The principal objective of this work was to study the molecular structure and chemical reactivity (electronic affinity, A; ionization potential, I; electronegativity, ϰ; hardness, η; electrophilicity, ω; Fukui functions) of some trimethyltetrathiafulvalene functionalized by conjugated substitent employing the density functional theory (DFT) method. The electronic properties, such as excitation energies, HOMO and LUMO energies were performed which confirms the charge transfer of the molecules. Molecular electrostatic potential has also been computed. The chemometric methods PCA and HCA were employed to find the subset of variables that could correctly classify the compounds according to their reactivity. The theoretical results are valuable for providing a reliable insight into the molecular properties.