Entropy‐Driven Cooperativity in the Guest Binding of an Octaphosphonate Bis‐cavitand
Entropy‐Driven Cooperativity in the Guest Binding of an Octaphosphonate Bis‐cavitand
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八膦酸盐双腔配体客体结合中的熵驱动协同性
DOI：
10.1002/chem.201905036
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Haino Takeharu
中科院分区：
文献类型：
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作者：
Shimoyama Daisuke;Haino Takeharu
在八膦酸双空穴配体的客体结合中报道了不常见的熵驱动协同效应。等温滴定量热法测定了双空穴配体与铵客体在甲醇、乙醇、2-丙醇和氯仿中1：2主客体结合的热力学参数。氯仿驱动不常见的熵驱动的协同结合，而醇则导致焓驱动的非协同结合。1H NMR研究表明，每个空腔含有氯仿中的六个水分子，这些水分子在客体结合时被释放出来。 在氯仿中，熵-熵补偿关系产生了很大的正的内禀熵，这意味着水去溶剂化通过由于破坏水簇的氢键网络而支付的熵罚而导致相当大的熵增益。
Uncommon entropy‐driven cooperativity is reported in the guest binding of an octaphosphonate bis‐cavitand. Isothermal titration calorimetry determined the thermodynamic parameters for the 1:2 host–guest binding of bis‐cavitands with ammonium guests in methanol, ethanol, 2‐propanol, and chloroform. Chloroform drove uncommon entropy‐driven cooperative binding, whereas the alcohols resulted in enthalpy‐driven noncooperative binding.1H NMR studies revealed that each cavity contained six water molecules in chloroform, which were liberated on guest binding. The enthalpy–entropy compensation relationship produced a large positive intrinsic entropy in chloroform, which implies that water desolvation causes a considerable entropic gain by paying an enthalpic penalty due to breaking the hydrogen‐bonding networks of the water clusters.