Synthesis and Anisotropic Properties of Novel Asymmetric Diones Fused With 1,3-Oxazepine and Oxazepane Rings

Novel synthesis of heterocyclic liquid crystal compounds containing seven-membered 1,3-oxazepine-4,7-diones, 5,6-dihydro-1,3-oxazepane-4,7-diones, and 5,6-benzo[e] [1,3]oxazepine-4,7-diones rings at para position has been carried out from the reaction of maleic, succinic, and phthalic anhydrides with N-(4-(tetradecyloxy) benzylidene) alkylamine. The various lengths of the even-parity alkyl chains CnH2n+1, in which n ranges from 6 to 18, were employed in the present study. The molecular structures of these compounds were substantiated by Fourier transformed infrared and nuclear magnetic resonance along with elemental analysis. The correlation between the structures and the mesomorphic behaviors of N-(4-(tetradecyloxy) benzylidene) alkylamines and their derivatives was investigated. Present work shows that the formation of mesophases is strongly dependent on the type of coremoiety. Although the imines possessing the alkyl chain CnH2n+1 (n = 6-14) exhibit smectic A (SmA) phases, the nemactogenic properties can only be observed in the series of 3,4-dihydrobenzo[e][1,3] oxazepine-1,5-diones.