Nickel (II) tetraphenylporphyrin modified surfaces via electrografting of an aryldiazonium salt

We have prepared and isolated the monodiazonium salt of nickel (II) tetraphenylporphyrin and grafted the corresponding complex to glassy carbon, pyrolysed photoresist film, gold and indium tin oxide surfaces via reduction of the diazonium moiety. Characterisations of the films by voltammetry, UV–vis spectroscopy and atomic force microscopy depth profiling confirm that the metallated porphyrin is intact in the film and is stably attached to the surface with well-behaved, but highly solvent-dependent electrochemistry. Under the grafting conditions used, the films appear to have close to monolayer thickness with the porphyrin macrocycles oriented predominantly upright on the surface.

► Monodiazonium salt of nickel (II) tetraphenylporphyrin is isolated. ► Stable films of the porphyrin are grafted by electroreduction of the diazonium salt. ► Films exhibit well-behaved electrochemistry and UV–vis absorption spectra. ► Proposed structure is a monolayer of porphyrins with close to vertical orientation.