Investigations on thermal stability of some ferrocene liquid crystals bearing azo, ferrocenyl and cholesteryl units

• Published in: Journal of Optoelectronics and Advanced Materials 2006-04, Vol.8 (2), p.737-740
• Main Authors: Apreutesei, D, Lisa, G, Scutaru, D, Hurduc, N
• Format: Article
• Language: English
• ISSN: 1454-4164

Ferrocene liquid crystals received a great attention in the last years, mainly because of its interesting properties and the combination between liquid crystals properties with metals properties. Only few examples of ferrocene liquid crystals bearing either cholesteryl or azo aromatic unit could be found in the literature. The presence of each of three groups contribute by specific properties to the obtaining of materials capable of responding in electric or magnetic field or to UV light exposure. The azo aromatic units are photo-sensitive due to cis-trans photoizomerization and can be used as switchers in liquid crystals devises. On the other hand, the cholesteryl unit induces chiral mesophases with the advantage of fast response on stimuli, high birefringence and the presence of physical colors. Since mesomorphic behavior for the thermotropic liquid crystals are due to the increasing of temperature in the system, it is easy to understand the importance of thermal stability for such kind of systems. The purpose of the paper is the study the thermal stability of some ferrocene liquid crystals bearing both azo and cholesteryl and to evaluate the influence of each structural factor such as: ferrocenyl, cholesteryl, azo units and the length of the flexible chain on the thermal stability of these compounds.