Water-formamide mixtures: Topology of the hydrogen-bonded network

A neutron diffraction measurements and molecular dynamics simulations have been performed to study the hydrogen bonded structure of water-formamide mixtures. We showed that the calculated and measured total neutron diffraction radial distribution function agreed very well. After evaluation of this function, the hydrogen bonded structure of mixtures with various compositions has been studied, and the clustering properties and the topology of the hydrogen-bonded network were investigated. The results show that these mixtures exhibit an extended range structure in solution. In water-formamide mixtures the average number of hydrogen bonded neighbors (water, formamide) and the distribution of the number of H-bonded neighbors do not change significantly as a function of the formamide mole fraction. Molecules are shown to form percolated networks at each concentration. The composition of cyclic entities in these systems is very close to being ideal; that is, these systems are microscopically homogeneous. (C) 2016 Elsevier B.V. All rights reserved.