This study aims (i) to enrich the existing classical force field to accurately capture the cation-π interaction in the gas phase, and (ii) to examine the effects of the cation-π interaction in the solvated environment. With the optimized parameters in hand, we estimate the binding behavior of Li + ions and TBT and TriTBT (an oligomer of three TBT molecules) systems in solutions and compare these results with those obtained in the gas phase. We consider two solvation models in the MD: the "implicit solvent model", and the "explicit sol- This paper is organized as follows: In Section 2, we provide a detailed description of the methods, including the gas-phase density functional theory and molecular statics (MS) calculations setup, parameterization strategy, and verification procedure. This section also covers the implicit and explicit solvation models in classical MD and the procedures used to estimate the binding free energy in the solution environment. We then present and discuss the binding (free) energies and optimized parameters for benzene, benzenethiol, and thiophene in the gas phase, and "free TBT monomer", and "PTBT constituent monomer" both in the gas phase and the solvated environments in Section 3. Finally, Section 4 contains our concluding remarks.