Chiral discotic derivatives of 1,3,5-triphenyl-6-oxoverdazyl radical |
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| Authors: | Aleksandra Jankowiak Damian Pociecha Jacek Szczytko |
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| Institution: | 1. Organic Materials Research Group, Department of Chemistry, Vanderbilt University, Nashville, TN, USA;2. Department of Chemistry, University of Warsaw, Warsaw, Poland;3. Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland |
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| Abstract: | Two derivatives of 1,3,5-aryl-6-oxoverdazyl containing two 3,4,5-trioctyloxyphenyl and one 3,4,5-tri((S)-3,7-dimethyloctyloxy)phenyl group in position C(3) (1b) or N(1) (1c) were investigated by thermal, X-ray diffraction and magnetic methods. The results were compared to those obtained for achiral derivative 1a containing three 3,4,5-trioctyloxyphenyl groups. All three compounds exhibit an ordered columnar hexagonal phase, Colh(o), and for chiral derivatives, 1b and 1c, a superstructure with doubled periodicity was found. The introduction of the three chiral alkoxy substituents in 1a lowered the mesophase stability by about 50 K and induced a Colh phase in 1c. Thermochromic analysis showed a hypsochromic shift upon formation of the Colh(o) phase similar for all three derivatives 1 (~0.3 eV), which coincides with a 5% drop in effective magnetic moment, μeff, for 1c. Analysis of magnetisation data in a range of 2–370 K at 200 Oe revealed weak antiferromagnetic interactions (θ = – 4 K) in the Colh(o) phase. |
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| Keywords: | discotic verdazyl radical chiral thermochromism magnetic analysis powder XRD synthesis |
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