A Rotaxane Scaffold Bearing Multiple Redox Centers: Synthesis, Surface Modification and Electrochemical Properties
Résumé
A rotaxane scaffold incorporating two dithiolane
anchoring units for the modification of gold surfaces has
been functionalized with multiple copies of a redox unit,
namely ferrocene. Surface modification has been first assessed
at the single molecule level by atomic force microscopy
(AFM) and scanning tunneling microscopy (STM) imaging,
while tip enhanced Raman spectroscopy (TERS) provided
the local vibrational signature of the ferrocenyl subunits
of the rotaxanes grafted onto the gold surface. Finally, oxidation
of the redox moieties within a rotaxane scaffold grafted
onto gold microelectrodes has been investigated by ultrafast
cyclic voltammetry. Intramolecular electron hopping is
indeed extremely fast in this system. Moreover, the kinetics
of charge injection depends on the molecular coverage due
to the influence of intermolecular contacts on molecular motions.