1
|
Singer PM, Asthagiri D, Chen Z, Valiya Parambathu A, Hirasaki GJ, Chapman WG. Role of internal motions and molecular geometry on the NMR relaxation of hydrocarbons. J Chem Phys 2018; 148:164507. [DOI: 10.1063/1.5023240] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- P. M. Singer
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA
| | - D. Asthagiri
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA
| | - Z. Chen
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA
| | - A. Valiya Parambathu
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA
| | - G. J. Hirasaki
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA
| | - W. G. Chapman
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA
| |
Collapse
|
2
|
Emsley JW, Lelli M, Luckhurst GR, Zimmermann H. ^{13}C NMR study of the director distribution adopted by the modulated nematic phases formed by liquid-crystal dimers with odd numbers of atoms in their spacers. Phys Rev E 2017; 96:062702. [PMID: 29347294 DOI: 10.1103/physreve.96.062702] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Indexed: 11/07/2022]
Abstract
The orientational order of the molecules in the bent mesogen CB6OCB has been studied throughout the range of temperature stability of both the N_{U} and N_{TB} liquid-crystal phases by ^{13}C NMR spectroscopy. These spectra provide local order parameters for the para axes of both of the nonequivalent cyanobiphenyl groups and show how they change on entering the twist-bend nematic phase. A key feature of the order parameters is a weak, but clear maximum in the temperature variation of the order parameter prior to the N_{TB} phase. This suggests that the directors in both the N_{U} and N_{TB} phases are tilted with respect to the magnetic field of the spectrometer. Significantly the conformational states of the spacer are comparable in both phases, although the low temperature nematic is chiral but not that at high temperature. It is proposed that the higher temperature, tilted phase could be the splay-bend nematic phase.
Collapse
Affiliation(s)
- J W Emsley
- Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, United Kingdom
| | - M Lelli
- Department of Chemistry, Center for Magnetic Resonance, University of Florence, Sesto Fiorentino (FI) 50019, Italy
| | - G R Luckhurst
- Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, United Kingdom
| | - H Zimmermann
- Max-Planck-Institut für Medizinische Forschung, Department of Biomolecular Mechanisms, D-69120 Heidelberg, Germany
| |
Collapse
|
3
|
Sugimura A, Luckhurst GR. Deuterium NMR investigations of field-induced director alignment in nematic liquid crystals. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2016; 94-95:37-74. [PMID: 27247284 DOI: 10.1016/j.pnmrs.2016.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 12/08/2015] [Indexed: 06/05/2023]
Abstract
There have been many investigations of the alignment of nematic liquid crystals by either a magnetic and/or an electric field. The basic features of the important hydrodynamic processes for low molar mass nematics have been characterized for the systems in their equilibrium and non-equilibrium states. These have been created using electric and magnetic fields to align the director and deuterium nuclear magnetic resonance ((2)H NMR) spectroscopy has been used to explore this alignment. Theoretical models based on continuum theory have been developed to complement the experiments and found to describe successfully the static and the dynamic phenomena observed. Such macroscopic behaviour has been investigated with (2)H NMR spectroscopy, in which an electric field in addition to the magnetic field of the spectrometer is used to rotate the director and produce a non-equilibrium state. This powerful technique has proved to be especially valuable for the investigation of nematic liquid crystals. Since the quadrupolar splitting for deuterons observed in the liquid crystal phase is determined by the angle between the director and the magnetic field, time-resolved and time-averaged (2)H NMR spectroscopies can be employed to investigate the dynamic director alignment process in a thin nematic film following the application or removal of an electric field. In this article, we describe some seminal studies to illustrate the field-induced static and dynamic director alignment for low molar mass nematics.
