Şadan Özden, Nejmettin Avcı, Atilla Eren Mamuk, Pınar Özden

4-propoxy-biphenyl-4-carbonitrile Nematik Sıvı Kristalinin Dielektrik Özellikleri

Bu çalışmada, nematik fazdaki 4-propoxy-biphenyl-4-carbonitrile’in sıcaklığa bağlı dielektrik geçirgenliğinin ölçümleri raporlanmıştır. Bu amaçla 1 kHz ila 1MHz frekans aralığında sıcaklığa bağlı dielektrik karakterizasyonu gerçekleştirilmiştir. Sözü edilen malzeme nematik fazda pozitif dielektrik anizotropik özellik göstermektedir. Ayrıca uzun eksen etrafında molekül rotasyonuna karşılık gelen dielektrik gevşeme frekansları sıcaklığın bir fonksiyonu olarak ölçülmüş ve gevşeme sürecinin aktivasyon enerjisi Arrhenius metodu vasıtasıyla belirlenmiştir.

Anahtar Kelimeler:

Sıvı kristal, nematik, dielektrik geçirgenlik, aktivasyon enerjisi

The Dielectric Properties of 4-propoxy-biphenyl-4-carbonitrile Nematic Liquid Crystal

In the present investigation, the temperature dependent measurements of dielectric permittivity for 4-propoxy-biphenyl-4-carbonitrile was reported in the nematic region. Temperature-dependent dielectric characterization was carried out over the frequency range of 1 kHz to 1MHz. The compound shows positive dielectric anisotropy in the nematic phase. The dielectric relaxation frequencies corresponding to the molecular rotation around the long axis were measured as a function of temperature. The activation energy of relaxation process was determined by means of the Arrhenius relation.

Keywords:

