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Chiral Perylene Bisimide Dyes by Interlocked Arene Substituents in the Bay Area
Author(s) -
Renner Rebecca,
Mahlmeister Bernhard,
Anhalt Olga,
Stolte Matthias,
Würthner Frank
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202101877
Subject(s) - racemization , chemistry , perylene , chirality (physics) , circular dichroism , aryl , steric effects , photochemistry , molecule , crystallography , stereochemistry , organic chemistry , chiral symmetry breaking , physics , alkyl , quantum mechanics , nambu–jona lasinio model , quark
A series of perylene bisimide (PBI) dyes bearing various aryl substituents in 1,6,7,12 bay positions has been synthesized by Suzuki cross‐coupling reaction. These molecules exhibit an exceptionally large and conformationally fixed twist angle of the PBI π‐ core due to the high steric congestion imparted by the aryl substituents in bay positions. Single crystal X‐ray analyses of phenyl‐, naphthyl‐ and pyrenyl‐functionalized PBIs reveal interlocked π‐π ‐stacking motifs, leading to conformational chirality and the possibility for the isolation of enantiopure atropoisomers by semipreparative HPLC. The interlocked arrangement endows these molecules with substantial racemization barriers of about 120 kJ mol −1 for the tetraphenyl‐ and tetra‐2‐naphthyl‐substituted derivatives, which is among the highest racemization barriers for axially chiral PBIs. Variable temperature NMR studies reveal the presence of a multitude of up to fourteen conformational isomers in solution that are interconverted via smaller activation barriers of about 65 kJ mol −1 . The redox and optical properties of these core‐twisted PBIs have been characterized by cyclic voltammetry, UV/Vis/NIR and fluorescence spectroscopy and their respective atropo‐enantiomers were further characterized by circular dichroism (CD) and circular polarized luminescence (CPL) spectroscopy.