Collapse
Affiliation(s)
- Akihiko Sugimura
- School of Information Systems Engineering, Osaka Sangyo University, 3-1-1 Nakagaito, Daito, Osaka 574-8530, Japan.
| | - Geoffrey R Luckhurst
- Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| |
Collapse
|
4
|
Meirovitch E, Liang Z, Freed JH. Protein Dynamics in the Solid State from (2)H NMR Line Shape Analysis. II. MOMD Applied to C-D and C-CD3 Probes. J Phys Chem B 2015; 119:14022-32. [PMID: 26402431 PMCID: PMC4676681 DOI: 10.1021/acs.jpcb.5b07434] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Deuterium
line shape analysis from mobile C–D and C–CD3 groups has emerged as a particularly useful tool for studying
dynamics in the solid state. The theoretical models devised so far
consist typically of sets of independent dynamic modes. Each such
mode is simple and usually case-specific. In this scenario, model
improvement entails adding yet another mode (thereby changing the
overall model), comparison of different cases is difficult, and ambiguity
is unavoidable. We recently developed the microscopic order macroscopic
disorder (MOMD) approach as a single-mode alternative. In MOMD, the
local spatial restrictions are expressed by an anisotropic potential,
the local motion by a diffusion tensor, and the local molecular geometry
by relative (magnetic and model-related) tensor orientations, all
of adjustable symmetry. This approach provides a consistent method
of analysis, thus resolving the issues above. In this study, we apply
MOMD to PS-adsorbed LKα14 peptide and dimethylammonium tetraphenylborate
(C–CD3 and N–CD3 dynamics, respectively),
as well as HhaI methyltransferase target DNA and
phase III of benzene-6-hexanoate (C–D dynamics). The success
with fitting these four disparate cases, as well as the two cases
in the previous report, demonstrates the generality of this MOMD-based
approach. In this study, C–D and C–CD3 are
both found to execute axial diffusion (rates R⊥ and R∥) in the
presence of a rhombic potential given by the L =
2 spherical harmonics (coefficients c02 and c22). R⊥ (R∥) is in the 102–103 (104–105) s–1 range, and c02 and c22 are on the
order of 2–3 kBT. Specific parameter values are determined for each mobile site.
The diffusion and quadrupolar tensors are tilted at either 120°
(consistent with trans–gauche isomerization) or nearly 110.5° (consistent with methyl exchange).
Future prospects include extension of the MOMD formalism to include
MAS, and application to 15N and 13C nuclei.
Collapse
Affiliation(s)
- Eva Meirovitch
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University , Ramat-Gan 52900, Israel
| | - Zhichun Liang
- Baker Laboratory of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853-1301, United States
| | - Jack H Freed
- Baker Laboratory of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853-1301, United States
| |
Collapse
|
5
|
Urban S, Geppi M. Comparison of the dielectric and NMR results for liquid crystals: dynamic aspects. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2014; 52:656-663. [PMID: 25042413 DOI: 10.1002/mrc.4100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 06/07/2014] [Indexed: 06/03/2023]
Abstract
Critical analysis of the results of studies of molecular rotational dynamics in liquid crystalline substances with the aid of the dielectric spectroscopy (DS) and nuclear magnetic resonance (NMR) is given. Both methods are known to be sensitive to different aspects of molecular rotations: the polarization vector and the relaxation time τ(DS) in the case of DS, a tensor describing a nuclear interaction and the correlation time τ(NMR) for NMR method. Furthermore, both methods provide correlation functions with different rank values. A common basis for the comparison between τ(DS) and τ(NMR) is postulated. Several examples of the temperature dependence of the correlation times coming from the two spectroscopic methods are presented. Qualitative agreements of the correlation times were achieved in most cases.
