Chemical Complexity and Consequent Homochirality from Weak Neutral Currents Acting upon Paramagnetic Enantiomers

Abstract

It is certain that the origin of chiral excess must have arrived very early in the chemistry leading to the origin of life. Either chiral excess was initiated by one of the four universal forces or it was a result of a statistical thermodynamic fluctuation in the confines of the electromagnetic force involving a second law violation, followed by an unlikely amplification. Only the weak force expresses parity violation, arising from weak neutral currents, as a force of nature. For over 5 decades, weak-force parity violation’s role in the biomolecular selection, and consequently in homochirality, remains significant and beyond possible exclusion. Yamagata originally proposed that weak neutral currents interacting with Earth’s natural racemic materials lead to terrestrial homochirality. However, a number of authors have shown that the energy available in the electroweak field is insufficient to generate a chiral excess on Earth, even with a significant autocatalytic amplification process. Here, we revive the most important aspect of the hypothesis that the weak force is the origin of homochirality but caveat that the phenomena originally took place far from Earth via neutrino–electron interactions. Neutrinos exhibit chirality; only left-handed neutrinos interact with the weak force. Neutrino chirality can be quantum mechanically described by either right- or left-handed wave functions, Ψ(R) or Ψ(L). Unlike electrons, neutrinos travel near the speed of light, very rarely interact with matter, and are born only with left-handed chirality (Ψ(ν,L)). Conversely, antineutrinos only have right-handed chirality. Left-handed neutrinos interact preferentially with like-handed fermions (e.g., left-handed translating electrons). The unpaired electron in a stationary chiral radical transmits spin density into the chiral structure and is thus itself chiral. Consequently, when polarized (in either the “up” or “down” spin state) by a strong B-field, its chirality (Ψ(ρ,R) or Ψ(ρ,L)) is locked in place. The left-handed neutrinos interact preferentially with chiral radicals (via the weak-force Hamiltonian, H w) that have a complementary left-handed chirality: ⟨Ψ(ρ,L)|H w|Ψ(ν,L)⟩ is greater than ⟨Ψ(ρ,R)|H w|Ψ(ν,L) ⟩. In areas where there exist a very large neutrino (ν) flux and a very large B-field, as in the vicinity of a collapsing white dwarf, parity-violating neutrino-free radical reactions lead to an enantiomeric excess. The neutrino–electron scattering is mediated by the Zo boson, wherein the handedness of the neutrino leads to preferential interactions with one of the radical enantiomers: stereoselective neutrino unpaired electron ejection. This is consistent with predictions of Senami and Ito who have pointed out that, in space, one of an enantiomeric pair can be selectively destroyed by interactions with astronomical particles, such as neutrinos. As in the case of Hazen’s ur-minerals, hyperbolic ejection exports the weak force-generated ur-enantiomers upon the rest of the cosmos.

Chiral selectivity vs. noise in spontaneous mirror symmetry breaking

“…This scenario, called spontaneous mirror symmetry breaking (SMSB), bridges the gap between laboratory and prebiotic chemistries, since it is now widely accepted that enantiomeric excesses appeared very soon before the origin of life. 8–12…”

“…This scenario, called spontaneous mirror symmetry breaking (SMSB), bridges the gap between laboratory and prebiotic chemistries, since it is now widely accepted that enantiomeric excesses appeared very soon before the origin of life. [8][9][10][11][12] However, due to fluctuations and in the absence of any chiral polarization, there is a stochastic distribution of chiral signs around the ideal racemic composition. It is important to emphasize that SMSB represents a genuine bifurcation scenario, which can be highly sensitive to even slight chiral biases.…”

Origin of Chirality in the Molecules of Life

“…However, alternative pathways to achieve chiral selectivity have been identified. Kondepudi and Nelson have detailed the circumstances under which autocatalysis would provide a viable kinetic pathway to achieve such an outcome, ,, and Stevenson and Davis have considered the influence of weak neutral currents on paramagnetic enantiomers . In terms of a reversible Frank-type model, autocatalysis provides a mechanism that allows one enantiomer to dominate even under conditions of random fluctuations.…”

“…Kondepudi and Nelson have detailed the circumstances under which autocatalysis would provide a viable kinetic pathway to achieve such an outcome, 26,28,29 and Stevenson and Davis have considered the influence of weak neutral currents on paramagnetic enantiomers. 30 In terms of a reversible Franktype model, autocatalysis provides a mechanism that allows one enantiomer to dominate even under conditions of random fluctuations. They estimated time frames of the order of up to 100,000 years for such selectivity to arise, but these would depend on reaction rates, local concentrations, a continuous provision of starting materials, diffusion rates, and reaction reversibility.…”