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

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, similar to 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.