김윤진 (포항공과대학교)

서종철 (포항공과대학교)

김윤진 (포항공과대학교)

서종철 (포항공과대학교)

Molecules in the gas phase can form ionic clusters through electrostatic and non-covalent interactions, revealing unique behaviors not observed in bulk solution. In this study, we investigate alkali–halide ionic clusters composed of crown ethers serving as ligands and alkali metal chlorides. To investigate their formation, structure, and bonding characteristics, we combined ion mobility spectrometry–mass spectrometry (IMS–MS) to examine gas-phase structures, collision-induced dissociation (CID) to assess ligand–ion interaction strength, and density functional theory (DFT) calculations to support structural modeling. Among the observed species, we focused on dimer clusters of the form [L₂M₂Cl]⁺, featuring a [M–Cl–M]⁺ triple ion stabilized by two ligands. We found that the size complementarity between the ligand cavity and the alkali metal ion played a key role in modulating both the L–M and M–Cl interactions, which in turn influenced the overall geometry of the cluster. Notably, in the presence of size mismatch between the ligand and the metal ion, the clusters demonstrated unusual gas-phase behavior, implying differences in interaction strength and structural stability.