Efficient Colorimetric Anion Detection Based on Positive Allosteric System of Urea-Functionalized Poly(phenylacetylene) Receptor
Efficient Colorimetric Anion Detection Based on Positive Allosteric System of Urea-Functionalized Poly(phenylacetylene) Receptor
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DOI：
10.1021/ma1016852
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发表时间：
2010-09-28
期刊：
影响因子：
5.5
通讯作者：
Kakuchi, Toyoji
中科院分区：
文献类型：
--
作者：
Sakai, Ryosuke;Okade, Shota;Kakuchi, Toyoji
具有合理设计的脲基团的聚苯乙炔被证明是一种优异的阴离子受体，同时具有量热响应能力和正同向变构结合模式。通过与 Rh(nbd)BPh4 (nbd = 降冰片二烯) 进行立体选择性聚合，以高产率合成了目标聚合物，带有[双(三氟甲基)苯基氟脲 (poly-1)] 的聚苯乙炔。使用THF中一系列阴离子的四正丁基铵(rBA)盐评估Poly-1的阴离子感应能力。加入CH3CO2-、C6H5CO2-、F-、Cl-、Br-、NO3-、N-3(-)和HSO4-等阴离子后，Poly-1的THF溶液的黄色立即根据阴离子的类型变成不同的颜色，表明阴离子Poly-1 的识别能力。通过使用增加量的CH3CO2-对poly-1进行111 NM R旋转表明，poly]的比色响应被认为是脲官能团和阴离子之间形成氢键络合物的直接结果。有趣的是，在测定阴离子结合亲和力的过程中，我们遇到了poly-1的高度协同结合能力。希尔图分析提供了异常的正协同性，例如，poly-I 和 C6H5CO2- 之间的络合希尔系数为 8.4。这一结果清楚地表明，这种结合模式是基于正同向变构现象，其中聚合物链中部分形成的脲/阴离子复合物单元应产生整个主链构象的变化，从而促进进一步的阴离子结合。此外，通过比较 Poly-I 与先前制备的脲官能化聚（苯乙炔）（poly-2）的阴离子结合，发现基于两个吸电子 -CF3 基团的增强阴离子结合能力对于实现这种协同作用至关重要。
Poly(phenylacetylene) with rationally designed urea groups was demonstrated to be a superior anion receptor possessing both a calorimetric response ability and a positive homotropic allosteric binding mode. The target polymer, poly(phenylacetylene) with [bis(trifluoromethyl)phenyflurea pendants (poly-1), was synthesized by the stereoselective polymerization with Rh(nbd)BPh4 (nbd = norbornadiene) in high yield. The anion sensing ability of poly-1 was evaluated using the tetra-n-butylammonium (rBA) salts of a series of anions in TH F. Upon the addition of anions such as CH3CO2-, C6H5CO2-, F-, Cl-, Br-, NO3-, N-3(-), and HSO4-, the yellow color of the THF solution of poly-1 immediately turned to a different color depending on the types of anions, indicating the anion recognition capability of poly-1. The 111 NM R Otrations of poly-1 by using increasing amounts of CH3CO2- revealed that the colorimetric response of poly] was considered to be the direct consequence of the hydrogen-bonding complex formation between the urea functionality and the anions. Interestingly, during the course of the determination of the anion-binding affinity, we encountered highly cooperative binding ability of poly-1. The Hill plot analysis provided an exceptional positive cooperativity, e.g., 8.4 of Hill coefficient in the complexation between poly-I and C6H5CO2-. This result clearly indicated that this binding mode was based on a positive homotropic altosterism, in which the partially formed urea/anion complex units in the polymer chain should produce a change in the whole main chain conformation, facilitating further anion binding. Additionally, by comparing the anion binding of poly-I with that of previously prepared urea-functionalized poly(phenylacetylene) (poly-2), an enhanced anion binding ability based on two electron-withdrawing -CF3 groups was found to be essential to realize such cooperativity.