The invention provides methods for substituting polyaromatic hydrocarbons or polyheterocyclic compounds with perfluoroalkyl groups. The methods can include heating a polyaromatic hydrocarbon substrate or a polyheterocyclic compound substrate in the presence of a perfluoroalkyl iodide, typically in a closed system, wherein the heating is sufficient to bring both the polyaromatic hydrocarbons or polyheterocyclic compound, and the perfluoroalkyl iodide, into the gas phase, thereby allowing the substrate to react with the perfluoroalkyl iodide in the gas phase to form polyaromatic hydrocarbons or polyheterocyclic compounds having one or more perfluoroalkyl substituents. The methods allow for the creation of versatile libraries of novel perfluoroalkyl-containing derivatives that can serve as important building blocks and active components in biomedical, electronic, and materials applications.