Electrochemical synthesis and characterization of novel bile acid functionalized polypyrroles

A new series of pyrroles bearing bile acid moieties were synthesized and electrochemically polymerized in acetonitrile with tetrabutylammonium hexafluorophosphate (TBAFP6) as the supporting electrolyte. It is found that these functionalized monomers could form polypyrrole films, but their electrochemical properties and the stability of the films are strongly dependent on the length of the alkyl spacer between pyrrole ring and the pendant bile acid moiety. Each of the resulting polymers with different bile acid groups shows a distinctive behaviour in terms of its microstructure of surface, as well as electrochemical and optical properties. Compared to other analogous polypyrroles, the optical property of the cholic acid functionalized polymer is sensitive to the polarity of the used solvents, exhibiting solvatochromic behaviour. This phenomenon is probably derived from its unique facial amphiphilic structure.