Synthesis and Liquid Crystalline Properties of 3‐Substituted Pentane‐2,4‐dione, Pyrazole and Isoxazole Derivatives

The γ ‐substituted β ‐diketonate 2,4‐dioxo‐3‐pentyl 4‐[4‐( n ‐octyloxy)cinnamoyl]oxybenzoate 1 and its pyrazole and isoxazole derivatives ( 2 and 3 respectively) have been synthesized and characterized by the spectroscopic methods and elemental analysis. The mesogenic properties of these compounds have been studied by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). A monotropic nematic mesophase was observed for the β ‐diketonate 1 , in contrast, the pyrazole 2 displays an enantiotropic smectic A and isoxazole 3 exhibits an enantiotropic nematic mesophase. The relationship between the structure and liquid crystalline properties has also been discussed.