Triphenylene/carbazole mesogens and their electrochemistry

Molecular Crystals and Liquid Crystals

Volumn 397, Issue , 2003, Pages

  Manickam, M ^a   Cooke, Groaeme ^b   Kumar, Sandeep ^c   Ashton, Peter R ^a   Preece, Jon A ^a   Spencer, Neil ^a  

^a UNIVERSITY OF BIRMINGHAM   (United Kingdom)

^b HERIOT WATT UNIVERSITY   (United Kingdom)

^c CENTRE FOR NANO AND SOFT MATTER SCIENCES   (India)

Author keywords

Anisotropic ordering; Carbazole; Discotic liquid crysals; Electrochemistry; Photorefractive

Indexed keywords

ANISOTROPY; AROMATIC COMPOUNDS; CARBOXYLIC ACIDS; CHEMICAL MODIFICATION; CYCLIC VOLTAMMETRY; ELECTROCHEMISTRY; ESTERIFICATION; NITROGEN COMPOUNDS; PHOTOREFRACTIVE MATERIALS;

ANISOTROPIC ORDERING; CARBAZOLE; DISCOTIC LIQUID CRYSTALS;

LIQUID CRYSTALS;

EID: 3543026813     PISSN: 15421406     EISSN: None     Source Type: Journal    
DOI: 10.1080/714965597     Document Type: Conference Paper

References (45)

