Study of Liquid Crystals Showing Two Isotropic Phases by <sup>1</sup>H NMR Diffusometry and <sup>1</sup>H NMR Relaxometry
In this work, we report a study of two thermotropic liquid crystalline samples showing a not common mesophase behavior. The samples, namely a di-benzyloxy biphenyl derivative labelled <b>9/2 RS/RS</b>, and a bimesogenic liquid crystal labelled <b>L1</b>, show a direct transit...
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MDPI AG
2019-03-01
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| Series: | Crystals |
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| Online Access: | https://www.mdpi.com/2073-4352/9/3/178 |
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| author | Anton Gradišek Mario Cifelli Michal Wojcik Tomaž Apih Sergey V. Dvinskikh Ewa Gorecka Valentina Domenici |
| author_facet | Anton Gradišek Mario Cifelli Michal Wojcik Tomaž Apih Sergey V. Dvinskikh Ewa Gorecka Valentina Domenici |
| author_sort | Anton Gradišek |
| collection | DOAJ |
| description | In this work, we report a study of two thermotropic liquid crystalline samples showing a not common mesophase behavior. The samples, namely a di-benzyloxy biphenyl derivative labelled <b>9/2 RS/RS</b>, and a bimesogenic liquid crystal labelled <b>L1</b>, show a direct transition between two isotropic phases followed, at lower temperatures, by the optically isotropic, 3D structured, cubic phase. These systems have been investigated by means of <sup>1</sup>H NMR diffusometry and <sup>1</sup>H NMR relaxometry in order to characterize their isotropic–isotropic’–cubic mesophase behavior, mainly on the dynamic point of view. In particular, the temperature trend of the self-diffusion coefficients measured for both samples allowed us to significantly distinguish between the two isotropic phases, while the temperature dependence of the <sup>1</sup>H spin-lattice relaxation time (T<sub>1</sub>) did not show significant discontinuities at the isotropic–isotropic’ phase transition. A preliminary analysis of the frequency-dependence of <sup>1</sup>H T<sub>1</sub> at different temperatures gives information about the main motional processes active in the isotropic mesophases. |
| first_indexed | 2024-04-11T18:46:27Z |
| format | Article |
| id | doaj.art-8ba2ada656c64bc2abcc80d6618ab8ba |
| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-04-11T18:46:27Z |
| publishDate | 2019-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Crystals |
| spelling | doaj.art-8ba2ada656c64bc2abcc80d6618ab8ba2022-12-22T04:08:48ZengMDPI AGCrystals2073-43522019-03-019317810.3390/cryst9030178cryst9030178Study of Liquid Crystals Showing Two Isotropic Phases by <sup>1</sup>H NMR Diffusometry and <sup>1</sup>H NMR RelaxometryAnton Gradišek0Mario Cifelli1Michal Wojcik2Tomaž Apih3Sergey V. Dvinskikh4Ewa Gorecka5Valentina Domenici6Department of Solid State Physics, Jožef Stefan Institute, SI-1000 Ljubljana, SloveniaDipartimento di Chimica e Chimica Industriale, Università di Pisa, 56124 Pisa, ItalyDepartment of Chemistry, University of Warsaw, 02-093 Warsaw, PolandDepartment of Solid State Physics, Jožef Stefan Institute, SI-1000 Ljubljana, SloveniaDepartment of Chemistry, KTH Royal Institute of Technology, SE-100 44 Stockholm, SwedenDepartment of Chemistry, University of Warsaw, 02-093 Warsaw, PolandDipartimento di Chimica e Chimica Industriale, Università di Pisa, 56124 Pisa, ItalyIn this work, we report a study of two thermotropic liquid crystalline samples showing a not common mesophase behavior. The samples, namely a di-benzyloxy biphenyl derivative labelled <b>9/2 RS/RS</b>, and a bimesogenic liquid crystal labelled <b>L1</b>, show a direct transition between two isotropic phases followed, at lower temperatures, by the optically isotropic, 3D structured, cubic phase. These systems have been investigated by means of <sup>1</sup>H NMR diffusometry and <sup>1</sup>H NMR relaxometry in order to characterize their isotropic–isotropic’–cubic mesophase behavior, mainly on the dynamic point of view. In particular, the temperature trend of the self-diffusion coefficients measured for both samples allowed us to significantly distinguish between the two isotropic phases, while the temperature dependence of the <sup>1</sup>H spin-lattice relaxation time (T<sub>1</sub>) did not show significant discontinuities at the isotropic–isotropic’ phase transition. A preliminary analysis of the frequency-dependence of <sup>1</sup>H T<sub>1</sub> at different temperatures gives information about the main motional processes active in the isotropic mesophases.https://www.mdpi.com/2073-4352/9/3/178NMRcubic phaseisotropic phaseself-diffusionliquid crystalsrelaxation timedynamics<sup>1</sup>H NMR |
| spellingShingle | Anton Gradišek Mario Cifelli Michal Wojcik Tomaž Apih Sergey V. Dvinskikh Ewa Gorecka Valentina Domenici Study of Liquid Crystals Showing Two Isotropic Phases by <sup>1</sup>H NMR Diffusometry and <sup>1</sup>H NMR Relaxometry Crystals NMR cubic phase isotropic phase self-diffusion liquid crystals relaxation time dynamics <sup>1</sup>H NMR |
| title | Study of Liquid Crystals Showing Two Isotropic Phases by <sup>1</sup>H NMR Diffusometry and <sup>1</sup>H NMR Relaxometry |
| title_full | Study of Liquid Crystals Showing Two Isotropic Phases by <sup>1</sup>H NMR Diffusometry and <sup>1</sup>H NMR Relaxometry |
| title_fullStr | Study of Liquid Crystals Showing Two Isotropic Phases by <sup>1</sup>H NMR Diffusometry and <sup>1</sup>H NMR Relaxometry |
| title_full_unstemmed | Study of Liquid Crystals Showing Two Isotropic Phases by <sup>1</sup>H NMR Diffusometry and <sup>1</sup>H NMR Relaxometry |
| title_short | Study of Liquid Crystals Showing Two Isotropic Phases by <sup>1</sup>H NMR Diffusometry and <sup>1</sup>H NMR Relaxometry |
| title_sort | study of liquid crystals showing two isotropic phases by sup 1 sup h nmr diffusometry and sup 1 sup h nmr relaxometry |
| topic | NMR cubic phase isotropic phase self-diffusion liquid crystals relaxation time dynamics <sup>1</sup>H NMR |
| url | https://www.mdpi.com/2073-4352/9/3/178 |
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