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  1. Article ; Online: Photoacid-macroion assemblies: how photo-excitation switches the size of nano-objects.

    Zika, Alexander / Agarwal, Mohit / Zika, Wiebke / Guldi, Dirk M / Schweins, Ralf / Gröhn, Franziska

    Nanoscale

    2024  Volume 16, Issue 2, Page(s) 923–940

    Abstract: Electrostatic self-assembly of photoacids with oppositely charged macroions yields supramolecular nano-objects in aqueous solutions, whose size is controlled through light irradiation. Nano-assemblies are formed due to electrostatic attractions and ... ...

    Abstract Electrostatic self-assembly of photoacids with oppositely charged macroions yields supramolecular nano-objects in aqueous solutions, whose size is controlled through light irradiation. Nano-assemblies are formed due to electrostatic attractions and mutual hydrogen bonding of the photoacids. Irradiation with UV light leads to the deprotonation of the photoacid and, consequently, a change in particle size. Overall, the hydrodynamic radii of the well-defined photoacid-macroion nano-objects lie between 130 and 370 nm. For a set of photoacids, we determine the acidity constants in the ground and excited state, discuss the sizes of photoacid-macroion nano-objects (by dynamic and static light scattering), their composition and the particle shapes (by small-angle neutron scattering), and relate their charge characteristics to size, structure and shape. We investigate the association thermodynamics and relate nanoscale structures to thermodynamics and, in turn, thermodynamics to molecular features, particularly the ionization energy of the photoacid hydroxyl group proton. Structure-directing effects completely differ from those for previously investigated systems, with hydrogen bonding and entropic effects playing a major role herein. This combined approach allows developing a comprehensive understanding of assembly formation and photo-response, anchored in molecular parameters (p
    Language English
    Publishing date 2024-01-03
    Publishing country England
    Document type Journal Article
    ZDB-ID 2515664-0
    ISSN 2040-3372 ; 2040-3364
    ISSN (online) 2040-3372
    ISSN 2040-3364
    DOI 10.1039/d3nr04570f
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  2. Article ; Online: Tuning the Absorption, Fluorescence, Intramolecular Charge Transfer, and Intersystem Crossing in Spiro[fluorene]acridinone.

    Bo, Yifan / Zhang, He / Li, Yue / Reva, Yana / Xie, Linghai / Guldi, Dirk M

    Angewandte Chemie (International ed. in English)

    2024  Volume 63, Issue 13, Page(s) e202313936

    Abstract: In this work, we prepared a series of electron donor-acceptor systems based on spiro[fluorene-9,7'-dibenzo[c,h]acridine]-5'-one (SFDBAO). Our SFDBAOs consist of orthogonally positioned fluorenes and aromatic ketones. By fine-tuning the substitution of ... ...

    Abstract In this work, we prepared a series of electron donor-acceptor systems based on spiro[fluorene-9,7'-dibenzo[c,h]acridine]-5'-one (SFDBAO). Our SFDBAOs consist of orthogonally positioned fluorenes and aromatic ketones. By fine-tuning the substitution of electron-donating pyrenes, the complex interplay among different excited-state decay channels and the overall impact of solvents on these decay channels were uncovered. Placing pyrene, for example, at the aromatic ketones resulted in a profound solvatochromism in the form of a bright charge-transfer (CT) emission spanning from yellow to red-NIR. In contrast, a dark non-emissive CT was noted upon pyrene substitution at the fluorenes. In apolar solvents, efficient triplet-excited state generation was observed for all SFDBAOs. Either charge transfer was concluded to mediate the intersystem crossing (ISC) in the case of pyrene substitution or the El-Sayed rule was applicable when lacking pyrene substitution as in the case of SFABAO. In polar solvents, charge separation is the sole decay upon pyrene substitution. Moreover, competition between ISC and CT lowered the triplet-excited state generation in SFDBAO.
    Language English
    Publishing date 2024-02-20
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2011836-3
    ISSN 1521-3773 ; 1433-7851
    ISSN (online) 1521-3773
    ISSN 1433-7851
    DOI 10.1002/anie.202313936
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  3. Article: Unconventional singlet fission materials

    Ullrich, Tobias / Munz, Dominik / Guldi, Dirk M.

