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Beer P, Reichstein PM, Schötz K, Raithel D, Thelakkat M, Köhler J, Panzer F, Hildner R. Disorder in P3HT Nanoparticles Probed by Optical Spectroscopy on P3HT- b-PEG Micelles. J Phys Chem A 2021; 125:10165-10173. [PMID: 34797986 PMCID: PMC8647091 DOI: 10.1021/acs.jpca.1c08377] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We employ photoluminescence (PL) spectroscopy on individual nanoscale aggregates of the conjugated polymer poly(3-hexylthiophene), P3HT, at room temperature (RT) and at low temperature (LT) (1.5 K), to unravel different levels of structural and electronic disorder within P3HT nanoparticles. The aggregates are prepared by self-assembly of the block copolymer P3HT-block-poly(ethylene glycol) (P3HT-b-PEG) into micelles, with the P3HT aggregates constituting the micelles' core. Irrespective of temperature, we find from the intensity ratio between the 0-1 and 0-0 peaks in the PL spectra that the P3HT aggregates are of H-type nature, as expected from π-stacked conjugated thiophene backbones. Moreover, the distributions of the PL peak ratios demonstrate a large variation of disorder between micelles (inter-aggregate disorder) and within individual aggregates (intra-aggregate disorder). Upon cooling from RT to LT, the PL spectra red-shift by 550 cm-1, and the energy of the (effective) carbon-bond stretch mode is reduced by 100 cm-1. These spectral changes indicate that the P3HT backbone in the P3HT-b-PEG copolymer does not fully planarize before aggregation at RT and that upon cooling, partial planarization occurs. This intra-chain torsional disorder is ultimately responsible for the intra- and inter-aggregate disorder. These findings are supported by temperature-dependent absorption spectra on thin P3HT films. The interplay between intra-chain, intra-aggregate, and inter-aggregate disorder is key for the bulk photophysical properties of nanoparticles based on conjugated polymers, for example, in hierarchical (super-) structures. Ultimately, these properties determine the usefulness of such structures in hybrid organic-inorganic materials, for example, in (bio-)sensing and optoelectronics applications.
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Affiliation(s)
- Patrick Beer
- Spectroscopy of Soft Matter, University of Bayreuth, 95440 Bayreuth, Germany
| | - Paul M Reichstein
- Applied Functional Polymers, University of Bayreuth, 95440 Bayreuth, Germany
| | - Konstantin Schötz
- Soft Matter Optoelectronics, University of Bayreuth, 95440 Bayreuth, Germany
| | - Dominic Raithel
- Spectroscopy of Soft Matter, University of Bayreuth, 95440 Bayreuth, Germany
| | - Mukundan Thelakkat
- Applied Functional Polymers, University of Bayreuth, 95440 Bayreuth, Germany.,Bavarian Polymer Institute, University of Bayreuth, 95440 Bayreuth, Germany.,Bayreuther Institut für Makromolekülforschung (BIMF), University of Bayreuth, 95440 Bayreuth, Germany
| | - Jürgen Köhler
- Spectroscopy of Soft Matter, University of Bayreuth, 95440 Bayreuth, Germany.,Bavarian Polymer Institute, University of Bayreuth, 95440 Bayreuth, Germany.,Bayreuther Institut für Makromolekülforschung (BIMF), University of Bayreuth, 95440 Bayreuth, Germany
| | - Fabian Panzer
- Soft Matter Optoelectronics, University of Bayreuth, 95440 Bayreuth, Germany
| | - Richard Hildner
- Spectroscopy of Soft Matter, University of Bayreuth, 95440 Bayreuth, Germany.,Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
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Fluorescence spectral shape analysis for nucleotide identification. Proc Natl Acad Sci U S A 2019; 116:15386-15391. [PMID: 31308243 DOI: 10.1073/pnas.1820713116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report a conjugated polyelectrolyte fluorescence-based biosensor P-C-3 and a general methodology to evaluate spectral shape recognition to identify biomolecules using artificial intelligence. By using well-defined analytes, we demonstrate that the fluorescence spectral shape of P-C-3 is sensitive to minor structural changes and exhibits distinct signature patterns for different analytes. A method was also developed to select useful features to reduce computational complexity and prevent overfitting of the data. It was found that the normalized intensity of 3 to 5 selected wavelengths was sufficient for the fluorescence biosensor to classify 13 distinct nucleotides and distinguish as little as single base substitutions at distinct positions in the primary sequence of oligonucleotides rapidly with nearly 100% classification accuracy. Photophysical studies led to a model to explain the mechanism of these fluorescence spectral shape changes, which provides theoretical support for applying this method in complicated biological systems. Using the feature selection algorithm to measure the relative intensity of a few selected wavelengths significantly reduces measurement time, demonstrating the potential for fluorescence spectrum shape analysis in high-throughput and high-content screening.
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Urbánek P, Kuřitka I, Ševčík J, Toušková J, Toušek J, Nádaždy V, Nádaždy P, Végsö K, Šiffalovič P, Rutsch R, Urbánek M. An experimental and theoretical study of the structural ordering of the PTB7 polymer at a mesoscopic scale. POLYMER 2019. [DOI: 10.1016/j.polymer.2019.02.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Keheze FM, Raithel D, Wu T, Schiefer D, Sommer M, Hildner R, Reiter G. Signatures of Melting and Recrystallization of a Bulky Substituted Poly(thiophene) Identified by Optical Spectroscopy. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b01080] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Fanuel M. Keheze
- Physikalisches
Institut, Universität Freiburg, Hermann-Herder-Straße 3, 79104 Freiburg, Germany
| | - Dominic Raithel
- Experimentalphysik
IV, University of Bayreuth, 95440 Bayreuth, Germany
| | - Tianyu Wu
- Physikalisches
Institut, Universität Freiburg, Hermann-Herder-Straße 3, 79104 Freiburg, Germany
| | - Daniel Schiefer
- Institut
für Makromolekulare Chemie, Universität Freiburg, Stefan-Meier-Straße
31, 79104 Freiburg, Germany
| | - Michael Sommer
- Institut
für Makromolekulare Chemie, Universität Freiburg, Stefan-Meier-Straße
31, 79104 Freiburg, Germany
- Freiburger Materialforschungszentrum
FMF, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
- Freiburger Institut
für interaktive Materialien und bioinspirierte Technologien
FIT, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
- Polymerchemie, Technische Universität Chemnitz, Strasse der
Nationen 62, 09111 Chemnitz, Germany
| | - Richard Hildner
- Experimentalphysik
IV, University of Bayreuth, 95440 Bayreuth, Germany
| | - Günter Reiter
- Physikalisches
Institut, Universität Freiburg, Hermann-Herder-Straße 3, 79104 Freiburg, Germany
- Freiburger Materialforschungszentrum
FMF, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
- Freiburger Institut
für interaktive Materialien und bioinspirierte Technologien
FIT, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
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