Collapse
Affiliation(s)
- Stanislaw Urban
- Institute of Physics, Jagiellonian University, Reymonta 4, 30-059, Krakow, Poland
| | | |
Collapse
|
6
|
Impact of graphene incorporation on the orientational order of graphene/liquid crystal composites. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2013.11.044] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
7
|
Measuring dynamic and kinetic information in the previously inaccessible supra-τ(c) window of nanoseconds to microseconds by solution NMR spectroscopy. Molecules 2013; 18:11904-37. [PMID: 24077173 PMCID: PMC6270068 DOI: 10.3390/molecules181011904] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 08/28/2013] [Accepted: 09/17/2013] [Indexed: 11/16/2022] Open
Abstract
Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool that has enabled experimentalists to characterize molecular dynamics and kinetics spanning a wide range of time-scales from picoseconds to days. This review focuses on addressing the previously inaccessible supra-tc window (defined as τ(c) < supra-τ(c) < 40 μs; in which tc is the overall tumbling time of a molecule) from the perspective of local inter-nuclear vector dynamics extracted from residual dipolar couplings (RDCs) and from the perspective of conformational exchange captured by relaxation dispersion measurements (RD). The goal of the first section is to present a detailed analysis of how to extract protein dynamics encoded in RDCs and how to relate this information to protein functionality within the previously inaccessible supra-τ(c) window. In the second section, the current state of the art for RD is analyzed, as well as the considerable progress toward pushing the sensitivity of RD further into the supra-τ(c) scale by up to a factor of two (motion up to 25 μs). From the data obtained with these techniques and methodology, the importance of the supra-τ(c) scale for protein function and molecular recognition is becoming increasingly clearer as the connection between motion on the supra-τ(c) scale and protein functionality from the experimental side is further strengthened with results from molecular dynamics simulations.
Collapse
|
8
|
Pizzirusso A, Di Cicco MB, Tiberio G, Muccioli L, Berardi R, Zannoni C. Alignment of Small Organic Solutes in a Nematic Solvent: The Effect of Electrostatic Interactions. J Phys Chem B 2012; 116:3760-71. [DOI: 10.1021/jp3003799] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- A. Pizzirusso
- Dipartimento di Chimica Fisica e Inorganica, and INSTM, Viale Risorgimento 4, 40136 Bologna, Italy
| | - M. B. Di Cicco
- Dipartimento di Chimica Fisica e Inorganica, and INSTM, Viale Risorgimento 4, 40136 Bologna, Italy
| | - G. Tiberio
- Dipartimento di Chimica Fisica e Inorganica, and INSTM, Viale Risorgimento 4, 40136 Bologna, Italy
| | - L. Muccioli
- Dipartimento di Chimica Fisica e Inorganica, and INSTM, Viale Risorgimento 4, 40136 Bologna, Italy
| | - R. Berardi
- Dipartimento di Chimica Fisica e Inorganica, and INSTM, Viale Risorgimento 4, 40136 Bologna, Italy
| | - C. Zannoni
- Dipartimento di Chimica Fisica e Inorganica, and INSTM, Viale Risorgimento 4, 40136 Bologna, Italy
| |
Collapse
|
9
|
|
10
|
Sanchez-Castillo A, Osipov MA, Giesselmann F. Orientational order parameters in liquid crystals: a comparative study of x-ray diffraction and polarized Raman spectroscopy results. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:021707. [PMID: 20365582 DOI: 10.1103/physreve.81.021707] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Indexed: 05/29/2023]
Abstract
The orientational order parameters <P(2)> and <P(4)> in the nematic liquid crystal 4-pentyl-4'-cyanobipheny (5CB) have been determined by means of the two completely different techniques: polarized Raman spectroscopy and x-ray scattering. In particular, the values of <P(2)> and <P(4)> obtained using two different Raman methods, proposed by Jen [J. Chem. Phys 66, 4635 (1977)] and Jones [J. Mol. Struct. 708, 145 (2004)], respectively, are compared with the results of x-ray measurements. A good agreement between the experimental values of <P(2)> and <P(4)> and the results of the Humphries-James-Luckhurst mean field theory has been found whenever they were determined using either x-ray measurement or following the Jen method. In addition, a study of the influence of the intensity of the exiting laser source on the apparent values of the order parameters has been performed. Therefore, it was found that the discrepancies of the value of <P(4)> determined following Jen and Jones could be determined by nonlinear effects.
