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 through-space 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 high performance liquid chromatography (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.