Understanding the Role of Noncovalent Interactions in Gas Sensing with Metal-Coordinated Complexes (MCCs)

Gas sensing is vital for environmental monitoring, safety, and healthcare. This review highlights the role of noncovalent interactions, hydrogen bonding, π-π stacking, and electrostatic forces in enhancing the sensitivity and selectivity of metal-coordinated complexes (MCCs) in gas sensors. These reversible interactions enable rapid, real-time detection through measurable changes in properties. For example, hydrogen bonding in amino-functionalized metal-organic frameworks (MOFs) enhances the detection of ammonia, and π-π stacking in phthalocyanine films aids in identifying aromatic volatile organic compounds (VOCs) such as benzene. Open metal sites in frameworks allow electrostatic gas binding, affecting electrical resistance, while perturbing the coordination sphere in porphyrins enables optical sensing. This review encompasses MCC platforms, ranging from Schiff base complexes to 3D MOFs and 2D materials, and highlights their tunable properties for gases such as VOCs, CO₂, SO₂, and CH₄, as well as other gases. Despite the advantages of reversibility and quick response, challenges include environmental stability and complex interactions. Future directions involve integrating machine learning for data analysis and developing durable hybrid materials to improve sensing performance technology.