Perdeuteration

Perdeuteration is the chemical modification of a molecule in which essentially every hydrogen atom is replaced by the isotope deuterium. The resulting perdeuterated species is used as a tool in various scientific fields, particularly where isotope effects or neutron interactions are important. The term often implies near-complete replacement of C-H, N-H, O-H, and other X-H bonds, though practical perdeuteration may leave small fractions of remaining hydrogen.

In practice, perdeuteration is challenging for large, complex molecules, but it is routinely achieved for smaller molecules and many biomolecules through several approaches. These include synthesis with deuterated reagents, hydrogen–deuterium exchange for labile hydrogens, and biological production in deuterated media using D2O and deuterated carbon sources. For proteins and other biomolecules, expression in deuterated water or growth media, sometimes combined with selective protonation strategies, is common to obtain high levels of deuteration.

Applications are broad in physical chemistry, structural biology, and materials science. In neutron scattering and neutron diffraction, perdeuteration reduces incoherent scattering from hydrogen and improves contrast, facilitating more accurate structural analyses. In nuclear magnetic resonance spectroscopy, extensive deuteration suppresses background proton signals and simplifies spectra, aiding studies of large molecules. Perdeuteration can also influence vibrational spectroscopy, thermodynamic properties, and kinetic isotope effects, which may affect reactivity and stability.

Limitations include high cost, synthetic difficulty, and potential alterations to structure and function due to isotopic substitution.