Conformational analysis and molecular dynamics of glass-forming aromatic thiacrown ethers

Abstract

In this work we report synthesis, unexpected glass-forming properties, molecular dynamics and conformational analysis of two glass-forming thiacrown ethers: 6-methyl-2,3-dihydro-1,4-benzodithiine (1) of a six-membered heterocyclic ring and macrocyclic 2,3-(4’-methylbenzo)-1,4-dithia-7-oxacyclononane (2)....

Comparative Physical Study of Three Pharmaceutically Active Benzodiazepine Derivatives: Crystalline versus Amorphous State and Crystallization Tendency

“…Dielectric relaxation studies of flexible heterocyclic molecules are relatively uncommon, and, to the best of our knowledge, ours is one of the few dielectric spectroscopy studies that have provided a clear identification of the ring conformational dynamics in polycyclic molecules. 28,68,69 Finally, concerning the γ′ relaxation, both the range of temperature in which it is observed and its characteristic relaxation time are very different between DIA and TETRA, as mentioned, albeit that its activation energy is of the same order of magnitude in both compounds. Given that this relaxation is virtually absent in NOR, it is likely that it is suppressed or at least strongly hindered by the presence of intermolecular hydrogen bonds.…”

“…The same effect is expected to be visible for any relaxation process whose characteristic time is affected by the viscosity, and it could be that the interconversion rate between P and M conformers (γ relaxation time) is partially affected by changes of macroscopic properties of the sample such as its viscosity (although it cannot depend only on it, as Figure b shows). Dielectric relaxation studies of flexible heterocyclic molecules are relatively uncommon, and, to the best of our knowledge, ours is one of the few dielectric spectroscopy studies that have provided a clear identification of the ring conformational dynamics in polycyclic molecules. ,, …”

“…To the best of our knowledge, only a few very recent studies have focused on the interpretation of the dielectric relaxation of flexible heterocyclic molecules. 28 A further outcome of this work is therefore to expand the current experimental knowledge of the conformational dynamics of flexible cyclic or ring-containing molecules.…”

“…The study of molecular relaxation processes in diazepines is particularly interesting due to the inherent flexibility of the seven-membered diazepine ring, which leads to conformational diversity of the molecules and therefore to the possible existence of a relaxational inter-conformer conversion dynamics. To the best of our knowledge, only a few very recent studies have focused on the interpretation of the dielectric relaxation of flexible heterocyclic molecules . A further outcome of this work is therefore to expand the current experimental knowledge of the conformational dynamics of flexible cyclic or ring-containing molecules.…”

Glass transition, crystallization kinetics, and inter-conformer relaxation dynamics of amorphous mitotane and related compounds

“…4. Secondary relaxations are of two types: they may correspond either to intramolecular relaxation processes (e.g., interconversions between different molecular conformers, inversion dynamics of flexible rings, or reorientation of side groups) (Hellwig et al, 2020;Valenti et al, 2021), or else, they can stem from the local (subdiffusive), whole-molecule rototranslational relaxation dynamics known as Johari-Goldstein relaxation and which corresponds to the noncooperative version of the molecular motion responsible for the structural relaxation (Romanini et al, 2017;Caporaletti et al, 2019).…”