State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 30 Puzhunan Road, 211816, Nanjing, China.
Jiangsu National Synergetic Innovation Centre for Advanced Materials (SICAM), No. 5 Xinmofan Road, 210009, Nanjing, China.
Nat Commun. 2022 Apr 29;13(1):2353. doi: 10.1038/s41467-022-30092-2.
Porous liquids with chemical separation properties are quite well-studied in general, but there is only a handful of reports in the context of identification and separation of non-gaseous molecules. Herein, we report a Type II porous ionic liquid composed of coordination cages that exhibits exceptional selectivity towards L-tryptophan (L-Trp) over other aromatic amino acids. A previously known class of anionic organic-inorganic hybrid doughnut-like cage (HD) is dissolved in trihexyltetradecylphosphonium chloride (THTP_Cl). The resulting liquid, HD/THTP_Cl, is thereby composed of common components, facile to prepare, and exhibit room temperature fluidity. The permanent porosity is manifested by the high-pressure isotherm for CH and modeling studies. With evidence from time-dependent amino acid uptake, competitive extraction studies and molecular dynamic simulations, HD/THTP_Cl exhibit better selectivity towards L-Trp than other solid state sorbents, and we attribute it to not only the intrinsic porosity of HD but also the host-guest interactions between HD and L-Trp. Specifically, each HD unit is filled with nearly 5 L-Trp molecules, which is higher than the L-Trp occupation in the structure unit of other benchmark metal-organic frameworks.
多孔液体具有化学分离性能，在一般情况下研究得相当充分，但在识别和分离非气态分子方面的报道却寥寥无几。在此，我们报告了一种由配位笼组成的 II 型多孔离子液体，它对 L-色氨酸（L-Trp）具有非凡的选择性，而对其他芳香族氨基酸则没有。一种先前已知的阴离子有机-无机混合甜甜圈状笼（HD）溶解在三己基十四烷基氯化膦（THTP_Cl）中。由此得到的液体 HD/THTP_Cl 由常见的成分组成，易于制备，并具有室温流动性。通过高压等温线和建模研究证明了其具有永久孔隙率。通过氨基酸时变吸收、竞争萃取研究和分子动力学模拟的证据，HD/THTP_Cl 对 L-Trp 的选择性优于其他固态吸附剂，我们将其归因于不仅是 HD 的固有孔隙率，还有 HD 与 L-Trp 之间的主客体相互作用。具体来说，每个 HD 单元中填充了近 5 个 L-Trp 分子，这高于其他基准金属-有机骨架结构单元中 L-Trp 的占据量。
