Mo(VI)-Based Metallo-Supramolecular Polymer
This chapter introduces synthesis of Mo(VI)-based metallo-supramolecular polymer (polyMoL12) and the oxygenation (polyMoL12-C) and the proton conductivity. Chemical reactions with polymers (polymer reactions) are often performed to improve or modify the properties of the original polymer. Section 9.1 shows synthesis of a Mo(VI)-based metallo-supramolecular polymer (polyMoL12) by the 1:1 complexation of bis(phenanthroline) (L12) with MoO2(acac)2. L12 has methyl groups at the phenanthroline moieties. The polymer with carboxylic acid groups (polyMoL12-C) is obtained by the oxidation of the methyl groups in polyMoL12. A new broad peak attributed to acid protons (-COOH) appears at δ 11.97 ppm in polyMoL12-C. The degree of oxidation is calculated to be 84% by comparing the relative integration value of this broad peak with a peak based on an aromatic proton. Section 9.2 describes the proton conductivity of polyMoL12 and polyMoL12-C. The Nyquist plots of polyMoL12 and polyMoL12-C are obtained from ac impedance measurements. The ionic conductivities of the polymers are calculated from the x-axis intercept of the semicircle at higher frequencies. The introduction of carboxylic acids to the ligand enhances the ionic conductivity of the polymer more than tenfold. An FTIR study of the polymers is carried out at two different humidities to analyze the protonation sites in proton-conducting materials.