| Abstract
| - A novel type of redox-active mesoporous silica has been prepared by incorporating well-defined organometallic dendrimer guests within the well-ordered channels of MCM-41. The integrity of the guest after the inclusion process is kept and stable dendrimer−matrix complexes are obtained.
- A novel type of redox-active materials, which to our knowledge are the first examples ofmesoporous silica hosts containing dendritic guest molecules within their highly orderedchannels, is presented. A simple and efficient synthetic route has been used to incorporatepoly(propyleneimine) dendrimers containing 4, 8, and 64 amidoferrocenyl moieties (1−3)into MCM-41. In these new composite materials (dend-n-MCM-41, n = 1−3) the integrityof the guest after the inclusion process is maintained (as confirmed by elemental analyses,IR, and 13C CP MAS NMR spectroscopy), resulting in stable dendrimer−matrix complexes.X-ray diffraction, nitrogen adsorption isotherms, and transmission electron microscopy areconsistent with the full occupancy of the channels by the smallest dendrimer, whereas lesseffective inclusion is obtained with the bulkier macromolecules. One significant feature ofthese new composite materials is that the guest dendrimers, containing a controlled numberof ferrocenyl units, are easily accessible to electrochemical oxidation. Platinum disk electrodescoated with layers of dend-n-MCM-41/graphite powder/polystyrene composites have beenstudied by cyclic voltammetry and differential pulse voltammetry. The electrochemicalproperties of these hybrid materials are related to the dendrimers different sizes and werefound to differ significantly from those of the corresponding hybrid materials prepared witha nonporous silica.
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