    Chemical Society reviews. 2021 Mar. 15, v. 50, no. 5

    2021  

    Abstract: Singlet fission (SF) is a photophysical downconversion pathway, in which a singlet excitation transforms into two triplet excited states. As such, it constitutes an exciton multiplication generation process, which is currently at the focal point for ... ...

    Abstract Singlet fission (SF) is a photophysical downconversion pathway, in which a singlet excitation transforms into two triplet excited states. As such, it constitutes an exciton multiplication generation process, which is currently at the focal point for future integration into solar energy conversion devices. Beyond this, various other exciting applications were proposed, including quantum cryptography or organic light emitting diodes. Also, the mechanistic understanding evolved rapidly during the last year. Unfortunately, the number of suitable SF-chromophores is still limited. This is per se problematic, considering the wide range of envisaged applicability. With that in mind, we emphasize uncommon SF-scaffolds and outline requirements as well as strategies to expand the chromophore pool of SF-materials.
    Keywords energy conservation ; energy conversion ; light emitting diodes ; solar energy
    Language English
    Dates of publication 2021-0315
    Size p. 3485-3518.
    Publishing place The Royal Society of Chemistry
    Document type Article
    ZDB-ID 1472875-8
    ISSN 1460-4744 ; 0306-0012
    ISSN (online) 1460-4744
    ISSN 0306-0012
    DOI 10.1039/d0cs01433h
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  4. Article ; Online: Unconventional singlet fission materials.

    Ullrich, Tobias / Munz, Dominik / Guldi, Dirk M

    Chemical Society reviews

    2021  Volume 50, Issue 5, Page(s) 3485–3518

    Abstract: Singlet fission (SF) is a photophysical downconversion pathway, in which a singlet excitation transforms into two triplet excited states. As such, it constitutes an exciton multiplication generation process, which is currently at the focal point for ... ...

    Abstract Singlet fission (SF) is a photophysical downconversion pathway, in which a singlet excitation transforms into two triplet excited states. As such, it constitutes an exciton multiplication generation process, which is currently at the focal point for future integration into solar energy conversion devices. Beyond this, various other exciting applications were proposed, including quantum cryptography or organic light emitting diodes. Also, the mechanistic understanding evolved rapidly during the last year. Unfortunately, the number of suitable SF-chromophores is still limited. This is per se problematic, considering the wide range of envisaged applicability. With that in mind, we emphasize uncommon SF-scaffolds and outline requirements as well as strategies to expand the chromophore pool of SF-materials.
    Language English
    Publishing date 2021-01-26
    Publishing country England
    Document type Journal Article
    ZDB-ID 1472875-8
    ISSN 1460-4744 ; 0306-0012
    ISSN (online) 1460-4744
    ISSN 0306-0012
    DOI 10.1039/d0cs01433h
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Controlling Interchromophore Coupling in Diamantane-Linked Pentacene Dimers To Create a "Binary" Pair.

    Greißel, Phillip M / Schroeder, Zachary W / Thiel, Dominik / Ferguson, Michael J / Clark, Timothy / Guldi, Dirk M / Tykwinski, Rik R

    Journal of the American Chemical Society

    2024  Volume 146, Issue 15, Page(s) 10875–10888

    Abstract: Two isomeric pentacene dimers, each linked by a diamantane spacer, have been synthesized. These dimers are designed to provide experimental evidence to support quantum mechanical calculations, which predict the substitution pattern on the carbon-rich ... ...

    Abstract Two isomeric pentacene dimers, each linked by a diamantane spacer, have been synthesized. These dimers are designed to provide experimental evidence to support quantum mechanical calculations, which predict the substitution pattern on the carbon-rich diethynyldiamantane spacer to be decisive in controlling the interpentacene coupling. Intramolecular singlet fission (
    Language English
    Publishing date 2024-04-05
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.4c01507
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Bypassing the Single Junction Limit with Advanced Photovoltaic Architectures.

