Control of chiral symmetry breaking: Interplay between achiral reactant concentration and diffusive asymmetries

Chiral environments can bias the diffusion of enantiomers, a phenomenon known as chiral diffusive asymmetry (CDA). Such asymmetry provides a potential route to chiral symmetry breaking (CSB), a central process in deracemization and the emergence of homochirality. Here, we combine a Kondepudi-type reaction scheme with reaction-diffusion simulations to demonstrate that CDA, when coupled to a spatially nonuniform concentration of an achiral precursor, can induce CSB even in the absence of an initial enantiomeric excess. The resulting handedness is determined by the precursor distribution, providing a control parameter that is more experimentally accessible than diffusion asymmetry itself. We identify a mechanism in which CSB arises through the nucleation and growth of chiral domains, fueled by the mean precursor concentration and guided by its gradient. We further show that a linear relation captures the balance between CDA and precursor distribution, enabling predictive control of CSB.