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Abstract
A polar, rod-like liquid crystalline material was observed to exhibit two distinct nematic mesophases separated by a first-order phase transition.
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Affiliation(s)
| | | | - J. W. Goodby
- Department of Chemistry
- University of York
- York
- USA
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3
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Xu R, Ali-Rachedi F, Xavier NM, Chambert S, Ferkous F, Queneau Y, Cowling SJ, Davis EJ, Goodby JW. Self-organizing behaviour of glycosteroidal bolaphiles: insights into lipidic microsegregation. Org Biomol Chem 2015; 13:783-92. [PMID: 25388281 DOI: 10.1039/c4ob02191f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this article we describe work on the synthesis of bolaphile biomimics composed of glucose head groups and steroidal units linked together by a methylene chain of varying length. The condensed phases formed by self-organization of the products as a function of temperature were characterized by differential scanning calorimetry and thermal polarized light microscopy. The results of these studies show that the thermal stabilities of the lamellar mesophases formed vary linearly as a function of increasing aliphatic composition, which reflects a linear hydrophobic-hydrophilic balance with respect to transition temperatures.
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Affiliation(s)
- R Xu
- INSA Lyon, ICBMS, Bâtiment J. Verne, 20 av A. Einstein, F 69621 Villeurbanne, France.
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4
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Mandle RJ, Davis EJ, Lobato SA, Vol CCA, Cowling SJ, Goodby JW. Synthesis and characterisation of an unsymmetrical, ether-linked, fluorinated bimesogen exhibiting a new polymorphism containing the N(TB) or 'twist-bend' phase. Phys Chem Chem Phys 2014; 16:6907-15. [PMID: 24535404 DOI: 10.1039/c4cp00172a] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this article we report on the liquid crystal phases and properties of the bimesogen 4-((11-((4'-fluoro-[1,1'-biphenyl]-4-yl)oxy)undecyl)oxy)-2,3-difluoro-4'-(4-propylcyclohexyl)-1,1'-biphenyl. This material was shown to exhibit an Iso Liq-N-NTB-SmA phase sequence, thereby clearly indicating that the NTB phase possesses an ordering of the constituent molecules that is between that of a conventional nematic and the smectic A phase. This compound allows us to better understand the relationship between molecular structure and the NTB phase, and we conclude it is the gross topology that dictates the incidence of this fascinating phase and not molecular properties such as dipole moment and bend angle.
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Affiliation(s)
- R J Mandle
- Department of Chemistry, University of York, Heslington, York, UKYO10 5DD.
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5
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Affiliation(s)
- A. Belaissaoui
- Department
of Chemistry, University of York, Heslington Road, York YO10 5DD, U.K
| | - I. M. Saez
- Department
of Chemistry, University of York, Heslington Road, York YO10 5DD, U.K
| | - S. J. Cowling
- Department
of Chemistry, University of York, Heslington Road, York YO10 5DD, U.K
| | - J. W. Goodby
- Department
of Chemistry, University of York, Heslington Road, York YO10 5DD, U.K
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6
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Kaur S, Addis J, Greco C, Ferrarini A, Görtz V, Goodby JW, Gleeson HF. Understanding the distinctive elastic constants in an oxadiazole bent-core nematic liquid crystal. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 86:041703. [PMID: 23214599 DOI: 10.1103/physreve.86.041703] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Indexed: 06/01/2023]
Abstract
The splay and bend elastic constants of the bent-core oxadiazole material [C5-Ph-ODBP-Ph-OC12] have been investigated as a function of temperature across the nematic phase. The bend constant K(33) is found to take values of ~3.0 pN and to be almost temperature independent, whereas, the splay constant K(11) increases monotonically from ~3.5 pN close to the isotropic phase transition to values of ~9 pN deep in the nematic phase. No pretransitional divergence is observed in either K(11) or K(33) at temperatures approaching the underlying phase. This behavior of the elastic constants is distinct from that observed in rodlike liquid crystal systems but appears to share characteristics with the few other bent-core nematic systems studied to date. We discuss the interdependence of the elastic constants, the birefringence, and the order parameter to allow a comparison of the observed behavior with theory. We show that calculations of the elastic constants via molecular-field theory and atomistic modeling are in excellent qualitative as well as good quantitative (within 2 pN) agreement with the measurements across the temperature range, offering a deeper understanding of the elasticity in bent-core nematic materials than has been, hitherto, available.
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Affiliation(s)
- S Kaur
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
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7
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Kaur S, Belaissaoui A, Goodby JW, Görtz V, Gleeson HF. Nonstandard electroconvection in a bent-core oxadiazole material. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 83:041704. [PMID: 21599183 DOI: 10.1103/physreve.83.041704] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 01/20/2011] [Indexed: 05/30/2023]
Abstract
Electroconvection (EC) phenomena have been investigated in the nematic phase of a bent-core oxadiazole material with negative dielectric anisotropy and a frequency dependent conductivity anisotropy. The formation of longitudinal roll (LR) patterns is one of the predominant features observed in the complete frequency and voltage range studied. At voltages much above the LR threshold, various complex patterns such as the "crisscrossed" pattern, bimodal varicose, and turbulence are observed. Unusually, the nonstandard EC (ns-EC) instability in this material, is observed in a regime in which we measure the dielectric and conductivity anisotropies to be negative and positive respectively. A further significant observation is that the EC displays distinct features in the high and low temperature regimes of the nematic phase, supporting an earlier report that EC patterns could distinguish between regions that have been reported as uniaxial and biaxial nematic phases.
