TY  - JOUR
A1  - Ouyang, Guanghui
A1  - Rühe, Jessica
A1  - Zhang, Yang
A1  - Lin, Mei-Jin
A1  - Liu, Minghua
A1  - Würthner, Frank
T1  - Intramolecular Energy and Solvent-Dependent Chirality Transfer within a BINOL-Perylene Hetero-Cyclophane
JF  - Angewandte Chemie International Edition
N2  - Multichromophoric macrocycles and cyclophanes are important supramolecular architectures for the elucidation of interchromophoric interactions originating from precise spatial organization. Herein, by combining an axially chiral binaphthol bisimide (BBI) and a bay-substituted conformationally labile twisted perylene bisimide (PBI) within a cyclophane of well-defined geometry, we report a chiral PBI hetero-cyclophane (BBI-PBI) that shows intramolecular energy and solvent-regulated chirality transfer from the BBI to the PBI subunit. Excellent spectral overlap and spatial arrangement of BBI and PBI lead to efficient excitation energy transfer and subsequent PBI emission with high quantum yield (80–98 %) in various solvents. In contrast, chirality transfer is strongly dependent on the respective solvent as revealed by circular dichroism (CD) spectroscopy. The combination of energy and chirality transfer affords a bright red circularly polarized luminescence (CPL) from the PBI chromophore by excitation of BBI.
KW  - chirality transfer
KW  - solvent effects
KW  - perylene bisimide
KW  - energy transfer
KW  - cyclophanes
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-318818
VL  - 61
IS  - 31
ER  - 
TY  - JOUR
A1  - Turkin, Arthur
A1  - Holzapfel, Marco
A1  - Agarwal, Mohit
A1  - Fischermeier, David
A1  - Mitric, Roland
A1  - Schweins, Ralf
A1  - Gröhns, Franziska
A1  - Lambert, Christoph
T1  - Solvent Induced Helix Folding of Defined Indolenine Squaraine Oligomers
JF  - Chemistry—A European Journal
N2  - 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.
KW  - UV/Vis spectroscopy
KW  - dye chemistry
KW  - solvent effects
KW  - superstructure
KW  - supramolecular folding
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256869
VL  - 27
IS  - 32
ER  -