Characterisation and mesomorphic behaviour of new aliphatic–aromatic azomethines containing ester groups

Abstract

Two series of novel symmetrical azomethines prepared by the condensation of 4,4′-(butane-1,4-diylbis(oxy))bis(butane-4,1-diyl)bis(4-aminobenzoate) (PBBA470) and 5,10,15,20,25,30,35,40,45,50,55,60-dodecaoxatetrahexacontane-1,64-diylbis(4-aminobenzoate) (PBBA 1200) with a range of aldehydes have been characterised by ¹H and ¹³C nuclear magnetic resonance, Fourier transform infrared and UV–Vis spectroscopy. Current–voltage measurements were performed using a device comprising indium–tin oxide/compound/Alq₃/Al. The effect of rod length and the nature of the terminal chains on the thermal and mesomorphic behaviour of these materials were investigated by differential scanning calorimetry, polarising optical microscopy and wide- and small-angle X-ray diffraction. Additionally, the compounds were studied using various atomic force microscopy techniques, including mode and phase imaging, and measurements based on local contrast force–distance curves and roughness, together with skew and kurtosis, are presented.

Keywords:

• imines
• azomethines
• oligomers
• liquid crystals
• optical properties
• electrical properties

Acknowledgements

The authors are grateful to Dr Patrice Rannou for kindly supplying PBBA470 and PBBA1200. Mr M. Domanski carried out the I–V, Dr B. Kaczmarczyk the FTIR, and Mrs K. Zbikowska the NMR measurements.