The use of dimetal building blocks in convergent syntheses of large arrays

Within the broad field called “supramolecular chemistry,” there is a sector that is based on the use of metal atoms or ions as key elements in promoting the assembly and dictating the main structural features of the supramolecular products. Considerable success has been achieved by using M—M bonded dimetal entities in this role. Metal–metal bonded cationic complexes of the [M(2)(DAniF)(n)(MeCN)(8–2n)]((4−n)+) type, where M = Mo or Rh and DAniF is an N,N′-di-p-anisylformamidinate anion, have been used as subunit precursors and then linked by various equatorial and axial bridging groups such as polycarboxylate anions, polypyridyls, and polynitriles. Characterization of the products by single-crystal x-ray diffraction, cyclic voltammetry, differential pulse voltammetry, NMR, and other spectroscopic techniques has revealed the presence of discrete tetranuclear (pairs or loops), hexanuclear (triangles), octanuclear (squares), and dodecanuclear (cages) species and one-, two-, or three-dimensional molecular nanotubes. These compounds display a rich electrochemical behavior that is affected by the nature of the linkers.

在超分子化学（supramolecular chemistry）这一宽泛研究领域中，存在一个分支方向，其以金属原子或离子作为核心要素，用以推动组装过程并决定超分子产物的主要结构特征。在此方向中，采用M-M键合的双核金属实体作为核心要素已取得了可观的研究成果。[M₂(DAniF)ₙ(MeCN)₈₋₂ₙ]^((4−n)+) 型金属-金属键合阳离子配合物（其中M为钼（Mo）或铑（Rh），DAniF为N,N'-二对茴香基甲脒阴离子（N,N'-di-p-anisylformamidinate anion））已被用作亚基前驱体，随后通过各类赤道与轴向桥联基团（如多羧酸根阴离子、多吡啶类配体及多腈类配体）进行连接。通过单晶X射线衍射（single-crystal X-ray diffraction）、循环伏安法（cyclic voltammetry）、差分脉冲伏安法（differential pulse voltammetry）、核磁共振波谱（NMR）及其他光谱技术对产物进行表征后，研究人员发现体系中存在离散的四核（二聚体或环结构）、六核（三角形结构）、八核（正方形结构）及十二核（笼状结构）物种，以及一维、二维、三维分子纳米管。此类化合物展现出丰富的电化学行为，且该行为受桥联配体的性质所调控。