Collapse
Affiliation(s)
- Alberto Sanchez-Castillo
- Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | | | | |
Collapse
|
11
|
McKenzie I, Dilger H, Stoykov A, Scheuermann R. Muon Spin Spectroscopy of the Nematic Liquid Crystal 4-n-Pentyl-4′-cyanobiphenyl (5CB). J Phys Chem B 2009; 113:10135-42. [DOI: 10.1021/jp9025656] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Iain McKenzie
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, U.K. OX11 0QX, Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany, and Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Herbert Dilger
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, U.K. OX11 0QX, Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany, and Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Alexey Stoykov
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, U.K. OX11 0QX, Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany, and Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Robert Scheuermann
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, U.K. OX11 0QX, Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany, and Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| |
Collapse
|
12
|
Affiliation(s)
- Joel R Tolman
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA.
| | | |
Collapse
|
13
|
Scruggs NR, Kornfield JA. Synergistic Ordering of Side-Group Liquid Crystal Polymer and Small Molecule Liquid Crystal: Order and Phase Behavior of Nematic Polymer Solutions. MACROMOL CHEM PHYS 2007. [DOI: 10.1002/macp.200700342] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
14
|
Amovilli C, Cacelli I, Cinacchi G, De Gaetani L, Prampolini G, Tani A. Structure and dynamics of mesogens using intermolecular potentials derived from ab initio calculations. Theor Chem Acc 2006. [DOI: 10.1007/s00214-006-0209-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
15
|
Cross CW, Fung BM. Molecular Dynamics Simulations for Cyanobiphenyl Liquid Crystals. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587259508033553] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- C. W. Cross
- a Department of Chemistry , University of Oklahoma Norman , Oklahoma , 73019-3070 , U.S.A
| | - B. M. Fung
- a Department of Chemistry , University of Oklahoma Norman , Oklahoma , 73019-3070 , U.S.A
| |
Collapse
|
16
|
Counsell C, Emsley J, Heaton N, Luckhurst G. Orientational ordering in uniaxial liquid crystals. Mol Phys 2006. [DOI: 10.1080/00268978500103211] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
17
|
Avent A, Emsley J, Luckhurst G. The orientational ordering of a liquid crystal determined using fluorine spin echo spectroscopy. Mol Phys 2006. [DOI: 10.1080/00268978300101511] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
18
|
Boden N, Clark L, Clarke C, Kahol P. N.M.R. solid echoes in systems of coupled pairs of spins-1/2. Mol Phys 2006. [DOI: 10.1080/00268978300102621] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
19
|
|
20
|
Sinton S, Zax D, Murdoch J, Pines A. Multiple-quantum N.M.R. study of molecular structure and ordering in a liquid crystal. Mol Phys 2006. [DOI: 10.1080/00268978400102351] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
21
|
Emsley J, Luckhurst G, Timimi B. N.M.R. studies of orientational ordering in liquid crystals at high pressure. Mol Phys 2006. [DOI: 10.1080/00268978200101491] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- J.W. Emsley
- a Department of Chemistry , The University , Southampton , SO9 5NH , England
| | - G.R. Luckhurst
- a Department of Chemistry , The University , Southampton , SO9 5NH , England
| | - B.A. Timimi
- a Department of Chemistry , The University , Southampton , SO9 5NH , England
| |
Collapse
|
22
|
Emsley J, Luckhurst G, Shilstone G. The orientational order of nematogenic molecules with a flexible core. Mol Phys 2006. [DOI: 10.1080/00268978400102811] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
23
|
Stevensson B, Sandström D, Maliniak A. Conformational distribution functions extracted from residual dipolar couplings: A hybrid model based on maximum entropy and molecular field theory. J Chem Phys 2003. [DOI: 10.1063/1.1586914] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
24
|
Celebre G, De Luca G, Emsley JW, Foord EK, Longeri M, Lucchesini F, Pileio G. The conformational distribution in diphenylmethane determined by nuclear magnetic resonance spectroscopy of a sample dissolved in a nematic liquid crystalline solvent. J Chem Phys 2003. [DOI: 10.1063/1.1555631] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
25
|
SANDSTRÖM DICK, ZIMMERMANN HERBERT. Deuterium—carbon multiple-quantum NMR in liquid crystals: polarization transfer and off-magic-angle spinning. Mol Phys 2002. [DOI: 10.1080/00268970110099567] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
|
26
|
Dvinskikh SV, Furó I, Zimmermann H, Maliniak A. Anisotropic self-diffusion in thermotropic liquid crystals studied by 1H and 2H pulse-field-gradient spin-echo NMR. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2002; 65:061701. [PMID: 12188745 DOI: 10.1103/physreve.65.061701] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2002] [Indexed: 05/23/2023]
Abstract
The molecular self-diffusion coefficients in nematic and smectic-A thermotropic liquid crystals are measured using stimulated-echo-type 2H and 1H pulse-field-gradient spin-echo nuclear magnetic resonance (PGSE NMR) combined with multiple-pulse dipolar decoupling and slice selection. The temperature dependence of the principal components of the diffusion tensor in the nematic phase follows a simple Arrhenius relationship except in the region of nematic-isotropic phase transition where it reflects, merely, the decrease of the molecular orientational order. The average of the principal diffusion coefficients in the isotropic-nematic phase transition region is close to the diffusion coefficient in the isotropic phase. At the nematic-smectic-A phase transition the diffusion coefficients change continuously. The results in nematic phase are best described in terms of the affine transformation model for diffusion in nematics formed by hard ellipsoids. In the smectic-A phase the data are interpreted using a modified model for diffusion in presence of a periodic potential along the director.
