Reductive Functionalization of Graphenides with Nickel(II) Porphyrin Diazonium Compounds

TL;DR

This study reports the synthesis of a novel graphene/porphyrin hybrid with covalent linkage, comparing reactivity of different porphyrin derivatives and analyzing the functionalization process using spectroscopy and thermogravimetric methods.

Contribution

It introduces a new method for covalently attaching nickel(II) porphyrins to graphene via reductive functionalization, and compares the reactivity of different diazonium derivatives.

Findings

Successful synthesis of a covalently linked graphene/porphyrin hybrid.

Reactivity differences between two porphyrin derivatives were characterized.

Functionalization primarily occurs at graphene edges due to steric effects.

Abstract

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.