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Affiliation(s)
- S Kaur
- School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
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8
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McCoy BK, Pan L, Liu ZQ, Wang ST, Wang S, Goodby JW, Huang CC. Evolution of a rare sequence of surface transitions with temperature and film thickness. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:031712. [PMID: 20365756 DOI: 10.1103/physreve.81.031712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Indexed: 05/29/2023]
Abstract
In free-standing smectic films, layers near the surfaces of the film often contain molecules tilted away from the layer normal, while in the bulk of the film the magnitude of the tilt decays exponentially with distance from the surface. We have identified the detailed molecular tilt orientations in the surface layers of films for one antiferroelectric liquid crystal compound. A series of five surface structures exists with different nonplanar tilt arrangements for each structure. The molecular orientations in the surface layers evolve with temperature. The polarization of the film also evolves with temperature, corresponding to the tilt arrangements. Using ellipsometric data, we reconstruct the changes in the magnitude and azimuthal direction of the tilt as functions of temperature. We have also studied films of several different thicknesses. We present a phase diagram for the five surface structures showing the dependence on temperature and film thickness.
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Affiliation(s)
- B K McCoy
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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9
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Scaife BKP, Sigarev AA, Vij JK, Goodby JW. Propagation of an electromagnetic wave in an absorbing anisotropic medium and infrared transmission of liquid crystals: comparison with experiments. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:021704. [PMID: 19792143 DOI: 10.1103/physreve.80.021704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Indexed: 05/28/2023]
Abstract
The theory of the absorbance of a semi-infinite medium characterized by a second-rank dielectric tensor for the entire electromagnetic spectrum, as given by Scaife and Vij [J. Chem. Phys. 122, 174901 (2005)], is extended to include molecules of prolate spheriodal shape with longitudinal and transverse polarizabilities and to cover the case of elliptically polarized incident radiation. The theory is applied to the infrared transmission experiments of biaxial liquid crystals. It is found that the formula for the dependence on frequency and on angle of polarization of the absorbance A(omega,theta)= -log(10)[10(A(omega,0)) cos(2) theta + (10(-A(omega,pi/2)) sin(2) theta)] is unaffected by the anisotropy of the molecules and by the elliptical polarization of the incident radiation. A small (+/-5%) discrepancy between theory and experiment has been found for bands with high absorbances. It is found that this discrepancy does not depend on birefringence of the sample but may depend on the precise method of absorbance measurement and on effects at the surface of the cell containing the liquid crystal under test.
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Affiliation(s)
- B K P Scaife
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
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McCoy BK, Liu ZQ, Wang ST, Pan L, Wang S, Goodby JW, Huang CC. Nonplanar tilts in very thin smectic films of one liquid-crystal compound. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 79:061702. [PMID: 19658511 DOI: 10.1103/physreve.79.061702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Indexed: 05/28/2023]
Abstract
Surface effects cause tilted molecular arrangements in smectic layers near the surface of a free-standing liquid-crystal film in which the bulk of the film is in the smectic- A phase. One recent work has shown that the tilt directions in adjacent surface layers may be nonplanar. In this paper we study films with thicknesses of two to six smectic layers. Surface effects dominate in these very thin films. We show that the molecular tilts are nonplanar even in these very thin films.
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Affiliation(s)
- B K McCoy
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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11
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Archer P, Dierking I, Görtz V, Goodby JW. Probing the material properties and phase transitions of ferroelectric liquid crystals by determination of the Landau potential. Eur Phys J E Soft Matter 2008; 25:385-393. [PMID: 18425407 DOI: 10.1140/epje/i2007-10302-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Accepted: 02/20/2008] [Indexed: 05/26/2023]
Abstract
The full Landau potential of several, widely varying ferroelectric liquid-crystalline materials has been experimentally determined. Tilt angle and polarisation data is analysed across the SmA to SmC transition for varying applied electric-field amplitudes, allowing the determination of all the coefficients of the generalised Landau model of ferroelectric liquid crystals. The materials investigated encompass different materials, including low-polarisation mixtures to high-polarisation single-component materials. The materials also possess a variation in the order of the SmA to SmC phase transition from strongly first order to strongly second order. The effects of both the polarisation and order of phase transition of the system are discussed with respect to the various terms of the generalised Landau model. Further, the mechanisms behind the difference between a first- and second-order phase transition are discussed with respect to the Landau potential and the second Landau coefficient b .
