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 41 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 21.