Dynamic Covalent Platform for Chiroptically Tunable Figure-Eight Macrocycles from Preorganized Alkaloidal Scaffolds

High Resolution Image Download MS PowerPoint Slide Chiral D 2 -symmetric figure-eight macrocycles with extended π-conjugated systems represent versatile scaffolds for developing advanced chiroptical materials. Here, we present a dynamic covalent platform that transforms a preorganized alkaloidal bispyrrolidinoindoline (BPI) scaffold into a series of chiroptically tunable figure-eight macrocycles through thermodynamically controlled imine formation. Strategic installation of aryl-ethynyl substituents precisely preorganized the BPI scaffold, enabling highly efficient macrocyclization (up to a 81% yield) under reversible imine-forming conditions. This modular approach allowed systematic assembly of diverse intercrossing chromophores, affording 44–90-membered macrocycles exhibiting predictable variations in both optical and chiroptical responses. Postsynthetic conversion of dynamic imine linkages into rigid π-extended B–N chelates via boranil formation further fixed the macrocyclic conformation, producing a bright orange emitter (Φ fl = 0.54) with enhanced circularly polarized luminescence (CPL) activity ( g lum = 1.97 × 10 –3 ). This work establishes a general design principle integrating dynamic covalent chemistry and conformational preorganization to generate functional figure-eight macrocycles, translating natural-product-inspired molecular architecture into tunable chiroptical materials.