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Affiliation(s)
- P Archer
- School of Physics and Astronomy, University of Manchester, Manchester, UK
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12
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Sigarev AA, Vij JK, Hall AW, Cowling SJ, Goodby JW. Molecular orientational properties of a high-tilt chiral smectic liquid crystal determined from its infrared dichroism. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 76:051707. [PMID: 18233673 DOI: 10.1103/physreve.76.051707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Revised: 08/02/2007] [Indexed: 05/25/2023]
Abstract
The orientational characterisitics and the temperature dependencies of the molecular apparent tilt angle of a partly fluorinated chiral smectic liquid crystal (/S/)-4-(1-methylheptyloxycarbonyl)phenyl 4'-[6-(3,4,4,4-tetrafluoro-3-trifluoromethylbutylcarbonyloxy)hexyloxy] biphenyl-4-carboxylate (acronym MHPHFHHOBC) are studied using the polarized Fourier transform infrared (FTIR) spectroscopy. The molecular orientational distributions and the orientational order parameters for a homogeneously aligned liquid crystalline sample at various temperatures and external electric fields are examined. The analysis uses the dichroic parameters of the phenyl and the carbonyl bands. For a temperature range of 65-80 degrees C corresponding to the antiferroelectric SmCA* phase, the molecular apparent tilt angle lies within the range 43 degrees -44 degrees; antiferroelectric smectic structure being rather close to the orthoconic SmCA* phase. An application of sufficiently high dc field across the cell in its SmA* phase surprisingly shows that the dichroism first increases slowly and then rapidly in two stages and finally a saturated apparent tilt angle of approximately 30 degrees is reached. The IR dichroic data is used to estimate the polar angles and the degree of rotational biasing of the carbonyl groups with respect to the molecular long axis. In the SmA* phase, the sample appears to demonstrate some of the typical properties of a de Vries material.
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Affiliation(s)
- A A Sigarev
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
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13
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Goodby JW, Görtz V, Cowling SJ, Mackenzie G, Martin P, Plusquellec D, Benvegnu T, Boullanger P, Lafont D, Queneau Y, Chambert S, Fitremann J. Thermotropic liquid crystalline glycolipids. Chem Soc Rev 2007; 36:1971-2032. [PMID: 17982519 DOI: 10.1039/b708458g] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Are the liquid crystalline properties of the materials of living systems important in biological structures, functions, diseases and treatments? There is a growing consciousness that the observed lyotropic, and often thermotropic liquid crystallinity, of many biological materials that possess key biological functionality might be more than curious coincidence. Rather, as the survival of living systems depends on the flexibility and reformability of structures, it seems more likely that it is the combination of softness and structure of the liquid-crystalline state that determines the functionality of biological materials. The richest sources of liquid crystals derived from living systems are found in cell membranes, of these glycolipids are a particularly important class of components. In this critical review, we will examine the relationship between chemical structure and the self-assembling and self-organising properties of glycolipids that ultimately lead to mesophase formation.
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Affiliation(s)
- J W Goodby
- Department of Chemistry, The University of York, York, UK YO10 5DD
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14
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Meier JG, Nobili M, Carlsson T, Rudquist P, Petrenko AS, Goodby JW, Brunet M, Lagerwall ST. Possible model of an antiferroelectric twist grain boundary phase. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 76:011704. [PMID: 17677468 DOI: 10.1103/physreve.76.011704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Indexed: 05/16/2023]
Abstract
Using x-ray and optical methods we have probed the structural organization of an antiferroelectric twist grain boundary phase (TGBC(a)) lying between the regular antiferroelectric smectic-C (SmC(a)* and the smectic-Q (SmQ) or isotropic phase. We find that the twist axis is everywhere perpendicular to the local smectic layer normal and that the helical superstructure is incommensurate with the smectic layer structure. The twist grain boundaries consist of a periodic lattice of alternating +1/2 and -1/2 dispirations, i.e., unit screw dislocations in combination with half unit disclinations. The molecular tilt plane is alternatingly parallel and perpendicular to the twist axis. We find that the optically measured tilt angle in the SmC(a)* phase is smaller than that measured by x rays, which is the opposite to what is found in the SmC* phase. This means that the core part tilts less than the end chains in the SmC(a)* phase, while it tilts more in the SmC* phase. On entering the TGB phase a clear decrease is measured in the tilt angle. This is explained by the elastic influence from the disclinations, which appear in this phase.
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Affiliation(s)
- J G Meier
- Department of Microelectronics and Nanoscience, Chalmers University of Technology, S-41296 Göteborg, Sweden
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15
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Korlacki R, Steiner M, Meixner AJ, Vij JK, Hird M, Goodby JW. Conformational distribution of a ferroelectric liquid crystal revealed using fingerprint vibrational spectroscopy and the density functional theory. J Chem Phys 2007; 126:224904. [PMID: 17581080 DOI: 10.1063/1.2741557] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The authors have investigated the conformational structure of the ferroelectric liquid crystal compound 4-3-methyl-2-chloropentanoyloxy-4"-hexyloxy-biphenyl also known under the abbreviations 3M2CPHOB and C6 using vibrational (IR and Raman) spectroscopy. The measured spectra exhibit two bands corresponding to the C=O stretching vibration that are separated by 20 cm(-1). In contrast, the molecular structure comprises only one such group. They assigned the two bands to different conformers that coexist in a temperature range between 25 and 65 degrees C covering the entire mesophase of this material. This assignment is strongly confirmed by calculated vibrational spectra based on the density functional theory.
