Temperature dependence of the hydrogen bond network in Trimethylamine N-oxide and guanidine hydrochloride - water solutions

TL;DR

This study uses X-ray Compton scattering to analyze how temperature affects the hydrogen bond network in water solutions with TMAO and GdnHCl, revealing concentration-dependent differences in bond weakening.

Contribution

It provides new insights into the temperature-dependent hydrogen bonding behavior in TMAO and GdnHCl aqueous solutions using Compton scattering.

Findings

Hydrogen bonds decrease with temperature in all samples.

TMAO reduces bond weakening up to 5M concentration.

GdnHCl shows a weaker impact on hydrogen bonds up to 3.1 M.

Abstract

We present an X-ray Compton scattering study on aqueous Trimethylamine N-oxide (TMAO) and guanidine hydrochloride solutions (GdnHCl) as a function of temperature. Independent from the concentration of the solvent, Compton profiles almost resemble results for liquid water as a function of temperature. However, The number of hydrogen bonds per water molecule extracted from the Compton profiles suggests a decrease of hydrogen bonds with rising temperatures for all studied samples, the differences between water and the solutions are weak. Nevertheless, the data indicate a reduced bond weakening with rising TMAO concentration up to 5M of 7.2% compared to 8 % for pure water. In contrast, the addition of GdnHCl appears to behave differently for concentrations up to 3.1 M with a weaker impact on the temperature response of the hydrogen bond structure.