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Nowok A, Hellwig H, Dulski M, Książek M, Kusz J, Kuś P, Pawlus S. Revisiting Dynamic Processes and Relaxation Mechanisms in a Heterocyclic Glass-Former: Direct Observation of a Transient State. J Phys Chem B 2024; 128:1915-1926. [PMID: 38379513 PMCID: PMC10910497 DOI: 10.1021/acs.jpcb.3c06727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 01/10/2024] [Accepted: 02/07/2024] [Indexed: 02/22/2024]
Abstract
Despite decades of studies, a clear understanding of near-Tg phenomena remains challenging for glass-forming systems. This review delves into the intricate molecular dynamics of the small, heterocyclic thioether, 6-methyl-2,3-dihydro-1,4-benzodithiine (MeBzS2), with a particular focus on its near-Tg cold crystallization and relaxation mechanisms. Investigating isothermal crystallization kinetics at various temperatures reveals a significant interplay between its molecular dynamics and recrystallization from a supercooled liquid. We also identify two independent interconversion paths between energetically privileged conformers, characterized by strained transition states. We demonstrate that these spatial transformations induce substantial alterations in the dipole moment orientation and magnitude. Our investigation also extends to the complex salt PdCl2(MeBzS2), where we observe the transient conformers directly, revealing a direct relationship between their abundance and the local or macroscopic electric field. The initially energetically privileged isomers in an undisturbed system become less favored in the presence of an external electric field or ions, resulting even in an unexpected inversion of states. Consequently, we confirm the intramolecular character of secondary relaxation in MeBzS2 and its mechanism related to conformational changes within the heterocyclic ring. The research is based on the combination of broadband dielectric spectroscopy, X-ray diffraction, and quantum density functional theory calculations.
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Affiliation(s)
- Andrzej Nowok
- Department
of Experimental Physics, Wrocław University
of Science and Technology, Wybrzeże Wyspiańskiego 27, Wrocław 50-370, Poland
- Laboratoire
National des Champs Magnétiques Intenses, EMFL, CNRS UPR 3228,
Université Toulouse, Université
Toulouse 3, INSA-T, Toulouse 31400, France
| | - Hubert Hellwig
- Center
for Integrated Technology and Organic Synthesis (CiTOS), MolSys Research
Unit, University of Liège, B6a, Room 3/19, Allée Du
Six Août 13, Liège, Sart Tilman 4000, Belgium
| | - Mateusz Dulski
- Faculty
of Science and Technology, Institute of Materials Engineering, University of Silesia in Katowice, 75 Pułku Piechoty 1A, Chorzów 41-500, Poland
| | - Maria Książek
- August
Chełkowski Institute of Physics, University
of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - Joachim Kusz
- August
Chełkowski Institute of Physics, University
of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
| | - Piotr Kuś
- Institute
of Chemistry, University of Silesia in Katowice, Szkolna 9, Katowice 40-003, Poland
| | - Sebastian Pawlus
- August
Chełkowski Institute of Physics, University
of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland
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Arrese-Igor S, Alegría A, Colmenero J. Non-simple flow behavior in a polar van der Waals liquid: Structural relaxation under scrutiny. J Chem Phys 2023; 158:2888210. [PMID: 37139999 DOI: 10.1063/5.0145433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/06/2023] [Indexed: 05/05/2023] Open
Abstract
The non-exponential character of the structural relaxation is considered one of the hallmarks of the glassy dynamics, and in this context, the relatively narrow shape observed by dielectric techniques for polar glass formers has attracted the attention of the community for long time. This work addresses the phenomenology and role of specific non-covalent interactions in the structural relaxation of glass-forming liquids by the study of polar tributyl phosphate. We show that dipole interactions can couple to shear stress and modify the flow behavior, preventing the occurrence of the simple liquid behavior. We discuss our findings in the general framework of glassy dynamics and the role of intermolecular interactions.
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Affiliation(s)
- S Arrese-Igor
- Centro de de Física de Materiales (MPC), Centro Mixto CSIC-UPV/EHU, Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain
| | - A Alegría
- Centro de de Física de Materiales (MPC), Centro Mixto CSIC-UPV/EHU, Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain
- Departamento de Polímeros y Materiales Avanzados UPV/EHU, Apartado 1072, 20080 San Sebastián, Spain
| | - J Colmenero
- Centro de de Física de Materiales (MPC), Centro Mixto CSIC-UPV/EHU, Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain
- Departamento de Polímeros y Materiales Avanzados UPV/EHU, Apartado 1072, 20080 San Sebastián, Spain
- Donostia International Physics Center, Paseo Manuel Lardizabal 5, 20018 San Sebastián, Spain
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Cibotaru S, Nicolescu A, Marin L. Dynamic PEGylated phenothiazine imines; synthesis, photophysical behavior and reversible luminescence switching in response to external stimuli. J Photochem Photobiol A Chem 2023. [DOI: 10.1016/j.jphotochem.2022.114282] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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