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Affiliation(s)
- R Korlacki
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
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16
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Panov VP, Vij JK, Panarin YP, Blanc C, Lorman V, Goodby JW. Discontinuous change in the smectic layer thickness in ferrielectric liquid crystals. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 75:042701. [PMID: 17500942 DOI: 10.1103/physreve.75.042701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2006] [Revised: 01/05/2007] [Indexed: 05/15/2023]
Abstract
The temperature dependence of the thickness of thick free-standing films is studied using a high-resolution film thickness measurement technique. A small discontinuity in the temperature dependence of the smectic layer thickness at every phase transition between ferro-, ferri-, and antiferroelectric phases is observed. We show that the major contribution to it arises from a change in the smectic tilt angle.
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Affiliation(s)
- V P Panov
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
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Tuffin RP, Mehl GH, Toyne KJ, Goodby JW. Tilted Layered Phases: The Influence of the Inclusion of a Non-Linear Macrocycle in Calamitic Liquid Crystals - Synthesis and Phase Behaviour. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587259708046964] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- R. P. Tuffin
- a School of Chemistry, University of Hull , Hull , HU6 7RX , England
| | - G. H. Mehl
- a School of Chemistry, University of Hull , Hull , HU6 7RX , England
| | - K. J. Toyne
- a School of Chemistry, University of Hull , Hull , HU6 7RX , England
| | - J. W. Goodby
- a School of Chemistry, University of Hull , Hull , HU6 7RX , England
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Praefcke K, Blunk D, Singer D, Goodby JW, Toyne KJ, Hird M, Styring P, Norbert WDJA. Design of Low-molar Mass Thermomesogens in the Search for Biaxial Nematic Liquid Crystals. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587259808048444] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- K. Praefcke
- a Institute of Organic Chemistry, C3, Technische Universität Berlin , 0-10623 , Berlin , Germany
| | - D. Blunk
- a Institute of Organic Chemistry, C3, Technische Universität Berlin , 0-10623 , Berlin , Germany
| | - D. Singer
- a Institute of Organic Chemistry, C3, Technische Universität Berlin , 0-10623 , Berlin , Germany
| | - J. W. Goodby
- b The School of Chemistry, The University of Hull , Hull , HU6 7RX , England
| | - K. J. Toyne
- b The School of Chemistry, The University of Hull , Hull , HU6 7RX , England
| | - M. Hird
- b The School of Chemistry, The University of Hull , Hull , HU6 7RX , England
| | - P. Styring
- b The School of Chemistry, The University of Hull , Hull , HU6 7RX , England
| | - W. D. J. A. Norbert
- b The School of Chemistry, The University of Hull , Hull , HU6 7RX , England
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20
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Affiliation(s)
- G. H. Mehl
- a School of Chemistry, University of Hull , Hull , HU6 7RX , England
| | - J. W. Goodby
- a School of Chemistry, University of Hull , Hull , HU6 7RX , England
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21
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Goodby JW, Toyne KJ, Hird M, Styring P, Lewis RA, Beer A, Dong CC, Glendenning ME, Jones JC, Lymer KP, Slaney AJ, Minter V, Chan LKM. Ferroelectric Liquid Crystalline Materials: Hosts, Dopants and Gels for Display Applications. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587250008023876] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- J. W. Goodby
- a Department of Chemistry , The University of Hull , Hull , HU6 7RX , England
| | - K. J. Toyne
- a Department of Chemistry , The University of Hull , Hull , HU6 7RX , England
| | - M. Hird
- a Department of Chemistry , The University of Hull , Hull , HU6 7RX , England
| | - P. Styring
- a Department of Chemistry , The University of Hull , Hull , HU6 7RX , England
| | - R. A. Lewis
- a Department of Chemistry , The University of Hull , Hull , HU6 7RX , England
| | - A. Beer
- a Department of Chemistry , The University of Hull , Hull , HU6 7RX , England
| | - C. C. Dong
- a Department of Chemistry , The University of Hull , Hull , HU6 7RX , England
| | - M. E. Glendenning
- a Department of Chemistry , The University of Hull , Hull , HU6 7RX , England
| | - J. C. Jones
- b DERA , St Andrews Road, Gt Malvern, Worcs , WR14 3PS , UK
| | - K. P. Lymer
- b DERA , St Andrews Road, Gt Malvern, Worcs , WR14 3PS , UK
| | - A. J. Slaney
- b DERA , St Andrews Road, Gt Malvern, Worcs , WR14 3PS , UK
| | - V. Minter
- b DERA , St Andrews Road, Gt Malvern, Worcs , WR14 3PS , UK
| | - L. K. M. Chan
- c CRL Ltd , Dawley Road, Hayes, Middlesex , UB3 1HH , UK
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22
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Affiliation(s)
- J. W. Goodby
- a School of Chemistry, The University of Hull , Hull , HU6 7RX , England
| | - A. J. Slaney
- a School of Chemistry, The University of Hull , Hull , HU6 7RX , England
| | - C. J. Booth
- a School of Chemistry, The University of Hull , Hull , HU6 7RX , England
| | - I. Nishiyama
- a School of Chemistry, The University of Hull , Hull , HU6 7RX , England
| | - J. D. Vuijk
- a School of Chemistry, The University of Hull , Hull , HU6 7RX , England
| | - P. Styring
- a School of Chemistry, The University of Hull , Hull , HU6 7RX , England
| | - K. J. Toyne
