Stepwise Modification of Carborane‐Fused Heterocycles for Enhanced Circularly Polarized Luminescence

ABSTRACT Herein, we report the design and synthesis of m ‐carborane‐based chiral luminescent molecules with significantly improved chiroptical properties. These structurally unique molecules are constructed via a stepwise functionalization strategy. This includes an initial double B−N cross‐coupling with atropisomeric 1,1'‐binaphthyl‐2,2'‐diamine (BINAM) scaffolds to form a m ‐carborane‐fused eight‐membered heterocycle. Next, arylation occurs at spatially congested N–H sites, followed by final gold(I) complexation. Experimental and theoretical investigations show that this design systematically rigidifies the framework, which is demonstrated by comparing changes in the binaphthyl dihedral angles between the ground (S0) and excited (S1) states. Amplification of the photoluminescence dissymmetry factor (|g lum |) from approximately 1.5 × 10 −3 to as high as 1.1 × 10 −2 , a record for carborane‐containing chiroptical small molecules in fluidic solution, has also been achieved. The circularly polarized luminescence (CPL) signals of these molecules challenge the established paradigm linking CPL signs to dihedral angles, highlighting the unique influence of the m ‐carborane core. Additionally, doping a small amount of the heterocycle‐gold(I) complex into a gold(I) chloride matrix result in a long‐persistent afterglow lasting up to four seconds.