Liquid crystal, nematic, dielectric permittivity, activation energy,

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[1] P.G. de Gennes ve J. Prost, The Physics of Liquid Crystals, 2. Baskı, Oxford, İngiltere: Clarendon, 1993, ss. 45-57.
[2] K. Iam-Choon ve S.T. Wu, Optics and Nonlinear Optics of Liquid Crystals, 1. Baskı, Singapur: World Scientific Pub Co Inc., 1993, ss. 77-83.
[3] M. Kleman ve O.D. Lavrentovich, Soft Matter Physics: An Introduction, 1. Baskı, New York, Amerika: Springer, Verlag, 2003, ss. 127-134.
[4] S. T. Wu ve D.K. Yang, Fundamentals of Liquid Crystal Devices, 1. Baskı, West Sussex, İngiltere: Wiley, 2006, ss. 317-345.
[5] S. Singh ve D.A. Dunmur, Liquid Crystals: Fundamentals, 1. Baskı, New York, Amerika: World Scientific., 2002, ss. 102-119.
[6] P.V. Shibaev ve M.B. Guseva, “Molecular orientation in propyl-and hexyloxycyanobiphenyl vacuum deposited thin films,” Journal of Crystal Growth, c. 119, s. 3-4, ss. 399-402, 1992.
[7] D. Sharma, T. Gargi, ve S.N. Tiwari, “Thermodynamical properties and infrared spectra of 4-n-propoxy-4-cyanobiphenyl: Hartree-fock and density functional theory methods,” Int J Electroact Mater, c. 5, ss. 19-30, 2017.
[8] T-H. Tong, B.M. Fung, ve J.P. Bayle, “A database for the determination of orientational ordering of nine classes of liquid crystals using carbon-13 chemical shifts,” Liquid crystals, c. 22, s. 2, ss. 165-169, 1997.
[9] C. David ve D. Baeyens-Volan, “Absorption and Fluorescence Spectra of 4-Cyanobiphenyl and 4'-Alkyl-or 4'-Alkoxy-Substituted Liquid Crystalline Derivatives,” Molecular Crystals and Liquid Crystals, c. 59, s. 3-4, ss. 181-196, 1980.
[10] N.I. Giricheva, M.S. Fedorov, K.E. Shpilevaya, S.A. Syrbu, ve O.Y. Ditsina, “Characteristics of the hydrogen bond and the structure of Н-complexes of p-n-propyloxybenzoic acid and p-n-propyloxy-p′-cyanobiphenyl,” Journal of Structural Chemistry, c. 58, s. 1, ss. 9-16, 2017.
[11] A.N. Isaev ve P. P. Shorygin, “Charge transfer in systems of conjugated bonds in cyanobiphenyl molecules: Quantum-chemical calculations of the structure and vibrational spectra,” Russian Journal of Physical Chemistry A, c. 83, s. 3, ss. 430-435, 2009.
[12] K.I. Muta, H. Takezoe, A. Fukuda, ve E. Kuze, “Cotton-mouton effect of alkyl-and alkoxy-cyanobiphenyls in isotropic phase,” Japanese Journal of Applied Physics, c. 18, s. 11, ss. 2073-2080, 1979.
[13] J.W. Emsley, G.R. Luckhurst, ve H.S. Sachdev, “Dependence of solute orientational order on the structure and orientational order of the liquid crystal solvent. A deuterium NMR study of p-xylene-d10 dissolved in a series of 4-n-alkyloxy-4′-cyanobiphenyls,” Liquid Crystals, c. 5, s. 3, ss. 953-967, 1989.
[14] F. Eikelschulte, S.Y. Yakovenko, D. Paschek, ve A. Geiger, “Electrostatic properties of cyano-containing mesogens,” Liquid Crystals, c. 27, s. 9, ss. 1137-1146, 2000.
[15] L.M. Babkov, N.I. Davydova, G.A. Puchkovskaya, ve I.N. Khakimov. “IR absorption spectra and structure of 4-cyano-4′,-p-alkoxybiphenyls,” Journal of Structural Chemistry, c. 34, s. 1, ss. 92-97, 1993.
[16] K.J. McEwan, S.E. Day, D.G. McDonnell, ve K.J. Harrison “Measurement of x (3) in novel liquid-crystal materials,” In Nonlinear and Electro-Optic Materials for Optical Switching. International Society for Optics and Photonics, c. 1692, ss. 118-130, 1992.
[17] V. Krasnoholovets, I. Khakimov, G. Puchkovskaya, ve E. Gabrusenoks, “Mechanism of Q (C≡ N) Band Broadening in Condensed State of Alkoxycyanobiphenyles” ,Molecular Crystals and Liquid Crystals Science and Technology, Section A, Molecular Crystals and Liquid Crystals, c. 348, s. 1, ss. 101-109, 2000.
[18] L.G. Kuz’mina, N.S. Kucherepa, ve A.V. Churakov, “Mesophase design: II. Molecular structure and crystal packing of 4-alkyloxycyanobiphenyls,” Crystallography Reports., c. 57, s. 2, ss. 213-226, 2012.
[19] A. P. Emerson ve GR. Luckhurst, “On the relative propensities of ether and methylene linkages for liquid crystal formation in calamitics,” Liquid Crystals, c. 10, s. 6, ss. 861-868, 1991.
[20] C.J. Counsell, J.W. Emsley, G.R. Luckhurst, ve HS.Sachdev, “Orientational order in the 4-n-alkyloxy-4′-cyanobiphenyls: A comparison between experiment and theory,” Molecular Physics, c. 63, s. 1, ss. 33-47, 1988.
[21] L.M. Babkov, O.V. Gorshkova E.V., Gabrusyonok, G.A. Puchkovskaya, ve I.N. Khakimov, “Phase transitions, conformational lability, and intermolecular interactions in alkoxycyanobiphenyls,” Journal of Structural Chemistry, c. 36, s. 5, ss. 739-746, 1995.
[22] L.M. Babkov, S.I. Tatarinov, O.V. Gorshkova, G.A. Puchkovskaya, ve I.N. Khakimov, “Polymorphism and conformational mobility of molecules of long chain aliphatic compounds,” Journal of molecular structure, c. 482, ss. 453-456, 1999.