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2. (b) Yamashita, Y., Fujii, N., Murkata, C., Ashiawa, T., Okabe, M., & Nakano, H. (1992). Biochemistry, 31, 12069.
3. (c) Chakraborty, D. P. (1997). Prog. Chem. Org. Nat. Prod., Vol. 34, Heiz, W., Grisebach, H., & Kirby, G. W. Springer: Wien, 299.
4. Zhang, Y., Wada, T., & Sasabe, H. (1998). J. Mater. Chem., 8, 809.
5. 3 crystals by Ashkin, A., Boyd, G. D., Dziedic, J. M., Smith, R. G., Ballman, A. A., & Nassau, K. (1966). Appl. Phys. Lett., 9, 72.
6. The first report of a carbazole containing photorefractive material was by Zhang, Y., Cui, Y., & Prasad, P. N. (1992) Phys. Rev. B, 46, 9900.
7. Günter, P. & J.-P. Huignardm, Eds. Photorefractive Materials and Their Applications. Springer-Verlag: New York, 1988.
8. Maruyama, S., Tao, X.-t., Hokari, H., Noh, T., Zhang, Y., Wada, T., Sasabe, H., Watanabe, T., & Miyata, S. (1999). J. Mater. Chem., 9, 893.
9. Zhang, Y., Wang, L., Wada, T., & Sasabe, H. (1996). Chem. Commun., 559.
10. Scott, J. C., Pautmeier, L. Th., & Moemer, W. E. (1992). J. Opt. Soc. Am. B, 9, 2059.
11. The first report of an amorphous organic photorefractive material was by Ducharme, S., Scott, J. C., Twieg, R. J., & Moemer, W. E. (1991). Phys. Rev. Lett., 66, 1846.
12. Sutter, K , Hulliger, J., & Günter, P. (1990). Solid State Chem., 74, 867.
13. Zhang, Y., Wada, T., Wang, L., & Sasabe, H. (1997). Chem. Mater., 9, 2798.
14. The carbazole moiety has been introduced into a low molecular weight calamitic mesogenic structure which diplays a nematic mesophase, see Lux, M. & Strohriegl, P. (1987). Makromol. Chem., 188, 811. Additionally, a report of a polydiacetylene incorporating pendant carbazole moieties has been shown to organise into a self-organised structure, with columnar mesophases from room temperature to 250°C, see: Gallot, B., Cravino, A., Moggio, I., Comoretto, D.: Cuniberti, C., Dell'erba, C., & Dellepiane, G. (1999). Liq. Cryst., 26, 1437.
15. The carbazole moiety has been introduced into a low molecular weight calamitic mesogenic structure which diplays a nematic mesophase, see Lux, M. & Strohriegl, P. (1987). Makromol. Chem., 188, 811. Additionally, a report of a polydiacetylene incorporating pendant carbazole moieties has been shown to organise into a self-organised structure, with columnar mesophases from room temperature to 250°C, see: Gallot, B., Cravino, A., Moggio, I., Comoretto, D.: Cuniberti, C., Dell'erba, C., & Dellepiane, G. (1999). Liq. Cryst., 26, 1437.
16. Marcher, B , Chapoy, L., & Christensen, D. H. (1988). Macromolecules. 21, 677.
17. Manickam, M., Kurnar, S., Preece, J. A., & Spencer, N. (2000). Liq. Cryst., 27, 703.
18. We have chosen the triphenylene mesogenic structure for several reasons: (i) they have pronounced photoconductivity (Simmerr, J., Glüsen, B., Paulus, W., Kettner, A., Schumacher, P., Adam, D., Etzbach, K. H., Siemeseyer, K., Wendorf, J. H , Ringsdorf, H., & Haarer, D. (1996). Adv. Mater., 8, 815), (ii) they have a strong tendency to form columnar mesophases (Chandresekhar, S. & Kumar, S. (1997). Science Spectra, 8, 66; Allen, M. T , Diele, S., Harris, K. D. M., Hegmann, T., Kumari, N., Kariuki, B. M., Lose, D., Preece, J. A., & Tschierske, C. (2000). Liq. Cryst., 27, 689), and it is well recognised that the supramolecular structure of disc-shaped molecules, in general, is well suited for the one dimensional charge migration (see Markovitski, D., Marguet, S., Gallos, L. K., Sigal, H., Millie, P., Argyrakis, P., Ringsdorf, H., & Kumar, S (1999). Chem. Phys. Lett., 306, 163) and one dimensional chain migration (see Boden, N., Borner, R. C., Bushby, R. J., & Clements J. (1994). J. Am. Chem. Soc., 116, 10807; Balagurusamy, V. S. K., Krishna