- a School of Chemistry, The University of Hull , Hull , HU6 7RX , England
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23
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Mehl GH, Thornton AJ, Goodby JW. Oligomers and Dendrimers Based on Siloxane and Silsesquioxane Cores: Does the Structure of the Central Core Affect the Liquid-Crystalline Properties? ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587259908023791] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- G. H. Mehl
- a Department of Chemistry , University of Hull , Hull , HU6 7RX , UK
| | - A. J. Thornton
- a Department of Chemistry , University of Hull , Hull , HU6 7RX , UK
| | - J. W. Goodby
- a Department of Chemistry , University of Hull , Hull , HU6 7RX , UK
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24
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Mehl GH, Elsäßer R, Goodby JW, Veith M. Dendritic and Multipodal Liquid-Crystalline Materials Based on Organic-Inorganic Hybrid Carbosilazane Cores. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587250108024990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- G. H. Mehl
- a Department of Chemistry , University of Hull , Hull , HU6 7RX , UK
| | - R. Elsäßer
- a Department of Chemistry , University of Hull , Hull , HU6 7RX , UK
| | - J. W. Goodby
- a Department of Chemistry , University of Hull , Hull , HU6 7RX , UK
| | - M. Veith
- b Institut für Anorganische Chemie, Universität des Saarlandes , Postfach 151150, 66041 , Saarbrücken , Germany
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25
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Affiliation(s)
- Sin-Doo Lee
- a Physics Department , Sogang University , C. P. O. Box 1142, Seoul , Korea
| | - Jae-Hoon Kim
- a Physics Department , Sogang University , C. P. O. Box 1142, Seoul , Korea
| | | | - J. W. Goodby
- c School of Chemistry , The University , Hull , HU6 7RX , England
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Tuffin RP, Goodby JW, Bennemann D, Heppke G, Lötzsch D, Scherowsky G. Non-Chiral Compounds Exhibiting Alternating Tilt Smectic Phases. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/10587259508038683] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Panov VP, McCoy BK, Liu ZQ, Vij JK, Goodby JW, Huang CC. Investigations of nanoscale helical pitch in smectic-C*alpha and smectic-C* phases of a chiral smectic liquid crystal using differential optical reflectivity measurements. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 74:011701. [PMID: 16907105 DOI: 10.1103/physreve.74.011701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Revised: 05/16/2006] [Indexed: 05/11/2023]
Abstract
Differential optical reflectivity (DOR) was used to study the temperature dependence of the short helical pitch in freestanding films of a liquid crystal compound. The experimentally measured DOR signal was fitted using Berreman's 4 x 4 matrix method to get the pitch value in the smectic-C*alpha (sMC*alpha) phase. The results show continuous evolution of the pitch between the smectic-C*alpha and sMC*alpha phases. In sMC*alpha, the pitch decreases as temperature increases and is found to level off at 16+/-1 smectic layers at the sMC*alpha to smectic-A* transition.
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Affiliation(s)
- V P Panov
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
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Fernandes P, Barois P, Grelet E, Nallet F, Goodby JW, Hird M, Micha JS. Extension of the resonant scattering technique to liquid crystals without resonant element. Eur Phys J E Soft Matter 2006; 20:81-7. [PMID: 16733642 DOI: 10.1140/epje/i2006-10006-4] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Accepted: 03/28/2006] [Indexed: 05/09/2023]
Abstract
We report X-ray resonant scattering experiments performed on the prototype liquid-crystalline compound MHPOBC doped with a chemical probe containing a resonant atom (selenium). We determined directly for the first time the microscopic 3- and 4-layer structure of the ferrielectric subphases (SmC(FI1)* and SmC(FI2)*) present in MHPOBC. Despite the low fraction of the selenium probe, the resonant signal is strong enough to allow an unambiguous determination of the basic structure of the ferrielectric subphases. These experiments demonstrate that the resonant scattering technique can be extended to liquid crystalline materials without resonant element and may stimulate new studies. A non-resonant Bragg reflection was also found in the SmC(FI1)* phase in pure MHPOBC, consistent with the 3-layer distorted model, but never detected before.
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Affiliation(s)
- P Fernandes
- Centre de Recherche Paul-Pascal-CNRS, Université Bordeaux 1, Avenue A. Schweitzer, 33600, Pessac, France
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McCoy BK, Liu ZQ, Wang ST, Panov VP, Vij JK, Goodby JW, Huang CC. Surface-induced multiple reentrant transitions. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 73:041704. [PMID: 16711824 DOI: 10.1103/physreve.73.041704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Indexed: 05/09/2023]
Abstract
We have studied tilted surface layers in the bulk SmA temperature window of one liquid crystal using null transmission ellipsometry. Five distinct nonplanar surface structures were observed. We present analyses of the tilt and azimuthal profiles of the structures and examine the transitions between the structures. The transitions are identified as a double reentrant synclinic-anticlinic-synclinic-anticlinic transition. Meanwhile, the transitions also display reentrant ferroelectric-antiferroelectric-ferroelectric behavior.
