Department of Chemistry, University of Kentucky, Lexington, 40506, United States.
Anal Chem. 2011 May 1;83(9):3455-61. doi: 10.1021/ac200052q. Epub 2011 Apr 1.
Triazolophanes are ionophores, with preorganized cyclic cavities that have tunable selectivities for halides. The interaction with halides is based on hydrogen bonding between the eight CH hydrogen atoms of the cavity and the halide anion. The rigidity of the cavity in tetraphenylene triazolophane along with the hydrogen bonding favors planar 1:1 complexation of "snugly" encapsulated chloride and bromide. Manipulating the triazolophane's structure by introducing two pyridyl moieties into the cavity alters the receptor's binding mode. This change adds a dipole-promoted driving force that combines with hydrogen bonding to favor the formation of 2:1 sandwich complexes around halides. The potentiometric response of electrodes based on this new ionophore was evaluated for optimal halide selectivity. The new triazolophane-based electrode showed an anti-Hofmeister selectivity toward iodide with a submicromolar detection limit. The stoichiometry of complexation and the stability constants with different halides were evaluated using a segmented sandwich membranes method. The pyridyl-triazolophane demonstrated a response consistent with a 2:1 sandwich-type complex with iodide, in polyvinyl chloride (PVC) membranes.
三唑并并[4,5-f:1',2':4,5]菲咯啉是具有预组织的环状空腔的离子载体，其对卤素具有可调节的选择性。与卤素的相互作用基于空腔的八个 CH 氢原子与卤素阴离子之间的氢键。四苯并三唑并[4,5-f:1',2':4,5]菲咯啉中空腔的刚性以及氢键有利于“紧密”封装的氯化物和溴化物的平面 1:1 络合。通过在空腔中引入两个吡啶基部分来操纵三唑并并[4,5-f:1',2':4,5]菲咯啉的结构，改变了受体的结合模式。这种变化增加了偶极子促进的驱动力，与氢键一起有利于围绕卤素形成 2:1 夹层络合物。基于这种新离子载体的电极的电位响应得到了评估，以获得最佳的卤化物选择性。新的三唑并并[4,5-f:1',2':4,5]菲咯啉基电极对碘化物表现出反荷默斯特选择性，检测限低至亚微摩尔。使用分段夹层膜法评估了与不同卤素形成配合物的化学计量和稳定常数。吡啶-三唑并并[4,5-f:1',2':4,5]菲咯啉在聚氯乙烯 (PVC) 膜中表现出与碘化物形成 2:1 夹层型配合物的一致响应。