Prasad, S., Chandrasekhar, S., Kumar, S., Manickam, M., & Yelamaggad, C V. (1999). Pramana, 53, 3) as well as ferroelectrical properties (see, Bock, H. & Helfrich, W. (1995). Liq. Cryst., 18, 387), optoelectrical switching behaviour (Lin, C. Y., Pan, H. L., Fox, M. A., & Bard, A. J. (1993). Science, 261, 897), and photovoltaic behaviour (Greg, B. A., Foc, M. A., & Bard, A. J. (1990). J. Phys. Chem , 94, 1586), and (iii) doping with TNF can induce liquid crystalline behaviour in many triphenylene materials that initially do not show mesophase properties, Kranig, W., Boefield, C., & Spiess, H. W. (1990). Liq. Cryst., 8, 375, Bengs, H., Karthaus, O., Ringsdorf, H., Baehr. C., Ebert, M., & Wendorf, J. H. (1999). Liq. Cryst , 10, 161.
19. We have chosen the triphenylene mesogenic structure for several reasons: (i) they have pronounced photoconductivity (Simmerr, J., Glüsen, B., Paulus, W., Kettner, A., Schumacher, P., Adam, D., Etzbach, K. H., Siemeseyer, K., Wendorf, J. H , Ringsdorf, H., & Haarer, D. (1996). Adv. Mater., 8, 815), (ii) they have a strong tendency to form columnar mesophases (Chandresekhar, S. & Kumar, S. (1997). Science Spectra, 8, 66; Allen, M. T , Diele, S., Harris, K. D. M., Hegmann, T., Kumari, N., Kariuki, B. M., Lose, D., Preece, J. A., & Tschierske, C. (2000). Liq. Cryst., 27, 689), and it is well recognised that the supramolecular structure of disc-shaped molecules, in general, is well suited for the one dimensional charge migration (see Markovitski, D., Marguet, S., Gallos, L. K., Sigal, H., Millie, P., Argyrakis, P., Ringsdorf, H., & Kumar, S (1999). Chem. Phys. Lett., 306, 163) and one dimensional chain migration (see Boden, N., Borner, R. C., Bushby, R. J., & Clements J. (1994). J. Am. Chem. Soc., 116, 10807; Balagurusamy, V. S. K., Krishna Prasad, S., Chandrasekhar, S., Kumar, S., Manickam, M., & Yelamaggad, C V. (1999). Pramana, 53, 3) as well as ferroelectrical properties (see, Bock, H. & Helfrich, W. (1995). Liq. Cryst., 18, 387), optoelectrical switching behaviour (Lin, C. Y., Pan, H. L., Fox, M. A., & Bard, A. J. (1993). Science, 261, 897), and photovoltaic behaviour (Greg, B. A., Foc, M. A., & Bard, A. J. (1990). J. Phys. Chem , 94, 1586), and (iii) doping with TNF can induce liquid crystalline behaviour in many triphenylene materials that initially do not show mesophase properties, Kranig, W., Boefield, C., & Spiess, H. W. (1990). Liq. Cryst., 8, 375, Bengs, H., Karthaus, O., Ringsdorf, H., Baehr. C., Ebert, M., & Wendorf, J. H. (1999). Liq. Cryst , 10, 161.
20. We have chosen the triphenylene mesogenic structure for several reasons: (i) they have pronounced photoconductivity (Simmerr, J., Glüsen, B., Paulus, W., Kettner, A., Schumacher, P., Adam, D., Etzbach, K. H., Siemeseyer, K., Wendorf, J. H , Ringsdorf, H., & Haarer, D. (1996). Adv. Mater., 8, 815), (ii) they have a strong tendency to form columnar mesophases (Chandresekhar, S. & Kumar, S. (1997). Science Spectra, 8, 66; Allen, M. T , Diele, S., Harris, K. D. M., Hegmann, T., Kumari, N., Kariuki, B. M., Lose, D., Preece, J. A., & Tschierske, C. (2000). Liq. Cryst., 27, 689), and it is well recognised that the supramolecular structure of disc-shaped molecules, in general, is well suited for the one dimensional charge migration (see Markovitski, D., Marguet, S., Gallos, L. K., Sigal, H., Millie, P., Argyrakis, P., Ringsdorf, H., & Kumar, S (1999). Chem. Phys. Lett., 306, 163) and one dimensional chain migration (see Boden, N., Borner, R. C., Bushby, R. J., & Clements J. (1994). J. Am. Chem. Soc., 116, 10807; Balagurusamy, V. S. K., Krishna Prasad, S., Chandrasekhar, S., Kumar, S., Manickam, M., & Yelamaggad, C V. (1999). Pramana, 53, 3) as well as ferroelectrical properties (see, Bock, H. & Helfrich, W. (1995). Liq. Cryst., 18, 387), optoelectrical switching behaviour (Lin, C. Y., Pan, H. L., Fox, M. A., & Bard, A. J. (1993). Science, 261, 897), and photovoltaic behaviour (Greg, B. A., Foc, M. A., & Bard, A. J. (1990). J. Phys. Chem , 94, 1586), and (iii) doping with TNF can induce liquid crystalline behaviour in many triphenylene materials that initially do not show mesophase properties, Kranig, W., Boefield, C., & Spiess, H. W. (1990). Liq. Cryst., 8, 375, Bengs, H., Karthaus, O., Ringsdorf, H., Baehr. C., Ebert, M., & Wendorf, J. H. (1999). Liq. Cryst , 10, 161.
