Silanediol-Bay-Bridge Rigidified Axially Chiral Perylene Bisimide

Abstract

Chiral organic molecules with a complementing π-structure are highly desired to obtain materials with good semiconducting properties and pronounced chirality effects in the visible region. Herein, we introduce a novel design strategy to achieve an axially chiral and rigid perylene bisimide (PBI) dye by attaching the chirality-inducing 2,2′-biphenoxy moiety at one side of the bay area and the rigidity-inducing di-tert-butylsilanediol bridge on the other side. This yielded a new bay-functionalized PBI derivative carrying the combination of a highly rigid and, simultaneously, an axially chiral perylene core. As a result, the derivative exhibits well-resolved absorption and emission spectra in the visible region, with a fluorescence quantum yield close to unity. Furthermore, the M- and P-enantiomers were found to be stable with a racemization barrier of 102 kJ mol^–1 and, hence, could be successfully separated by chiral chromatography and studied by circular dichroism (CD) spectroscopy. This rigidified chiral-PBI could also be crystallized and analyzed by X-ray diffraction, showing the highest torsion angle of the perylene core with a value of up to 30.3° in the family of PBIs carrying the same di-tert-butylsilanediol bridge.