Evaluation of heavy metal ion discrimination and application of entropic host molecule to soft metal ion sensor

虽然碱金属和碱土金属离子的离子载体分子设计的指向性已经确立，但对于重金属和过渡金属离子载体的分子设计的指向性还没有确立。本文采用电化学方法对23种希夫碱进行了表征，以考察其对提高银离子识别能力的指向性。在席夫碱中，由α-异硝基丙烯酮和1,3 -二氨基丙烷衍生而来的N， N'-二（2'-羟基亚胺-1'-苯丙烯）- 1,3 -丙二胺PHO3是最实用的银离子载体。即PHO3-NPOE^<I)>（增塑剂）-KTpC1PB^<II)>（阴离子排除剂）体系PVC^<III)>膜电极具有良好的能氏响应，在活性范围为5.0 × 10^<-7> ~ 7.9 × 10^<-7> mol dm^<-3>的范围内具有较宽的Ag^+活性变化。用固定干涉法（FIM）评价了Ag +离子对K +离子（-log K^ <pot>_<Ag， K>）的选择性为3.35。这种电极的唯一缺陷是寿命短，大约20天左右。因此，PHO3的甲基部分被转化为长链烷基，以提高其亲脂性。在希夫基长烷基单元N， N'-二（2'-羟基亚胺-1'-苯基丁基）- 1,3 -丙二胺中，PHEtO3基NPOE-KTpC1PB体系电极在2个多月的观察期内表现出优异的性能，但由于希夫碱的水解作用，Ag^+相对于K^+的选择系数从4.35逐渐降低到2.95。为了考察配位原子数对银离子选择性配位的影响，合成了三种三齿配体，并与类似的四齿配体PHO3进行了比较。具有一个肟和一个吡啶取代基的3-（2-吡啶基乙基柠檬酸）-2-丁酮肟（Me-PyO3）是银离子电极的最佳离子载体。基于Me-PyO3的PVC膜电极表现出良好的Ag^+离子选择性，-logo k^<pot>_<Ag, k >=3.8，与四齿PHO3相当，除了伪能斯汀响应（3.6mV decade^1）， Ag^+离子活度从5 × 10^<-7>到7.9 × 10^<-2>mol dm^<-3>的变化幅度较大。I)：聚氯乙烯；II)：邻硝基辛基醚；四（4-氯苯基）硼酸钾较少

Though the directivity of the molecular design of the ionophore for alkali and alkaline-earth metal ion has been established, it has not been established for the heavy and transition metal ionophore. In the present work, twenty-three kinds of Schiff bases were characterized by electrochemical measurement to examine the directivity for improving the silver-ion discrimination ability. Among the Schiff bases, N, N'-bis(2'-hydroxyimino-1'-phenylpropylidene)-1, 3-propanediamine, PHO3, derived from α-isonitrosopropiophenone and 1, 3-diaminopropane was found to be the most practical Ag^+-ionophore. That is, PHO3-NPOE^<I)>(plasticizer)-KTpC1PB^<II)>(anion excluder) system PVC^<III)> membrane electrode gave good results with a Nernstian response in accordance with the wide Ag^+ activity change in the activity range 5.0x10^<-7> to 7.9x10^<-7> mol dm^<-3>. The Ag^+ ion selectivity with respect to K^+ ion, -log k^<pot>_<Ag, K> was 3.35 evaluated by fixed interference method, FIM. This electrodes h … More as the only defect to be a short life time in about 20 days. Therefore, methyl moiety of PHO3 was converted in the long-chain alkyl groups in order to improve the lipophilicity. Among the Schiff based having long alkyl unit, N, N'-bis(2'-hydroxyimino-1'-phenylbuthylidene)-1, 3-propanediamine, PHEtO3 based NPOE-KTpC1PB system electrode showed superior performance during an observation period of more than 2 months, though the Ag^+ selectivity coefficient with respect to K^+, was gradually reduced from 4.35 to 2.95 due to the hydrolysis of Schiff bases. Further, to examine the effect of the number of coordination atom on selective complexation with Ag ion, three kinds of tridentate ligands were synthesized and compared with similar quadoridentate ligand, PHO3. 3-(2-pyridyleethylimono)-2-butanoneoxime, Me-PyO3, having one oxime and a pyridine substituent was found to be the best ionophore for Ag ion electrode. The PVC membrane electrode based on Me-PyO3 exhibit good Ag^+ ion selectivity, -logo k^<pot>_<Ag, K>=3.8, comparable to that of quadridentate PHO3, except for pseudo Nernstian response(3.6mV decade^1) with a wide Ag^+-ion activity change in the activity change from 5.0x10^<-7> to 7.9x10^<-2>mol dm^<-3>.I) : poly (vinyl chloride) ; II) : o-nitorophenyl octyl ether ; III) : potassium tetrakis (4-chlorophenyl) borate Less