Liquid crystalline hexa-amides and side chain polysiloxanes of azacrown [18]-N6 |
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| Authors: | Mingyang Zhao Warren T. Ford Stefan H. J. Idziak Nicholas C. Maliszewskyj Paul A. Heiney |
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| Affiliation: | a Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma, U.S.A.b Department of Physics, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A.c Materials Department and the Materials Research Laboratory, University of California, Santa Barbara, California, U.S.A. |
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| Abstract: | The hexa-4-dodecyloxybenzoyl derivative 1 of azacrown [18]-N6 was originally reported to have a 'tubular' mesophase on the basis of its large central ring and 6-fold symmetry. Starting in the mesophase, annealing of 1 under a cover slip results in formation of a new crystalline phase that melts directly to an isotropic liquid at the temperature previously observed for the mesophase to isotropic transition. Thus the phase behaviour of 1 is kinetically controlled. The analogous hexa-3,4-bisdodecyloxybenzoyl derivative 2 of azacrown [18]-N6 has no kinetic limitations to its phase changes and has an enantiotropic columnar liquid crystalline phase. We have synthesized side chain copolysiloxanes with a (CH2)11 spacer and 75-84 per cent by weight of the same 4-dodecyloxybenzoyl-[18]-N6 mesogen. The polysiloxanes also display a liquid crystalline phase. |
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