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Affiliation(s)
- B K McCoy
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
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Korlacki R, Fukuda A, Vij JK, Kocot A, Görtz V, Hird M, Goodby JW. Self-assembly of biaxial ordering and molecular tilt angle of chiral smectic liquid crystals in homeotropically aligned cells investigated using infrared spectroscopy. Phys Rev E Stat Nonlin Soft Matter Phys 2005; 72:041704. [PMID: 16383399 DOI: 10.1103/physreve.72.041704] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2005] [Revised: 04/21/2005] [Indexed: 05/05/2023]
Abstract
Temperature dependences of the infrared absorbance have been measured for the four chiral liquid crystal samples in the homeotropic cell configuration. It is shown that the values of the orientational order parameter obtained using this method exhibit a remarkable similarity to the x-ray diffraction results of the smectic layer spacing and lead to accurate values of the molecular tilt angle. This has important consequences for the existing interpretation of the x-ray data. The proposed method, in many cases, may be considered as a valuable alternative to the x-ray diffraction, giving additional, important information about the orientations and the ordering of the molecular fragments. It is found that if the experimentally obtained order parameter is low, then the molecular biaxiality is exceptionally large. The average phenyl ring plane is found to lie close to the molecular tilt plane.
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Affiliation(s)
- R Korlacki
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
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Panov VP, Shtykov NM, Fukuda A, Vij JK, Suzuki Y, Lewis RA, Hird M, Goodby JW. Self-assembled uniaxial and biaxial multilayer structures in chiral smectic liquid crystals frustrated between ferro- and antiferroelectricity. Phys Rev E Stat Nonlin Soft Matter Phys 2004; 69:060701. [PMID: 15244533 DOI: 10.1103/physreve.69.060701] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2003] [Indexed: 05/24/2023]
Abstract
With a view to obtain a molecular model for the subphases produced by the frustration between ferro- and antiferroelectricity in chiral smectic liquid crystals, we report results on two compounds and observe (i) the staircase character of uniaxial Sm C(*)(alpha) itself in the bulk and (ii) the multipeaked characteristic reflection bands due to the modulated helical structures just above the Sm C(*)(A) temperature range. We suggest the emergence of several uniaxial and biaxial subphases. The results show that both types of subphases can be specified by q(T) = [F] / ( [A] + [F] ) in the zero-order approximation; [A] and [F] are the numbers of antiferroelectric and ferroelectric orderings in the unit cell. We consider the basis of both types of subphases, particularly the description of the short-pitch helical structure of Sm C(*)(alpha), in terms of the molecular models so far proposed and emphasize the important role played by the discrete flexoelectric polarization.
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Affiliation(s)
- V P Panov
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
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Mehl GH, Valvo F, Lacey D, Goodby JW, Das-Gupta DK. Properties of side chain liquid crystal polyesters containing chiral groups in the main chain. POLYM ENG SCI 2004. [DOI: 10.1002/pen.10693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Panov VP, Vij JK, Shtykov NM, Seomun SS, Parghi DD, Hird M, Goodby JW. Optical rotatory power, biaxiality, and models of chiral tilted smectic phases. Phys Rev E Stat Nonlin Soft Matter Phys 2003; 68:021702. [PMID: 14524988 DOI: 10.1103/physreve.68.021702] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2003] [Indexed: 11/07/2022]
Abstract
Among the chiral tilted smectics, the stable existence has been confirmed in numerous investigations of SmC(*)(A), (antiferroelectric smectic-C(A)) SmC(*)(F11) (SmC(*)(gamma)), SmC(*)(F12) (antiferroelectric, AF) and SmC* phases. The structures of the ferrielectric SmC(*)(F11) and SmC(*)(F12) phases suggested by different models are essentially different although all the models use the three-layer and four-layer periodicity for them. The structures of the phases were investigated using the optical rotatory power (ORP) measurements technique. The ORP was simulated using Berreman's 4 x 4-matrix method. The compound under investigation (S)-1-methylheptyl 4-(4(')-n-undecyloxy-biphenyl-4-yl-carbonyloxy) [acronym (S)-11OF1M7] clearly provides SmC(*)(F11) and SmC(*)(F12) phases, the temperature range for the existence of these phases is about 5 degrees C each. This had not been achieved for the earlier investigated antiferroelectric liquid crystal (AFLC) samples. The results obtained confirm that the unit cell of the molecular structure of these subphases is highly biaxial. Due to the biaxiality the texture of the homeotropic cell under a polarizing microscope appears nonuniform. This requires a special approach to the measurements and a simulation of the ORP, which is discussed in detail. A technique has been designed where the transmitted intensity through a polarizing microscope is measured as a function of the angle of polarization of the incident light. From the observed output, which is a biased sine wave, the ORP is being determined. In the same scan, the wavelength of light is also being automatically altered. Comparing the simulated and measured data, we can conclude that in the SmC(*)(F12) phase the distortion angle of the directors in the Ising model is lower than 10 degrees. Using the Ising model, the pitch in SmC(*)(F11) has been determined and this is found to have a strong temperature dependence.
