Living Ring-Opening Metathesis Polymerization Synthesis and Redox-Sensing Properties of Norbornene Polymers and Copolymers Containing Ferrocenyl and Tetraethylene Glycol Groups

The controlled synthesis of monodisperse, redox-active metallopolymers and their redox properties and functions, including robust electrode derivatization and sensing, remains a challenge. Here a series of polynorbornene homopolymers and block copolymers containing side-chain amidoferrocenyl groups and tetraethylene glycol linkers were prepared via living ring-opening metathesis polymerization initiated by Grubbs' third-generation catalyst (1). Their molecular weights were determined using MALDI-TOF mass spectra, size exclusion chromatography (SEC), end-group analysis, and the empirical Bard-Anson electrochemical equation. All polymerizations followed a living and controlled manner, and the number of amidoferrocenyl units varied from 5 to 332. These homopolymers and block copolymers were successfully used to prepare modified Pt electrodes that showed excellent stability. The modified Pt electrodes show excellent qualitative sensing of ATP(2-) anions, in particular those prepared with the block copolymers. The quantitative recognition and titration of [n-Bu4N](2)[ATP] was carried out using the CH2Cl2 solution of the homopolymers, showing that two amidoferrocenyl groups of the homopolymers interacted with each ATP(2-) molecule. This stoichiometry led us to propose the H-bonding modes in the supramolecular polymeric network.