUniversitätsstraße 3193053RegensburgGermany
| | - Dominik Blank
- Institut für Experimentelle und Angewandte PhysikUniversität RegensburgUniversitätsstraße 3193053RegensburgGermany
| | - John M. Lupton
- Institut für Experimentelle und Angewandte PhysikUniversität RegensburgUniversitätsstraße 3193053RegensburgGermany
| | - Jan Vogelsang
- Institut für Experimentelle und Angewandte PhysikUniversität RegensburgUniversitätsstraße 3193053RegensburgGermany
| |
Collapse
|