Deuterium Isotope Effects on Hydrophobic Interactions:  The Importance of Dispersion Interactions in the Hydrophobic Phase

Abstract

Hydrogen/deuterium isotope effects on hydrophobic binding were examined by means of reversed-phase chromatographic separation of protiated and deuterated isotopologue pairs for a set of 10 nonpolar and low-polarity compounds with 10 stationary phases having alkyl and aryl groups bonded to the silica surface. It was found that protiated compounds bind to nonpolar moieties attached to silica more strongly than deuterated ones, demonstrating that the CH/CD bonds of the solutes are weakened or have less restricted motions when bound in the stationary phase compared with the aqueous solvent (mobile phase). The interactions responsible for binding have been further characterized by studies of the effects of changes in mobile phase composition, temperature dependence of binding, and QSRR (quantitative structure-chromatographic retention relationship) analysis, demonstrating the importance of enthalpic effects in binding and differentiation between the isotopologues. To explain our results showing the active role of the hydrophobic (stationary) phase we propose a plausible model that includes specific contributions from aromatic edge-to-face attractive interactions and attractive interactions of aliphatic groups with the pi clouds of aromatic groups present as the solute or in the stationary phase.

The isotopic effects of deuteration on optoelectronic properties of conducting polymers

“…These factors could in principle lead to a change of non-covalent (for example, hydrogen bonding, CH-p, p-p, and cation-p) interactions upon deuteration. There have been a few studies in the past showing that deuteration of C-H oscillators can lead to decreased non-covalent interactions in a non-conjugated system, but the observed differences were too small to be statistically significant, and the exact causality could therefore not be established unambiguously [5][6][7][8] .…”

Retention Behavior of Halogenated Benzenes on a Stationary Phase Having a 2,4-Dibromophenoxy Group as the Halogen Recognition Functional Group

“…[13][14][15] They showed that the 3-(pentabromobenzyloxy)-propyl (PBB) group immobilizes silica (PBB-silica) and had a high specificity for halogenated benzenes based on the dispersibility. The separation factors α value calculated from the retention factors of dihalogenated benzenes and p-xylene on the DBP-resin in this study were all larger than those reported for the PBB-silica in the previous study (Table 2).…”

“…Tanaka and coworkers [13][14][15] developed several silica stationary phases immobilized with halogenated aromatic rings to examine the dispersibility of heavy atoms. These columns were used to separate fullerene isomers, halogenated compounds and deuterium compounds.…”

Testing odorant-receptor interaction theories in humans through discrimination of isotopomers

“…However, it has to be noted that some physical properties, such as the molecule's dispersion forces, are also slightly changed by the deuteration. 23,24 By now, various behavioural studies of isotopomer discrimination were performed in humans, [24][25][26] in Drosophila, 20,27 and in honeybees. 28 While outcomes of human tests were mixed, insect behavioural tests showed isotopomer discrimination.…”