Chiral discotic derivatives of 1,3,5-triphenyl-6-oxoverdazyl radical

<div><p>Two derivatives of 1,3,5-aryl-6-oxoverdazyl containing two 3,4,5-trioctyloxyphenyl and one 3,4,5-tri((<i>S</i>)-3,7-dimethyloctyloxy)phenyl group in position C(3) (<b>1b</b>) or N(1) (<b>1c</b>) were investigated by thermal, X-ray diffraction and magnetic methods. The results were compared to those obtained for achiral derivative <b>1a</b> containing three 3,4,5-trioctyloxyphenyl groups. All three compounds exhibit an ordered columnar hexagonal phase, <i>Col</i><sub>h(o)</sub>, and for chiral derivatives, <b>1b</b> and <b>1c</b>, a superstructure with doubled periodicity was found. The introduction of the three chiral alkoxy substituents in <b>1a</b> lowered the mesophase stability by about 50 K and induced a <i>Col</i><sub>h</sub> phase in <b>1c</b>. Thermochromic analysis showed a hypsochromic shift upon formation of the <i>Col</i><sub>h(o)</sub> phase similar for all three derivatives <b>1</b> (~0.3 eV), which coincides with a 5% drop in effective magnetic moment, <i>μ</i><sub>eff</sub>, for <b>1c</b>. Analysis of magnetisation data in a range of 2–370 K at 200 Oe revealed weak antiferromagnetic interactions (<i>θ</i> = – 4 K) in the <i>Col</i><sub>h(o)</sub> phase.</p></div>