Columnare und nematische Phasen neuer makrodiscotischer Materialien [1]

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Abstract
The first radially multi(biphenylethinyl) substituted arenes possessing benzene or naphthalene cycles as molecular centers as well as Palladium atoms containing macrocyclic complexes derived from hexaalkoxy substituted aldobisimines by cyclopalladation have been synthesized and investigated by physical methods. Most of these flat compounds with molecular core diameters ≧24 Å and molecular weights up to 4000 are novel thermotropic liquid crystals, in part highly unsaturated or metallomesogens in structure, respectively, exhibiting columnar and/or nematic phases. Sterical influences on the mesophase formation of these spacious molecules are discussed as well as interesting changes of their properties by variation of their self‐organization occurring in binary systems. Thus, addition of an electron acceptor, for example 2,4,7‐trinitrofluorenone, leads to the formation of charge transfer complexes, mesophase stabilizations or even to inductions of other mesophases including nematic ones of the ND or NC type. Dissolving such thermotropic columnar mesogens in various organic solvents gives rise to lyomesomorphism; in case of at least one of the palladomesogens a transition between two different lyotropic nematic phases (N1 and N2) has been observed.