19871
2019
eng
preprint
1
2020-01-27
--
--
Dynamic exciton localisation in a pyrene-BODIPY-pyrene dye conjugate
The photophysics of a molecular triad consisting of a BODIPY dye and two pyrene chromophores attached in 2-position are investigated by steady state and fs-time resolved transient absorption spectroscopy as well as by field induced surface hopping (FISH) simulations. While the steady state measurements indicate moderate chromophore interactions within the triad, the time resolved measurements show upon pyrene excitation a delocalised excited state which localises onto the BODIPY chromophore with a time constant of 0.12 ps. This could either be interpreted as an internal conversion process within the excitonically coupled chromophores or as an energy transfer from the pyrenes to the BODIPY dye. The analysis of FISH-trajectories reveals an oscillatory behaviour where the excitation hops between the pyrene units and the BODIPY dye several times until finally they become localised on the BODIPY chromophore within 100 fs. This is accompanied by an ultrafast nonradiative relaxation within the excitonic manifold mediated by the nonadiabatic coupling. Averaging over an ensemble of trajectories allowed us to simulate the electronic state population dynamics and determine the time constants for the nonradiative transitions that mediate the ultrafast energy transfer and exciton localisation on BODIPY.
Physical Chemistry Chemical Physics
https://doi.org/10.1039/C9CP00908F
urn:nbn:de:bvb:20-opus-198718
Accepted manuscript
Physical Chemistry Chemical Physics, 2019,21, 9013-9025. https://doi.org/10.1039/C9CP00908F
646737
false
true
Deutsches Urheberrecht
Nina Auerhammer
Alexander Schulz
Alexander Schmiedel
Marco Holzapfel
Joscha Hoche
Merle I. S. Röhr
Roland Mitric
Christoph Lambert
eng
uncontrolled
Exciton localization dynamics
Physikalische Chemie
open_access
Institut für Physikalische und Theoretische Chemie
OpenAIRE
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/19871/mitric_roland_bodipy_triade.pdf
25656
2022
eng
1
61
article
1
2022-02-12
--
--
Macrocyclic donor-acceptor dyads composed of a perylene bisimide dye surrounded by oligothiophene bridges
Two macrocyclic architectures comprising oligothiophene strands that connect the imide positions of a perylene bisimide (PBI) dye have been synthesized via a platinum-mediated cross-coupling strategy. The crystal structure of the double bridged PBI reveals all syn-arranged thiophene units that completely enclose the planar PBI chromophore via a 12-membered macrocycle. The target structures were characterized by steady-state UV/Vis absorption, fluorescence and transient absorption spectroscopy, as well as cyclic and differential pulse voltammetry. Both donor–acceptor dyads show ultrafast Förster Resonance Energy Transfer and photoinduced electron transfer, thereby leading to extremely low fluorescence quantum yields even in the lowest polarity cyclohexane solvent.
Angewandte Chemie Internationale Edition
10.1002/anie.202113598
urn:nbn:de:bvb:20-opus-256569
publish
Angewandte Chemie Internationale Edition (2021) 61:1, e202113598. DOI: 10.1002/anie.202113598
false
true
CC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International
Kevin Bold
Matthias Stolte
Kazutaka Shoyama
Marco Holzapfel
Alexander Schmiedel
Christoph Lambert
Frank Würthner
eng
uncontrolled
organic chemistry
eng
uncontrolled
photoinduced electron transfer
eng
uncontrolled
donor–acceptor dyads
eng
uncontrolled
macrocycles
eng
uncontrolled
oligothiophenes
eng
uncontrolled
perylenebisimide
Organische Chemie
open_access
Institut für Organische Chemie
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/25656/Angew_Chem_Int_Ed_2021_Bold.pdf
27643
2022
eng
30
28
article
1
--
--
--
Macrocyclic Donor‐Acceptor Dyads Composed of Oligothiophene Half‐Cycles and Perylene Bisimides
A series of donor‐acceptor (D−A) macrocyclic dyads consisting of an electron‐poor perylene bisimide (PBI) π‐scaffold bridged with electron‐rich α‐oligothiophenes bearing four, five, six and seven thiophene units between the two phenyl‐imide substituents has been synthesized and characterized by steady‐state UV/Vis absorption and fluorescence spectroscopy, cyclic and differential pulse voltammetry as well as transient absorption spectroscopy. Tying the oligothiophene strands in a conformationally fixed macrocyclic arrangement leads to a more rigid π‐scaffold with vibronic fine structure in the respective absorption spectra. Electrochemical analysis disclosed charged state properties in solution which are strongly dependent on the degree of rigidification within the individual macrocycle. Investigation of the excited state dynamics revealed an oligothiophene bridge size‐dependent fast charge transfer process for the macrocyclic dyads upon PBI subunit excitation.
