Neohexanol (2,2-dimethyl-1-butanol) and some of its isomers, differing for the positions of the OH and CH3 substituents, constitute a very interesting family of alcohols showing a rich polymorphism at low temperatures with several solid-solid phase transitions. Indeed, due to their globular shape and to the possibility to associate through hydrogen bonds, neohexanols give rise to orientationally disordered crystal (ODIC) phases and glasses of liquid and ODIC phases.1 In this work, we exploited 1H Fast Field-Cycling (FFC) NMR relaxometry2,3 for characterizing the molecular dynamic properties of 2,2-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, and 3,3-dimethyl-1-butanol, in the phases (ordered and orientationally disordered crystals, supercooled and isotropic liquids) formed upon different thermal treatments in the temperature range from -60 to 30 °C. The FFC NMR measurements were complemented by static 1H, 13C, and, in some cases, 2H solid state NMR spectroscopy experiments. The spectroscopic and relaxation data here acquired were analyzed and discussed in reference to data previously obtained on the investigated neohexanols by calorimetric techniques and dielectric spectroscopy in order to establish relationships between chemical structure, polymorphism, and dynamic properties. References: [1] E. Juszy?ska, M. Massalska-Arod?, I. Natkaniec, J. Krawczyk Physica B, 2008, 403,109-114 (2008); E. Juszy?ska-Ga??zka, P. M. Zieli?ski, M. Massalska-Arod?, J. Krawczyk Acta Phys. Pol. A 2013, 124, 917-925 (2013). [2] D. Kruk, A. Herrmann, E. A. Rössler Prog. Nucl. Mag. Reson. Spectrosc. 2012, 63, 33-64. [3] R. Kimmich, N. Fatkullin Prog. Nucl. Mag. Reson. Spectrosc. 2017, 101, 18-50.
Dynamics of dimethyl butanols in liquid, supercooled liquid, and orientationally disordered crystalline phases studied by 1H FFC NMR relaxometry
E Carignani;L Calucci;C Forte;M Geppi
2018
Abstract
Neohexanol (2,2-dimethyl-1-butanol) and some of its isomers, differing for the positions of the OH and CH3 substituents, constitute a very interesting family of alcohols showing a rich polymorphism at low temperatures with several solid-solid phase transitions. Indeed, due to their globular shape and to the possibility to associate through hydrogen bonds, neohexanols give rise to orientationally disordered crystal (ODIC) phases and glasses of liquid and ODIC phases.1 In this work, we exploited 1H Fast Field-Cycling (FFC) NMR relaxometry2,3 for characterizing the molecular dynamic properties of 2,2-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, and 3,3-dimethyl-1-butanol, in the phases (ordered and orientationally disordered crystals, supercooled and isotropic liquids) formed upon different thermal treatments in the temperature range from -60 to 30 °C. The FFC NMR measurements were complemented by static 1H, 13C, and, in some cases, 2H solid state NMR spectroscopy experiments. The spectroscopic and relaxation data here acquired were analyzed and discussed in reference to data previously obtained on the investigated neohexanols by calorimetric techniques and dielectric spectroscopy in order to establish relationships between chemical structure, polymorphism, and dynamic properties. References: [1] E. Juszy?ska, M. Massalska-Arod?, I. Natkaniec, J. Krawczyk Physica B, 2008, 403,109-114 (2008); E. Juszy?ska-Ga??zka, P. M. Zieli?ski, M. Massalska-Arod?, J. Krawczyk Acta Phys. Pol. A 2013, 124, 917-925 (2013). [2] D. Kruk, A. Herrmann, E. A. Rössler Prog. Nucl. Mag. Reson. Spectrosc. 2012, 63, 33-64. [3] R. Kimmich, N. Fatkullin Prog. Nucl. Mag. Reson. Spectrosc. 2017, 101, 18-50.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
