1,3-DISUBSTITUTED FERROCENE-CONTAINING THERMOTROPIC LIQUID-CRYSTALS - SYNTHESIS, MESOMORPHIC PROPERTIES AND THE CRYSTAL AND MOLECULAR-STRUCTURE

Two families of 1,3-disubstituted ferrocene derivatives have been synthesized and their liquid-crystal behavior investigated. Compounds of series 1, (eta5-C5H5)Fe[(eta5-C5H3)-1,3-(COOC6H4OOCC6H4OCnH2n+1)2] (n = 1-14,16,18), exhibited remarkable mesomorphic properties. Indeed, nematic and/or smectic C phases, associated with large anisotropic domains, were observed. Derivatives of series II, (eta5-C5H5)Fe[(eta5-C5H3)-1,3-(COOC6H4OCnH2n+1)2] (n = 1-9), were found to be non-mesogenic. The crystal and molecular structure of Ih (n = 8) was determined by means of X-ray analysis. The crystallographic data confirmed both a highly anisometric structure for Ih and a compact arrangement of the molecules in the crystal. The present results have shown that a critical length/depth ratio of ca. 5-7 must be passed for obtaining liquid-crystal properties.