West LA Times

Researchers from UCLA and several partner institutions have discovered that the handedness, or chirality, of molecules influences the strength of coupling between nuclear spins. This finding challenges previous assumptions that chirality did not affect such couplings. The study involved researchers from Arizona State University, Penn State, MIT, and Technische Universität Dresden.

The research, published in Nature Communications, shows that in chiral molecules with a specific handedness—either left- or right-handed—the nuclear spin aligns in one direction. In contrast, molecules with opposite chirality exhibit alignment in the opposite direction. This discovery is significant as it contradicts decades-old beliefs about the independence of spin-spin coupling from molecular chirality.

Nuclear spins are quantum properties found within an atom's nucleus, consisting of protons and neutrons. These spins generate magnetic fields akin to bar magnets or electrical currents. When magnetic nuclei are near each other, they influence each other's spins through a process known as spin-spin coupling.

This phenomenon has applications in chemistry for determining molecular structures and in biomedical research through techniques like magnetic resonance spectroscopic imaging (MRSI). MRSI helps measure chemical concentrations in tissues for medical diagnostics and research purposes.

Understanding how nuclear spin states can be influenced by factors such as chirality could provide insights into electron spin roles in chemistry and biology. Chirality is a fundamental property where molecules exist as non-superimposable mirror images called enantiomers. Since 1999, scientists have recognized its impact on spin state but not on coupling until now.

Professor Louis Bouchard from UCLA highlighted the potential applications of this discovery: “We discovered that the coupling between nuclear spins can vary depending on whether the molecule is left-handed or right-handed.” He noted that this knowledge could help selectively probe molecules based on their chirality without disturbing chemical reactions involving chiral groups.

Bouchard further emphasized the need for improved methods to examine electrons' state and spin within chemical and biological systems: “This discovery adds a new tool to the chemistry and biochemistry toolboxes.”