Smectogenic properties of N,N′‐bis[(2‐hydroxy‐4‐alkoxyphenyl)methylene]benzene‐1,4‐diamine liquid crystals with double lateral H‐bonds

Abstract

A series of eight liquid crystalline compounds, N,N′‐bis[(2‐hydroxy‐4‐alkoxyphenyl)methylene]benzene‐1,4‐diamines, has been synthesized and characterized. These homologous compounds differ in the length of terminal alkyl group C _n H_2n+1 wherein n is an even number ranging from 4 to 18. The spectroscopic techniques, FTIR, ¹H NMR and ¹³C NMR, were employed to characterize the molecular structure. The transition temperatures of all the title compounds and their mesophases were studied by differential scanning calorimetry and polarizing microscopy. All the compounds were smectogenic, exhibiting both tilted and non‐tilted molecular orientation in their smectic phases. Further investigation to ascertain the anisotropic nature of subphases within the smectogenic region was carried out using X‐ray diffraction.

Acknowledgements

G.‐Y. Y. thanks Universiti Sains Malaysia and the Malaysian Government, especially the Ministry of Science, Technology and Innovation (MOSTI), for the intensified research grant no. 305/PKIMIA/612923 and USM Short‐Term grant no. 304/PKIMIA/636103. We are also grateful to all staff in the Research and Creativity Management Office (RCMO) in University Sains Malaysia for assistance and support given indirectly to make this project a success.