Supramolecular Assemblies of Polyaniline through Cooperative Bundling by a Palladium‐Complex‐Appended Synthetic Cross‐Linker

A synthetic cross‐linker ( 1 ) bearing two binding sites for imine moieties in polyaniline has been used to organize polyaniline emeraldine base ( EB ) or polyaniline emeraldine salt ( ES ) into aligned assemblies. Complex 1 exhibited highly cooperative binding toward mEB (a repeating unit analogue of EB ), for which the association constants K 1 and K 2 were evaluated to be 2.2×10 4 and 9.4×10 5   M ‐1 , respectively. 1 H NMR studies revealed that the diimine moieties in mEB are recognized cooperatively in anti ‐conformation by 1 . The ordered structures organized from 1 and EB or ES were efficiently formed through supramolecular bundling. These ordered assemblies have a periodicity of 2.5 nm that was confirmed by means of transmittance electron microscopy (TEM) and high‐resolution TEM (HRTEM). The cooperative binding would be important for the bundling and alignment of the polymers, as evidenced by the fact that neither reference compounds 2 nor 3 were capable of producing similar assemblies. The electric conductivity of the samples was measured and the results were discussed.