Conceptual DFT Reactivity Descriptors Computational Study of Graphene and Derivatives Flakes: Doped Graphene, Graphane, Fluorographene, Graphene Oxide, Graphyne, and Graphdiyne

Allotropes of carbon such as graphene, graphane, fluorographene, doped graphene with N, B or P, graphene oxide, graphyne, and graphdiyne were studied through conceptual DFT reactivity descriptor indexes. To understand their chemical behavior and how they interact with different types of molecules, for instance, drugs (due to their potential use in drug carrier applications). This work shows the results of the changes in the global and local reactivity descriptor indexes and geometrical characteristics within the different graphene derivatives and rationalizes how they can interact with small molecules. Molecular hardness, the ionization energy, the electron affinity, electrodonating power index, and electroaccepting power indexes are the computed global reactivity descriptors. While, fukui functions, local softness, and molecular electrostatic potential are the local reactivity descriptors. The results suggest that the hybridization of carbons in the derivatives is kept close to sp, while for graphene is sp, the symmetry changes have as consequence changes in their chemical behavior. We found that doping with B or P (one or two atoms doped) and functionalizing with -OH or -COOH groups (as in graphene oxide), decreases the ionization energy in water solvent calculations, allowing for easier electron donation. On the other hand, doping with N atoms and functionalizing with F atoms increases the electron affinity. These types of changes enhance the chemisorption or physisorption by non-covalent interactions and covalent interactions with small molecules, principally, in the carbon atoms nearest to the doped/functionalized atom.