On-Surface Hydrogen-Induced Covalent Coupling of Polycyclic Aromatic Hydrocarbons via a Superhydrogenated Intermediate

TL;DR

This paper introduces a novel surface-based method for covalent coupling of polycyclic aromatic hydrocarbons (PAHs) using atomic hydrogen, enabling formation of nanostructures without traditional catalysts, characterized by STM and DFT.

Contribution

It presents the first thermally activated, catalyst-free covalent coupling of PAHs via superhydrogenation on surfaces, expanding nanostructure fabrication methods.

Findings

Superhydrogenation enables covalent coupling of PAHs.

STM and DFT confirm the mechanism.

Method facilitates nanostructure formation on low-reactive surfaces.

Abstract

The activation and subsequent covalent coupling of polycyclic aromatic hydrocarbons (PAHs) are of great interest in fields like chemistry, energy, biology, or health, among others. However, this is not a trivial process. So far, it is based on the use of catalysts that drive and increase the efficiency of the reaction. Here, we report on an unprecedented method in which the dehydrogenation and covalent coupling is thermally activated in the presence of atomic hydrogen and a surface. This mechanism, which requires of the superhydrogenation of the PAHs, has been characterized by high-resolution scanning tunnelling microscopy (STM) and rationalized by density functional theory (DFT) calculations. This work opens a door toward the formation of covalent, PAH-based, macromolecular nanostructures on low-reactive surfaces, thus facilitating its applicability.