Supramolecular Attachment of Metalloporphyrins to Graphene Oxide and its Pyridine‐Containing Derivative

Abstract

Graphene is a unique material due to its remarkable mechanical, electrical, and optical properties. [1] Although the optical properties of graphene can be exploited in a variety of applications, the use of graphene in transparent electrodes in solar cells or liquid-crystal devices [2] has rarely been explored. Therefore, modulation of its optical properties by chemically functionalizing graphene with optoelectronically active porphyrins could result in interesting multifunctional, nanoscale materials for optical and/or optoelectronic applications. To pursue this goal, enhancement of the solubility of graphene [3] through chemical functionalization is often required. The extended oxidation of graphene, which produces single layers of graphene oxide (GO), has been especially useful in this regard. The resulting water-soluble nanomaterial, which contains hydroxyl, epoxide, and carboxylic groups, [4] offers a platform to explore further functionalization by means of conventional organic reactions. [5] The processability and chemical reactivity of GO allow the functionalization of GO with porphyrins from different perspectives. To date, graphene or graphene oxide porphyrin hybrid materials have been produced by supramolecular interaction of porphyrins with graphene/GO and by covalent attachment of porphyrins to graphene/GO. Following the former strategy, several examples of protoporphyrins containing charged meso-groups have been reported to interact with reduced GO through a combination of ionic and p–p interactions. [6] In addition, neutral proto- and metallopor