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首页> 外文期刊>Chemistry: A European journal >Sensing Abilities of Crown Ether Functionalized Polythiophenes
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Sensing Abilities of Crown Ether Functionalized Polythiophenes

机译：冠醚官能化聚噻吩的传感能力

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摘要

This work reports a theoretical study of the affinity of three different [15]crown-5 ether functionalized polythiophenes for alkali ions. Ab initio and DFT quantum mechanical calculations have evidenced that the binding energy between neutral conducting polymers and metallic ions, which interact attractively, decreases as the size of the ion increases. However, the preferences of these polythiophene derivatives have been found to be influenced by the entropic contribution, which favors binding with Na+ in preference to Li+. Molecular dynamics simulations have shown that this behavior can be accounted for on the basis of the large fluctuations that Li+ undergoes when it is contained in the cavity of the [15]crown-5 ether macrocycle. In contrast, the fluctuations detected for complexes with Na+ and K+ were particularly low, even though only the former ion fits into the center of the macrocyclic cavity. Oxidation of these polythiophene derivatives produces a drastic change in their sensing abilities, their affinities towards alkali ions becoming low or even nonexistent. Moreover, calculations indicate that the presence of unsubstituted thiophene rings directly attached to a functionalized thiophene modulates the strength of the binding in the oxidized state by reducing the repulsive interaction between the metallic cation and the pi-conjugated system. On the other hand, the influence of alkali ions on the electronic properties, in particular, on the ionization potentials and the lowest pi-pi* transitions, of both the neutral and oxidized polythiophenes is discussed.
机译：这项工作报告了三种不同的[15] crown-5醚官能化聚噻吩对碱金属离子的亲和力的理论研究。从头算和DFT量子力学计算已证明，中性导电聚合物与金属离子之间的结合能会随着离子大小的增加而降低，而金属离子之间的吸引力相互作用。然而，已经发现这些聚噻吩衍生物的偏好受到熵的贡献的影响，熵的贡献有利于与Na +结合而不是Li +。分子动力学模拟表明，这种行为可以根据Li +包含在[15] cro-5醚大环的空腔中时发生的大波动来解决。相反，即使只有前一个离子适合大环腔的中心，对于与Na +和K +的配合物检测到的波动也特别小。这些聚噻吩衍生物的氧化作用使它们的感应能力发生巨大变化，它们对碱离子的亲和力变低甚至不存在。此外，计算表明，直接连接到官能化噻吩上的未取代噻吩环的存在通过减少金属阳离子与pi共轭体系之间的排斥相互作用来调节氧化态下的结合强度。另一方面，讨论了碱离子对中性和氧化型聚噻吩的电子性能，特别是电离势和最低pi-pi *跃迁的影响。

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