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Direct Crystallization Resolution of Racemates Enhanced by Chiral Nanorods: Experimental, Statistical, and Quantum
Jiaojiao Cao1, Boxuan Lou1, Yue Xu1
1Chemical Engineering Department, Frontier Medical Technologies Institute, Shanghai University of Engineering Science, Shanghai 201620, China.
ACS Omega
|June 20, 2022
Summary
Chiral nanorods effectively resolved racemic aspartic acid (Asp) through direct crystallization, promoting desired enantiomers while inhibiting others. This method achieved high enantiomeric excess (ee) in initial nuclei and final products, demonstrating stability and recyclability.
Area of Science:
- Chiral chemistry
- Crystallization science
- Nanotechnology
Background:
- Racemic mixtures present challenges in chiral separation.
- Heterogeneous nucleation is a promising strategy for enantiomeric resolution.
- Chiral nanorods offer potential as effective nucleating agents.
Purpose of the Study:
- To synthesize chiral nanorods for heterogeneous nucleation.
- To enhance the enantiomeric resolution of racemic aspartic acid (Asp).
- To investigate the chiral recognition mechanism using computational simulations.
Main Methods:
- Synthesis of C14-l-Thea, C14-l-Phe, and C14-d-Phe chiral nanorods.
- Direct crystallization experiments using nanorods as heterogeneous nucleants.
- Statistical analysis of nucleation experiments (320 batches).
- Quantum mechanics (QM) and molecular dynamics (MD) simulations.
Main Results:
- Chiral nanorods significantly promoted nuclei of the same chirality and inhibited opposite enantiomers.
- Maximum enantiomeric excess (ee) of initial nuclei reached 23.51%.
- Product ee reached 76.85% with 14.41% yield under optimized conditions.
- C14-l-Thea showed superior chiral recognition compared to C14-l-Phe due to distinct interactions.
Conclusions:
- Chiral nanorods are effective heterogeneous nucleants for resolving racemic Asp.
- The nanorods demonstrate good stability and recyclability for practical applications.
- Computational simulations elucidated the mechanism behind differential chiral recognition.
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