Spontaneous Emergence of Homochiral Suspensions from Racemic Solutions via Stochastic Nucleation

Area of Science:

• Astrobiology
• Organic Chemistry
• Crystallography

Background:

• Homochirality is essential for life, but its origin on early Earth is unclear.
• Chiral molecules exist as non-superimposable mirror images (enantiomers).
• A racemic mixture contains equal amounts of both enantiomers.

Purpose of the Study:

• To demonstrate a spontaneous pathway for homochirality emergence from a racemic solution.
• To investigate the role of temperature fluctuations and a base in deracemization.
• To explore the formation of global homochirality from local homochiral states.

Main Methods:

• Utilized a conglomerate-forming chiral species, N-(2-methylbenzylidene)-phenylglycine amide (NMPA).
• Established supersaturated conditions via solvent evaporation or cooling.
• Employed stochastic modeling and laboratory experiments with temperature cycling and a base (DBU).

Main Results:

• Observed spontaneous evolution from a racemic to a homochiral state.
• Demonstrated symmetry breaking via stochastic nucleation of enantiopure crystals.
• Confirmed asymmetry amplification and complete deracemization through temperature fluctuations.

Conclusions:

• The proposed pathway, involving supersaturation, nucleation, and deracemization, is plausible.
• Conditions required for this pathway likely existed on prebiotic Earth.
• This mechanism may have contributed to the origin of homochirality in early life.