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

We examined a series of structurally related glass-forming liquids in which a phenothiazine-based tricyclic core (PTZ) was modified by attaching n-alkyl chains of different lengths (n = 4, 8, 10). We systematically disentangled the impact of chemical structure modification on the intermolecular organization and molecular dynamics probed by broadband dielectric spectroscopy (BDS). X-ray diffraction (XRD) patterns evidenced that all PTZ-derivatives are not 'ordinary' liquids and form nanoscale clusters.

Broadband Dielectric Study of Sizable Molecular Glass Formers: Relationship Between Local Structure and Dynamics.

In this Letter we report significant differences in the dielectric behavior of four nonpolymeric and sizable glass-forming molecules with related chemical structures. They belong to the recently constituted class of sizable glass-formers [Jedrzejowska et al. 2020, 101, 010603], for which the pattern of change in dielectric properties with structure has not yet been fully discovered.

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

In this work, we report the synthesis, unexpected glass-forming properties, molecular dynamics and conformational analysis of two thiacrown ethers: 6-methyl-2,3-dihydro-1,4-benzodithiine (1), with a six-membered heterocyclic ring, and macrocyclic 2,3-(4'-methylbenzo)-1,4-dithia-7-oxacyclononane (2). Based on the calorimetric studies, we showed that compound 1 is a viscous liquid at room temperature undergoing vitrification at 192 K. Compound 2 is a crystalline solid at room temperature characterized by a melting point at 331 K; however, it can be vitrified with ease after being melted by cooling down to 224 K.

Theoretical and Experimental Study of Compression Effects on Structural Relaxation of Glass-Forming Liquids.

We develop the elastically collective nonlinear Langevin equation theory of bulk relaxation of glass-forming liquids to investigate molecular mobility under compression conditions. The applied pressure restricts more molecular motion and therefore significantly slows down the molecular dynamics when increasing the pressure. We quantitatively determine the temperature and pressure dependence of the structural relaxation time.

New paradigm of dielectric relaxation of sizable and rigid molecular glass formers.

In this Rapid Communication we report the unusual dynamics of planar, rigid, and anisotropy glass-forming molecules of unusually large size by dielectric spectroscopy by using two examples. The size of the molecules is much larger than the dipolar moiety located at the end of the longer axis of each molecule. The observed dynamics deviates strongly from the anticorrelation between β_{KWW} (fractional exponent of the Kohlrausch-Williams-Watts function) and dielectric strength, Δɛ(T_{g}), established generally for small van der Waals molecular glass formers.