Chiral Perylene Bisimide Dyes by Interlocked Arene Substituents in the Bay Area. Issue 46 (7th July 2021)

• Record Type: Journal Article
• Authors: Renner, Rebecca; Mahlmeister, Bernhard; Anhalt, Olga; Stolte, Matthias; Würthner, Frank
• Is Part Of: Chemistry. Volume 27:Issue 46(2021)
• Page Start: 11997
• Page End: 12006
• Publication Date: 2021-07-07
• Subjects: chirality -- circular polarized luminescence -- perylene bisimide dyes -- Suzuki coupling; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202101877
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: 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. Abstract : The interlocked π‐π ‐stacking motif of bay‐tetraarylated perylene bisimides endows these molecules with chirality and rich conformational isomerism. These structural features are elucidated by X‐ray crystallography and NMR. Optical spectroscopy including CD and CPL provide insights into their functional properties.