Boosting quantum yields and circularly polarized luminescence of penta- and hexahelicenes by doping with two
Yannik Appiarius1,2, Sandra Míguez-Lago3, Pim Puylaert4
1University of Bremen, Institute for Organic and Analytical Chemistry 28359 Bremen Germany staubitz@uni-bremen.de.
Abstract:
The incorporation of boron-nitrogen (BN) units into polycyclic aromatic hydrocarbons (PAHs) as an isoelectronic replacement of two carbon atoms can significantly improve their optical properties, while the geometries are mostly retained. We report the first non-π-extended penta- and hexahelicenes comprising two aromatic 1,2-azaborinine rings. Comparing them with their all-carbon analogs regarding structural, spectral and (chir)optical properties allowed us to quantify the impact of the heteroatoms. In particular, BN-hexahelicene BN[6] exhibited a crystal structure congruent with its analog CC[6], but displayed a fivefold higher fluorescence quantum yield (φfl = 0.17) and an outstanding luminescence dissymmetry factor (|glum| = 1.33 × 10-2). Such an unusual magnification of both properties at the same time makes BN-helicenes suitable candidates as circularly polarized luminescence emitters for applications in materials science.
Related Concept Videos
Hybridization of Atomic Orbitals I
Hybridization of Atomic Orbitals II
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
VSEPR Theory and the Effect of Lone Pairs
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Variables Affecting Phosphorescence and Fluorescence