Collapse
Affiliation(s)
- S V Dvinskikh
- Division of Physical Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden.
| | | | | | | |
Collapse
|
27
|
Zalar B, Blinc R, Zumer S, Jin T, Finotello D. Behavior of mesogenic molecules deposited at the alumina-air interface: a deuteron NMR study. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2002; 65:041703. [PMID: 12005842 DOI: 10.1103/physreve.65.041703] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2001] [Indexed: 05/23/2023]
Abstract
Thin molecular depositions of 4(')-pentyl-4-cyonobiphenyl (5CB) mesogenic molecules are investigated via quadrupole-perturbed deuteron nuclear magnetic resonance (DNMR) spectroscopy. Uniform and controlled thickness molecular surface depositions are prepared on the inner cylindrical surfaces of Anopore membranes by the solvent-evaporation technique. As a result, 5CB molecules are found in two different configurations: a bulklike one with parallel axial arrangement, and a surface one with planar radial arrangement. If the 5CB surface coverage exceeds c approximately 0.35, only the bulk state is present. In the coverage range between 0.015 and 0.35, the bulklike state and the surface layer coexist, conforming to a typical dewetting scenario. Below c approximately 0.015, only the surface layer is present. The dilution of the surface deposition with decreasing coverage is manifested as an increase in the DNMR doublet frequency splitting. The surface orientational order parameter Q, the surface biaxiality eta, and the diffusion coefficient D(S) are determined from the DNMR spectral patterns obtained at different sample orientations in the external magnetic field. These angular patterns prove that in highly diluted surface depositions the molecules lie flat on the surface. However, they are not frozen and their molecular axes rapidly reorient on the DNMR measurement time scale, typically 10(-4) s, while remaining confined to the surface. Simultaneously, molecules diffuse over the surface with a surface diffusion constant on the order of 10(-11) m(2) s(-1). Such molecular diffusion is responsible for an effective biaxiality on the DNMR time scale. However, an inherent biaxiality cannot be completely ruled out and thus may play a minor role. The surface phase has a two-dimensional (2D) gas character with some (possible) indicators of 2D-liquid properties.
