TY  - JOUR
A1  - Bold, Kevin
A1  - Stolte, Matthias
A1  - Shoyama, Kazutaka
A1  - Krause, Ana‐Maria
A1  - Schmiedel, Alexander
A1  - Holzapfel, Marco
A1  - Lambert, Christoph
A1  - Würthner, Frank
T1  - Macrocyclic Donor‐Acceptor Dyads Composed of Oligothiophene Half‐Cycles and Perylene Bisimides
JF  - Chemistry – A European Journal
N2  - 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.
KW  - donor-acceptor dyad
KW  - macrocycle
KW  - oligothiophene
KW  - perylene bisimide
KW  - photoinduced electron transfer
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-276435
VL  - 28
IS  - 30
ER  - 
TY  - JOUR
A1  - Bold, Kevin
A1  - Stolte, Matthias
A1  - Shoyama, Kazutaka
A1  - Holzapfel, Marco
A1  - Schmiedel, Alexander
A1  - Lambert, Christoph
A1  - Würthner, Frank
T1  - Macrocyclic donor-acceptor dyads composed of a perylene bisimide dye surrounded by oligothiophene bridges
JF  - Angewandte Chemie Internationale Edition
N2  - 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.
KW  - organic chemistry
KW  - photoinduced electron transfer
KW  - donor–acceptor dyads
KW  - macrocycles
KW  - oligothiophenes
KW  - perylenebisimide
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256569
VL  - 61
IS  - 1
ER  - 
TY  - JOUR
A1  - Spenst, Peter
A1  - Young, Ryan M.
A1  - Wasielewski, Michael R.
A1  - Würthner, Frank
T1  - Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane
JF  - Chemical Science
N2  - Cofacial positioning of two perylene bisimide (PBI) chromophores at a distance of 6.5 angstrom in a cyclophane structure prohibits the otherwise common excimer formation and directs photoexcited singlet state relaxation towards intramolecular symmetry-breaking charge separation (τ\(_{CS}\) = 161 +/- 4 ps) in polar CH\(_2\)Cl\(_2\), which is thermodynamically favored with a Gibbs free energy of ΔG\(_{CS}\) = -0.32 eV. The charges then recombine slowly in τ\(_{CR}\) = 8.90 +/- 0.06 ns to form the PBI triplet excited state, which can be used subsequently to generate singlet oxygen in 27% quantum yield. This sequence of events is eliminated by dissolving the PBI cyclophane in non-polar toluene, where only excited singlet state decay occurs. In contrast, complexation of electron-rich aromatic hydrocarbons by the host PBI cyclophane followed by photoexcitation of PBI results in ultrafast electron transfer (<10 ps) from the guest to the PBI in CH\(_2\)Cl\(_2\). The rate constants for charge separation and recombination increase as the guest molecules become easier to oxidize, demonstrating that charge separation occurs close to the peak of the Marcus curve and the recombination lies far into the Marcus inverted region.
KW  - photoinduced electron transfer
KW  - Marcus inverted region
KW  - cyclic perylene bisimide
KW  - PBI cyclophane
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-191252
VL  - 7
IS  - 8
ER  -