# Controlled Growth of Oligophenylene‐Structures on Graphene for Facile Secondary Functionalization

## TL;DR

Researchers developed a method to grow controlled dendrimeric structures on graphene, enabling efficient secondary functionalization for tailored material properties.

## Contribution

A novel approach to use controlled oligophenylene structures on graphene for high-density, versatile secondary functionalization.

## Key findings

- Oligophenylene structures up to 10 nm thick were grown on graphene via controlled thermal decomposition of BPO-based peroxides.
- Functionalization with bromomethyl groups enabled subsequent nucleophilic substitution with azide, nitrile, and phosphonate groups.
- The method allows for high-density functionalization and opens new avenues for graphene-based material design.

## Abstract

Functionalization of graphene derivatives is a common approach to tune material properties for use in various applications. Because of the low reactivity of the unsaturated carbon lattice of graphene, not only are few chemical approaches suitable for successful functionalization, such as those involving highly reactive in situ formed radical species or nitrene and carbene compounds, but also the degree of functionalization is usually limited, modifying only a few percent of the carbon atoms. Typically, uncontrolled side reactions such as homocoupling and oligomerization of newly introduced functional groups can occur instead of direct coupling to the carbon lattice. We want to turn this unwanted side reaction into an advantage and use intentionally formed covalent dendrimeric oligophenylene structures for secondary functionalization. We show that these oligomeric structures can be grown to specific thicknesses and used for further functionalization with bromomethyl groups at high density on the surface. This functionalization opens further avenues for subsequent nucleophilic substitution, as exemplified by the introduction of versatile azide, nitrile, and phosphonate groups. The results presented here are not only applicable to large oligophenylene structures, but also demonstrate that, in principle, single aryl moieties on graphene of any size and density can be successfully functionalized.

By thermal decomposition of different BPO‐based peroxides with different substituents, dendrimeric oligophenylene structures with thicknesses up to 10 nm have been grown on graphene in a controlled manner. These newly introduced structures provide active sites for further functionalization as they have a higher reactivity than the graphene lattice, as shown by their subsequent functionalization with bromomethyl groups. These functional oligophenylene structures can serve as a versatile platform for secondary functionalization, as shown by the introduction of azide, nitrile, and phosphonate groups. The approach presented here opens up a novel route to generate nanometer‐sized graphene‐based materials with tailored properties for subsequent applications.