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Dell'Angelo D, Karamanis I, Saeb MR, Balan L, Badawi M. Tailoring van der Waals interactions in ultra-thin two dimensional metal-organic frameworks (MOFs) for photoconductive applications. Phys Chem Chem Phys 2024. [PMID: 39373066 DOI: 10.1039/d4cp03347g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/08/2024]
Abstract
The diverse structural tunability of 2-dimensional π-stacked layered metal-organic frameworks (2D MOFs) enables the control of charge carrier mobility to achieve specific photoconductive characteristics. This study demonstrates the potential of various theoretical methodologies and frameworks in establishing a correlation between structure and functionality for such purposes. Through a focus on the archetypal Ni3(HITP)2 2D MOF, we examine the impact of quantum confinement and stacking fault defects on the absorption spectra using our recently-developed Frenkel-Holstein Hamiltonian. Specifically, the relationship between optical properties and number of layer units along the π-stacking direction is discussed. We employ Marcus rate theory to evaluate vertical carrier mobility subject to inter-layer proximity and different crystal packing which affect van der Waals interactions between layers. The insights presented in this research can inform the development of guidelines for enhancing photoconductive properties in 2D MOF nanosheets.
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Affiliation(s)
| | | | - Mohammad Reza Saeb
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, J. Hallera 107, 80-416 Gdańsk, Poland
| | - Lavinia Balan
- CEMHTI-UPR 3079 CNRS, Site Haute Température, 1D avenue de la Recherche Scientifique, 45071 Orl éans, France.
| | - Michael Badawi
- Université de Lorraine, CNRS, L2CM, F-57000 Metz, France.
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Höger S, Lupton JM. From π-Conjugated Rods to Shape-Persistent Rings, Wheels, and Ladders: The Question of Rigidity. Acc Chem Res 2024; 57:2561-2571. [PMID: 39150763 DOI: 10.1021/acs.accounts.4c00383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
ConspectusRigid-rod oligomers and polymers are mostly based on (hetero)aromatic rings connected with each other, either directly or via ethynylene or butadiynylene linkers, or by a combination of both structural elements. Although they are much more rigid than vinyl polymers, they exhibit considerable structural flexibility, often more than would be expected merely from their chemical structure. This disparity holds for both linear as well as for cyclic structures. The flexibility of rigid-rod polymers, which is directly observable for defined oligomers of different lengths at the solid-liquid interface by means of scanning-tunneling microscopy, also impacts their optical and electronic properties. The flexibility can be used, for example, to control whether an oligomer with two different fluorescent end-groups emits from either the one or the other. The flexibility of shape-persistent macrocycles also has an impact on the overall thermal stability of mechanically interlocked molecular architectures. However, the degree of flexibility can be reduced when rigid struts are covalently mounted into the inside of the rings, leading to the formation of so-called molecular spoked wheels. The combination of these two elements─rings and rods─stiffens both of them: the ring perimeter is prevented from collapsing and the internal rods from bending. These compounds have been further developed as platform molecules, where three spokes stiffen the ring and together form a tripod-like platform, while a fourth arm points─after adsorption to a solid substrate─above the plane of the molecule. This pillar makes it possible to decouple a functional group at the end of the arm from the surface. Rigidity enhancement by the introduction of rigid spacer elements can also be applied to the case of rigid-rod polymers and is visualized by sophisticated molecular dynamics simulations. In this case, formation of single-stranded oligomers and polymers, and a subsequent zipping reaction to form ladder-like structures, directly allows, by means of single-molecule fluorescence spectroscopy, a comparison of the single- and double-stranded molecules. In particular in the case of the polymers, which can be up to 100 nm in length, the enhancement of rigidity is quite remarkable. Overall, the covalent connection of two or more rigid molecular entities has a self-reinforcing effect: all parts of the molecule gain rigidity. Since overall synthetic yields for such complex high-molecular weight covalently bound shape-persistent structures can still be low, scanning tunneling microscopy and single-molecule fluorescence spectroscopy are the methods of choice for structural analyses. Preliminary results illustrate how these compounds can serve as versatile sources of deterministic single photons on demand, since rigidity also enhances the intramolecular flow of excitation energy, and suggest a range of applications in optoelectronic devices.
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Affiliation(s)
- Sigurd Höger
- Kekulé-Institut für Organische Chemie und Biochemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
| | - John M Lupton
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
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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.
