Magnetic behaviour of bent-core mesogens derived from the 1,4-dihydrobenzo[e][1,2,4]triazin-4-yl

摘要

A series of bent-core mesogens 2[m,n] and 3[4,6][6, n] derived from the 1,4-dihydrobenzo[e][1,2,4]triazin-4-yl radical and containing two partially fluorinated alkyl tails and the non-fluorinated derivative 1[12] were prepared and investigated by optical, thermal, XRD and magnetic methods. All compounds with six CF2 units in each terminal tail (2[6, n]) exhibit a smectic A phase with clearing temperatures in a range of 150-180 degrees C. Introduction of two different alkyl chain lengths into the molecular structure of 2 depressed the SmA-I transition temperature to about 120 degrees C in 3[4,6][6, n]. Solid-state EPR and magnetic susceptibility measurements (SQUID) for 3[4,6][6,8] revealed paramagnetic behaviour with weak intermolecular spin-spin interactions in the SmA phase suggesting low organization of the spin containing molecular units.