Non-Covalent Isotope Effects

Abstract

In this Perspective, we present examples of isotope effects that originate from noncovalent interactions, mainly hydrogen bonding, electrostatics, and confinement. They are traditionally widely used in isotopic enrichment processes, as well as in studies of mechanisms of different (bio)chemical and physical phenomena. We then show the emerging areas of their applications, mainly medical and material sciences. We stress that these emerging applications require either high enrichment or isotopic substitution, which requires the development of new effective techniques of isotopic purification.

Graphene-based electrochemical system for tritium enrichment

“…Electrostatic interaction between oxygen in the sulfonate group and hydrogen in hydroxonium ions has been reported to be much stronger in SPEEK than in Nafion TM , leading to a lower diffusion coefficient of H 3 O + in SPEEK [30]. A slower diffusion process through the membrane can lead to a better separation due to the contribution of the isotopic effect in electrostatic interactions [31] in addition to the kinetics of the hydrogen evolution reaction of different isotopes [12]. Therefore, a higher separation factor using SPEEK as a PEM was expected.…”

Determining the chemical composition of diamagnetic mixed solids via measurements of their magnetic susceptibility

“…1–5 The ions can also be replaced by the same element but with a different isotope. 6 During the synthesis process of a sample with such mixed concentrations, often the chemical composition of the final product is different than the molar ratios of the starting solution. For example, a solution comprising deionized H 2 O with 85% of NH 4 I and 15% of KI powder yields crystals of the composition NH 4 I 0.83 K 0.17 .…”

“…11,12 In contrast, research on deliberate synthesis of compounds with mixed isotopes remains in its infancy. 6,10 Nevertheless, more and more applications with mixed isotopes are flourishing and accurate determination of their isotope concentrations is increasing in demand. For instance, precision deuteration of pharmaceutical drugs may favorably alter their pharmacokinetics and metabolic rates; 13 selective substitution of hydrogen by deuterium can result in different photoelectronic responses in conducting polymers; 14,15 and partial replacement of H by D, such as NH 3.36 D 0.64 Br, induces a ferroelectric phase.…”