Computational Study of Metal Complexes and Their Interactions with Various Gas Molecules: Electronic Structure, Binding Mechanisms and Emerging Applications

Abstract

Metal complexes provide versatile and tunable platforms for molecular recognition and interaction with small gas molecules. Computational chemistry has become an important approach for understanding these interactions by revealing structural, energetic, and electronic changes that are often difficult to examine experimentally. Density functional theory and related quantum-chemical methods are widely applied to study gases such as CO, CO₂, NO, NO₂, NH₃, SO₂, H₂, O₂, N₂, and CH₄. Important computational descriptors include adsorption or binding energy, metal–gas distance, molecular geometry, charge transfer, frontier molecular orbitals, HOMO–LUMO energy gap, and electron-density-based analyses. These parameters help distinguish weak adsorption, coordination, and molecular activation mechanisms. Computational studies also support designing metal complexes for gas sensing, capture, separation, and catalytic applications. However, challenges remain in accurately treating transition-metal electronic structure, dispersion, realistic environmental conditions, selectivity, and adsorption–desorption balance. Future progress will require improved computational methods, experimental validation, and data-driven screening strategies.