Synthesis, characterization and theoretical study of a new liquid crystal compound with an oxazepine core

• A novel heterocyclic compounds based liquid crystal were synthesized and identified.
• The relationship of the core structures and the mesomorphic were investigated.
• Theoretical studies was studied.
• The SmA and N phases were observed.
• The nematic phase can only observed in long-chain derivatives.

A novel synthesis of heterocyclic liquid crystal compounds containing a seven-membered 1,3-oxazepine with terminal alkyloxy chains has been carried out. The molecular structures of these compounds were substantiated by FT-IR NMR elemental analysis. The relationship between the structures and the mesomorphic behaviours of their derivatives were investigated. The results showed that the formation of mesophases is strongly dependent on the type of core moiety. All compounds with oxazepinediones and oxazepanediones are non-mesogenic and only exhibit Cr1Cr2 upon cooling and heating. However, the SmA and N phases were observed in the 5,6-benzo [1,3] oxazepine-4,7-diones series of compounds. The study also revealed that the length of the alkyl chain has a significant effect on the liquid crystalline properties; the nematic phase can only observed in long-chain derivatives of 5,6-benzo [1,3] oxazepine-4,7-diones. Theoretical studies are in agreement with our result.