21. We have chosen the triphenylene mesogenic structure for several reasons: (i) they have pronounced photoconductivity (Simmerr, J., Glüsen, B., Paulus, W., Kettner, A., Schumacher, P., Adam, D., Etzbach, K. H., Siemeseyer, K., Wendorf, J. H , Ringsdorf, H., & Haarer, D. (1996). Adv. Mater., 8, 815), (ii) they have a strong tendency to form columnar mesophases (Chandresekhar, S. & Kumar, S. (1997). Science Spectra, 8, 66; Allen, M. T , Diele, S., Harris, K. D. M., Hegmann, T., Kumari, N., Kariuki, B. M., Lose, D., Preece, J. A., & Tschierske, C. (2000). Liq. Cryst., 27, 689), and it is well recognised that the supramolecular structure of disc-shaped molecules, in general, is well suited for the one dimensional charge migration (see Markovitski, D., Marguet, S., Gallos, L. K., Sigal, H., Millie, P., Argyrakis, P., Ringsdorf, H., & Kumar, S (1999). Chem. Phys. Lett., 306, 163) and one dimensional chain migration (see Boden, N., Borner, R. C., Bushby, R. J., & Clements J. (1994). J. Am. Chem. Soc., 116, 10807; Balagurusamy, V. S. K., Krishna Prasad, S., Chandrasekhar, S., Kumar, S., Manickam, M., & Yelamaggad, C V. (1999). Pramana, 53, 3) as well as ferroelectrical properties (see, Bock, H. & Helfrich, W. (1995). Liq. Cryst., 18, 387), optoelectrical switching behaviour (Lin, C. Y., Pan, H. L., Fox, M. A., & Bard, A. J. (1993). Science, 261, 897), and photovoltaic behaviour (Greg, B. A., Foc, M. A., & Bard, A. J. (1990). J. Phys. Chem , 94, 1586), and (iii) doping with TNF can induce liquid crystalline behaviour in many triphenylene materials that initially do not show mesophase properties, Kranig, W., Boefield, C., & Spiess, H. W. (1990). Liq. Cryst., 8, 375, Bengs, H., Karthaus, O., Ringsdorf, H., Baehr. C., Ebert, M., & Wendorf, J. H. (1999). Liq. Cryst , 10, 161.
22. We have chosen the triphenylene mesogenic structure for several reasons: (i) they have pronounced photoconductivity (Simmerr, J., Glüsen, B., Paulus, W., Kettner, A., Schumacher, P., Adam, D., Etzbach, K. H., Siemeseyer, K., Wendorf, J. H , Ringsdorf, H., & Haarer, D. (1996). Adv. Mater., 8, 815), (ii) they have a strong tendency to form columnar mesophases (Chandresekhar, S. & Kumar, S. (1997). Science Spectra, 8, 66; Allen, M. T , Diele, S., Harris, K. D. M., Hegmann, T., Kumari, N., Kariuki, B. M., Lose, D., Preece, J. A., & Tschierske, C. (2000). Liq. Cryst., 27, 689), and it is well recognised that the supramolecular structure of disc-shaped molecules, in general, is well suited for the one dimensional charge migration (see Markovitski, D., Marguet, S., Gallos, L. K., Sigal, H., Millie, P., Argyrakis, P., Ringsdorf, H., & Kumar, S (1999). Chem. Phys. Lett., 306, 163) and one dimensional chain migration (see Boden, N., Borner, R. C., Bushby, R. J., & Clements J. (1994). J. Am. Chem. Soc., 116, 10807; Balagurusamy, V. S. K., Krishna Prasad, S., Chandrasekhar, S., Kumar, S., Manickam, M., & Yelamaggad, C V. (1999). Pramana, 53, 3) as well as ferroelectrical properties (see, Bock, H. & Helfrich, W. (1995). Liq. Cryst., 18, 387), optoelectrical switching behaviour (Lin, C. Y., Pan, H. L., Fox, M. A., & Bard, A. J. (1993). Science, 261, 897), and photovoltaic behaviour (Greg, B. A., Foc, M. A., & Bard, A. J. (1990). J. Phys. Chem , 94, 1586), and (iii) doping with TNF can induce liquid crystalline behaviour in many triphenylene materials that initially do not show mesophase properties, Kranig, W., Boefield, C., & Spiess, H. W. (1990). Liq. Cryst., 8, 375, Bengs, H., Karthaus, O., Ringsdorf, H., Baehr. C., Ebert, M., & Wendorf, J. H. (1999). Liq. Cryst , 10, 161.
