Homoleptic copper (II) dimers with long chain bridging carboxylates exhibit liquid crystalline mesophases. Previous work at Knox has shown that heteroleptic copper (II) carboxylate dimers have liquid crystalline phases with lower melting points than related homoleptic copper (II) dimers. Both homoleptic and heteroleptic dimers are blue; however an orange intermediate is observed during the synthesis of the heteroleptic copper (II) dimers. Crystals grown from the intermediate were analyzed by x ray crystallography revealing a copper (II) oxo cluster with four copper atoms surrounding a central oxygen with six chlorides bridging the edge of a copper tetrahedron. We report that the sodium salts of long chain carboxylates (chain length varies from 4 to 16) replace the bridging chlorides of oxo centered copper (II) tetramer in an acetonitrile-toluene mixed solvent system. The resulting blue products appear to be mixtures, and were characterized by IR, POM, DSC and Elemental Analysis. The isolated mixed products both exhibited birefringence above room temperature and are liquid crystals. In addition, we have attempted separation of the products by capillary action in order to determine whether the melting points and mesophase textures of these new products are distinct from the parent homoleptic copper (II) carboxylate dimers.

Synthesis and analysis of liquid crystals based on copper (II) tetramers

255th National Meeting (2018)

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