Mesogen ligand

In the above complexes, mesogens were formed by the complexation of mesogenic ligands to a metal centre. Using entirely different chemistry, Ghedini and co-workers had previously used the same approach in obtaining palladium complexes of... 

In the above section, we have established some simple ideas concerning the way in which a metal may influence liquid crystal properties when bound to mesogenic ligands. The behaviour may also be influenced by lateral substituents which may... 

In many cases the uncomplexed ligand also demonstrates mesogenic behaviour, but incorporation of a metal increases the phase transition temperatures over those of the mesogenic ligands. 

Lateral monofluorination of the p-alkoxyphenyl isocyanide system [XAu (CNC6H40C H2 +i)] (X = C1, Br, I), in ortho-(3-F) (6a) and meta-(2-F) (6b) positions relative to the alkoxy chain was also studied [18]. None of the free fluorinated ligands is a LC, but their gold complexes display mesomorphic properties. This is a typical case of a promesogenic ligand which yields a mesogen upon coordination to a metal. 

Compounds presented in Scheme 9 have provided evidence for the influence of the otherwise rarely investigated />-anilino-ethynyl group and a variety of auxiliary ligands on the luminescence, NLO, and mesogenic properties of this type of complexes.98... 

In a search for liquid crystalline phases, a series of (/>-alkoxy-phenyl)isocyanide complexes was prepared from (Me2S)AuCl and the corresponding ligands RNG, where R = C H2n + iO-C6H4 with n = 2-12 (in even numbers).206 The chlorides were converted into the bromides and iodides in metathesis reactions using KBr/KI. Mesogenic behavior was found for most of the new materials with transition temperatures in the range from ca. 95 to 160 °C. 

Similar work was carried out with ligands featuring different flexible or rigid spacers (X = -C(0)0-, -C=C-, -CH2-CH2-) and terminal alkoxy groups where n = 9-12. These compounds and the carbene complexes derived therefrom by addition of alcohols also show mesogenic properties (Scheme 49).211 212... 

Most gold mesogens with perhaloaryl ligands as promesogen also contain isocyanide (mesogen or promesogen) ligands. Therefore, they were introduced in Section 7.2.5.3. 

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