Noncovalent interactions of 1,4-dithiafulvene and nitroaromatics: A combined DFT and ab initio molecular dynamics (AIMD) study

The noncovalent interactions between a redox-active molecule, phenyl-substituted 1,4-dithiafulvene (Ph-DTF), and ten commonly encountered nitroaromatic compounds (NACs) were systematically investigated by means of density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations. Our modeling studies examined their 1:1 complexes in terms of equilibrium geometries, frontier molecular orbitals (FMOs), nature of noncovalent forces, intermolecular charge transfer (ICT), and interaction energies at the omega B97XD/6-31+G(d,p) level of theory. Vertical electronic transition properties were investigated through time-dependent density functional theory (TD-DFT) calculations, and energy decomposition analysis was conducted according to the symmetry-adapted perturbation theory (SAPT). The computational results indicate that Ph-DTF can form thermodynamically stable 1:1 complexes with trinitro-substituted benzenes (e.g., 2,4,6-trinitrotoluene and picric acid), but its interactions with mono- and dinitrobenzenes do not exhibit such stability. The selective binding properties are further corroborated by AIMD simulations. Overall, this computational work establishes a comprehensive understanding of the nature of noncovalent interactions of Ph-DTF with various NACs, and the results can be used as theoretical guidance for the rational design of selective receptors and/or chemosensors for certain NACs that are of great concern in current industrial applications and environmental control.