23. We have chosen the triphenylene mesogenic structure for several reasons: (i) they have pronounced photoconductivity (Simmerr, J., Glüsen, B., Paulus, W., Kettner, A., Schumacher, P., Adam, D., Etzbach, K. H., Siemeseyer, K., Wendorf, J. H , Ringsdorf, H., & Haarer, D. (1996). Adv. Mater., 8, 815), (ii) they have a strong tendency to form columnar mesophases (Chandresekhar, S. & Kumar, S. (1997). Science Spectra, 8, 66; Allen, M. T , Diele, S., Harris, K. D. M., Hegmann, T., Kumari, N., Kariuki, B. M., Lose, D., Preece, J. A., & Tschierske, C. (2000). Liq. Cryst., 27, 689), and it is well recognised that the supramolecular structure of disc-shaped molecules, in general, is well suited for the one dimensional charge migration (see Markovitski, D., Marguet, S., Gallos, L. K., Sigal, H., Millie, P., Argyrakis, P., Ringsdorf, H., & Kumar, S (1999). Chem. Phys. Lett., 306, 163) and one dimensional chain migration (see Boden, N., Borner, R. C., Bushby, R. J., & Clements J. (1994). J. Am. Chem. Soc., 116, 10807; Balagurusamy, V. S. K., Krishna Prasad, S., Chandrasekhar, S., Kumar, S., Manickam, M., & Yelamaggad, C V. (1999). Pramana, 53, 3) as well as ferroelectrical properties (see, Bock, H. & Helfrich, W. (1995). Liq. Cryst., 18, 387), optoelectrical switching behaviour (Lin, C. Y., Pan, H. L., Fox, M. A., & Bard, A. J. (1993). Science, 261, 897), and photovoltaic behaviour (Greg, B. A., Foc, M. A., & Bard, A. J. (1990). J. Phys. Chem , 94, 1586), and (iii) doping with TNF can induce liquid crystalline behaviour in many triphenylene materials that initially do not show mesophase properties, Kranig, W., Boefield, C., & Spiess, H. W. (1990). Liq. Cryst., 8, 375, Bengs, H., Karthaus, O., Ringsdorf, H., Baehr. C., Ebert, M., & Wendorf, J. H. (1999). Liq. Cryst , 10, 161.
24. We have chosen the triphenylene mesogenic structure for several reasons: (i) they have pronounced photoconductivity (Simmerr, J., Glüsen, B., Paulus, W., Kettner, A., Schumacher, P., Adam, D., Etzbach, K. H., Siemeseyer, K., Wendorf, J. H , Ringsdorf, H., & Haarer, D. (1996). Adv. Mater., 8, 815), (ii) they have a strong tendency to form columnar mesophases (Chandresekhar, S. & Kumar, S. (1997). Science Spectra, 8, 66; Allen, M. T , Diele, S., Harris, K. D. M., Hegmann, T., Kumari, N., Kariuki, B. M., Lose, D., Preece, J. A., & Tschierske, C. (2000). Liq. Cryst., 27, 689), and it is well recognised that the supramolecular structure of disc-shaped molecules, in general, is well suited for the one dimensional charge migration (see Markovitski, D., Marguet, S., Gallos, L. K., Sigal, H., Millie, P., Argyrakis, P., Ringsdorf, H., & Kumar, S (1999). Chem. Phys. Lett., 306, 163) and one dimensional chain migration (see Boden, N., Borner, R. C., Bushby, R. J., & Clements J. (1994). J. Am. Chem. Soc., 116, 10807; Balagurusamy, V. S. K., Krishna Prasad, S., Chandrasekhar, S., Kumar, S., Manickam, M., & Yelamaggad, C V. (1999). Pramana, 53, 3) as well as ferroelectrical properties (see, Bock, H. & Helfrich, W. (1995). Liq. Cryst., 18, 387), optoelectrical switching behaviour (Lin, C. Y., Pan, H. L., Fox, M. A., & Bard, A. J. (1993). Science, 261, 897), and photovoltaic behaviour (Greg, B. A., Foc, M. A., & Bard, A. J. (1990). J. Phys. Chem , 94, 1586), and (iii) doping with TNF can induce liquid crystalline behaviour in many triphenylene materials that initially do not show mesophase properties, Kranig, W., Boefield, C., & Spiess, H. W. (1990). Liq. Cryst., 8, 375, Bengs, H., Karthaus, O., Ringsdorf, H., Baehr. C., Ebert, M., & Wendorf, J. H. (1999). Liq. Cryst , 10, 161.
