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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Institution: |
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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