TY - JOUR

T1 - Glass-like behavior of intercalated organic solvents in graphite oxide detected by spin-probe EPR

AU - Syryamina, Victoria N

AU - Astvatsaturov, Dmitry A

AU - Dzuba, Sergei A

AU - Chumakova, Natalia A

N1 - This work was supported by the Russian Science Foundation (grant number 23-23-00016), and, partially, by the Lomonosov Moscow State University Program of Development. V.N.S. and S.A.D. (Voevodsky Institute of Chemical Kinetics and Combustion SB RAS) acknowledge the core funding from the Russian Federal Ministry of Science and Higher Education (FWGF-FWGF-2021-0003).

PY - 2023/9/27

Y1 - 2023/9/27

N2 - Membranes based on graphite oxide (GO) are promising materials for the separation of polar liquids and gases. Understanding the properties of solvents immersed in GO is important for the development of various technological applications. Here, the molecular motions of the TEMPO nitroxide spin probe in acetonitrile intercalated into the GO inter-plane space were studied using electron paramagnetic resonance (EPR), including its pulsed version, and electron spin echo (ESE). For a sample containing 75% acetonitrile relative to equilibrium sorption at room temperature, ESE-detected stochastic librations were observed for TEMPO molecules above 135 K. Since these librations are an inherent property of molecular glasses, this fact indicates that intercalated acetonitrile forms a two-dimensional glass state. Above 225 K, an acceleration of stochastic librations was observed, indicating the manifestation of a glass-like dynamical cross-over. Continuous wave (CW) EPR spectra of TEMPO showed the absence of overall tumbling motions in the entire investigated temperature range of up to 340 K, indicating that the intercalated acetonitrile does not behave as a bulk liquid (the melting point of acetonitrile is 229 K). Dynamical librations of TEMPO molecules detected by CW EPR were found to accelerate above 240 K.

AB - Membranes based on graphite oxide (GO) are promising materials for the separation of polar liquids and gases. Understanding the properties of solvents immersed in GO is important for the development of various technological applications. Here, the molecular motions of the TEMPO nitroxide spin probe in acetonitrile intercalated into the GO inter-plane space were studied using electron paramagnetic resonance (EPR), including its pulsed version, and electron spin echo (ESE). For a sample containing 75% acetonitrile relative to equilibrium sorption at room temperature, ESE-detected stochastic librations were observed for TEMPO molecules above 135 K. Since these librations are an inherent property of molecular glasses, this fact indicates that intercalated acetonitrile forms a two-dimensional glass state. Above 225 K, an acceleration of stochastic librations was observed, indicating the manifestation of a glass-like dynamical cross-over. Continuous wave (CW) EPR spectra of TEMPO showed the absence of overall tumbling motions in the entire investigated temperature range of up to 340 K, indicating that the intercalated acetonitrile does not behave as a bulk liquid (the melting point of acetonitrile is 229 K). Dynamical librations of TEMPO molecules detected by CW EPR were found to accelerate above 240 K.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85172791432&origin=inward&txGid=b3071c1d8425cdc342650bf2574409dd

UR - https://www.mendeley.com/catalogue/91a008d9-3b0e-38e1-b96a-ce9ba6e1360e/

U2 - 10.1039/d3cp03253a

DO - 10.1039/d3cp03253a

M3 - Article

C2 - 37721717

VL - 25

SP - 25720

EP - 25727

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 37

ER -