Synthesis and liquid crystalline properties of T-shaped dimesogenic compounds

Two series of new dimesogenic liquid crystalline compounds were synthesized and their LC and other thermal properties were characterized. These compou nds consist of two mesogenic units connected through polymethylene spacer o f varying length in the shape of the letter 'T'. The difference between the two series is in the structure of tail groups attached on the pendant azob enzene mesogens; one of which is n-butyl and the other is phenyl. The compo unds were characterized for their liquid crystallinity by the differential scanning calorimetry (DSC), X-ray diffractometry and visual observation of the melts on a hot-stage attached to a polarizing microscope. All these com pounds were found to form only the nematic phase enantiotropically.