Wednesday, August 10, 2016

Enantioselective Amplification on Circularly Polarized laser-Induced Chiral Nucleation from a NaClO3 Solution Containing Ag Nanoparticles

Hiromasa Niinomi, Teruki Sugiyama, Miho Tagawa, Kenta Murayama, Shunta Harada and Toru Ujihara

We demonstrate that statistically-significant chiral bias in NaClO3 chiral crystallization can be provoked by inducing nucleation via the optical trapping of Ag nano-aggregates using continuous wave visible circularly polarized laser (λ= 532 nm). The laser was focused at the interface between air and an unsaturated NaClO3 aqueous solution containing Ag nanoparticles. The “dominant” enantiomorph was switchable by changing the handedness of the incident circularly polarized laser, indicating the chiral bias is enantioselective. Moreover, it has been found that the resulting crystal enantiomeric excess (CEE) reached approximately 25 %. The CEE is much higher than the typical enantiomeric excess (EE) in the asymmetric photosynthesis of organic compounds ranging from 0.5 to 2%. The efficient induction of the nucleation and the large chiral bias implies the contribution of localized surface plasmon resonance of the Ag nanoaggregates on chiral nucleation. Our method has a potential to offer the benefit for studies on the spatiotemporal nucleation control, optical resolution of chiral compounds and biohomochirality.
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