  Fullerenes have attracted interest for their possible applications in various
electronic, biological, and optoelectronic devices. However, for efficient use
in such devices, a suitable anchoring group has to be employed that forms
well-defined and stable contacts with the electrodes. In this work, we propose
a novel fullerene tetramalonate derivate functionalized with trans-1
4,5-diazafluorene anchoring groups. The conductance of single-molecule
junctions, investigated in two different setups with the mechanically
controlled break junction technique, reveals the formation of molecular
junctions at three conductance levels. We attribute the conductance peaks to
three binding modes of the anchoring groups to the gold electrodes. Density
functional theory calculations confirm the existence of multiple binding
configurations and calculated transmission functions are consistent with
experimentally determined conductance values.