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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
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Dell’Angelo D, Momeni MR, Pearson S, Shakib FA. Modeling energy transfer and absorption spectra in layered metal–organic frameworks based on a Frenkel–Holstein Hamiltonian. J Chem Phys 2022; 156:044109. [DOI: 10.1063/5.0076640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- David Dell’Angelo
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - Mohammad R. Momeni
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - Shaina Pearson
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, USA
| | - Farnaz A. Shakib
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, USA
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Li Y, Wang H, Li X. Over one century after discovery: pyrylium salt chemistry emerging as a powerful approach for the construction of complex macrocycles and metallo-supramolecules. Chem Sci 2020; 11:12249-12268. [PMID: 34123226 PMCID: PMC8163312 DOI: 10.1039/d0sc04585c] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/13/2020] [Indexed: 11/21/2022] Open
Abstract
Over one century after its discovery, pyrylium salt chemistry has been extensively applied in preparing light emitters, photocatalysts, and sensitizers. In most of these studies, pyrylium salts acted as versatile precursors for the preparation of small molecules (such as furan, pyridines, phosphines, pyridinium salts, thiopyryliums and betaine dyes) and poly(pyridinium salt)s. In recent decades, pyrylium salt chemistry has emerged as a powerful approach for constructing complex macrocycles and metallo-supramolecules. In this perspective, we attempt to summarize the representative efforts of synthesizing and self-assembling large, complex architectures using pyrylium salt chemistry. We believe that this perspective not only highlights the recent achievements in pyrylium salt chemistry, but also inspires us to revisit this chemistry to design and construct macrocycles and metallo-supramolecules with increasing complexity and desired function.
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Affiliation(s)
- Yiming Li
- College of Chemistry and Environmental Engineering, Shenzhen University Shenzhen 518055 China
- Department of Chemistry, University of South Florida Tampa Florida 33620 USA
| | - Heng Wang
- College of Chemistry and Environmental Engineering, Shenzhen University Shenzhen 518055 China
| | - Xiaopeng Li
- College of Chemistry and Environmental Engineering, Shenzhen University Shenzhen 518055 China
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Eder T, Vogelsang J, Bange S, Remmerssen K, Schmitz D, Jester SS, Keller TJ, Höger S, Lupton JM. Interplay Between J- and H-Type Coupling in Aggregates of π-Conjugated Polymers: A Single-Molecule Perspective. Angew Chem Int Ed Engl 2019; 58:18898-18902. [PMID: 31596527 PMCID: PMC6973276 DOI: 10.1002/anie.201912374] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Indexed: 11/07/2022]
Abstract
Strong dipole–dipole coupling within and between π‐conjugated segments shifts electronic transitions, and modifies vibronic coupling and excited‐state lifetimes. Since J‐type coupling between monomers along the conjugated‐polymer (CP) chain and H‐type coupling of chromophores between chains of a CP compete, a superposition of the spectral modifications arising from each type of coupling emerges, making the two couplings hard to discern in the ensemble. We introduce a single‐molecule H‐type aggregate of fixed spacing and variable length of up to 10 nm. HJ‐type aggregate formation is visualized intuitively in the scatter of single‐molecule spectra.
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Affiliation(s)
- Theresa Eder
- Institut für Angewandte und Experimentelle Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Jan Vogelsang
- Institut für Angewandte und Experimentelle Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Sebastian Bange
- Institut für Angewandte und Experimentelle Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
| | - Klaas Remmerssen
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Strasse 1, 53121, Bonn, Germany
| | - Daniela Schmitz
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Strasse 1, 53121, Bonn, Germany
| | - Stefan-S Jester
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Strasse 1, 53121, Bonn, Germany
| | - Tristan J Keller
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Strasse 1, 53121, Bonn, Germany
| | - Sigurd Höger
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Gerhard-Domagk-Strasse 1, 53121, Bonn, Germany
| | - John M Lupton
- Institut für Angewandte und Experimentelle Physik, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
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7
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Eder T, Vogelsang J, Bange S, Remmerssen K, Schmitz D, Jester S, Keller TJ, Höger S, Lupton JM. Interplay Between J‐ and H‐Type Coupling in Aggregates of π‐Conjugated Polymers: A Single‐Molecule Perspective. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201912374] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Theresa Eder