25. We have chosen the triphenylene mesogenic structure for several reasons: (i) they have pronounced photoconductivity (Simmerr, J., Glüsen, B., Paulus, W., Kettner, A., Schumacher, P., Adam, D., Etzbach, K. H., Siemeseyer, K., Wendorf, J. H , Ringsdorf, H., & Haarer, D. (1996). Adv. Mater., 8, 815), (ii) they have a strong tendency to form columnar mesophases (Chandresekhar, S. & Kumar, S. (1997). Science Spectra, 8, 66; Allen, M. T , Diele, S., Harris, K. D. M., Hegmann, T., Kumari, N., Kariuki, B. M., Lose, D., Preece, J. A., & Tschierske, C. (2000). Liq. Cryst., 27, 689), and it is well recognised that the supramolecular structure of disc-shaped molecules, in general, is well suited for the one dimensional charge migration (see Markovitski, D., Marguet, S., Gallos, L. K., Sigal, H., Millie, P., Argyrakis, P., Ringsdorf, H., & Kumar, S (1999). Chem. Phys. Lett., 306, 163) and one dimensional chain migration (see Boden, N., Borner, R. C., Bushby, R. J., & Clements J. (1994). J. Am. Chem. Soc., 116, 10807; Balagurusamy, V. S. K., Krishna Prasad, S., Chandrasekhar, S., Kumar, S., Manickam, M., & Yelamaggad, C V. (1999). Pramana, 53, 3) as well as ferroelectrical properties (see, Bock, H. & Helfrich, W. (1995). Liq. Cryst., 18, 387), optoelectrical switching behaviour (Lin, C. Y., Pan, H. L., Fox, M. A., & Bard, A. J. (1993). Science, 261, 897), and photovoltaic behaviour (Greg, B. A., Foc, M. A., & Bard, A. J. (1990). J. Phys. Chem , 94, 1586), and (iii) doping with TNF can induce liquid crystalline behaviour in many triphenylene materials that initially do not show mesophase properties, Kranig, W., Boefield, C., & Spiess, H. W. (1990). Liq. Cryst., 8, 375, Bengs, H., Karthaus, O., Ringsdorf, H., Baehr. C., Ebert, M., & Wendorf, J. H. (1999). Liq. Cryst , 10, 161.
26. We have chosen the triphenylene mesogenic structure for several reasons: (i) they have pronounced photoconductivity (Simmerr, J., Glüsen, B., Paulus, W., Kettner, A., Schumacher, P., Adam, D., Etzbach, K. H., Siemeseyer, K., Wendorf, J. H , Ringsdorf, H., & Haarer, D. (1996). Adv. Mater., 8, 815), (ii) they have a strong tendency to form columnar mesophases (Chandresekhar, S. & Kumar, S. (1997). Science Spectra, 8, 66; Allen, M. T , Diele, S., Harris, K. D. M., Hegmann, T., Kumari, N., Kariuki, B. M., Lose, D., Preece, J. A., & Tschierske, C. (2000). Liq. Cryst., 27, 689), and it is well recognised that the supramolecular structure of disc-shaped molecules, in general, is well suited for the one dimensional charge migration (see Markovitski, D., Marguet, S., Gallos, L. K., Sigal, H., Millie, P., Argyrakis, P., Ringsdorf, H., & Kumar, S (1999). Chem. Phys. Lett., 306, 163) and one dimensional chain migration (see Boden, N., Borner, R. C., Bushby, R. J., & Clements J. (1994). J. Am. Chem. Soc., 116, 10807; Balagurusamy, V. S. K., Krishna Prasad, S., Chandrasekhar, S., Kumar, S., Manickam, M., & Yelamaggad, C V. (1999). Pramana, 53, 3) as well as ferroelectrical properties (see, Bock, H. & Helfrich, W. (1995). Liq. Cryst., 18, 387), optoelectrical switching behaviour (Lin, C. Y., Pan, H. L., Fox, M. A., & Bard, A. J. (1993). Science, 261, 897), and photovoltaic behaviour (Greg, B. A., Foc, M. A., & Bard, A. J. (1990). J. Phys. Chem , 94, 1586), and (iii) doping with TNF can induce liquid crystalline behaviour in many triphenylene materials that initially do not show mesophase properties, Kranig, W., Boefield, C., & Spiess, H. W. (1990). Liq. Cryst., 8, 375, Bengs, H., Karthaus, O., Ringsdorf, H., Baehr. C., Ebert, M., & Wendorf, J. H. (1999). Liq. Cryst , 10, 161.
