Liquid crystallinity of unsymmetrical ferrocene derivatives (I) synthesis of unsymmetrically 1,1 '-disubstituted ferrocene derivatives and their phase transition behavior

A new series of unsymmetrically 1,1'-disubstituted ferrocene derivatives, 1 -[4'-(4-substitutedbenzoyloxy)biphenyl-4-oxycarbonyl]-1'-alkoxycarbonylferr ocene, was prepared and their phase transition behavior was studied by a di fferential scanning calorimeter and a polarizing microscope. Some structura l parameters, such as the length of the alkyl chain and the nature of the t erminal substituent, have been modified. In the case of no substituent at a terminal position of the mesogenic group, the derivative showed no liquid crystallinity. Monotropic liquid crystalline phases were observed for the d erivatives having a polar terminal group. The compounds with a flexible alk oxy chain as the terminal group gave rise to an enantiotropic nematic phase .