1
|
Gradišek A, Apih T, Beira MJ, Cruz C, Fernandes SN, Godinho HM, Sebastião PJ. Observing short-range orientational order in small-molecule liquids. Sci Rep 2022; 12:22500. [PMID: 36577850 PMCID: PMC9797480 DOI: 10.1038/s41598-022-27187-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 12/27/2022] [Indexed: 12/29/2022] Open
Abstract
Local molecular ordering in liquids has attracted a lot of interest from researchers investigating crystallization, but is still poorly understood on the molecular scale. Classical nucleation theory (CNT), a macroscopic thermodynamic description of condensation, has shortcomings when dealing with clusters consisting of tens of molecules. Cluster formation and local order fluctuations in liquid media are difficult to study due to the limited spatial resolution of electron- and photon-imaging methods. We used NMR relaxometry to demonstrate the existence of dynamic clusters with short-range orientational order in nominally isotropic liquids consisting of elongated molecules. We observed clusters in liquids where the local ordering is driven by polar, steric, and hydrogen-bond interactions between the molecules. In the case of a liquid crystal, measuring the local orientational order fluctuations allowed us to observe the size of these clusters diverging when approaching the phase transition from the isotropic to the nematic phase. These fluctuations are described in terms of rotational elasticity as a consequence of the correlated reorientations of the neighbouring molecules. Our quantitative observations of the dynamic clusters in liquids, numbering about ten or fewer molecules, indicate that this is a general phenomenon in various types of liquids.
Collapse
Affiliation(s)
- Anton Gradišek
- grid.11375.310000 0001 0706 0012Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia
| | - Tomaž Apih
- grid.11375.310000 0001 0706 0012Jožef Stefan Institute, Jamova Cesta 39, 1000 Ljubljana, Slovenia
| | - Maria J. Beira
- grid.9983.b0000 0001 2181 4263Center of Physics and Engineering of Advanced Materials, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal ,grid.9983.b0000 0001 2181 4263Department of Physics, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Carlos Cruz
- grid.9983.b0000 0001 2181 4263Center of Physics and Engineering of Advanced Materials, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal ,grid.9983.b0000 0001 2181 4263Department of Physics, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Susete N. Fernandes
- grid.10772.330000000121511713CENIMAT/I3N, Departamento de Ciência Dos Materiais, Faculdade de Ciências E Tecnologia, UNL, 2829-516 Caparica, Portugal
| | - Helena M. Godinho
- grid.10772.330000000121511713CENIMAT/I3N, Departamento de Ciência Dos Materiais, Faculdade de Ciências E Tecnologia, UNL, 2829-516 Caparica, Portugal
| | - Pedro J. Sebastião
- grid.9983.b0000 0001 2181 4263Center of Physics and Engineering of Advanced Materials, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal ,grid.9983.b0000 0001 2181 4263Department of Physics, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| |
Collapse
|
2
|
Dong RY, Michal CA, Saccone M, Spengler M, Wölper C, Giese M. On the blue phase structure of hydrogen-bonded liquid crystals via F NMR. Chem Phys Lett 2018; 710:39-44. [DOI: 10.1016/j.cplett.2018.08.056] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
3
|
Bubnov A, Domenici V, Hamplová V, Kašpar M, Veracini CA, Glogarová M. Orientational and structural properties of ferroelectric liquid crystal with a broad temperature range in the SmC(*) phase by (13)C NMR, x-ray scattering and dielectric spectroscopy. J Phys Condens Matter 2009; 21:035102. [PMID: 21817261 DOI: 10.1088/0953-8984/21/3/035102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Thermotropic liquid crystalline materials laterally substituted by a methyl group on the aromatic ring of the alkoxybenzoate unit far from the chiral centre exhibit a very broad temperature range in the ferroelectric smectic C* (SmC(*)) phase on cooling (including supercooling) with a very high spontaneous polarization (∼210 nC cm(-2)) and tilt angle (∼43°) at saturation. We are presenting a detailed study of the physical properties of a ferroelectric compound, representative of this category of liquid crystals, by means of solid state (13)C-NMR, small angle x-ray scattering, dielectric spectroscopy and optical methods of the tilted SmC(*). Values of the spontaneous tilt angle measured optically are compared to those determined from the x-ray data and discussed. In addition, the viscosity has been determined in the SmC(*) phase by different experimental methods. (13)C NMR data allowed us to get information about the degree of orientational order of the SmC(*) phase and revealed the complete unwinding of the helical axis at the magnetic field of 9.4 T. This result is discussed in the framework of recent publications on the effect of the magnetic field on the supra-molecular structure of the SmC(*) phase.
Collapse
Affiliation(s)
- Alexej Bubnov
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
| | | | | | | | | | | |
Collapse
|
4
|
Zhang J, MacGregor RP, Balcom BJ. Liquid crystal diffusion in thin films investigated by PFG magnetic resonance and magnetic resonance imaging. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.06.090] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
5
|
Domenici V, Marini A, Veracini CA, Zhang J, Dong RY. Effect of the Magnetic Field on the Supramolecular Structure of Chiral SmecticC Phases:2H NMR Studies. Chemphyschem 2007; 8:2575-87. [DOI: 10.1002/cphc.200700307] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|