Thermotropic ferrocene

The esterification of ferrocene-1,1 -dicarboxylic acid with substituted phenols to produce hexacatenar substituted ferrocenes, which are thermotropic liquid crystals, is also mediated by carbodiimides. ... 

Organothiols chemisorbed on gold surfaces are especially usefiil for electrochemical and chemical studies. For example, carboxylic acid terminated monolayers are often used. An example is the attachment of cytochrome C with its side chain lysine groups to acid terminated self assembled monolayer gold electrodes. Carbodiimide mediated esterification of ferrocene-l,l -dicarboxylic acid with phenols is used to construct thermotropic liquid crystals. ... 

This contribution presents the results published up to June 1993 on ferrocene-containing thermotropic liquid crystals and should be considered as a comple-... 

Fig. 9-3. Monosubstituted ferrocene-containing thermotropic liquid crystals.

The cyclopentane ring has already been used to prepare thermotropic liquid crystals [23]. In 17, the bulky ferrocene core, due to its depth, acts as a spacer... 

P Ferrocene-Containing Thermotropic Liquid Crystals COzR ... 

Fig. 9-21. Unsymmetrically l,l -disubstituted ferrocene-containing thermotropic liquid crystals and examples of their transition temperatures.

The research on ferrocene-containing thermotropic liquid crystals has concentrated, so far, on design, synthesis, and investigations of thermal properties. These efforts, and more particularly the results obtained, could be a source of inspiration for the development of new metallomesogens. As an example, we recently reported the first liquid crystalline ruthenocene derivatives [29]. 

Gao et al. have recently prepared a number of thermotropic liquid crystalline main-chain fer-rocenes exhibiting fluorescent properties.182 The reaction of 1,1 -bisf functionalized)ferrocenes, 95, with 1,4-dibromobutane, 97a, or a,a -dibromo-p-xylene 97b generated polyelectrolytes 97a,b with Mn ranging from 5400-14,700 (Scheme 2.29). These polymers were highly thermally stable with the first weight loss occurring between 172 and 330°C. The liquid crystalline properties showed these materials formed smectic liquid-crystal phases and displayed batonnet textures. 

Liquid crystalline polymers containing ferrocene in their side chains have been reported.235-240 Deschenaux used free-radical synthesis to prepare thermotropic liquid crystalline polymethacrylates containing ferrocene (Scheme 2.46).235 Polarized light microscopy showed that monomer 171 and its corresponding polymer 172 exhibited enantiotropic smectic A and C phases. 

The first ferrocene-containing thermotropic liquid crystals, compounds 19 to 21, were reported by Malthete and Billard in 1976. Enantiotropic, 19, or monotropic, 20 and 21, N phases were observed. Compounds 19-21 were designed to undertake Mossbauer studies in mesomorphic media. Ferrocenyl Schiff bases 19-21 represent the first well-characterized organotransition metallomesogens. 

Ferrocene was functionalized at the 1,1 -positions by a sugar moiety (1-amino-l-deoxy-D-sorbitol) and a long alkyl chain 44 in order to obtain lyotropic properties. The substituents, in particular the sugar framework, were selected in view of successful investigations performed with organic-type amphiphilic carbohydrate surfactants. Compound 44 showed both thermotropic and lyotropic mesophases. In the bulk, a SmA phase formed from 98 to 137 °C. When 44 was mixed with an excess of water, a fluid phase was obtained. For the thermotropic SmA phase, a r/-layer spacing... 

Deschenaux and co-workers have recently reported the first 1,1, 3-trisubsti-tuted ferrocene-containing thermotropic liquid crystals [123]. The first series of materials (59 x=l), showed monotropic Sa and Sc phases (n=12, 14), and monotropic Sc phases (n=16, 18), all the complexes melting in the isotropic... 

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