Inherent heterogeneities and nanostructural anomalies in organic glasses revealed by EPR

Abstract

Intriguing heterogeneities and nanostructural reorganizations of glassy ionic liquids (ILs) have recently been found using electron paramagnetic resonance (EPR) spectroscopy. Alkyl chains of IL cations play the key role in...

Structural properties of supercooled deep eutectic solvents: choline chloride–thiourea compared to reline

“…Spectra in Fig. 1 may be assigned to a mixture of immobile and mobile tempone components (see simulations of the analogous spectra performed for glassy ILs in Fedin's group 23–31 ). The appearance of three isosbestic points (Fig.…”

“…Spin-probe EPR, in its conventional continuous wave (CW) version and in the pulsed version of electron spin echo (ESE) spectroscopy, has been shown to be a promising tool for elucidating features of molecular packing in glassy ILs. 23–31 In these studies, density/rigidity heterogeneities in ILs were found near the glass transition temperature ( T g ), with nanostructural anomalies revealed.…”

Structural Anomaly in Glasses: Molecular Dynamics Study of Organic Radical in Dibutylphthalate at Different Temperatures

“…Furthermore, it was found that some non-IL compounds, such as those mimicking imidazolium cations, also exhibit similar structural anomalies. In particular, this was clearly evidenced experimentally for phthalates [ 14 ]. However, despite the clear role of alkyl chains, the mechanism of such anomalies is still far from being understood.…”

“…Molecular Dynamics (MD) simulations are and have been actively employed to understand the local structures and dynamics of various molecular liquids and their glasses [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. Therefore, we used MD in an attempt to explain the structural anomalies previously observed in ILs [ 11 ] and phthalates [ 14 ]. The MD studies of ILs are more challenging compared to phthalates, because of the precise treatment required due to the charged nature of ILs.…”

“…Therefore, in this work we performed the first in-depth study of structural anomalies in dibutyl phthalate (DBP) and compared our results with previously obtained experimental data. The experiments were conducted using electron paramagnetic resonance (EPR) spectroscopy, where the mobility of DBP was measured vs. temperature [ 11 , 14 ]. Two types of motion—large-scale diffusive rotation and small-angle wobbling (below referred to as stochastic molecular librations) were identified and investigated.…”