Sodium and Potassium Ion Directed Self-Assembled Multinuclear Assembly of Divalent Nickel or Copper and L-Leucine Derived Ligand
Sodium and Potassium Ion Directed Self-Assembled Multinuclear Assembly of Divalent Nickel or Copper and L-Leucine Derived Ligand
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DOI：
10.1021/ic9011444
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发表时间：
2009-10-05
影响因子：
4.6
通讯作者：
Ray, Manabendra
中科院分区：
文献类型：
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作者：
Dubey, Mrigendra;Koner, Rik Rani;Ray, Manabendra
l -亮氨酸衍生的配体（H2LL-leu）、KOH和Ni（II）盐以2:21的比例自组装成一个相当大的（类似于13埃）超分子组装体，其式为[K{Ni(HLL-leu)(2)}3](+)(1)，结构表征显示三个[Ni(HLL-leu)(2)]单元包裹K+，类似于有机冠醚/隐式。将Ni（II）替换为Cu(II)， K+替换为Na+，得到一组结构相同的组合，其通式为[M‘{M(HLL-leu)(2)}(3)](+)，其中M’为K+或Na+， M为Cu（II）或Ni(II)；(Na{倪(HLL-leu) (2)} (3)] ClO4 (2), (Na{倪(HLL-leu)(2)}(3)]传递(3),(K{铜(HLL-leu) (2)} (3)] ClO4 (4), (Na{铜(HLL-leu) (2)} (3)] ClO4 (5), [K{铜(HLL-leu)(2)}(3)](6)。聚类化合物在MeOH中的电喷雾电离(ESI)-质谱显示了聚类化合物在溶液中的保留。可见光谱研究表明，在N，N-二甲基甲酰胺（DMF）中，即使在加入5等量的[18]-冠-6后，组装体1仍保持稳定。在强氢键的甲醇中，2-6中的组装体表现出不同程度的解离为[M(HLL-leu)(2)]和M'。加入过量的KNO3/NaNO3盐可以逆转解离。对[Cu(hhl -leu)(2)(MeCN)](7)及其在K+盐存在下转化为[K{Cu(hhl -leu)(2)}(3)]（+）的结构表征表明，在[Cu(hhl -leu)(2)]单元内，碱金属离子诱导配体重定向形成[Cu(hhl -leu)(2)]单元，并通过六个强氢键保持组装体进一步稳定。有趣的是，1和2的可见光谱显示，用Na+取代K+引起的微小结构变化足以使Ni（II）的d-d跃迁位移约70 nm，从而提供了一种间接区分K+和Na+的方法，两者在可见范围内都没有光谱特征。
L-Leucine derived ligand (H2LL-leu), KOH, and Ni(II) salt in 2:21 ratio self-assembled into a rather large (similar to 13 angstrom) supramolecular assembly with the formula [K{Ni(HLL-leu)(2)}3](+) (1), Structural characterization showed three [Ni(HLL-leu)(2)] units encapsulated K+ similar to organic crown ethers/cryptand. Substituting Ni(II) with Cu(II) and K+ with Na+ in the above reaction resulted in a set of structurally identical assemblies with the general formula [M'{M(HLL-leu)(2)}(3)](+), where M' is either K+ or Na+ and M is either Cu(II) or Ni(II); [Na{Ni(HLL-leu)(2)}(3)]ClO4 (2), [Na{Ni(HLL-leu)(2)}(3)]OTf (3), [K{Cu(HLL-leu)(2)}(3)]ClO4 (4), [Na{Cu(HLL-leu)(2)}(3)]ClO4 (5), [K{Cu(HLL-leu)(2)}(3)]NO3 (6). Electrospray Ionization (ESI)-mass spectra of the assemblies in MeOH showed the retention of assemblies in solution. Visible spectroscopic studies showed retention of assembly 1 in N,N-dimethylformamide (DMF) which is stable even after the addition of 5 equiv of [18]-crown-6. The assemblies in 2-6 show various degrees of dissociation to [M(HLL-leu)(2)] and M', in stronger H-bonding methanol. The dissociation can be reversed upon addition of excess KNO3/NaNO3 salt. Structural characterization of [Cu(HLL-leu)(2)(MeCN)] (7) along with its transformation to [K{Cu(HLL-leu)(2)}(3)](+) in the presence of K+ salt demonstrated that the assembly formation proceeds through an alkali metal ion induced ligand reorientation within the [Cu(HLL-leu)(2)] units which is further stabilized by six strong H-bonds holding the assembly. Interestingly, visible spectra of 1 and 2 shows that minor structural changes caused by replacing K+ with Na+ is sufficient to shift the d-d transition of Ni(II) by similar to 70 nm, thereby providing an indirect way of distinguishing K+ and Na+, none of which have spectroscopic signature in the visible range.