N-(二茂铁酰胺基)硫脲类阴离子受体  

N-(Ferrocamido)thiourea-Based Anion Receptors

作　　者：韩洁[1] 黎朝[1] 刘文侠[1] 杨睿[1,2] 江云宝[1] 

机构地区：[1]厦门大学化学化工学院化学系现代分析科学教育部重点实验室 [2]西南大学化学化工学院重庆400715

出　　处：《化学学报》2006年第16期1716-1722,共7页Acta Chimica Sinica

摘　　要：我们将N-(苯甲酰胺基)硫脲类阴离子识别受体研究拓展至N-(二茂铁酰胺基)硫脲,设计合成了N-(二茂铁甲酰胺基)-N'-(取代苯基)硫脲(3a～3e,取代基X=p-OCH3,p-CH3,H,m-Br,m-CF3),其中二茂铁基系芳香性的电化学活性基团、“—NH—”为连接臂.研究的目的是进一步理解“—NH—”连接臂的特性和3a～3e作为阴离子的电化学响应受体的可行性.我们发现,3a～3e分子中的N'-苯环取代基不影响其半波电位(0.31Vvs.Ag/AgNO3);二茂铁环芳香质子和酰胺基—NH质子的核磁化学位移不受取代基的影响,而N'-苯基芳香质子和硫脲—NH质子的化学位移显著地受制于取代基;说明受体3分子中酰肼基N—N单键高度扭曲,阻碍了N'-苯环取代基电子效应传递至二茂铁基.我们观察到乙腈中3的氧化电位因阴离子如CH3CO-2和F-的结合负移200mV,二茂铁基芳香质子的化学位移向高场移动,意味着阴离子结合诱导了受体3分子中酰肼基N—N单键构型变化,使阴离子结合信息得以传递至二茂铁环.吸收光谱滴定实验表明,乙腈中3a～3e与阴离子结合时在约315nm处出现新的吸收峰,光谱红移达5820cm-1,阴离子如CH3CO-2和F-的结合常数在106mol-1?L,均远高于传统的二苯基硫脲类受体(1);我们还发现,尽管1和3a～3e分子中硫脲—NH质子酸性对取代基的依赖性相近,3a～3e之阴离子结合常数的取代基效应强于1.我们认为,这是由于N—N键的变构作用导致3a～3e的吸收光谱红移、阴离子结合常数和阴离子结合常数的取代基效应远高于传统的N,N'-二苯基硫脲类受体,因而体现了“—NH—”连接臂的独特性质.We extended our research on N-benzamidothiourea based anion receptors to N-ferrocamidothioureas and synthesized N-ferrocamido-N＇（substituted phenyl）thioureas （3a-3e, substituent X =p-OCH3, p-CH3, H, m-Br, and m-CF3）. In 3a-3e an electrochemically active ferrocene moiety was employed as an aromatic counterpart of phenyl and --NH-- was a spacer linking ferrocene signal reporter and the thiourea binding-site. Cyclic voltammetric experiments carded out in acetonitrile indicated that the half-wave potentials of 3a-3e of 0.31 V vs. Ag/AgNO3 were independent of the substituent at N＇-phenyl ring. It was found that the 1H NMR chemical shifts of the aromatic protons at ferrocene moiety and the amido --NH proton in 3 did not, whereas those of the N＇-phenyl aromatic protons and the thioureido --NH protons did vary when the N＇-phenyl substituent was changed. The azino N--N bond was hence concluded to be twisted that blocked the electronic communication between the ferrocene moiety and thiourea anion-binding site. Yet we experimentally observed that the oxidation potentials of 3a-3e shifted by ca. --200 mV in the presence of anions such as CH3CO2^- and F^- in acetonitrile and the chemical shifts of the ferrocene aromatic protons shifted to high field upon anion binding to the thiourea moiety in 3a-3e. A conformation change in the N-- N bond was hence assumed for 3a-3e upon anion binding. Absorption titrations indicated that anion binding to 3a-3e resulted in a new absorption band at ca. 315 nm with a spectral red-shift of 5820 cm^-1 irre- spective of the substituent. The spectral red-shift, anion affinity of 106 mol^-l·L orders of magnitude for CHaCO2^- and F^-, and substituent effect on the anion affinity of 3a-3e were found much higher than those of the corresponding traditional N,N＇-diphenylthiourea counterparts （1）. It was concluded that anion binding induced conformational change in 3a-3e led to enhanced anion affinity and substituent effect on the anion affinity, information indicative of allosteri

关 键 词：阴离子受体 二茂铁 硫脲 变构作用 -NH-连接臂 循环伏安 

分 类 号：O627.81[理学—有机化学]