Highly Strained Oxygen‐Doped Chiral Molecular Belts of the Zigzag‐Type with Strong Circularly Polarized Luminescence

A two-directional cyclization strategy has been used to synthesize depth-expanded oxygen-doped chiral molecular belts of the zigzag-type. The approach involved the closure of fjords at the upper rim and the growth of fused rings at the lower rim of resorcin[4]arene derivatives to afford highly strained chiral belts having excellent CPL properties, with |g _lum| up to 0.022.

Abstract

Herein we report a two-directional cyclization strategy for the synthesis of highly strained depth-expanded oxygen-doped chiral molecular belts of the zigzag-type. From the easily accessible resorcin[4]arenes, an unprecedented cyclization cascade generating fused 2,3-dihydro-1H-phenalenes has been developed to access expanded molecular belts. Stitching up the fjords through intramolecular nucleophilic aromatic substitution and ring-closing olefin metathesis reactions furnished a highly strained O-doped C₂-symmetric belt. The enantiomers of the acquired compounds exhibited excellent chiroptical properties. The calculated parallelly aligned electric (μ) and magnetic (m) transition dipole moments are translated to the high dissymmetry factor (|g _lum| up to 0.022). This study provides not only an appealing and useful strategy for the synthesis of strained molecular belts but also a new paradigm for the fabrication of belt-derived chiroptical materials with high CPL activities.

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