Chemistry – A European Journal
10.1002/chem.202200355
urn:nbn:de:bvb:20-opus-276435
2022-06-14T22:21:44+00:00
sword
swordwue
attachment; filename=deposit.zip
5f0eb962da21a0e0e1d9d4c7d2ead162
Chemistry – A European Journal 2022, 28(30):e202200355. DOI: 10.1002/chem.202200355
false
true
CC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International
Kevin Bold
Matthias Stolte
Kazutaka Shoyama
Ana‐Maria Krause
Alexander Schmiedel
Marco Holzapfel
Christoph Lambert
Frank Würthner
eng
uncontrolled
donor-acceptor dyad
eng
uncontrolled
macrocycle
eng
uncontrolled
oligothiophene
eng
uncontrolled
perylene bisimide
eng
uncontrolled
photoinduced electron transfer
Chemie und zugeordnete Wissenschaften
open_access
Institut für Organische Chemie
Import
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/27643/CHEM_CHEM202200355.pdf
20816
2019
eng
15463-15471
68
25
article
1
2020-07-13
--
--
Luminescent Mono-, Di-, and Tri-radicals: Bridging Polychlorinated Triarylmethyl Radicals by Triarylamines and Triarylboranes
Up to three polychlorinated pyridyldiphenylmethyl radicals bridged by a triphenylamine carrying electron withdrawing (CN), neutral (Me), or donating (OMe) groups were synthesized and analogous radicals bridged by tris(2,6‐dimethylphenyl)borane were prepared for comparison. All compounds were as stable as common closed‐shell organic compounds and showed significant fluorescence upon excitation. Electronic, magnetic, absorption, and emission properties were examined in detail, and experimental results were interpreted using DFT calculations. Oxidation potentials, absorption and emission energies could be tuned depending on the electron density of the bridges. The triphenylamine bridges mediated intramolecular weak antiferromagnetic interactions between the radical spins, and the energy difference between the high spin and low spin states was determined by temperature dependent ESR spectroscopy and DFT calculations. The fluorescent properties of all radicals were examined in detail and revealed no difference for high and low spin states which facilitates application of these dyes in two‐photon absorption spectroscopy and OLED devices.
