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Oligomeric ferrocene rings


Cyclic oligomers comprising strongly interacting redox-active monomer units represent an unknown, yet highly desirable class of nanoscale materials. Here we describe the synthesis and properties of the first family of molecules belonging to this compound category—differently sized rings comprising only 1,1′-disubstituted ferrocene units (cyclo[n], n = 5–7, 9). Due to the close proximity and connectivity of centres (covalent Cp–Cp linkages; Cp = cyclopentadienyl) solution voltammograms exhibit well-resolved, separated 1e waves. Theoretical interrogations into correlations based on ring size and charge state are facilitated using values of the equilibrium potentials of these transitions, as well as their relative spacing. As the interaction free energies between the redox centres scale linearly with overall ring charge and in conjunction with fast intramolecular electron transfer (107 s−1), these molecules can be considered as uniformly charged nanorings (diameter 1–2 nm).

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Figure 1: Synthesis and structure of oligomeric ferrocene rings.
Figure 2: 1H NMR spectroscopy of ferrocene rings (n = 2, 5–7, 9).
Figure 3: Solution electrochemistry for ferrocene rings.
Figure 4: Solution voltammetry correlations for different ring sizes.


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M.S.I., T.A. and N.J.L. acknowledge the Leverhulme Trust (RPG 2012-754) for funding. The authors are grateful to the referees for useful comments and suggestions concerning the extent of charge delocalization in these materials.

Author information




M.S.I., T.A. and N.J.L. conceived the work and designed the experiments. M.S.I. synthesized the materials and performed the solution electrochemical measurements. A.J.P.W. performed the X-ray crystallographic experiments. S.S., M.L. and R.F.W. performed the UV/vis/NIR spectroscopy experiments. All authors contributed to writing the paper.

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Correspondence to Tim Albrecht or Nicholas J. Long.

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The authors declare no competing financial interests.

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Inkpen, M., Scheerer, S., Linseis, M. et al. Oligomeric ferrocene rings. Nature Chem 8, 825–830 (2016).

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