    Lüer, Larry / Peters, Ian Marius / Corre, Vincent M Le / Forberich, Karen / Guldi, Dirk M / Brabec, Christoph J

    Advanced materials (Deerfield Beach, Fla.)

    2024  Volume 36, Issue 14, Page(s) e2308578

    Abstract: Multijunction devices and photon up- and down-conversion are prominent concepts aimed at increasing photovoltaic efficiencies beyond the single junction limit. Integrating these concepts into advanced architectures may address long-standing issues such ... ...

    Abstract Multijunction devices and photon up- and down-conversion are prominent concepts aimed at increasing photovoltaic efficiencies beyond the single junction limit. Integrating these concepts into advanced architectures may address long-standing issues such as processing complexity, microstructure control, and resilience against spectral changes of the incoming radiation. However, so far, no models have been established to predict the performance of such integrated architectures. Here, a simulation environment based on Bayesian optimization is presented, that can predict and virtually optimize the electrical performance of multi-junction architectures, both vertical and lateral, in combination with up- and down-conversion materials. Microstructure effects on performance are explicitly considered using machine-learned predictive models from high throughput experimentation on simpler architectures. Two architectures that would surpass the single junction limit of photovoltaic energy conversion at reasonable complexity are identified: a vertical "staggered half octave system," where selective absorption allows the use of 6 different bandgaps, and the lateral "overlapping rainbow system" where selective irradiation allows the use of a narrowband energy acceptor with reduced voltage losses, according to the energy gap law. Both architectures would be highly resilient against spectral changes, in contrast with two terminal multi-junction architectures which are limited by Kirchhoff's law.
    Language English
    Publishing date 2024-01-05
    Publishing country Germany
    Document type Journal Article ; Review
    ZDB-ID 1474949-X
    ISSN 1521-4095 ; 0935-9648
    ISSN (online) 1521-4095
    ISSN 0935-9648
    DOI 10.1002/adma.202308578
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  7. Article ; Online: Investigating Electronic Communications in meso-meso Ethene-Bridged Unsymmetrical Diporphyrins.

    Zieleniewska, Anna / Guldi, Dirk M

    Chemistry (Weinheim an der Bergstrasse, Germany)

    2019  Volume 25, Issue 41, Page(s) 9602–9607

    Abstract: At the focal point of this work is the photophysical characterization of three meso-meso ethene-bridged diporphyrins featuring a diverse metallation pattern. Detailed investigations by means of cyclic voltammetry, absorption, fluorescence, and femto-/ ... ...

    Abstract At the focal point of this work is the photophysical characterization of three meso-meso ethene-bridged diporphyrins featuring a diverse metallation pattern. Detailed investigations by means of cyclic voltammetry, absorption, fluorescence, and femto-/nanosecond transient absorption spectroscopy revealed the impact of open-shell nickel(II) on the electronic communication in ethene-bridged heterobimetallic diporphyrins.
    Language English
    Publishing date 2019-06-27
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1478547-X
    ISSN 1521-3765 ; 0947-6539
    ISSN (online) 1521-3765
    ISSN 0947-6539
    DOI 10.1002/chem.201901716
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  8. Article: Probing Charge Management across the π-Systems of Nanographenes in Regioisomeric Electron Donor–Acceptor Architectures

    Hölzel, Helen / Haines, Philipp / Kaur, Ramandeep / Lungerich, Dominik / Jux, Norbert / Guldi, Dirk M.

    Journal of the American Chemical Society. 2022 May 11, v. 144, no. 20

    2022  

    Abstract: Inspired by light-induced processes in nature to mimic the primary events in the photosynthetic reaction centers, novel functional materials combine electron donors and acceptors, i.e., (metallo)porphyrins (ZnP) and fullerenes (C₆₀), respectively, with ... ...

