High‐performance nano‐splitters containing aggregation‐induced emission luminogens for stereoselective crystallization obtained via polymerization‐induced self‐assembly

Abstract

Abstract Collecting both enantiomorphs with high optical purity and yield in a single crystallization process can be achieved by adding aggregated polymeric “tailor‐made” additives, known as nano‐splitters. Inefficient preparation and large addition amount have hindered the practical application of such amazing nanoparticles. Herein, we report the first nano‐splitters containing aggregation‐induced emission luminogens prepared via polymerization‐induced self‐assembly of block copolymer, poly[(S)‐2‐(tert‐butoxycarbonylamino)‐6‐(methacrylamido)hexanoic acid]‐b‐polystyrene, followed by the removal of tert‐butoxycarbonyl groups. When added into the supersaturated solution of racemic amino acids (a.a.) with seeds, the fluorescent labeled nano‐assemblies enantioselectivity dyed the crystals of S‐a.a. and enabled the separation from colorless R‐a.a. crystals in terms of fluorescent difference. Both enantiomers were obtained with high optical purity and yield (e.g., R‐ asparagine monohydrate, >99 ee%; S‐ asparagine monohydrate, ∼94 ee%; 88% total yield). Owing to a low detection limit of fluorescence, the addition amount was reduced to 0.03 wt% without remarkably compromising the ee values of both enantiomorphs. Due to the low addition amount and efficient synthesis, the output–input ratio was increased greatly.

Keywords

• aggregation‐induced emission (AIE)
• chiral
• conglomerate
• polymerization‐induced self‐assembly
• RAFT
• stereoseparation