Chemistry - A European Journal
10.1002/chem.201903007
urn:nbn:de:bvb:20-opus-208162
Chemistry - A European Journal (2019) 25(68):15463-15471. DOI: 10.1002/chem.201903007
false
true
CC BY-NC: Creative-Commons-Lizenz: Namensnennung, Nicht kommerziell 4.0 International
Yohei Hattori
Evripidis Michail
Alexander Schmiedel
Michael Moos
Marco Holzapfel
Ivo Krummenacher
Holger Braunschweig
Ulrich Müller
Jens Pflaum
Christoph Lambert
eng
uncontrolled
density functional calculations
eng
uncontrolled
fluorescence
eng
uncontrolled
NIR OLED
eng
uncontrolled
radical
eng
uncontrolled
two-photon absorption
Chemie und zugeordnete Wissenschaften
open_access
Physikalisches Institut
Institut für Anorganische Chemie
Institut für Organische Chemie
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/20816/Hattori_Chemistry.pdf
2161
2007
eng
doctoralthesis
1
2007-12-07
--
2007-12-03
Photoinduced Charge Transfer Processes in Triarylamine Based Redox Cascades
Photoinduzierte Ladungstransferprozesse in Triarylamin-Redoxkaskaden
In the first part of this work a new approach to measure transient absorption spectra of fluorescent compounds by means of laser flash photolysis technique was presented. Generally, the recorded transient absorption signal consists of transient absorption, fluorescence and ground state bleaching. Thus, for fluorescent chromophores a fluorescence correction is indispensable in order to obtain undisturbed absorption decay curves as well as accurate transient absorption spectra. Due to time response characteristics of the PMT detector the fluorescence contribution cannot be corrected by recording the fluorescence separately. Measuring two transient absorption signals with probe light differing in intensity, compounds with quantum yields up to ~ 35 % can be investigated. This is a major improvement because transient absorption spectroscopy is a powerful method to gain insight into the kinetics and the energy of excited states and information in the time domain of fluorescence are no longer lost. In the second part the synthesis and the photophysical characterisation of redox cascades were reported. These cascades consist of an acridine acceptor and up to three triarylamine donor subunits. The redox potentials of the triarylamines were tuned by adequate substituents in the para-position of the phenyl ring to ensure a directed redox gradient. Upon photoexcitation a locally excited state or a CT state is populated which then injects a hole onto the adjacent donor and consequently results in a CS state. Fluorescence and transient absorption measurements revealed that HT depends strongly on donor strength and solvent polarity. Formation of a CS state was only observed in case of strong terminal donors or polar solvents. A low lying localised triplet state acts as an energy trap and quenches all CS states even in case of the cascade with the strongest terminal donor in very polar solvents. Furthermore, population of a CS state catalyses the formation of this triplet states which results in a shorter lifetime of the CS state compared to the lifetime of the CT state of the corresponding reference compound. Compared to redox cascades already reported in literature, the electronic coupling between the redox centres was decreased by sterical as well as electronic effects. To prolong the lifetime of the CS state saturated spacers on the one hand and a perpendicular orientation of the acceptor and the adjacent donor on the other hand were selected. The twisting of the subunits forming the CT state results in a higher degree of charge separation but its contribution to increase the lifetimes of the CS states is of minor importance. The longer lifetime of the CS states can be ascribed to the saturated spacers. Experimental data in combination with calculated values indicate that charge recombination takes place in the Marcus normal region by a superexchange mechanisms. Although charge recombination of the known cascades is located in the Marcus inverted region, these CS states decay faster than the CS states of the compounds investigated in this work.