- Institut für Angewandte und Experimentelle Physik Universität Regensburg Universitätsstrasse 31 93053 Regensburg Germany
| | - Jan Vogelsang
- Institut für Angewandte und Experimentelle Physik Universität Regensburg Universitätsstrasse 31 93053 Regensburg Germany
| | - Sebastian Bange
- Institut für Angewandte und Experimentelle Physik Universität Regensburg Universitätsstrasse 31 93053 Regensburg Germany
| | - Klaas Remmerssen
- Kekulé-Institut für Organische Chemie und Biochemie Universität Bonn Gerhard-Domagk-Strasse 1 53121 Bonn Germany
| | - Daniela Schmitz
- Kekulé-Institut für Organische Chemie und Biochemie Universität Bonn Gerhard-Domagk-Strasse 1 53121 Bonn Germany
| | - Stefan‐S. Jester
- Kekulé-Institut für Organische Chemie und Biochemie Universität Bonn Gerhard-Domagk-Strasse 1 53121 Bonn Germany
| | - Tristan J. Keller
- Kekulé-Institut für Organische Chemie und Biochemie Universität Bonn Gerhard-Domagk-Strasse 1 53121 Bonn Germany
| | - Sigurd Höger
- Kekulé-Institut für Organische Chemie und Biochemie Universität Bonn Gerhard-Domagk-Strasse 1 53121 Bonn Germany
| | - John M. Lupton
- Institut für Angewandte und Experimentelle Physik Universität Regensburg Universitätsstrasse 31 93053 Regensburg Germany
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8
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Wilhelm P, Vogelsang J, Höger S, Lupton JM. Homo-FRET in π-Conjugated Polygons: Intermediate-Strength Dipole-Dipole Coupling Makes Energy Transfer Reversible. NANO LETTERS 2019; 19:5483-5488. [PMID: 31294999 DOI: 10.1021/acs.nanolett.9b01998] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The concept of homo-FRET is often used to describe energy transfer between like chromophores of molecular aggregates such as in π-conjugated polymers. Homo-FRET is revealed by a dynamic depolarization in fluorescence but strictly only applies to the limit of weak dipole-dipole coupling, where energy transfer occurs on time scales much longer than those of nuclear relaxation. By considering the polarization anisotropy of photoluminescence emission and excitation of model multichromophoric aggregates on the single-molecule level, we demonstrate the transition of energy-transfer dynamics from the case of weak coupling to that of strong coupling, revealing the elusive regime of intermediate-strength coupling where energy transfer between degenerate donor and acceptor chromophores becomes reversible so that information on the excitation route of the emitting chromophore is lost.
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Affiliation(s)
- Philipp Wilhelm
- 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
| | - Sigurd Höger
- Kekulé-Institut für Organische Chemie und Biochemie , Universität Bonn , Gerhard-Domagk-Straße 1 , 53121 Bonn , Germany
| | - John M Lupton
- Institut für Experimentelle und Angewandte Physik , Universität Regensburg , Universitätsstrasse 31 , 93053 Regensburg , Germany
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Ondarse-Alvarez D, Nelson T, Lupton JM, Tretiak S, Fernandez-Alberti S. Let Digons be Bygones: The Fate of Excitons in Curved π-Systems. J Phys Chem Lett 2018; 9:7123-7129. [PMID: 30508376 DOI: 10.1021/acs.jpclett.8b03160] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We explore the diverse origins of unpolarized absorption and emission of molecular polygons consisting of π-conjugated oligomer chains held in a bent geometry by strain controlled at the vertex units. For this purpose, we make use of atomistic nonadiabatic excited-state molecular dynamics simulations of a bichromophore molecular polygon (digon) with bent chromophore chains. Both structural and photoexcited dynamics were found to affect polarization features. Bending strain induces exciton localization on individual chromophore units of the conjugated chains. The latter display different transition dipole moment orientations, a feature not present in the linear oligomer counterparts. In addition, bending makes exciton localization very sensitive to molecular distortions induced by thermal fluctuations. The excited-state dynamics reveals an ultrafast intramolecular energy redistribution that spreads the exciton equally among spatially separated chromophore fragments within the molecular system. As a result, digons become virtually unpolarized absorbers and emitters, in agreement with recent experimental studies on the single-molecule level.
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Affiliation(s)
| | - Tammie Nelson
- Theoretical Division, Physics and Chemistry of Materials (T-1) , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | - John M Lupton
- Institut für Angewandte und Experimentelle Physik , Universität Regensburg , Universitätsstrasse 31 , 93053 Regensburg , Germany
| | - Sergei Tretiak
- Theoretical Division, Physics and Chemistry of Materials (T-1) , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
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