Chiral linear isocyanide palladium(II) and gold(I) complexes as ferroelectric liquid crystals

(Note: The full text of this document is currently only available in the PDF Version )

Ana Omenat, José-Luis Serrano, Teresa Sierra, David B. Amabilino, María Minguet, Elena Ramos and Jaume Veciana


Abstract

Creation of helical SmC* and Ch mesophases has been achieved by means of metal ion complexation by chiral isocyanide ligands, which have already proven their ability to induce high optical activity in helical synthetic polymers. Thus, from unstable isocyanide compounds with a mesogenic core derived from phenyl benzoate, five stable complexes have been prepared. Four palladium(II) complexes have been obtained with different chiral tails and, in one case, with a three-ring mesogenic core. Their corresponding SmC* phases have been studied in terms of their ferroelectric properties. High Ps values have been found for complexes derived from (S)-octan-2-ol: 93 nC cm–2 for I2Pd(C8*)2 and 59 nC cm–2 for I2Pd(COOPhC8*)2. A gold(I) complex with (R)-2-octyl as the chiral tail is presented as the first SmC* gold(I) complex whose ferroelectric behaviour has been studied. Indeed, the complex has been used as a chiral dopant in a binary mixture, the Ps value of which has been estimated.


References

  1. J. L. Serrano and T. Sierra, in Metallomesogens. Synthesis, Properties and Applications, ed. J. L. Serrano, VCH, Weinheim, 1996, ch. 3 Search PubMed.
  2. (a) Y. Okamoto and T. Nakano, Chem. Rev., 1994, 94, 349 CrossRef CAS; (b) A. E. Rowan and R. J. M. Nolte, Angew. Chem., Int. Ed., 1998, 37, 63 CrossRef CAS.
  3. (a) T. Kaharu and S. Takahashi, Chem. Lett., 1992, 1515 CAS; (b) T. Kaharu, T. Tanaka, M. Sawada and S. Takahashi, J. Mater. Chem., 1994, 4, 859 RSC; (c) T. Kaharu, R. Ishii and S. Takahashi, J. Chem. Soc., Chem. Commun., 1994, 1349 RSC; (d) T. Kaharu, R. Ishii, T. Adachi, T. Yoshida and S. Takahashi, J. Mater. Chem., 1995, 5, 687 RSC.
  4. (a) M. Benouazzane, S. Coco, P. Espinet and J. M. Martín-Álvarez, J. Mater. Chem., 1995, 5, 441 RSC; (b) S. Coco, P. Espinet, S. Falagán and J. M. Martín-Álvarez, New J. Chem., 1995, 19, 959 Search PubMed; (c) P. Alejos, S. Coco and P. Espinet, New J. Chem., 1995, 19, 799 Search PubMed; (d) S. Coco, P. Espinet, J. M. Martín-Álvarez and A. M. Levelut, J. Mater. Chem., 1997, 7, 19 RSC; (e) R. Bayón, S. Coco, P. Espinet, C. Fernández-Mayordomo and J. M. Martín-Álvarez, Inorg. Chem., 1997, 36, 2329 CrossRef CAS; (f) S. Coco, F. Díez-Expósito, P. Espinet, C. Fernández-Mayordomo, J. M. Martín-Álvarez and A. M. Levelut, Chem. Mater., 1998, 10, 3666 CrossRef CAS.
  5. S. Wang, A. Mayr and K.-K. Cheung, J. Mater. Chem., 1998, 8, 1561 RSC.
  6. F. Millich, J. Polym. Sci., Macromol. Rev., 1980, 15, 207 Search PubMed; R. J. M. Nolte, Chem. Soc. Rev., 1994, 23, 11 RSC.
  7. (a) E. Ramos, J. Bosch, J. L. Serrano, T. Sierra and J. Veciana, J. Am. Chem. Soc., 1996, 118, 4703 CrossRef CAS; (b) D. B. Amabilino, E. Ramos, J. L. Serrano, T. Sierra and J. Veciana, J. Am. Chem. Soc., 1998, 120, 9126 CrossRef CAS.
  8. The reason for employing the formamide precursors in this way was that none of them presented thermotropic mesophases and we considered study of the isocyanide monomers unreliable on account of their instability.
  9. (a) M. Marcos, J. L. Serrano, T. Sierra and M. J. Giménez, Angew. Chem., Int. Ed. Engl., 1992, 31, 1471 CrossRef; (b) M. Marcos, J. L. Serrano, T. Sierra and M. J. Giménez, Chem. Mater., 1993, 5, 1332 CrossRef CAS; (c) R. Iglesias, M. Marcos, J. L. Serrano, T. Sierra and M. A. Pérez-Jubindo, Chem. Mater., 1996, 8, 2611 CrossRef CAS; (d) P. Espinet, J. Etxebarría, M. Marcos, J. Pérez, A. Remón and J. L. Serrano, Angew. Chem., Int. Ed. Engl., 1989, 28, 1065 CrossRef; (e) M. J. Baena, J. Barberá, P. Espinet, A. Ezcurra, M. B. Ros and J. L. Serrano, J. Am. Chem. Soc., 1994, 116, 1899 CrossRef CAS; (f) M. J. Baena, P. Espinet, M. B. Ros, J. L. Serrano and A. Ezcurra, Angew. Chem., Int. Ed. Engl., 1993, 32, 1203 CrossRef; (g) N. Thompson, J. L. Serrano, M. J. Baena and P. Espinet, Chem. Eur. J., 1996, 2, 214 CrossRef CAS.
  10. (a) A. Omenat and M. Ghedini, J. Chem. Soc., Chem. Commun., 1994, 1309 RSC; (b) R. Deschenaux and J. Santiago, Tetrahedron Lett., 1994, 35, 2169 CrossRef CAS; (c) C. Imrie and C. Loubser, J. Chem. Soc., Chem. Commun., 1994, 2159 RSC.
  11. R. Usón, A. Laguna and J. Vicente, J. Organomet. Chem., 1977, 131, 471 CrossRef CAS.
  12. (a) K. Miyasato, S. Abe, H. Takezoe, A. Fukuda and E. Kuze, Jpn. J. Appl. Phys., 1983, 22, L661; (b) M. R. de la Fuente, A. Ezcurra, M. A. Pérez-Jubindo and J. Zubía, Liq. Cryst., 1990, 7, 51 CAS.
  13. M. R. de la Fuente, A. Ezcurra, M. A. Pérez-Jubindo and J. Zubía, Liq. Cryst., 1990, 7, 51 CAS.
  14. J. Barberá, F. Navarro, L. Oriol, M. Piñol and J. L. Serrano, J. Polym. Sci., Part A: Polym. Chem., 1990, 28, 703 CAS.
  15. p-Hexyloxyphenyl-p'-decyloxybenzoate was used as an SmC* host, C 62.5 °C SmC 78.2 °C SmA 84.5 °C N 90.5 °C I. See P. Keller, P. E. Cladis, P. L. Finn and H. R. Brand, J. Phys., 1985, 46, 2203 Search PubMed.
Click here to see how this site uses Cookies. View our privacy policy here.