Si(OCH2Fc)4: Synthesis, Electrochemical Behavior, and Twin Polymerization

Abstract

AbstractThe preparation and twin polymerization of the twin monomer Si(OCH2Fc)4 [Fc = Fe(η5‐C5H4)(η5‐C5H5)] (2) by the reaction of FcCH2OH (1) with SiCl4 in the presence of pyridine was explored. The electronic properties of 2 were investigated by cyclic voltammetry, square‐wave voltammetry, and UV/Vis/near‐IR spectroelectrochemistry, which showed a redox separation caused by electrostatic repulsion. Thermally induced condensation of 2 is characteristic, as evidenced by differential scanning calorimetry (DSC) and thermogravimetry coupled mass spectrometry (TG–MS). Upon heating 2 to 210 °C, twin polymerization occurred and a hybrid material was formed that showed similarities with known systems derived from 2,2′‐spirobi[4H‐1,3,2‐benzodioxasiline] (SBS), such as the nanopatterning of the formed silicon dioxide, which is characteristic for twin polymerization. Electron microscopy of this material revealed the absence of typical microstructuring found for other twin polymers, and hence, the herein presented system can be characterized as a borderline system if compared to known twin monomers such as SBS. The copolymerization of 2 and SBS afforded a hybrid material from which porous carbon or silica materials containing iron oxide nanoparticles could be obtained. The oxidation state of the incorporated particles was examined by Mössbauer experiments, which confirmed that only FeIII was incorporated within the porous carbon and silica materials, respectively. The preparation of iron oxide containing porous carbon capsules was achieved by applying a mixture of 2 and SBS to silicon dioxide spheres (d = 200 nm). After twin polymerization and carbonization, porous carbon capsules with incorporated iron oxide nanostructures were obtained.