Im ersten Teil der vorliegenden Arbeit wurde eine neue Methode vorgestellt, mit dem transiente Absorptionsspektren von fluoreszierenden Verbindungen mit Hilfe der Laser-Blitzlichtphotolyse aufgenommen werden können. Ein transientes Absorptionssignal setzt sich im Allgemeinen aus transienter Absorption, Fluoreszenz und einer Ausbleichung des Grundzustands zusammen. Daher ist es für fluoreszierende Verbindungen unerlässlich, die Fluoreszenz zu korrigieren, um sowohl einwandfreie Abklingkurven als auch korrekte Spektren zu erhalten. Aufgrund der Charakteristik der Ansprechzeit des Photomultiplier-Detektors kann der Fluoreszenzbeitrag nicht durch ein eigens aufgenommenes Fluoreszenzsignal korrigiert werden. Jedoch können Verbindungen mit einer Fluoreszenzquantenausbeute bis ungefähr 35 % fehlerfrei gemessen werden, sofern das transiente Signal aus zwei Messungen mit unterschiedlicher Weißlichtintensität bestimmt wird. Dieser neue Ansatz zur Ermittlung transienter Absorptionsspektren ist eine entscheidende Verbesserung, da die Laser-Blitzlichtphotolyse eine leistungsstarke Methode zur Ermittlung kinetischer und energetischer Eigenschaften angeregter Zustände darstellt. Im zweiten Abschnitt wurde die Synthese von Redoxkaskaden vorgestellt und gerichtete Elektronentransferprozesse an diesen Verbindungen untersucht. Die Chromophore bestehen stets aus einem Acridin-Akzeptor und bis zu drei Triarylamin-Untereinheiten als Donoren. Die Redoxpotenziale der Triarylamine können in gewissem Maße durch geeignete Substituenten in para-Position der Phenylringe abgestimmt werden, womit ein gerichteter Redoxgradient erzielt wird. Nach Anregung mit Licht geeigneter Wellenlänge wird ein lokal angeregter oder ein CT-Zustand bevölkert. Anschließend wird ein Loch in die benachbarte Donoreinheit injiziert, was schließlich zu einem ladungsgetrennten Zustand führt. Fluoreszenz- und transiente Absorptionsmessungen zeigen, dass der Lochtransfer in starkem Maße von der Lösungsmittelpolarität sowie der Stärke des terminalen Donors abhängt. Die Ausbildung eines ladungsgetrennten Zustands konnte nur bei starken terminalen Donoren oder polaren Lösungsmitteln beobachtet werden. Ein energetisch tief liegender lokal angeregter Triplettzustand agiert als energetische Falle und löscht alle ladungsgetrennten Zustände – selbst im Falle der stärksten Donoruntereinheit in sehr polaren Lösungsmitteln. Darüber hinaus beschleunigt die Bevölkerung eines ladungsgetrennten Zustands die Ausbildung dieses Triplettzustands, was sich in einer kürzeren Lebensdauer dieses ladungsgetrennten Zustands, verglichen mit dem CT-Zustand der Referenzverbindung, äußert. Die elektronische Kopplung zwischen den einzelnen Redoxzentren wurde im Vergleich zu ähnlichen bereits bekannten Redoxkaskaden sowohl durch sterische als auch durch elektronische Effekte verringert. Um die Lebensdauer des ladungsgetrennten Zustands zu verlängern, wurden einerseits gesättigte Einheiten, die die Untereinheiten verbrücken, eingebaut. Andererseits wurde mit Hilfe sterischer Faktoren die Akzeptoreinheit gegenüber dem benachbarten Donor verdrillt, was zwar in einer stärker ausgeprägten Ladungstrennung resultiert, jedoch nur geringfügig zu einer Verlängerung des ladungsgetrennten Zustands beiträgt. Somit kann die verlängerte Lebensdauer dieses ladungsgetrennten Zustands eindeutig auf die gesättigten Brückeneinheiten zurückgeführt werden. Experimentelle Daten stimmen mit berechneten Größen dahin gehend überein, dass die Ladungsrekombination in der normalen Marcus-Region über einen Superaustausch-Mechanismus erfolgt. Obwohl diese Rekombination bei den bekannten Kaskaden in der invertierten Marcus-Region erfolgt, werden die entsprechenden ladungsgetrennten Zustände schneller entvölkert als bei den Verbindungen, die Gegenstand dieses Kapitels waren.
