Thermodynamic comparison of molecular recognition of vaporous guests by solid calixarene and diol hosts
Thermodynamic comparison of molecular recognition of vaporous guests by solid calixarene and diol hosts
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DOI：
10.1039/b003477k
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发表时间：
2000-01-01
期刊：
影响因子：
--
通讯作者：
Baitalov, F
中科院分区：
文献类型：
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作者：
Gorbatchuk, VV;Tsifarkin, AG;Baitalov, F
研究了固体主体 2,2'-双(9-羟基芴-9-基)联苯 (1) 和叔丁基杯[4]芳烃 (2) 对气态客体的分子识别。为此，通过静态气相色谱顶空分析测定了 15 种具有不同分子大小和基团组成的有机化合物与固体基质 1 和 2 的蒸气吸附等温线。获得的大多数等温线显示出特定客体活性的明确包含阈值和对应于化学计量超分子化合物形成的饱和部分。确定了基于不同标准状态的主客体化合物的化学计量及其形成的自由能。假定客体从甲苯中无限稀释客体溶液的标准状态转移到固体包合物的自由能是所研究的系统中的分子识别参数。对于主体 1，这种转移自由能与客体摩尔折射以及客体和醇之间的氢键自由能表现出相当良好的 2 参数相关性。固体主体2的相关性较差。根据主体晶体中不同大小的潜在空穴以及主体与客体形成氢键的不同能力，讨论了客体结构参数对主体1和2分子识别的影响。
Molecular recognition of vaporous guests by the solid hosts 2,2'-bis(9-hydroxyfluoren-9-yl)biphenyl (1) and tert-butylcalix[4]arene (2) was studied. For this purpose the vapour sorption isotherms of 15 organic compounds with various molecular size and group composition with the solid hosts 1 and 2 were determined by static gas chromatographic headspace analysis. Most of the isotherms obtained show a definite inclusion threshold at a specific guest activity and a saturation part corresponding to the formation of stoichiometric supramolecular compounds. The stoichiometry of the host-guest compounds and free energies of their formation based on different standard states were determined. The free energy of guest transfer from the standard state of an infinitely dilute guest solution in toluene to the solid inclusion compound was assumed to be a molecular recognition parameter in the systems studied. For host 1 this transfer free energy exhibits a reasonably good 2-parameter correlation with guest molar refraction and free energy of H-bonding between guest and alcohols. Bad correlation was obtained for solid host 2. The effect of the guest structural parameters on molecular recognition by hosts 1 and 2 is discussed in terms of the different size of potential cavities in the host crystals and different ability of the hosts to H-bond with guests.