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Affiliation(s)
- V P Panov
- Institute of Advanced Materials Science and Department of Electronic Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
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Sigarev AA, Vij JK, Lewis RA, Hird M, Goodby JW. Molecular orientation and the infrared dichroism of a chiral smectic liquid crystal in a homogeneously aligned cell at different temperature and bias fields. Phys Rev E Stat Nonlin Soft Matter Phys 2003; 68:031707. [PMID: 14524788 DOI: 10.1103/physreve.68.031707] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2003] [Indexed: 05/24/2023]
Abstract
The molecular orientation and the dichroic behavior of the vibrational bands of a homogeneously aligned helical cell containing chiral smectic liquid crystal (R)-(-)-1-methylheptyl 4-(4(')-dodecyloxybiphenyl-4-ylcarbonyloxy)-3-fluorobenzoate are studied at various temperatures as a function of the bias field. These temperatures correspond to the various phase states of the sample at zero field. For those bands that exhibit significant dichroism, the field dependencies of the dichroic parameters (the dichroic ratio and the polarization angle of maximum absorbance) are found to be dependent on temperature, phase state, and helical unwinding. For the SmA* and SmC(*)(alpha) phases, the phenyl band dichroic ratio and the corresponding orientational order parameter are found to be almost independent of the bias field. The temperature dependence of the orientational order for zero field is discussed by taking into account the structures of the phases and the molecular tilt angles. The field dependencies of the phenyl band dichroic parameters for the SmC(*)(A) and SmC(*)(gamma) phases yield results about the distribution of directors in the layers of their unit cells and the state of helical unwinding. The azimuthal orientational distribution function of the carbonyl transition moments with respect to the long molecular axis has been determined. It is found that the degrees of the polar and quadrupolar biasing increase with decrease in temperature and the azimuthal biasing angle for the chiral carbonyl group increases significantly with a reduction in temperature.
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Affiliation(s)
- A A Sigarev
- Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland
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Tajber L, Kocot A, Vij JK, Merkel K, Zalewska-Rejdak J, Mehl GH, Elsässer R, Goodby JW, Veith M. Orientational Order and Dynamics of Nematic Multipodes Based on Carbosilazane Cores Using Optical and Dielectric Spectroscopy. Macromolecules 2002. [DOI: 10.1021/ma020714p] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Patel JS, Goodby JW. Observation of polarization sign inversion in ferroelectric liquid crystals produced by doping SC liquid crystals. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100307a003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Goodby JW, Chin E, Leslie TM, Geary JM, Patel JS. Helical twist sense and spontaneous polarization direction in ferroelectric smectic liquid crystals. 1. J Am Chem Soc 2002. [DOI: 10.1021/ja00276a008] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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42
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Hirst LS, Watson SJ, Gleeson HF, Cluzeau P, Barois P, Pindak R, Pitney J, Cady A, Johnson PM, Huang CC, Levelut AM, Srajer G, Pollmann J, Caliebe W, Seed A, Herbert MR, Goodby JW, Hird M. Interlayer structures of the chiral smectic liquid crystal phases revealed by resonant X-ray scattering. Phys Rev E Stat Nonlin Soft Matter Phys 2002; 65:041705. [PMID: 12005844 DOI: 10.1103/physreve.65.041705] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2001] [Indexed: 05/23/2023]
Abstract
The structures of the liquid crystalline chiral subphases exhibited by several materials containing either a selenium or sulphur atom have been investigated using a resonant x-ray scattering technique. This technique provides a unique structural probe for the ferroelectric, ferrielectric, antiferroelectric, and SmC(*)(alpha) phases. An analysis of the scattering features allows the structural models of the different subphases to be distinguished, in addition to providing a measurement of the helical pitch. This paper reports resonant scattering features in the antiferroelectric hexatic phase, the three- and four-layer intermediate phases, the antiferroelectric and ferroelectric phases and the SmC(*)(alpha) phase. The helicoidal pitch has been measured from the scattering peaks in the four-layer intermediate phase as well as in the antiferroelectric and ferroelectric phases. In the SmC(*)(alpha) phase, an investigation into the helical structure has revealed a pitch ranging from 5 to 54 layers in different materials. Further, a strong resonant scattering signal has been observed in mixtures of a selenium containing material with as much as 90% nonresonant material.
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Affiliation(s)
- L S Hirst
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
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Han XF, Olson DA, Cady A, Goodby JW, Huang CC. Surface structures and transitions in the smectic-C* phase of one chiral liquid crystal compound. Phys Rev E Stat Nonlin Soft Matter Phys 2002; 65:010704. [PMID: 11800669 DOI: 10.1103/physreve.65.010704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2001] [Indexed: 05/23/2023]
Abstract
Three optical probes have been employed on free-standing films to study surface structure and transitions of the SmC* phase of one liquid crystal compound. While the interior layers show the SmC* structure, the tilt in adjacent surface layers is found to be anticlinic. The number of anticlinic surface layers grows rapidly as the transition to the SmC*(FI2) phase is approached.