urn:nbn:de:bvb:20-opus-25276
2527
X121627
Marco Holzapfel
deu
swd
Ladungstransfer
deu
swd
Fluoreszenzspektroskopie
deu
uncontrolled
transiente Absorptionsspektroskopie
deu
uncontrolled
Redoxkaskade
deu
uncontrolled
Triplett
eng
uncontrolled
transient absorption spectroscopy
eng
uncontrolled
redox cascade
eng
uncontrolled
triplet
Chemie und zugeordnete Wissenschaften
open_access
Institut für Organische Chemie
Universität Würzburg
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/2161/holzapfeldiss.pdf
15960
2015
eng
preprint
1
2018-03-22
--
--
Energy Transfer Between Squaraine Polymer Sections: From helix to zig-zag and All the Way Back
Joint experimental and theoretical study of the absorption spectra of squaraine polymers in solution provide evidence that two different conformations are present in solution: a helix and a zig-zag structure. This unique situation allows investigating ultrafast energy transfer processes between different structural segments within a single polymer chain in solution. The understanding of the underlying dynamics is of fundamental importance for the development of novel materials for light-harvesting and optoelectronic applications. We combine here femtosecond transient absorption spectroscopy with time-resolved 2D electronic spectroscopy showing that ultrafast energy transfer within the squaraine polymer chains proceeds from initially excited helix segments to zig-zag segments or vice versa, depending on the solvent as well as on the excitation wavenumber. These observations contrast other conjugated polymers such as MEH-PPV where much slower intrachain energy transfer was reported. The reason for the very fast energy transfer in squaraine polymers is most likely a close matching of the density of states between donor and acceptor polymer segments because of very small reorganization energy in these cyanine-like chromophores.
Journal of the American Chemical Society
10.1021/jacs.5b03644
http://dx.doi.org/10.1021/jacs.5b03644
urn:nbn:de:bvb:20-opus-159607
This document is the unedited Author's version of a Submitted Work that war subsequently accepted for publication in Journal of the American Chemical Society, copyright American Chemical Society after peer review. To access the final edited and published work see doi:10.1021/jacs.5b03644.
Journal of the American Chemical Society, 2015, 137 (24), pp 7851–7861 DOI: 10.1021/jacs.5b03644
Center for Nanosystems Chemistry (CNC), Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
Deutsches Urheberrecht
Christoph Lambert
Sebastian F. Völker
Federico Koch
Alexander Schmiedel
Marco Holzapfel
Alexander Humeniuk
Merle I. S. Röhr
Roland Mitric
Tobias Brixner
eng
uncontrolled
energy transfer dynamics
eng
uncontrolled
squaraine polymer
Physikalische Chemie
ATOMIC AND MOLECULAR PHYSICS
open_access
Institut für Organische Chemie
Institut für Physikalische und Theoretische Chemie
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/15960/Lambert_et_al_Squaraine_Polymer_Sections_JACS_submitted_version.pdf
20748
2020
eng
438-453
2
26
article
1
2020-07-06
--
--
Synthesis, Photophysical and Electronic Properties of New Red-to-NIR Emitting Donor-Acceptor Pyrene Derivatives
We synthesized new pyrene derivatives with strong bis(para ‐methoxyphenyl)amine donors at the 2,7‐positions and n ‐azaacene acceptors at the K‐region of pyrene. The compounds possess a strong intramolecular charge transfer, leading to unusual properties such as emission in the red to NIR region (700 nm), which has not been reported before for monomeric pyrenes. Detailed photophysical studies reveal very long intrinsic lifetimes of >100 ns for the new compounds, which is typical for 2,7‐substituted pyrenes but not for K‐region substituted pyrenes. The incorporation of strong donors and acceptors leads to very low reduction and oxidation potentials, and spectroelectrochemical studies show that the compounds are on the borderline between localized Robin‐Day class‐II and delocalized Robin‐Day class‐III species.
