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首页> 外文期刊>Chemistry: A European journal >Electrochemically Controlled Assembling/Disassembling Processes with a Bis-imine Bis-quinoline Ligand and the Cu~(II)/Cu~I Couple
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Electrochemically Controlled Assembling/Disassembling Processes with a Bis-imine Bis-quinoline Ligand and the Cu~(II)/Cu~I Couple

机译：双亚胺双喹啉配体和Cu〜（II）/ Cu〜I偶的电化学控制组装/拆卸过程

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The bis-iminoquinoline quadridentate ligand L is capable of forming air- and moisture-stable complexes both with Cu~(II) and Cu~I; thus the L/Cu~(II/I) set is a bistable system. Owing to its quite rigid preorganized structure, L forms the 1:1 complex [Cu~(II)L]~(2+) when binding the d~9 cation Cu~(2+), while with the d~(10) cation Cu~+, dimeric complexes of the [Cu~(I)L]~(2+) type are formed in which each copper cation is coordinated by two iminoquinoline fragments belonging to two different ligands. Crystal and molecular structure determinations showed that, in [Cu~(II)L] (CF_3SO_3)_2, L binds to the metal center in a square-planar fashion, while in [Cu_2~(I)L_2](CF_3SO_3)_2 the Cu~+ cations are coordinated with a tetrahedral geometry, with the two ligands L intertwined in a double helix. On the other hand, in the case of [Cu_2~(I)L_2](ClO_4)_2 both a helical species and a dimeric nonhelical one were found to coexist in the same crystal cell. However, spectrophotometric and ~1H NMR studies demonstrated that, in acetonitrile solution, only two helical forms exist, one of which is more prevalent (87%, at 20 deg C). The interconversion equilibrium between the two helical forms has been studied in acetonitrile by temperature variable ~1H NMR and the pertinent #DELTA#H~ and #DELTA#S~ values have been determined; these account for the small difference in energy between the two species. Finally, cyclic voltammetry and spectroelectrochemical experiments demonstrated that in acetonitrile solution it is possible to rapidly transform [Cu~(II)L]~(2+) into the helical [Cu_2~(I)L_2]~(2+) dimer (or vice versa) by changing the potential applied to the working electrode, that is, it is possible to electrochemically control the self-assembly/disassembly process through the Cu~(II)/Cu~I redox couple. Moreover, it has been shown that self-assembly (reduction)/disassembly (oxidation) cycles can be repeated at will, without any degradation of the system.
机译：双亚氨基喹啉四齿配体L能够与Cu〜（II）和Cu〜I形成空气和水分稳定的配合物。因此，L / Cu〜（II / I）集是双稳态系统。由于其相当刚性的预组织结构，当与d〜9阳离子Cu〜（2+）结合时，L与d〜（10）结合时形成1：1的[Cu〜（II）L]〜（2+）。形成[Cu〜（I）L]〜（2+）型二聚体Cu〜+，其中每个铜阳离子都由属于两个不同配体的两个亚氨基喹啉片段配位。晶体和分子结构的确定表明，在[Cu〜（II）L]（CF_3SO_3）_2中，L以正方形平面方式结合到金属中心，而在[Cu_2〜（I）L_2]（CF_3SO_3）_2中， Cu +阳离子与四面体几何结构配位，两个配体L缠绕在双螺旋中。另一方面，在[Cu_2〜（I）L_2]（ClO_4）_2的情况下，发现在同一晶胞中同时存在螺旋物质和二聚体非螺旋物质。但是，分光光度法和〜1H NMR研究表明，在乙腈溶液中，仅存在两种螺旋形式，其中一种更为普遍（在20℃时为87％）。已通过温度变量〜1H NMR在乙腈中研究了两种螺旋形式之间的相互转化平衡，并确定了相关的＃DELTA＃H〜和＃DELTA＃S〜值;这些解释了两个物种之间能量的微小差异。最后，循环伏安法和光谱电化学实验表明，在乙腈溶液中可以将[Cu〜（II）L]〜（2+）快速转化为螺旋型[Cu_2〜（I）L_2]〜（2+）二聚体（或反之亦然）通过改变施加到工作电极上的电势，也就是说，可以通过Cu〜（II）/ Cu〜I氧化还原对来电化学控制自组装/拆卸过程。而且，已经表明自组装（还原）/分解（氧化）循环可以任意重复，而不会降低系统的性能。

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