Collapse
Affiliation(s)
- Bostjan Zalar
- J. Stefan Institute, University of Ljubljana, Jamova 39, 1000 Ljubljana, Slovenia
| | | | | | | | | |
Collapse
|
28
|
Dvinskikh SV, Furó I. Anisotropic self-diffusion in the nematic phase of a thermotropic liquid crystal by 1H-spin-echo nuclear magnetic resonance. J Chem Phys 2001. [DOI: 10.1063/1.1381059] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
29
|
Stevensson B, Komolkin AV, Sandström D, Maliniak A. Structure and molecular ordering extracted from residual dipolar couplings: A molecular dynamics simulation study. J Chem Phys 2001. [DOI: 10.1063/1.1337046] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
30
|
Zalar B, Lavrentovich OD, Zeng H, Finotello D. Deuteron NMR investigation of a photomechanical effect in a smectic-A liquid crystal. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 2000; 62:2252-2262. [PMID: 11088692 DOI: 10.1103/physreve.62.2252] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2000] [Indexed: 05/23/2023]
Abstract
Deuteron quadrupole-perturbed NMR is used to study the perturbation of orientational order in a smectic-A liquid crystal (octylcyanobiphenyl or 8CB) caused by photoinduced trans-to-cis isomerization of a photosensitive dopant (diheptylazobenzene or 7AB). The time and temperature dependences of the orientational order were independently studied for 8CB, 7AB, and their mixtures. Upon UV irradiation that causes trans-to-cis isomerization of 7AB, the orientational order parameter of the smectic-A phase is reduced. Relaxation in the dark exponentially restores the equilibrium value of the order parameter. The characteristic time for this process closely matches the lifetimes of the 7AB excited state. While in the 8CB smectic-A matrix, the cis-isomerized 7AB molecules retain a uniaxial orientational order with the director oriented along the normal to the smectic layers. The highly bent 7AB cis molecules act as a disorienting factor, decreasing the orientational order in the layers and causing a small increase in layer spacing. This disorder-induced increase in layer spacing is much smaller than the actual increase as observed by in situ x-ray experiments on UV-irradiated mixtures of 8CB:7AB. Concomitant with the experimental observation that only a fraction of 7AB molecules are converted to the cis state, this work provides indirect evidence for a nanophase segregation with the 7AB cis-isomers arranged within the interlayer space, thus significantly increasing the smectic layer spacing.
Collapse
Affiliation(s)
- B Zalar
- Jozef Stefan Institute, University of Ljubljana, Jamova 39, 1000 Ljubljana, Slovenia
| | | | | | | |
Collapse
|
31
|
Sandström D, Zimmermann H. Correlation of Deuterium Quadrupolar Couplings and Carbon-13 Chemical Shifts in Ordered Media by Multiple-Quantum NMR. J Phys Chem B 2000. [DOI: 10.1021/jp9938765] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dick Sandström
- Division of Physical Chemistry, Arrhenius Laboratory, Stockholm University, S-10691 Stockholm, Sweden
| | - Herbert Zimmermann
- Max-Planck-Institut für Medizinische Forschung, AG Molekülkristalle, Jahnstrasse 29 D-69120 Heidelberg, Germany
| |
Collapse
|
32
|
Cook MJ, Wilson MR. Calculation of helical twisting power for liquid crystal chiral dopants. J Chem Phys 2000. [DOI: 10.1063/1.480703] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
33
|
Syvitski RT, Burnell EE. NMR and molecular structure of partially oriented mono and para methyl- and chlorobenzenes dissolved in nematic liquid crystals. CAN J CHEM 1999. [DOI: 10.1139/v99-144] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Spectral parameters, order parameters, and structural parameters, including the vibrationally corrected ralpha structure of the partially oriented solutes p-xylene, p-chlorotoluene, p-dichlorobenzene, toluene, and chlorobenzene dissolved in three liquid crystal mixtures, are reported. For samples containing the three solutes p-xylene, p-dichlorobenzene, and 1,3,5-trichlorobenzene, multiple quantum (MQ) nuclear magnetic resonance was used to aid in the analysis of the complex high-resolution spectra of the p-xylene. The high-resolution spectra of 1,3,5-trichlorobenzene and p-dichlorobenzene were easily identified and analyzed once the calculated p-xylene spectrum was subtracted from the experimental one. The methyl groups of p-xylene, p-chlorotoluene, and toluene have similar geometries when the structure is determined from dipolar couplings corrected for harmonic vibrations.Key words: nematic liquid crystal, NMR, molecular structure, order parameter.