Chemistry - A European Journal
10.1002/chem.201904219
urn:nbn:de:bvb:20-opus-207486
Chemistry - A European Journal (2020) 26(2):438-453. DOI: 10.1002/chem.201904219
false
true
CC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International
Julia Merz
Maximilian Dietz
Yvonne Vonhausen
Frederik Wöber
Alexandra Friedrich
Daniel Sieh
Ivo Krummenacher
Holger Braunschweig
Michael Moos
Marco Holzapfel
Christoph Lambert
Todd B. Marder
eng
uncontrolled
orylation
eng
uncontrolled
K-region
eng
uncontrolled
luminescence
eng
uncontrolled
polycyclic aromatic hydrocarbons
eng
uncontrolled
redox
Anorganische Chemie
open_access
Institut für Anorganische Chemie
Institut für Organische Chemie
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/20748/Merz_Chemistry.pdf
25452
2021
eng
3549
12
article
1
2022-02-02
--
--
Large Stokes shift fluorescence activation in an RNA aptamer by intermolecular proton transfer to guanine
Fluorogenic RNA aptamers are synthetic functional RNAs that specifically bind and activate conditional fluorophores. The Chili RNA aptamer mimics large Stokes shift fluorescent proteins and exhibits high affinity for 3,5-dimethoxy-4-hydroxybenzylidene imidazolone (DMHBI) derivatives to elicit green or red fluorescence emission. Here, we elucidate the structural and mechanistic basis of fluorescence activation by crystallography and time-resolved optical spectroscopy. Two co-crystal structures of the Chili RNA with positively charged DMHBO+ and DMHBI+ ligands revealed a G-quadruplex and a trans-sugar-sugar edge G:G base pair that immobilize the ligand by π-π stacking. A Watson-Crick G:C base pair in the fluorophore binding site establishes a short hydrogen bond between the N7 of guanine and the phenolic OH of the ligand. Ultrafast excited state proton transfer (ESPT) from the neutral chromophore to the RNA was found with a time constant of 130 fs and revealed the mode of action of the large Stokes shift fluorogenic RNA aptamer.
Nature Communications
10.1038/s41467-021-23932-0
urn:nbn:de:bvb:20-opus-254527
Georg August University School of Science
Max Planck Institute for Biophysical Chemistry
Institute of Cancer Research (ICR) London
publish
Nature Communications 12, 3549 (2021). https://doi.org/10.1038/s41467-021-23932-0
682586
false
true
CC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International
Mateusz Mieczkowski
Christian Steinmetzger
Irene Bessi
Ann-Kathrin Lenz
Alexander Schmiedel
Marco Holzapfel
Christoph Lambert
Vladimir Pena
Claudia Höbartner
eng
uncontrolled
Fluorogenic RNA Aptamers
eng
uncontrolled
Synthetic Functional RNAs
eng
uncontrolled
Chili RNA Aptamer
eng
uncontrolled
Co-Crystal Structures of Chili RNA
eng
uncontrolled
RNA
eng
uncontrolled
Optical Spectroscopy
eng
uncontrolled
Structural Biology
eng
uncontrolled
X-ray Crystallography
Organische Chemie
open_access
Institut für Organische Chemie
OpenAIRE
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/25452/Hoebartner_Large_Stokes_Shift_RNA_Aptamers_NatCommun.pdf
27027
2021
eng
12
article
1
--
--
--
Large Stokes shift fluorescence activation in an RNA aptamer by intermolecular proton transfer to guanine
Fluorogenic RNA aptamers are synthetic functional RNAs that specifically bind and activate conditional fluorophores. The Chili RNA aptamer mimics large Stokes shift fluorescent proteins and exhibits high affinity for 3,5-dimethoxy-4-hydroxybenzylidene imidazolone (DMHBI) derivatives to elicit green or red fluorescence emission. Here, we elucidate the structural and mechanistic basis of fluorescence activation by crystallography and time-resolved optical spectroscopy. Two co-crystal structures of the Chili RNA with positively charged DMHBO+ and DMHBI+ ligands revealed a G-quadruplex and a trans-sugar-sugar edge G:G base pair that immobilize the ligand by π-π stacking. A Watson-Crick G:C base pair in the fluorophore binding site establishes a short hydrogen bond between the N7 of guanine and the phenolic OH of the ligand. Ultrafast excited state proton transfer (ESPT) from the neutral chromophore to the RNA was found with a time constant of 130 fs and revealed the mode of action of the large Stokes shift fluorogenic RNA aptamer.
