• Українська
  • English

< | >

Current issue   Ukr. J. Phys. 2017, Vol. 62, N 4, p.294-298


Bordyuh A.B.

National Aviation University
(1, Prosp. Komarova, Kyiv 03058, Ukraine; e-mail: a.bordyuh@gmail.com)

Mechanism of Dimerization of Viologens in Liquid Crystalline Medium

Section: Atoms and Molecules
Original Author's Text: English

Abstract: This work presents the analysis of experimental data on electrooptical properties of viologens incorporated into the liquid crystalline medium. These data along with theoretical considerations allow specifying the mechanism, which leads to the double color change in the liquid crystal – viologen samples stipulated by the application of increasing voltage values. Specifically, it is proved that the first color change takes place due to the one-electron reduction of viologen molecules, and the second color change is caused by the dimerization between viologen molecules, which were fully reduced under the action of a voltage applied, and initial viologen molecules.

Key words: lyotropic liquid crystals, viologens, optical spectroscopy, absorption, dimerization.


  1. T.V. Timofeeva, E.E. Boda, A.P. Polischuk, M.Yu. Antipin, E.V. Matukhina, I.M. Petrova, N.N. Makarova, Yu.T. Struchkov. Structure investigations of thermotropic liquid crystalline monomer and polymer organosilicon compounds. Mol. Cryst. Liq. Cryst. 248, 125 (1994).
  2. A.P. Polishchuk, N.N. Makarova, T.V. Astapova. X-ray diffraction investigation of trans-2,8-dihydroxy-2,8-diphenyl-4,4′ ,6,6′ ,10,10′ ,12,12′ -octamethylcyclohexasiloxane and trans-2,8-dihydroxy-2,4,4′ ,6,6′ ,8,10,10′ ,12,12′ -decamethyl-5-carbohexacyclosiloxane. Kristallografiya 47, 863 (2002).
  3. A.P. Polishchuk, T.V. Timofeeva. Metal-containing liquidcrystal phases. Russian Chem. Rev. 62, 291 (1993).
  4. L.M. Babkov, N.A. Golovina, A.V. Kosov, A.P. Polishchuk, G.A. Puchkovskaya. Molecular structure and conformation changes of mesogen crystals. J. Molec. Struct. 218, 207 (1990).
  5. A.V. Gridyakina, Yu.A. Garbovskiy, G.V. Klimusheva, A.P. Polishchuk. Nonlinear optical response of smectic glasses based on cobalt alkanoates. Ukr. J. Phys. 57, 177 (2012).
  6. G.V. Klimusheva, Yu. Garbovskii, S. Bugaichuk, A.S. Tolochko, A.V. Gridyakina, A.P. Polishchuk, T.A. Mirnaya. Novel nanocomposite materials based on mesomorphic glasses of metal alkanoates: structure and nonlinear optical properties. High Energy Chem. 43, 532 (2009).
  7. S. Bugaychuk, G. Klimusheva, Yu. Garbovskiy, T. Mirnaya, A. Ischenko. Nonlinear optical properties of composites based on conductive metal-alkanoate liquid crystals. Opto-Electron. Rev. 14, 275 (2006).
  8. A.B. Bordyug, A.P. Polishchuk, G.V. Klimusheva, A.S. Tolochko, T.A. Mirnaya, G.G. Yaremchuk. Structure and intermolecular interactions in ionic liquid crystals doped with electrochromic viologen. Russian J. of Phys. Chem. 79, 866 (2005).
  9. A. Bordyuh, Yu. Garbovskiy, S. Bugaychuk, G. Klimusheva, V. Reshetnyak. Fast nonlinear optical mechanisms in bi-layered cells composed by lyotropic ionic liquid crystals with dye and viologen films. Mol. Cryst. Liq. Cryst. 508, 296 (2009).
  10. A.B. Bordyuh, Yu.A. Garbovskiy, S.A. Bugaychuk, G.V. Klimusheva, T.A. Mirnaya, G.G. Yaremchuk, A.P. Polishchuk. Dynamic grating recording in lyotropic ionic smectics of metal alkanoates doped with electrochromic impurities. Opt. Mat. 31, 1109 (2009).
  11. E.M. Kosower, J.L. Cotter. Stable free radicals. II. The reduction of 1-methyl-4-cyanopiridinium ion to methylviologen cation radical. J. Amer. Chem. Soc. 86, 5524 (1964).
  12. V.N. Gratchev, S.I. Zhdanov, G.S. Supin. The investigation of chemical properties of bis-(0,0-dimethylphosphate)-N,N′ -dimethyl-4,4-dipyridilium using methods of classic and alternating current polarography. Electrochem. XIV, 1353 (1978).
  13. P.M.S. Monk, R.D. Fairweather, M.D. Ingram, J.A. Duffy. Pulsed electrolysis enhancement of electrochromism in viologen systems: influence of comproportionation reactions. J. Electroanal. Chem. 359, 301 (1993).
  14. P.M.S. Monk. The Viologens: Physicochemical Properties, Synthesis and Applications of the Salts of 4,4′ -Bipyridine (Wiley-VCH, 1998) [ISBN: 978-0-471-98603-4].
  15. P.M.S. Monk, N.M. Hodgkinson, R.D. Partridge. The colours of charge-transfer complexes of methyl viologen: effects of donor, ionic strength and solvent. Dyes and Pigments. 43, 241 (1999).
  16. M. Pope, C.E. Swenberg. Electronic Processes in Organic Crystals (Clarendon Press, 1982) [ISBN: 9780195129632].