Effect of beta radiation on the crystallization of sodium chlorate from water: A new type of asymmetric synthesis

Abstract

Sodium chlorate is an achiral molecule that crystallizes from water in the chiral space group P2(1)3. In the absence of chiral perturbations, a random distribution of (+) and (-) crystals is obtained. Kondepudi(2) has shown that constantly stirring an evaporating NaClO(3) solution gives mostly either (+) or (-) crystals. Repeating this experiment many times gives equal numbers of (+) and (-) sets of crystals. Herein we report that when evaporating aqueous NaClO(3) is subjected to beta particles from an Sr-90 source, an asymmetric distribution of (+) and (-) crystals favoring the (+) crystals is obtained. The beta particles are energetic polarized electrons that are approximately 80% of left-handed helicity. By a poorly understood mechanism, the spin polarized electrons produce chiral nucleating sites that favor formation of the (+)-NaClO(3) crystals. Exposure of the evaporating solution instead to energetic positrons from an Na-22 source yields mainly (-)-NaClO(3) crystals. Polarized positrons are of predominantly right-handed helicity. One may conclude that the chirality of the radiation is correlated with the chirality of the crystals being generated.

Untitled

“…Experimental findings that BioDisc-3 may alter the structure of water cannot fully explain chiral symmetry breaking in this study. This is consistent with earlier research demonstrating that certain external treatments, beta and positron radiation, lead to chiral symmetry breaking for this crystal system (Mahurin et al, 2001). In addition, a direct current electric field stimulation (3.5 -17.5 V/cm) of the aqueous solution was also shown to yield more dcrystals (Chen and Chen, 2006).…”

“…2002). Solutions exposed to beta particles, which are spinpolarized, from radioactive 38 Sr 90 , yielded predominantly d-crystals (Mahurin et al, 2001). NaClO3 crystallizations exposed to positrons, which are spin-polarized in a direction opposite that of beta particles, from radioactive Is there an effect of various subtle external stimuli, some of which purportedly affect water structure, on chiral symmetry breaking during sodium chlorate crystallization?…”

Positron scattering from chiral enantiomers

“…An excellent summary of that work from the University of Michigan can also be found in Rich [7]. A somewhat more recent relevant study, on the effect of β radiation on the crystallization of sodium chlorate from water, by Mahurin et al [8] concluded that the polarization of the electrons (in this case) was correlated with the chirality of the crystals being generated. Finally, for completeness, we also note that early work on the origins of biological chirality was also conducted with energetic β particles rather than slow β particles.…”

Characterization of unidirectionally grown NaCl1−xBrxO3 crystals

“…Both NaClO 3 and NaBrO 3 are cubic with space group P2 1 3. The convenient determination of crystal chirality without orientation makes NaClO 3 an ideal material for the investigation of crystal chiral symmetry breaking ͑Kondepudi et al., 1990;Mahurin et al, 2001;Chen and Chen, 2007;Song et al, 2008͒. There are a number of studies on the investigations of the mechanism of chiral symmetry breaking of NaClO 3 crystals ͑Kondepudi et al., 1990;Martin et al, 1996;Cartwright et al, 2004;Viedma, 2004;Viedma, 2005͒. However, studies of the chirality of NaCl 1−x Br x O 3 mixed crystals are few.…”