Collapse
|
34
|
|
35
|
ADAM CJ, FERRARINI A, WILSON MR, ACKLAND GJ, CRAIN J. A first principles and mean field investigation of the conformational properties of 5CB. Mol Phys 1999. [DOI: 10.1080/00268979909482853] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
36
|
|
37
|
Auger C, Lesage A, Caldarelli S, Hodgkinson P, Emsley L. Assignment and Measurement of Deuterium Quadrupolar Couplings in Liquid Crystals by Deuterium−Carbon NMR Correlation Spectroscopy. J Phys Chem B 1998. [DOI: 10.1021/jp9805398] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Céline Auger
- Laboratoire de Stéréochimie et des Interactions Moléculaires, UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon, 69364 Lyon, France, and Institut de Recherches sur la Catalyse, UPR-5401 CNRS, 2, av. Albert Einstein, 69626 Villeurbanne, France
| | - Anne Lesage
- Laboratoire de Stéréochimie et des Interactions Moléculaires, UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon, 69364 Lyon, France, and Institut de Recherches sur la Catalyse, UPR-5401 CNRS, 2, av. Albert Einstein, 69626 Villeurbanne, France
| | - Stefano Caldarelli
- Laboratoire de Stéréochimie et des Interactions Moléculaires, UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon, 69364 Lyon, France, and Institut de Recherches sur la Catalyse, UPR-5401 CNRS, 2, av. Albert Einstein, 69626 Villeurbanne, France
| | - Paul Hodgkinson
- Laboratoire de Stéréochimie et des Interactions Moléculaires, UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon, 69364 Lyon, France, and Institut de Recherches sur la Catalyse, UPR-5401 CNRS, 2, av. Albert Einstein, 69626 Villeurbanne, France
| | - Lyndon Emsley
- Laboratoire de Stéréochimie et des Interactions Moléculaires, UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon, 69364 Lyon, France, and Institut de Recherches sur la Catalyse, UPR-5401 CNRS, 2, av. Albert Einstein, 69626 Villeurbanne, France
| |
Collapse
|
38
|
CARL MCBRIDE MARK R. WILSON JUDITH. Molecular dynamics simulations of liquid crystal phases using atomistic potentials. Mol Phys 1998. [DOI: 10.1080/002689798168655] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
|
39
|
Wilson MR. Molecular dynamics simulations of flexible liquid crystal molecules using a Gay-Berne/Lennard-Jones model. J Chem Phys 1997. [DOI: 10.1063/1.475017] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
40
|
Tabayashi K, Akasaka K. Natural Abundance 2H NMR for Liquid Crystal Studies. Application to 4‘-(Hexyloxy)-4-cyanobiphenyl. J Phys Chem B 1997. [DOI: 10.1021/jp9702255] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kazuteru Tabayashi
- Division of Material Science, Graduate School of Science and Technology, Kobe University, Kobe 657, Japan
| | - Kazuyuki Akasaka
- Department of Chemistry, Faculty of Science, and Division of Molecular Science, Graduate School of Science and Technology, Kobe University, Kobe 657, Japan
| |
Collapse
|
41
|
A theory of orientational ordering in uniaxial liquid crystals composed of molecules with alkyl chains. ACTA ACUST UNITED AC 1997. [DOI: 10.1098/rspa.1982.0061] [Citation(s) in RCA: 268] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The constituent molecules of thermotropic liquid crystals invariably contain an aromatic core to which is attached one and often two
n
-alkyl chains. Nuclear magnetic resonance investigations have revealed that the chain does not exist entirely in an all-
trans
configuration and that the orientational order of the methylene groups varies markedly along the chain. In this paper we develop a theory to explain these variations for a uniaxial phase at a given temperature and pressure. Our theory contains two distinct parts: one is a model for the conformational distribution of the alkyl chains while the other is for the potential of mean torque experienced by a conformer and which is responsible for its alignment with respect to the director. We use the rotameric state model developed by Flory to describe the conformations adopted by the alkyl chain. The potential of mean torque presents a more difficult problem and we assume that it may be represented by a sum of contributions from each rigid group in the molecule. The order parameters for the methylene and methyl groups in the alkyl chains of the 4-
n
-pentyl and 4-
n
-octyl-4'-cyanobiphenyls predicted by the theory are found to be in good accord with those obtained experimentally. We have also used the theory to predict the conformational distributions for both the isotropic and nematic phases of these mesogens; the calculated distributions are contrasted with those assumed by other models. In addition we have obtained the ordering matrices for the various conformers adopted by the two 4-
n
-alkyl-4'-cyanobiphenyls. The results of these calculations do not support the notion that the orientational order of such molecules can be described by a single, cylindrically symmetric ordering matrix.
