Synthesis, Structure, and Chiroptical Properties of Indolo‐ and Pyridopyrrolo‐Carbazole‐Based <i>C₂</i>‐Symmetric Azahelicenes

Abstract Treatment of 11,12‐bis(1,1’‐biphenyl‐3‐yl or 6‐phenylpyridin‐2‐yl)‐substituted 11,12‐dihydro‐indolo[2,3‐ a ]carbazole with an oxidizing system Pd(II)/Ag(I) induced effective double dehydrogenative cyclization to afford the corresponding π‐extended azahelicenes. The optical resolutions were readily achieved by preparative chiral HPLC. It was found that pyridopyrrolo‐carbazole‐based azahelicene contains four nitrogen atoms exhibits ca. 6 times larger dissymmetry factors both in circularly dichroism (CD) and polarized luminescence (CPL), | g CD CPL values being 1.1×10 −2 4.4×10 −3 , respectively, as compared parent indolocarbazole‐based azahelicene. Theoretical calculations at RI‐CC2 level employed rationalize observed enhanced chiroptical responses. (chir)optical properties former helicene further tuned protonation leading remarkable red‐shift considerable enhancement value.