Arathi Puthiyavalappil K, Suresh Cherumuttathu H
Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, 695019, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
Phys Chem Chem Phys. 2025 Jul 10;27(27):14630-14644. doi: 10.1039/d5cp01075f.
Hydroxy-substituted aromatic N-heterocycles, including hydroxy pyridine (py), dihydroxy naphthyridines (nt), and trihydroxy pyridonaphthyridines (pn), have been investigated for their potential as CO adsorbents using density functional theory (DFT) calculations. Building on the pioneering work of Luo , who demonstrated exceptional CO capture capacities in pyridine-containing anion-functionalized ionic liquids, this study extends the exploration to a broader range of N-heterocycles. These N-heterocycles exhibit exceptional CO capture capabilities, driven by cooperative interactions between nitrogen and oxygen centres with CO. The adsorption capacity increases with the number of nitrogen centres and hydroxy groups, with py, nt, and pn systems binding one, two, and three CO molecules, respectively. Notably, anionic N-heterocycles exhibit dramatically improved CO adsorption compared to their neutral counterparts, forming covalent bonds with CO. The presence of counter cations, such as lithium or tetramethylphosphonium ions, further stabilizes CO adsorption, resulting in shorter interaction distances and higher exergonic free energy values. Solvent effects modeled using monoethanolamine (MEA) indicate a modest reduction in interaction energies for neutral and anionic systems, while ion-paired systems exhibit enhanced CO affinity in solution. Additionally, molecular electrostatic potential (MESP) analysis highlights the key adsorption sites and charge delocalization mechanisms that facilitate CO capture. The study also finds that enol-keto transformations, which could lead to CO conversion into carboxylates, are energetically unfavorable due to the loss of aromatic stability. These findings underscore the potential of hydroxy-substituted N-heterocycles, particularly in their anionic and cation-stabilized forms, as promising candidates for efficient CO capture. The insights gained from this study provide valuable guidelines for the design of next-generation CO sequestration materials and highlight new directions for experimental validation and real-world applications.
已使用密度泛函理论（DFT）计算研究了羟基取代的芳香族氮杂环化合物，包括羟基吡啶（py）、二羟基萘啶（nt）和三羟基吡啶并萘啶（pn）作为CO吸附剂的潜力。基于Luo的开创性工作，他证明了含吡啶阴离子官能化离子液体具有出色的CO捕获能力，本研究将探索范围扩展到更广泛的氮杂环化合物。这些氮杂环化合物表现出出色的CO捕获能力，这是由氮和氧中心与CO之间的协同相互作用驱动的。吸附容量随着氮中心和羟基数量的增加而增加，py、nt和pn体系分别结合一个、两个和三个CO分子。值得注意的是，与中性氮杂环化合物相比，阴离子氮杂环化合物的CO吸附能力显著提高，它们与CO形成共价键。锂或四甲基鏻离子等抗衡阳离子的存在进一步稳定了CO吸附，导致相互作用距离缩短和放能自由能值更高。使用单乙醇胺（MEA）模拟的溶剂效应表明，中性和阴离子体系的相互作用能略有降低，而离子对体系在溶液中表现出增强的CO亲和力。此外，分子静电势（MESP）分析突出了促进CO捕获的关键吸附位点和电荷离域机制。该研究还发现，由于芳香稳定性的丧失，可能导致CO转化为羧酸盐的烯醇-酮转化在能量上是不利的。这些发现强调了羟基取代的氮杂环化合物的潜力，特别是其阴离子和阳离子稳定形式，作为高效CO捕获的有前途的候选物。本研究获得的见解为下一代CO封存材料的设计提供了有价值的指导方针，并突出了实验验证和实际应用的新方向。