Collapse
|
42
|
Caldarelli S, Lesage A, Emsley L. Long-Range Dipolar Couplings in Liquid Crystals Measured by Three-Dimensional NMR Spectroscopy. J Am Chem Soc 1996. [DOI: 10.1021/ja9623931] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stefano Caldarelli
- Laboratoire de Stéréochimie et des Interactions Moléculaires UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon 69364 Lyon, France
| | - Anne Lesage
- Laboratoire de Stéréochimie et des Interactions Moléculaires UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon 69364 Lyon, France
| | - Lyndon Emsley
- Laboratoire de Stéréochimie et des Interactions Moléculaires UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon 69364 Lyon, France
| |
Collapse
|
43
|
Iwamoto M, Sugimura A, Zhong-can OY. Biaxiality ordering of molecular orientation in a monolayer at the liquid-air interface. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1996; 54:6537-6540. [PMID: 9965877 DOI: 10.1103/physreve.54.6537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
|
44
|
Caldarelli S, Hong M, Emsley L, Pines A. Measurement of Carbon−Proton Dipolar Couplings in Liquid Crystals by Local Dipolar Field NMR Spectroscopy. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp962023z] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stefano Caldarelli
- Laboratoire de Stéréochimie et des Interactions Moléculaires, UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon, 69364 Lyon, France, Materials Science Division, Lawrence Berkeley Laboratory, 1 Cyclotron Road, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Mei Hong
- Laboratoire de Stéréochimie et des Interactions Moléculaires, UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon, 69364 Lyon, France, Materials Science Division, Lawrence Berkeley Laboratory, 1 Cyclotron Road, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Lyndon Emsley
- Laboratoire de Stéréochimie et des Interactions Moléculaires, UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon, 69364 Lyon, France, Materials Science Division, Lawrence Berkeley Laboratory, 1 Cyclotron Road, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Alexander Pines
- Laboratoire de Stéréochimie et des Interactions Moléculaires, UMR-117 CNRS/ENS, Ecole Normale Supérieure de Lyon, 69364 Lyon, France, Materials Science Division, Lawrence Berkeley Laboratory, 1 Cyclotron Road, and Department of Chemistry, University of California, Berkeley, California 94720
| |
Collapse
|
45
|
Hong M, Pines A, Caldarelli S. Measurement and Assignment of Long-Range C−H Dipolar Couplings in Liquid Crystals by Two-Dimensional NMR Spectroscopy. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp960972m] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mei Hong
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Alexander Pines
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, and Department of Chemistry, University of California, Berkeley, California 94720
| | - Stefano Caldarelli
- Section de Chimie de l'Université, BCH-Dorigny, CH-1015 Lausanne, Switzerland
| |
Collapse
|
46
|
Sandström D, Levitt MH. Structure and Molecular Ordering of a Nematic Liquid Crystal Studied by Natural-Abundance Double-Quantum 13C NMR. J Am Chem Soc 1996. [DOI: 10.1021/ja9601853] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- D. Sandström
- Contribution from the Division of Physical Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden
| | - M. H. Levitt
- Contribution from the Division of Physical Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden
| |
Collapse
|
47
|
CVIKL B. QNS investigation of d-EBBA core reorientations in oriented nematic and isotropic phases. Mol Phys 1996. [DOI: 10.1080/00268979650026433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
48
|
Cross CW, Fung BM. A simplified approach to molecular dynamics simulations of liquid crystals with atom–atom potentials. J Chem Phys 1994. [DOI: 10.1063/1.468313] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
49
|
Komolkin AV, Laaksonen A, Maliniak A. Molecular dynamics simulation of a nematic liquid crystal. J Chem Phys 1994. [DOI: 10.1063/1.467460] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
50
|
Ferrarini A, Luckhurst GR, Nordio PL, Roskilly SJ. Prediction of the transitional properties of liquid crystal dimers. A molecular field calculation based on the surface tensor parametrization. J Chem Phys 1994. [DOI: 10.1063/1.466625] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|