Asymmetric chiral growth of micron-size NaClO3 crystals in water aerosols

We describe an aerosol-liquid cycle that launches the autocatalytic amplification of any initial imbalance of the order of
10
−
7
%
(1 ppb) up to total chiral purity in a single step process. Crystal nucleation of
NaClO
3
is initiated at the aerosol air-water interface where, due to the accumulation of ambient chiral impurities or added hydrophobic chiral aminoacids in tiny concentrations (ppb), the initial levorotatory (
l
) and dextrorotatory (
d
) excess will not be produced with equal probability. The enantiomeric yield is then enhanced up to homochirality by recycling the crystallites through a liquid phase. In the absence of added catalysts this process leads to preferential (
d
) homochiral crystallizations in a ratio of
4
∶
1
which is due to ambient contamination. By adding only 2 ppb of (
L
) or (
D
) Phe, we induce a final preferential homochiral crystallization of (
d
) or (
l
) handedness, respectively, in a ratio of
2
∶
1
.