27. We have chosen the triphenylene mesogenic structure for several reasons: (i) they have pronounced photoconductivity (Simmerr, J., Glüsen, B., Paulus, W., Kettner, A., Schumacher, P., Adam, D., Etzbach, K. H., Siemeseyer, K., Wendorf, J. H , Ringsdorf, H., & Haarer, D. (1996). Adv. Mater., 8, 815), (ii) they have a strong tendency to form columnar mesophases (Chandresekhar, S. & Kumar, S. (1997). Science Spectra, 8, 66; Allen, M. T , Diele, S., Harris, K. D. M., Hegmann, T., Kumari, N., Kariuki, B. M., Lose, D., Preece, J. A., & Tschierske, C. (2000). Liq. Cryst., 27, 689), and it is well recognised that the supramolecular structure of disc-shaped molecules, in general, is well suited for the one dimensional charge migration (see Markovitski, D., Marguet, S., Gallos, L. K., Sigal, H., Millie, P., Argyrakis, P., Ringsdorf, H., & Kumar, S (1999). Chem. Phys. Lett., 306, 163) and one dimensional chain migration (see Boden, N., Borner, R. C., Bushby, R. J., & Clements J. (1994). J. Am. Chem. Soc., 116, 10807; Balagurusamy, V. S. K., Krishna Prasad, S., Chandrasekhar, S., Kumar, S., Manickam, M., & Yelamaggad, C V. (1999). Pramana, 53, 3) as well as ferroelectrical properties (see, Bock, H. & Helfrich, W. (1995). Liq. Cryst., 18, 387), optoelectrical switching behaviour (Lin, C. Y., Pan, H. L., Fox, M. A., & Bard, A. J. (1993). Science, 261, 897), and photovoltaic behaviour (Greg, B. A., Foc, M. A., & Bard, A. J. (1990). J. Phys. Chem , 94, 1586), and (iii) doping with TNF can induce liquid crystalline behaviour in many triphenylene materials that initially do not show mesophase properties, Kranig, W., Boefield, C., & Spiess, H. W. (1990). Liq. Cryst., 8, 375, Bengs, H., Karthaus, O., Ringsdorf, H., Baehr. C., Ebert, M., & Wendorf, J. H. (1999). Liq. Cryst , 10, 161.
28. We have chosen the triphenylene mesogenic structure for several reasons: (i) they have pronounced photoconductivity (Simmerr, J., Glüsen, B., Paulus, W., Kettner, A., Schumacher, P., Adam, D., Etzbach, K. H., Siemeseyer, K., Wendorf, J. H , Ringsdorf, H., & Haarer, D. (1996). Adv. Mater., 8, 815), (ii) they have a strong tendency to form columnar mesophases (Chandresekhar, S. & Kumar, S. (1997). Science Spectra, 8, 66; Allen, M. T , Diele, S., Harris, K. D. M., Hegmann, T., Kumari, N., Kariuki, B. M., Lose, D., Preece, J. A., & Tschierske, C. (2000). Liq. Cryst., 27, 689), and it is well recognised that the supramolecular structure of disc-shaped molecules, in general, is well suited for the one dimensional charge migration (see Markovitski, D., Marguet, S., Gallos, L. K., Sigal, H., Millie, P., Argyrakis, P., Ringsdorf, H., & Kumar, S (1999). Chem. Phys. Lett., 306, 163) and one dimensional chain migration (see Boden, N., Borner, R. C., Bushby, R. J., & Clements J. (1994). J. Am. Chem. Soc., 116, 10807; Balagurusamy, V. S. K., Krishna Prasad, S., Chandrasekhar, S., Kumar, S., Manickam, M., & Yelamaggad, C V. (1999). Pramana, 53, 3) as well as ferroelectrical properties (see, Bock, H. & Helfrich, W. (1995). Liq. Cryst., 18, 387), optoelectrical switching behaviour (Lin, C. Y., Pan, H. L., Fox, M. A., & Bard, A. J. (1993). Science, 261, 897), and photovoltaic behaviour (Greg, B. A., Foc, M. A., & Bard, A. J. (1990). J. Phys. Chem , 94, 1586), and (iii) doping with TNF can induce liquid crystalline behaviour in many triphenylene materials that initially do not show mesophase properties, Kranig, W., Boefield, C., & Spiess, H. W. (1990). Liq. Cryst., 8, 375, Bengs, H., Karthaus, O., Ringsdorf, H., Baehr. C., Ebert, M., & Wendorf, J. H. (1999). Liq. Cryst , 10, 161.
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