Nuclear spin effects in molecular chirality

• Applicant: Dr. Andrey Yachmenev
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas ; Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 572502325

The discovery of the critical role of electron spin in chiral molecular interactions (Chirality-Induced Spin Selectivity (CISS) effect) is transforming our understanding of intermolecular forces in chemistry and biology. Traditionally, enantioselectivity, i.e., the ability of chiral molecules to interact differently with left- and right-handed counterparts, was attributed primarily to differences in relative molecular structures and charge distributions of interacting species. However, the CISS effect reveals that even subtle interactions, such as spin exchange and spin-orbit coupling, may play a critical role in these processes. Building on this insight, we propose to conduct theoretical quantum mechanical studies of the role of nuclear spins in molecular chirality. Despite being weaker than electron spins and electrostatic forces, nuclear spins can substantially influence chiral interactions due to their entanglement with spatial nuclear and electronic quantum states. We propose that nuclear spin symmetry breaking, driven by internal hyperfine interactions, such as nuclear quadrupole, spin-rotation, and spin-spin interactions, combined with the inherent parity symmetry breaking in chiral molecules, leads to the polarization of nuclear spin density. This polarized nuclear spin density is intrinsically linked to the absolute molecular structure through the anisotropy of hyperfine tensors, offering new insights into molecular chirality. The interdisciplinary impact of this study could advance experimental efforts in parity violation measurements, particularly in the nuclear-spin-dependent domain. Moreover, linking nuclear spin polarization with electronic CISS could bridge existing gaps in understanding spin-induced enantioselectivity and the interplay between spin and molecular chirality. The remarkable stability of nuclear spin states suggests that these mechanisms could serve as new markers for tracing the history of chiral molecules in cosmic environments, potentially offering insights into the origins of homochirality in life on Earth.

• DFG Programme: Research Grants