Connecting structurally and dynamically detected signatures of supramolecular Debye liquids

Abstract

The monohydroxy alcohol 2-ethyl-1-hexanol mixed with the halogen-substituted alkyl halides 2-ethyl-1-hexyl chloride and 2-ethyl-1-hexyl bromide was studied using synchrotron-based x-ray scattering. In the diffraction patterns, an oxygen-related prepeak appears. The concentration dependence of its intensity, shape, and position indicates that the formation of the hydrogen-bonded associates of monohydroxy alcohols is largely hindered by the halogen alkane admixture. Using dielectric spectroscopy and high-resolution rheology on the same liquid mixtures, it is shown that these structural features are correlated with the relaxation mechanisms giving rise to supramolecular low-frequency dynamics.

Relationship between Nanoscale Supramolecular Structure, Effectiveness of Hydrogen Bonds, and Appearance of Debye Process

“…Recent thorough studies on a series of monohydroxy alcohols characterized by varying chemical backbone by means of broadband dielectric spectroscopy (BDS) shed new light on this issue. It was found that the characteristic prominent Debye (D) process, slower than the structural (α) relaxation, is most likely related to the dynamics of nanosized supramolecular structures. − In fact, variation in the relaxation time and dielectric strength of this mode was strictly connected to the change in the concentration, architecture (chain- or ring-like), and/or size of the associates formed at different conditions in these materials. , In this context it is worth to stress that systematic studies on 5-methyl-3-heptanol and 2-ethyl-1-hexanol revealed that the concentration of chain- and ring-like structures can be affected by the compression, high electric field, and dilution in low polar solvent. ,,− Finally, it should also be mentioned that recent reports have pointed out that the supramolecular organization in alcohols can be detected by other experimental methods like the dynamic light scattering and mechanical spectroscopy. ,, It is worth emphasizing that studies with the use of the latter method allowed to disentangle the impact of the variation in the geometry of the supramolecular structures and growing length of chain-like associates on the increase in the dielectric strength of the D-relaxation in the series of octanol isomers …”

Influence of High Pressure on the Local Order and Dynamical Properties of the Selected Azole Antifungals

“…Many simple as well as complex compounds possessing characteristic functional units, e.g., hydroxyl, amine, and thiol (H-bonded (HB) systems), or specific chemical motifs, such as long alkyl chains and aromatic moieties (van der Waals (vdW) materials), tend to self-assemble into supramolecular clusters that may organize themselves in domains obeying a few nanometers. − Although this phenomenon, influencing basic physical properties of soft materials, − water, or biological activity of proteins, is well-known and thoroughly studied, especially for binary and ternary mixtures, − its nature is much less understood for single-component supercooled systems. It is directly related to the fact that, in contrast to the investigations carried out in solutions, there are only a few experimental methods capable of detecting and monitoring the self-association process in neat supercooled liquids.…”

The dielectric response of phenothiazine-based glass-formers with different molecular complexity

“…In contrast, a sub-group of liquids with the ability to self-organization can be given, in which an additional slow Debye peak may appear 24 – 28 . Its emergence is usually accompanied by the presence of a so-called ‘pre-peak’ in the diffraction pattern before the main amorphous halo ubiquitous for ordinary liquids 29 . However, our knowledge of the relationships between the features of the supramolecular organization seen by the X-ray and neutron diffraction methods and the slow relaxation processes probed by the dielectric spectroscopy is still limited 30 .…”