Abstract

A quantitative characteristic of associations in solutions can be determined by calculating the fraction of molecules of each component containing a specified number of molecules of the same or another component in their immediate environment. In our previous work [1], we considered the proximity only between solute molecules. The analysis of calculated characteristics revealed features of structural changes exhibited by aqueous tert-butyl alcohol (TBA) and trimethylamine oxide (TMAO) solutions upon the concentration increase. In the present study, we apply this approach to other types of neighborhoods and consider water molecules surrounded by solute molecules and solute molecules surrounded by water molecules. The obtained data provide additional important information on the structural features of the studied solutions. It is shown that the TBA solutions have a heterogeneous structure manifested both as the presence of close aggregates of alcohol molecules and as the preservation of water regions composed of water molecule containing only water molecules in their environment.