The selective carbon dioxide (CO₂) absorption properties of ionic liquids (ILs) are highly pertinent to the development of methods to capture CO₂. Although it has been reported that fluorinated components give ILs enhanced CO₂ solubilities, it has been challenging to gain a deep understanding of the interactions occurring between ILs and CO₂. In this investigation, we have utilized the soft crystalline material [Cu(NTf₂)₂(bpp)₂] (NTf₂^‒ = bis(trifluoromethylsulfonyl)imide, bpp = 1,3-bis-(4-pyridyl)propane) as a surrogate for single-crystal X-ray diffraction analysis to visualize interactions occurring between CO₂ and NTf₂^‒, the fluorinated IL component that is responsible for high CO₂ solubility. Analysis of the structure of a CO₂-loaded crystal reveals that CO₂ interacts with both fluorine and oxygen atoms of NTf₂^‒ anions in a trans rather than cis conformation about the S–N bond. Theoretical analysis of the structure of the CO₂-loaded crystal indicates that dispersion and electrostatic interactions exist between CO₂ and the framework. The overall results provide important insight into understanding and improving the CO₂ absorption properties of ILs.

离子液体 (IL)的选择性二氧化碳 (CO _{2 ) 吸收特性与捕获 CO 2}的方法的开发高度相关。尽管据报道氟化成分使 IL 具有增强的 CO ₂溶解度，但深入了解 IL 和 CO ₂之间发生的相互作用一直具有挑战性。在本研究中，我们利用软结晶材料 [Cu(NTf ₂ ) ₂ (bpp) ₂ ] (NTf ₂ ^‒  = 双(三氟甲基磺酰基)亚胺，bpp = 1,3-双-(4-吡啶基)丙烷) 作为单晶 X 射线衍射分析的替代品，以可视化 CO 之间发生的相互作用₂和 NTf ₂ ^‒是导致 CO ₂高溶解度的氟化 IL 成分。_{对载有 CO 2}的晶体的结构分析表明，CO ₂与 NTf ₂阴离子的氟和氧原子以^反式而非顺式构象的 S-N 键相互作用。_{对负载CO 2}的晶体结构的理论分析表明，CO ₂和框架之间存在分散和静电相互作用。_{总体结果为理解和改进 CO 2}提供了重要的见解离子液体的吸收特性。