Effect of solvation on induce-fit molecular recognition in supercritical fluid to organic crystals immobilized on a quartz crystal microbalance.
Effect of solvation on induce-fit molecular recognition in supercritical fluid to organic crystals immobilized on a quartz crystal microbalance.
复制标题
溶剂化对超临界流体中固定在石英晶体微天平上的有机晶体的诱导拟合分子识别的影响。
DOI：
10.1021/ja0164935
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发表时间：
2001
影响因子：
15
通讯作者：
Y. Okahata
中科院分区：
文献类型：
--
作者：
M. Naito;Y. Sasaki;T. Dewa;Y. Aoyama;Y. Okahata
用9 MHz石英晶体微天平（QCM）研究了超临界CO2（scCO（2））中客体分子与正交蒽-双（间苯二酚）四醇（1）的包结行为。化合物1形成由通过广泛的氢键网络结合在一起的分子片组成的晶体。在scCO（2）溶液中，乙酸乙酯与固定化QCM的选择性结合，当[Guest]（th）= 0.08 M时，乙酸乙酯的包合量急剧增加，结合的表观吉布斯自由能Δ G（app）= -1.3 kcal mol（-1）。在气相和水中观察到乙酸乙酯或乙醇的类似选择性结合：[客体]（th）= 0.002 M，Δ G（app）= -3.5 kcal mol（-1）;[客体]（th）= 0.5 M，Δ G（app）= -0.41 kcal mol（-1）。在scCO（2）中获得的这些值介于气相和水相中的值之间。由于已知超临界流体的各种物理性质（粘度、密度、极性、扩散常数和溶剂化）介于气体和液体之间，因此这些值清楚地反映了客体分子的溶剂化行为。因此，客体分子的溶剂化程度越低，其阈值浓度越低，结合能越大，其顺序为：在空气中>在scCO（2）中>在水中。
The inclusion behavior of guest molecules to a solid apohost of an orthogonal anthracene-bis(resorcinol)tetraol (1) was investigated in supercritical carbon dioxide (scCO(2)) by using a 9 MHz quartz-crystal microbalance (QCM). Compound 1 forms crystals composed of molecular-sheet bound together by an extensive hydrogen-bonded network. The selective binding of gaseous ethyl acetate to the apohost-immobilized QCM in scCO(2) was observed, and the inclusion amount of ethyl acetate showed a drastic increase above a threshold concentration, [Guest](th) = 0.08 M, and the apparent Gibbs' free energy for the binding was DeltaG(app) = -1.3 kcal mol(-1). Similar selective bindings of ethyl acetate or ethanol had been observed in the gas phase and in water: [Guest](th) = 0.002 M with DeltaG(app) = -3.5 kcal mol(-1) and [Guest](th) = 0.5 M with DeltaG(app) = -0.41 kcal mol(-1), respectively. These values obtained in scCO(2) were intermediate between those in the gas and water phases. Since various physical properties (viscosity, density, polarity, diffusion constant, and solvation) of supercritical fluid are known to be intermediate between gas and liquid, these values clearly reflect the solvation behavior of guest molecules. Thus, the lower solvation of guest molecules indicates the lower threshold concentration and the larger binding energy in the following order: in air > in scCO(2) > in water.