  A novel type of a graphene/porphyrin hybrid with a direct covalent linker
between graphene and a nickel(II) tetraphenylporphyrin unit has successfully
been synthesized by the reductive exfoliation/functionalization of potassium
intercalated graphite as starting material. Moreover, we directly compared the
reactivity of two structurally different porphyrin derivatives, namely,
meso-NiTPP-N2+, with the diazonium group in 4-position of a peripheral phenyl
ring and a novel \b{eta} NiTPP N2+ diazonium cation, where the diazonium group
is directly attached to the \b{eta}-pyrrolic position of the 18 {\pi} electron
core. Due to sterical restraints, this intermediately generated porphyrin
radical can not attack the extended {\pi}-surface of graphene and only a
functionalization of present dangling bonds at the flake edges may be obtained
in this case. All reaction products have been analyzed in detail be means of
Raman- and UV/Vis spectroscopy as well as thermogravimetric analysis.