Nature Communications
10.1038/s41467-021-23932-0
urn:nbn:de:bvb:20-opus-270274
Nature Communications (2021) 12:3549. https://doi.org/10.1038/s41467-021-23932-0
false
true
CC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International
Mateusz Mieczkowski
Christian Steinmetzger
Irene Bessi
Ann-Kathrin Lenz
Alexander Schmiedel
Marco Holzapfel
Christoph Lambert
Vladimir Pena
Claudia Höbartner
eng
uncontrolled
RNA
eng
uncontrolled
optical spectroscopy
eng
uncontrolled
structural biology
eng
uncontrolled
X-ray crystallography
Organische Chemie
open_access
Institut für Organische Chemie
Förderzeitraum 2021
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/27027/s41467-021-23932-0.pdf
34520
2023
eng
submitted version
preprint
1
2023-11-20
--
--
Push-Pull [7]Helicene Diimide: Excited-State Charge Transfer and Solvatochromic Circularly Polarised Luminescence
In this communication we describe a helically chiral push-pull molecule named 9,10-dimethoxy-[7]helicene diimide, displaying fluorescence (FL) and circularly polarised luminescence (CPL) over nearly the entire visible spectrum dependent on solvent polarity. The synthesised molecule exhibits an unusual solvent polarity dependence of FL quantum yield and nonradiative rate constant, as well as remarkable gabs and glum values along with high configurational stability.
https://doi.org/10.1039/D3CC04470J
urn:nbn:de:bvb:20-opus-345207
publish
Chemical Communications (2023) 94:59, 14005-14008. DOI https://doi.org/10.1039/D3CC04470J
false
true
Deutsches Urheberrecht
Fridolin Saal
Asim Swain
Alexander Schmiedel
Marco Holzapfel
Christoph Lambert
Prince Ravat
eng
uncontrolled
Helicene diimide
Organische Chemie
open_access
Institut für Organische Chemie
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/34520/Ravat_Prince_Push-pull-diimide_ChemComm_Submittedversion.pdf
25686
2021
eng
8380–8389
32
27
article
1
2022-02-14
--
--
Solvent Induced Helix Folding of Defined Indolenine Squaraine Oligomers
A protecting group strategy was employed to synthesise a series of indolenine squaraine dye oligomers up to the nonamer. The longer oligomers show a distinct solvent dependence of the absorption spectra, that is, either a strong blue shift or a strong red shift of the lowest energy bands in the near infrared spectral region. This behaviour is explained by exciton coupling theory as being due to H- or J-type coupling of transition moments. The H-type coupling is a consequence of a helix folding in solvents with a small Hansen dispersity index. DOSY NMR, small angle neutron scattering (SANS), quantum chemical and force field calculations agree upon a helix structure with an unusually large pitch and open voids that are filled with solvent molecules, thereby forming a kind of clathrate. The thermodynamic parameters of the folding process were determined by temperature dependent optical absorption spectra.
Chemistry—A European Journal
10.1002/chem.202101063
urn:nbn:de:bvb:20-opus-256869
publish
Chemistry—A European Journal 2021, 27(32):8380–8389. DOI: 10.1002/chem.202101063
654000
false
true
CC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International
Arthur Turkin
Marco Holzapfel
Mohit Agarwal
David Fischermeier
Roland Mitric
Ralf Schweins
Franziska Gröhns
Christoph Lambert
eng
uncontrolled
UV/Vis spectroscopy
eng
uncontrolled
dye chemistry
eng
uncontrolled
solvent effects
eng
uncontrolled
superstructure
eng
uncontrolled
supramolecular folding
Organische Chemie
open_access
Institut für Organische Chemie
Institut für Physikalische und Theoretische Chemie
OpenAIRE
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/25686/Turkin_Chemistry.pdf