    Abstract Inspired by light-induced processes in nature to mimic the primary events in the photosynthetic reaction centers, novel functional materials combine electron donors and acceptors, i.e., (metallo)porphyrins (ZnP) and fullerenes (C₆₀), respectively, with emerging materials, i.e., nanographenes. We utilized hexa-peri-hexabenzocoronene (HBC) due to its versatility regarding functionalization and physicochemical properties, to construct three regioisomeric ZnP-HBC-C₆₀ conjugates, which foster geometrical diversity by arranging ZnP and C₆₀ in ortho-, meta-, and para-positions to each other. The corresponding hexaarylbenzene (HAB) motifs, with an interrupted π-system, were also prepared. Transient absorption measurements disclosed the fast population of charge transfer as well as singlet and triplet charge-separated states. With the help of density functional theory (DFT) calculations, we further conceive the communication across the HBCs and HABs. This work reveals the impact of both the geometrical arrangement with respect to through-space versus through-bond interactions and the structural rigidity/flexibility on the charge management across the different π-systems.
    Keywords absorption ; density functional theory ; fullerene
    Language English
    Dates of publication 2022-0511
    Size p. 8977-8986.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 3155-0
    ISSN 1520-5126 ; 0002-7863
    ISSN (online) 1520-5126
    ISSN 0002-7863
    DOI 10.1021/jacs.2c00456
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    In stock of ZB MED Bonn / Germany

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  9. Article ; Online: Dirk M. Guldi.

    Guldi, Dirk M

    Angewandte Chemie (International ed. in English)

    2014  Volume 53, Issue 10, Page(s) 2534–2535

    Language English
    Publishing date 2014-03-03
    Publishing country Germany
    Document type Interview
    ZDB-ID 2011836-3
    ISSN 1521-3773 ; 1433-7851
    ISSN (online) 1521-3773
    ISSN 1433-7851
    DOI 10.1002/anie.201309697
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  10. Article ; Online: Cascades of energy and electron transfer in a panchromatic absorber.

    Joseph, Jan / Bauroth, Stefan / Charisiadis, Asterios / Charalambidis, Georgios / Coutsolelos, Athanassios G / Guldi, Dirk M

    Nanoscale

    2022  Volume 14, Issue 26, Page(s) 9304–9312

    Abstract: The investigation of molecular model systems is fundamental towards a deeper understanding of key photochemical steps in natural photosynthesis. Herein, we report an entirely non-covalent triad consisting of boron dipyrromethene (BDP), porphyrin (ZnP), ... ...

    Abstract The investigation of molecular model systems is fundamental towards a deeper understanding of key photochemical steps in natural photosynthesis. Herein, we report an entirely non-covalent triad consisting of boron dipyrromethene (BDP), porphyrin (ZnP), and fullerene (C60). Non-covalent binding motifs such as an amidinium-carboxylate salt bridge as well as axial pyridyl-metal coordination offer substantial electronic coupling and establish efficient pathways for photoactivated energy and electron transfer processes along a well-tuned gradient. Experimental findings from steady-state and time-resolved spectroscopic assays, as well as (spectro-)electrochemical measurements corroborate the formation of BDP|ZnP|C60 in solution, on one hand, and significant communication in the excited states, on the other hand. BDP acts as an energy harvesting antenna towards ZnP, which eventually undergoes charge separation with C60 by electron transfer from ZnP to C60. Notably, full spectral deconvolution of the transient species was achieved, supporting the successful self-assembly as well as giving a clear view onto the occurring photophysical processes and their spectral footprints upon photoexcitation.
    Language English
    Publishing date 2022-07-07
    Publishing country England
    Document type Journal Article
    ZDB-ID 2515664-0
    ISSN 2040-3372 ; 2040-3364
    ISSN (online) 2040-3372
    ISSN 2040-3364
    DOI 10.1039/d2nr02404g
    Database MEDical Literature Analysis and Retrieval System OnLINE

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