Cubic phase of 4′‐n‐Hexadecyloxy‐3′‐cyanobiphenyl‐4‐carboxylic acid (ACBC‐16)

Abstract

The cubic phase structure of 4′‐n‐hexadecyloxy‐3′‐cyanobiphenyl‐4‐carboxylic acid (ACBC‐16) was examined by X‐ray diffraction. Unlike the octadecyloxy homologue showing an Im3m‐type cubic phase, the cubic phase of ACBC‐16 was of Ia3d type, both on heating and on cooling, similarly to the corresponding nitro‐substituted analogue (ANBC‐16). The lattice dimension a at 453 K was a = 11.0 nm, 2.5% larger than the value for ANBC‐16 and rather close to the value of ANBC‐17 or ‐18. It is expected that the appearance of the cubic phase type, as a function of the number of carbon atoms n in the alkoxy chain in the ACBC‐n series, is essentially the same as in the ANBC‐n series, but shifted towards shorter n by 1 or 2. In the latter ANBC‐n series, the cubic phase type is Ia3d for 15⩽n⩽18, while an Im3m type is formed for 19⩽n⩽21, both on heating and on cooling.

Acknowledgements

We first thank Dr Yuji Naruse and Prof. Keiichi Moriya at Gifu University and Prof. Kazuchika Ohta at Shinshu University for stimulating discussions. We also thank Ms Shouko Nishiura and Mr Hiroyuki Mori at Gifu University and Ms Mayumi Ikeda at Osaka University for their experimental help. This work was supported by Grant‐in‐Aid for Scientific Research on Priority Areas (A), ‘Dynamic Control of Strongly Correlated Soft Materials’ (No. 413/14045232) from the Ministry of Education, Science, Sports, Culture, and Technology, Japan, and by Grant‐in‐Aid for Scientific Research (C) 14550846 from the Japan Society for the Promotion of Science (JSPS), both of which were given to S.K., and by Grant‐in‐Aid for Scientific Research (B) 15350110 from JSPS, given to K.S. Beam time at PF‐KEK provided by Program 2002G095 is also acknowledged.

Notes

†. As in similar calculations, the estimation corresponds to that at T = 0 K. At finite temperatures where the alkoxy chains obtain complete flexibility, the chain length becomes as short as about 70% of the extended form on the basis of Flory's theory [45]. However, this temperature effect would be the same on both compounds, producing no meaningful difference.