Stepwise assembly of mixed-metal coordination cages containing both kinetically inert and kinetically labile metal ions: introduction of metal-centred redox and photophysical activity at specific sites.-猫眼课题宝

DOI：

10.1039/c5dt02957k

发表时间：

2015-10

期刊：

Dalton transactions

影响因子：

通讯作者：

中科院分区：

化学2区

文献类型：

作者：

A. Wragg;A. J. Metherell;William M Cullen;M. Ward

报道了异金属八核配合物[（M（a））4（M（B））4L 12]（16+）的分步合成，其中M（a）= Ru或Os，M（B）= Cd或Co（均为+2氧化态）.这需要初始制备动力学惰性单核络合物[（M（a））L3]（2+），其中L是具有两个双齿螯合吡唑基-吡啶单元的双配位配体：在配合物[（M（a））L3]（2+）中，每个配体的一端与金属离子结合，使得该络合物具有三个悬垂的双齿位点，在该位点处笼状组装体可以在单独的步骤中通过与另外的不稳定离子M（B）配位而传播。因此，四个[（M（a））L3]（2+）单元和四个[M（B）]（2+）离子的组合导致完整笼[（M（a））4（M（B））4L 12]（16+）的组装，其中金属离子位于立方体的八个顶点中的每一个，并且桥接配体跨越立方体的十二个边缘中的每一个。不同类型的金属离子必须围绕外围交替，其中每个桥接配体结合到每种类型的一个金属离子。所有四个笼的结构特征如下：在Ru（ii）/Cd（ii）笼中，（在最近的通信中报道）Ru（ii）和Cd（ii）离子在晶体学上是不同的;在其他三个笼[Ru（ii）/Co（ii）、Os（ii）/Cd（ii）和Os（ii）/Co（ii），在此报道]中，离子在外围周围是无序的，使得每个金属位点细化为50：50两种金属原子类型的混合物。将Os（ii）单元并入笼中导致氧化还原活性[在适度电位下同时对所有四种金属离子的可逆Os（ii）/Os（iii）对]和发光[Os（ii）单元具有发光（3）MLCT激发态，其将是良好的光电子供体]两者并入笼超结构中。

Stepwise preparation of the heterometallic octanuclear coordination cages [(M(a))4(M(b))4L12](16+) is reported, in which M(a) = Ru or Os and M(b) = Cd or Co (all in their +2 oxidation state). This requires initial preparation of the kinetically inert mononuclear complexes [(M(a))L3](2+) in which L is a ditopic ligand with two bidentate chelating pyrazolyl-pyridine units: in the complexes [(M(a))L3](2+) one terminus of each ligand is bound to the metal ion, such that the complex has three pendant bidentate sites at which cage assembly can propagate by coordination to additional labile ions M(b) in a separate step. Thus, combination of four [(M(a))L3](2+) units and four [M(b)](2+) ions results in assembly of the complete cages [(M(a))4(M(b))4L12](16+) in which a metal ion lies at each of the eight vertices, and a bridging ligand spans each of the twelve edges, of a cube. The different types of metal ion necessarily alternate around the periphery with each bridging ligand bound to one metal ion of each type. All four cages have been structurally characterised: in the Ru(ii)/Cd(ii) cage (reported in a recent communication) the Ru(ii) and Cd(ii) ions are crystallographically distinct; in the other three cages [Ru(ii)/Co(ii), Os(ii)/Cd(ii) and Os(ii)/Co(ii), reported here] the ions are disordered around the periphery such that every metal site refines as a 50 : 50 mixture of the two metal atom types. The incorporation of Os(ii) units into the cages results in both redox activity [a reversible Os(ii)/Os(iii) couple for all four metal ions simultaneously, at a modest potential] and luminescence [the Os(ii) units have luminescent (3)MLCT excited states which will be good photo-electron donors] being incorporated into the cage superstructure.

Stepwise assembly of mixed-metal coordination cages containing both kinetically inert and kinetically labile metal ions: introduction of metal-centred redox and photophysical activity at specific sites.

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