Towards detection of molecular parity violation via chiral co-sensing: the 1H/31P model system

Abstract

Fundamental weak interactions have been shown to violate parity in both nuclear and atomic systems. However, observation of parity violation in a molecular system has proven an elusive target. Nuclear spin dependent contributions of the weak interaction are expected to result in energetic differences between enantiomers manifesting in nuclear magnetic resonance (NMR) spectra as chemical shift differences on the order of parts-per-trillion to parts-per-billion ($\upmu$Hz to mHz) for high-$Z$ nuclei. This method seeks to use simultaneous measurements of the diastereomeric splittings for a light and a heavy nucleus in solution-state NMR to resolve chemical shift differences persisting in a non-chiral environment between enantiomers of chiral compounds smaller than the typical high-field NMR linewidth. Sources of error must be identified and minimized to verify that the observed effect is, in fact, due to parity violation and not systematic effects. This paper presents a detailed analysis of a system incorporating $^{31}$P and $^{1}$H NMR to elucidate the systematic effects and to guide experiments with higher-$Z$ nuclei where molecular parity violation may be resolved.