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Affiliation(s)
- X F Han
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Cady A, Pitney JA, Pindak R, Matkin LS, Watson SJ, Gleeson HF, Cluzeau P, Barois P, Levelut AM, Caliebe W, Goodby JW, Hird M, Huang CC. Orientational ordering in the chiral smectic-C*FI2 liquid crystal phase determined by resonant polarized x-ray diffraction. Phys Rev E Stat Nonlin Soft Matter Phys 2001; 64:050702. [PMID: 11735886 DOI: 10.1103/physreve.64.050702] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2001] [Indexed: 05/23/2023]
Abstract
High-resolution resonant polarized x-ray diffraction experiments near the sulfur K edge have been performed on free-standing liquid crystal films exhibiting the chiral smectic-C*FI2 phase. It is widely accepted that this phase has a four-layer repeat unit, but the internal structure of the repeat unit remains controversial. We report different resolved features of the resonant x-ray diffraction peaks associated with the smectic-C*FI2 phase that unambiguously demonstrate that the four-layer repeat unit is locally biaxial about the layer normal and that the measured angle, describing the biaxiality, is in good agreement with optical measurements.
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Affiliation(s)
- A Cady
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Shishkina SV, Drushlyak TG, Kutulya LA, Shishkin OV, Goodby JW. Molecular and crystal structures of 1R,4S-2-(4-carbomethoxy)benzylidene-n-menthan-3-one. CRYSTALLOGR REP+ 2001. [DOI: 10.1134/1.1405865] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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47
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Matkin LS, Watson SJ, Gleeson HF, Pindak R, Pitney J, Johnson PM, Huang CC, Barois P, Levelut AM, Srajer G, Pollmann J, Goodby JW, Hird M. Resonant x-ray scattering study of the antiferroelectric and ferrielectric phases in liquid crystal devices. Phys Rev E Stat Nonlin Soft Matter Phys 2001; 64:021705. [PMID: 11497606 DOI: 10.1103/physreve.64.021705] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2001] [Indexed: 05/23/2023]
Abstract
Resonant x-ray scattering has been used to investigate the interlayer ordering of the antiferroelectric and ferrielectric smectic C* subphases in a device geometry. The liquid crystalline materials studied contain a selenium atom and the experiments were carried out at the selenium K edge allowing x-ray transmission through glass. The resonant scattering peaks associated with the antiferroelectric phase were observed in two devices containing different materials. It was observed that the electric-field-induced antiferroelectric to ferroelectric transition coincides with the chevron to bookshelf transition in one of the devices. Observation of the splitting of the antiferroelectric resonant peaks as a function of applied field also confirmed that no helical unwinding occurs at fields lower than the chevron to bookshelf threshold. Resonant features associated with the four-layer ferrielectric liquid crystal phase were observed in a device geometry. Monitoring the electric field dependence of these ferrielectric resonant peaks showed that the chevron to bookshelf transition occurs at a lower applied field than the ferrielectric to ferroelectric switching transition.
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Affiliation(s)
- L S Matkin
- Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
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Abstract
A hexadecamer, first-generation, octasilsesquioxane liquid-crystalline dendrimer was synthesized by a platinum-catalyzed hydrosilylation reaction of the parent first-generation vinyl octasilsesquioxane dendrimer with a modified, laterally substituted mesogen. The structure and purity of the octasilsesquioxane substrate was confirmed by 1H, 13C, and 29 Si NMR spectroscopy, microanalysis, and size exclusion chromatography (SEC). The mesogenic substrate was found to exhibit only a chiral nematic phase, whereas the resulting hexadecamer dendrimer displays enantiotropic chiral nematic, disordered hexagonal columnar, and disordered rectangular columnar phases, with a glass transition below room temperature. The lateral or side-on attachment of the mesogen to the dendritic core was found to be a key design feature in the formation of the mesophases.
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Affiliation(s)
- I M Saez
- Department of Chemistry, University of Hull, UK.
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Elsäßer R, Mehl GH, Goodby JW, Veith M. Nematic Phase Behaviour of Inorganic-Organic Hybrid Systems Based on Dendritic Carbosilazane Cores. PHOSPHORUS SULFUR 2001. [DOI: 10.1080/10426500108546580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- R. Elsäßer
- a Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- b Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- c Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- d Institut für Anorganische Chemie , Universität des Saarlandes , Postfach 151150, 66041 Saarbrücken, Germany
| | - G. H. Mehl
- a Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- b Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- c Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- d Institut für Anorganische Chemie , Universität des Saarlandes , Postfach 151150, 66041 Saarbrücken, Germany
| | - J. W. Goodby
- a Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- b Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- c Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- d Institut für Anorganische Chemie , Universität des Saarlandes , Postfach 151150, 66041 Saarbrücken, Germany
| | - M. Veith
- a Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- b Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- c Department of Chemistry , University of Hull , Hull HU6 7RX, UK
- d Institut für Anorganische Chemie , Universität des Saarlandes , Postfach 151150, 66041 Saarbrücken, Germany
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Kutulya LA, Pivnenko NS, Petrenko AS, Vashchenko VV, Goodby JW. J STRUCT CHEM+ 2001; 42:84-91. [DOI: 10.1023/a:1010424206790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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