Comparative studies of three‐ and four‐ring mesogenic esters containing p‐carborane, bicyclo[2.2.2]octane, cyclohexane, and benzene†

†. Presented in part at the 36th GLRM‐ACS, Peoria, IL 17–20 Oct, 2004 (Abstract 221) and at the Argonne Undergraduate Symposium, Nov 5th, 2004.

Abstract

Twelve esters were prepared from pentyl‐substituted p‐carborane, bicyclo[2.2.2]octane, cyclohexane, and benzene carboxylic acids and three substituted phenols. The mesogenic properties of the series of esters were examined using thermal analysis and optical microscopy. The relationships between structure and mesogenic properties were analysed by comparison of the series of homostructural esters. Thus, the effects of variation of the carboxylic acid structure, introduction of fluorine into the phenol part, and replacement of the central phenyl ring with the –CH₂CH₂– group on the stability of mesophases and their widths were investigated. In general, carborane derivatives exhibit broad nematic phases and narrow SmA phases, while other derivatives demonstrate rich smectic and soft crystal polymorphism.

†. Presented in part at the 36th GLRM‐ACS, Peoria, IL 17–20 Oct, 2004 (Abstract 221) and at the Argonne Undergraduate Symposium, Nov 5th, 2004.

‡Visiting VU from Augustana College, Chemistry Department Rock Island, IL 61201, USA.

§Military Technical University, Warsaw, Poland.

Acknowledgement

This project was supported by NSF grant DMR‐0111657. Funds for the summer research program for Prof. Jensen and two undergraduate students (B.R. and J.V.) were generously provided by a supplement to the DMR grant.

Notes

†. Presented in part at the 36th GLRM‐ACS, Peoria, IL 17–20 Oct, 2004 (Abstract 221) and at the Argonne Undergraduate Symposium, Nov 5th, 2004.

‡Visiting VU from Augustana College, Chemistry Department Rock Island, IL 61201, USA.

§Military Technical University, Warsaw, Poland.