Substituent-Dependent Magnetic Behavior of Discotic Benzo[e][1,2,4]triazinyls

Discotic mesogens containing the benzo­[e]­[1,2,4]­triazinyl radical as the central unit exhibit a Colh phase below 80 °C. Depending on the substituent at the N(1) position, they show different modes of thermal expansion and magnetic behavior, presumably due to differences in molecular organization. Thus, for 1-phenyl (1a) and 1-PhF-m (1b) derivatives, the Colh phase has positive thermal expansion coefficient κ and antiferromagnetic interactions, while for the 1-(3,4,5-(C12H25X)3C6H2) derivatives 1c (X = O) and 1d (X = S), κ is negative and weak ferromagnetic interactions in the crystalline phase are observed for 1c (J/k B = +4.76 K). Compounds 1a and 1c exhibit photoinduced hole transport (μ ≈ 1.3 × 10–3 cm2 V–1 s–1) in the Colh phase.