Chirally autocatalytic reaction performed in highly supersaturated conditions

Spontaneous chiral asymmetry generation, which is the preferential producti on of one enantiomer in a non-chiral environment by chiral autocatalysis, c ould be observed in a preparation of a octahedral cobalt complex, cis-[CoBr (NH3)(en)(2)]Br-2. A concentration fluctuation in a far-from-equilibrium ch emical system will grow if the rate of local autocatalytic production of a compound in a small volume overcomes its loss due to diffusion. In a chiral ly autocatalytic system, this phenomenon could produce a large variation in the enantiomeric excess. In a reaction that produces the cobalt complex, t he reaction rate was found to increase in the highly supersaturated solutio n of the product. In supersaturated solutions, before crystals of the solut e have nucleated, embryos, which are the clusters of the solute, are formed . Ternary water-solubility isotherm of each enantiomer of the cobalt comple x suggests that each embryo consists of one exclusive enantiomer. Each chir al cluster, which could be regarded as polymeric material, thus formed in a highly supersaturated solution, may act as catalyst for the production of the same enantiomer. Life is a far-from-equilibrium self-organized polymeri c system in which chiral symmetry is broken. This reaction system is thus a model for the generation and amplification of chiral asymmetry in polymeri c materials; it provides some insight in to the mechanisms that might have produced the observed biomolecular homochirality.