Construction of chiral through-space luminophores via symmetry breaking triggered by sequenced chlorination

Abstract

The construction of molecular chirality is crucial for exploring novel luminophores with chiroptical properties. Classic asymmetric synthesis of chiral center or axial is not powerful enough on throughspace architecture. Accessible methodologies for breaking molecular symmetry could be promising but remain less investigated. Herein, we report a novel methodology for constructing chiral through-space luminophores via simple chlorination on bridged carbazole motifs. The chlorination breaks the molecular symmetry and thus results in molecular chirality by eliminating the mirror plane or rotating axis.Interestingly, continuous multiple chlorinations can rebuild and break the symmetry of the skeleton in succession. Several chiral and achiral isomeric analogues are synthesized and characterized with impressive chiroptical properties. Results of chiral HPLC, single-crystal X-ray diffraction, kinetic racemization, and chiroptical property investigation demonstrate the effectiveness of our rational design strategy. It provides a feasible methodology for exploring novel chiral luminescent materials based on versatile though-space skeletons.

Initialing Circularly Polarized Room-Temperature Phosphorescence from Purely Organic Luminophore Aggregate

“…Planar chirality, compared to axial and point chirality, has sig-nificant practical implications for the construction of intrinsic CP-RTP materials but is challenging. 32 Zuo et al recently reported a series of chiral molecules based on the [2.2]paracyclophane unit, which exhibits prominent RTP upon aggregation and excellent CPL in solution through asymmetric substitution on the chiral center (as shown in Scheme 4a). 33 Helicenes display pronounced conformational asymmetry attributed to their inherent planar chirality.…”