Chemical functionalization of a unique 2D material – Computational prediction for cyclooctyne on the biphenylene network

The chemical functionalization of the biphenylene network with the organic adsorbate cyclooctyne is predicted using density functional theory. As a novel 2D material, the biphenylene network has attracted a lot of attention in the material science community due to possible applications in superconductivity, photocatalysis, or hydrogen storage. First studies show the decoration of the biphenylene network using metal atoms, hydrogenation, or the adsorption of simple molecules like CO2. However, covalent functionalization of the material is an unsolved challenge, which could allow tailoring of the material's properties owing to the variability of organic adsorbates. We show that the biphenylene network can be functionalized with cyclooctyne by exploiting its strained triple bond. The reaction mechanism proceeds via the asynchronous [2+2] cycloaddition found for cyclooctyne adsorption before using the energy decomposition analysis for extended systems (pEDA). Chemical functionalization leads to a coverage-dependent change in the effective band structure with the disappearance of the type II Dirac cone known for pristine biphenylene for higher coverages. A brief comparison with other 2D carbon materials shows the high reactivity of the biphenylene network, making it a promising first study for exploring new avenues for the creation of novel functional materials and interfaces and the chemical tuning of their electronic structure.