부산대학교 도서관

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 derivative1acontaining three 3,4,5-trioctyloxyphenyl groups. All three compounds exhibit an ordered columnar hexagonal phase,Colh(o), and for chiral derivatives,1band1c, a superstructure with doubled periodicity was found. The introduction of the three chiral alkoxy substituents in1alowered the mesophase stability by about 50 K and induced aColhphase in1c. Thermochromic analysis showed a hypsochromic shift upon formation of theColh(o)phase similar for all three derivatives1(~0.3 eV), which coincides with a 5% drop in effective magnetic moment,μeff, for1c. Analysis of magnetisation data in a range of 2–370 K at 200 Oe revealed weak antiferromagnetic interactions (θ = – 4 K) in theColh(o)phase. [ABSTRACT FROM PUBLISHER]