[23] L.M. Babkov, E. Gabrusenoks, V. Krasnoholovets, G.A. Puchkovskaya, ve I.N. Khakimov, “Raman spectra and molecular dynamics of alkoxycyanobiphenyles,” International Society for Optics and Photonics, c. 4069, ss. 109-114, 2000.
[24] MJ. Richardson, “The derivation of thermodynamic properties by DSC: free energy curves and phase stability,” Thermochimica acta, c. 229, ss. 1-4, 1993.
[25] S. Gupta ve S. Paul, “The Structure Property Relationship of a Homologous Series of Mesogenic Compounds,” Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, c. 260, s. 1, ss. 483-489, 1995.
[26] G.W. Gray ve A. Mosley, “Trends in the nematic–isotropic liquid transition temperatures for the homologous series of 4-n-alkoxy-and 4-n-alkyl-4′-cyanobiphenyls,” Journal of the Chemical Society, Perkin Transactions, c. 2, s. 1, ss. 97-102, 1976.
[27] L.M. Babkov, E, Gabrusyonok, V.V. Krasnoholovets, G.A. Puchkovskaya, ve I.N. Khakimov, “Vibrational spectra and molecular dynamics of alkoxycyanobiphenyls,” Journal of molecular structure, c. 482, ss. 475-480, 1999.
[28] L.M. Babkov, O.V. Gorshkova, G.A. Puchkovskaya, ve I.N. Khakimov, “Vibrational spectra and structure of 4-cyano-4′-pentalkoxybiphenyl in different physical states,” Journal of structural chemistry, c. 39, s. 1, ss. 44-48, 1998.
[29] V.F. Chuvaev, M.N. Rodnikova, M.R. Kiselev, A.A. Syrbu, and S.A. Syrbu, “Wide-Line 1 H NMR ve DSC study of phase states of mesomorphic states of 4′-n-alkoxy-4-biphenylcarbonitrile mesogens (n= 3 and 7),” Russian Journal of Inorganic Chemistry, c. 54, s. 12, ss. 1969-1974, 2009.
[30] I. Penchev, I. Dozov, N. Kirov, N. Afanasyeva, ve J. Ruoliene, “Orientational Order Parameters of Some 4-Cyano 4′, n-Alkoxybiphenyls,” Spectroscopy Letters, c. 15, s. 4, ss. 265-274, 1982.
[31] L. M. Blinov, Structure and Properties of Liquid Crystals, 1. Baskı, New York., Amerika: Springer, 2011, ss. 19-32.
[32] L. Walz, Η. Paulus, ve W. Haase, “Crystal and molecular structures of four mesogenic 4’-alkoxy-4-cyanobiphenyls,” Zeitschrift für Kristallographie-Crystalline Materials, c. 180, s. 1-4, ss. 97-112, 1987.
[33] J. Constant ve E.P. Raynese, “Flow aligned viscosities of cyanobiphenyls,” Molecular Crystals and Liquid Crystals, c. 62, s. 1-2, ss. 115-123, 1980.
[34] J.W. Emsley, “Conformational properties of alkyloxy end chains in NOCB liquid crystals,” Liquid Crystals, c. 20, ss. 1-5, 2018.
[35] J.P. Abberley, R. Killah, R. Walker, J.M. Storey, C.T. Imrie, M. Salamończyk, ve D. Pociecha, “Heliconical smectic phases formed by achiral molecules,” Nat. Commun., c. 9, s. 1, ss. 1-7, 2018.
[36] D.A. Paterson, J.P. Abberley, W.T. Harrison, J. M.,Storey, ve C.T. Imrie, “Cyanobiphenyl-based liquid crystal dimers and the twist-bend nematic phase,” Liquid Crystals, c. 44, s. 1, ss. 127–146, 2017.
[37] M.A. Grunwald, J.C. Haenle, K.C. Kreß, R. Forschner, T. Wöhrle, W. Frey, ve S. Laschat, “Mesomorphic properties of cyanobiphenyl dimers with a central malonate unit,” Liquid Crystals, c. 45, s. 11, ss. 1626–1636, 2018.
[38] D.A. Paterson, C.A. Crawford, D. Pociecha, R. Walker, J. M. Storey, E. Gorecka, ve C.T. Imrie, “The role of a terminal chain in promoting the twist-bend nematic phase: the synthesis and characterisation of the 1-(4-cyanobiphenyl-4 ‘-yl)-6-(4-alkyloxyanilinebenzylidene-4 ‘-oxy)hexanes,” Liquid Crystals, c. 45, s. 13–15, ss. 2341–2351, 2018.
[39] K. Wang, M. Jirka, P. Rai, R. J. Twieg, T. Szilvási, H. Yu, ve M. Mavrikakis, “Synthesis and properties of hydroxy tail-terminated cyanobiphenyl liquid crystals,” Liquid Crystals, c. 46, s. 3, ss. 397–407, 2019.
[40] W. Haase, S. Wróbel, Relaxation phenomena: liquid crystals, magnetic systems, polymers, high-Tc superconductors, metallic glasses, 1. Baskı, New York, Amerika: Springer Science & Business Media, 2013, ss. 25-77.
[41] W.H. De Jeu, “Physical properties of liquid crystalline materials in relation to their applications,” Molecular Crystals and Liquid Crystals, c. 63, s. 1, ss. 83-109, 1981.
[42] W. Maier ve G.A. Meier, “Simple theory of the dielectric are some homogeneous criteria oriented liquid crystal phases of nematic type,” Z Naturforsch. A, c. 16, ss. 262-267, 1961.
[43] S. Urban, B. Gestblom, D. Tuma, ve R. Dąbrowski, “Dielectric studies of two liquid crystalline benzoates with coupled and decoupled CN groups,” Liquid crystals, c. 29, s. 2, ss. 301-307, 2002.
[44] P.K. Tripathi, R, Manohar, ve S.Singh, “Dielectric Relaxation Spectroscopy of Liquid Crystal in Nematogenic Mesophase,” Molecular Crystals and Liquid Crystals, c. 626, s. 1, ss. 160-168, 2016.
[45] W.H. De Jeu, T.W. Lathouwers, ve P. Bordewijk, “Dielectric properties of di-n-heptyl azoxybenzene in the nematic and in the smectic-A phases,” Physical Review Letters, c. 32, s. 2, ss. 40-43, 1974.
[46] A. Ghanadzadeh, “Dielectric investigations and molecular association in non-mesogenic and mesogenic solutions,” Journal of molecular liquids, c. 102, s. 1-3, ss. 365-377, 2003.