Heteronukleare

Heteronukleare is a term used in physics and chemistry to describe phenomena or measurements that involve nuclei of different types. In practice it is most common in nuclear magnetic resonance (NMR) spectroscopy, where heteronukleare interactions occur between nuclei of distinct nuclear species or isotopes.

In NMR, heteronukleare couplings connect nuclei such as hydrogen with carbon-13, nitrogen-15, phosphorus-31, or fluorine-19. These couplings can be scalar (J) couplings or dipolar couplings and are exploited to reveal connectivities between atoms and to aid resonance assignment, often in molecules where multiple types of nuclei are present.

Two-dimensional NMR experiments that rely on heteronukleare interactions include HSQC, HMQC, HMBC, and HETCOR. These methods correlate protons with a heteronucleus and help determine how atoms are connected, providing structural information that complements homonuclear experiments. In solid-state NMR, heteronuklear correlations arising from dipolar couplings are also used, with techniques such as REDOR and related methods to study distances between different nuclei in solids.

Heteronukleare contrasts with homonukleare interactions, which occur between nuclei of the same type, such as 1H-1H couplings. The use of heteronukleare information expands the range of nuclei that can be observed and increases the level of structural detail attainable, particularly for complex organic compounds, biomolecules, and materials.

Etymology and scope: the term derives from Greek heteros meaning other and nucleus, reflecting interactions between different nuclear species. While often framed in NMR, the concept also appears in other spectroscopic and analytical contexts that involve multiple nuclear types.