Hydrogen-exchange kinetics studied through analysis of self-decoupling of nuclear magnetic resonance

Abstract

Hydrogen exchange between solute and water molecules occurs across a wide range of timescales. Rapid hydrogen-exchange processes can effectively diminish ¹H-¹⁵N scalar couplings. We demonstrate that the self-decoupling of ¹⁵N nuclear magnetic resonance can allow quantitative investigations of hydrogen exchange on a micro- to millisecond timescale, which is relatively difficult to analyze with other methods. Using a Liouvillian matrix incorporating hydrogen exchange as a mechanism for scalar relaxation, the hydrogen exchange rate can be determined from ¹⁵N NMR line shapes recorded with and without ¹H decoupling. Self-decoupling offers a simple approach to analyze the kinetics of hydrogen exchange in a wide range of timescale.

Keywords: Hydrogen exchange; Ions; Kinetics; Nuclear magnetic resonance; Self-decoupling.