Nickel complexes metallomesogens

Very few discogenic complexes with a hydrazone moiety have been so far studied. One nickel complex based on 2,6-diacetylpyridinebis(3,4,5-tridodecyloxybenzoylhydrazone) has been previously reported by Battistini et al. as a potential columnar metallomesogen." The mononuclear complex showed an apparently unidentified mesophase during the first heating which was not... 

Some of these materials display the potentially chiral ferroelectric SmC phase in addition to a SmA or cholesteric mesophase. Pyzuk [108] found for copper and nickel complexes some blue phase or novel type of amorphous phase between a tightly twisted chiral nematic phase and the isotropic liquid. These ferroelectric metallomesogens are interesting as they can be aligned par-... 

A series of aroylhydrazinato-nickel and -copper complexes, 62, was synthesized in high yield and shown to form metallomesogens with SmC and N phases around 150 °C. The nickel complexes were found to be highly stable while the copper complexes decompose soon after entering the isotropic phase [144]. 

The colour of metallomesogens was a property that attracted the attention of the earliest workers in this field. Giroud and Mueller-Westerhoff reported that mesogenic nickel(II) dithiolene complexes formed dark, highly reflective crystals and were green in solution. The corresponding... 

Lattermann et al. reported the first metallomesogenic dendrimer when they described results on trigonal bipyramidal metal complexes of ethylene-imine dendrimers of the first and second generation, based on derivatives of tris(2-aminoethyl)amine. Complexes of cobalt, nickel, copper, and zinc were prepared and found to exhibit relatively low temperature mesophases, which generally possessed hexagonal columnar structures. These materials therefore provided the first examples of metallomesogenic dendrimers [72,73]. 

The first systematic study of d-block metallomesogens were carried out by Giroud and Mueller-Westerhoff [11] and marked, in 1977, the beginning of interest in metal-containing systems. They were dithiolene complexes of nickel, palladium and platinum with two p-alkyl phenyl substituents (see structure 3). Nickel and platinum complexes showed nematic and smectic phases, depending on the chain length. Palladium analogs do not possess any mesomorphic properties [81]. 

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