Ab initio calculations Were used to identify CO2-philic groups. Over SS neutral molecules were screened for CO, affinity via binding energetics. It is found that poly(ethylene oxide)s (PEO) oligomers with more than three repeating units are good CO2-binding groups, consistent with the high-performance of PEO-based materials for CO2/N-2 separation. More interestingly, two triazole groups linked with a methylene chain are also excellent for CO2 binding with a favorable interaction of more than 28 kJ/mol, indicating that polymers or covalent-organic framework s (COFS) with triazole may be utilized for CO, capture. This Work provides a useful: guide to introduce promising organic groups into polymeric membranes and COFs for CO2/N-2 separation media.