Ferrocenyl polyethers

These contain redox-active centers able to switch on/off cation or anion complexation when treated with redox reagents or electrochemical stimulation. Examples include some ferrocenyl-containing macrocycles, such as (159), or donors with an anthraquinone fragment, as in (160).252 The functionalization of electroactive polymers by monocyclic polyethers has been used for the building of cation-responsive electrodes. 

Organometallic polyurethanes containing backbone polyether units have been reported.184,185 The incorporation of ferrocenyl segments into the backbone of polyurethanes enhanced thermal stability.186 There have been a number of studies on the incorporation of ferrocenyl units into the backbone of polyesters 101.187-191 A number of polymers of this class exhibited liquid crystalline properties.189-192 The thermal stability and glass transition temperatures of these polymers decreased with an increase in the length of the alkyl chains. 

Rausch also reported the synthesis of polyurethanes however, these polymers exhibited low solubihty and they precipitated from solution during the polymerization reactions. Polyurethanes with polyether segments in their backbones have also been synthesized. It has also been reported that polyurethanes with ferrocenyl units in their backbones exhibit enhanced thermal stability. Polyesters containing ferrocenyl units in the mainchain have been the focus of numerous studies. It has been reported that many of these organometallic polymers exhibit liquid crystalline properties. " Scheme 25 shows the synthesis of a liquid crystalline polyester (103) via polycondensation reactions. Increasing the length of the alkyl chains decreased the thermal stability and glass transition temperatures of these polymers. 

Weaver et al. [130] synthesized several ferrocene-functionalized phosphonium ILs carrying PFg- or OTs anions and found the apparent diffusion coefficients for electron transport and for the IL counterions are similar to one another. These fer-rocenated phosphonium ILs show similar electron transport properties as those redox ILs based on the combinations of redox groupings with imidazolium and with short-chain polyether functionalities. Forgie et al. [131] prepared a ferrocenyl-substimted imidazolium IL (Scheme 8.15). In its neat form, this IL has a high viscosity and low conductivity. However, after mixing with ethylene carbonate-dielhyl carbonate solvent, the electrolytic solutions exhibit reasonable viscosity and conductivity and could be used an additive in lithium battery electrolytes in standard coin cells with a metallic Li anode and a Li4Ti50i2 cathode. 

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