Main chain 1,1′‐ferrocene‐containing polyelectrolytes exhibiting thermotropic liquid‐crystalline and fluorescent properties

A series of 1,1′-ferrocene-containing polyelectrolytes (3, 4) were prepared when 1,1′-bis(N,N-dimethylaminomethyl)ferrocene (1a) or 1, 1′-bis{[1-(2-methyl)imidazol-1-yl]methyl}ferrocene (1b) was quaternized with 1,4-dibromobutane or α, α′-dibromo-p-xylene. The counterion was bromide or bis(trifluoromethanesulfonyl)-amide formed after metathesis with the lithium salt. Their chemical structures were determined by IR and NMR spectra. Molecular weights in the range of ∼5400 (4a)– ∼14,700 (4c) for number-average molecular weights (Mn) over narrow molecular weight distributions were determined for polymers 4 by gel permeation chromatography. Thermal properties of these materials were obtained by differential scanning calorimetry and thermogravimetric analysis that showed the polymers had thermal stabilities ranging between 172 and 330 °C. Liquid-crystalline behavior was investigated on a hot stage polarizing optical microscope. Polymers 3a, 4b, and 4d formed either a high-order or a low-order smectic phase above their melting or fusion temperatures, and exhibited smectic-to-isotropic transitions. The ranges of the liquid-crystalline phases for these materials were 22, 46, and >55 °C. Compounds 3b, 4a, and 4c are crystalline before melting or decomposing. All of the polymers exhibited absorption bands at ∼430 nm. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 974–983, 2005