Formation of Metallo-Polymers and -Macrocycles by Complexation of Alkyl-Linked Di-Terpyridines with Iron(II) Ions
作者:Ulrich S. Schubert、Philip R. Andres
DOI:10.1055/s-2004-822378
日期:——
The complexation of bridged di-terpyridine ligands with iron(II) leads to new metallo-supramolecular assemblies. Di-terpyridine ligands were synthesized using nucleophilic substitution of 4′-chloro-2,2′:6′,2′′-terpyridine with different dialcoholate alkyl and dithiolate alkyl nucleophiles. Upon addition of iron(II) chloride the formation of metallo-polymeric structures via metal-to-ligand complexation is observed. The metallo-polymeric assemblies presented here contain low molar mass (cyclo)-alkyl bridged di-terpyridine ligands of which one is achiral and two others are enantiomers. For both cases, characterization using NMR and UV/Vis spectroscopy shows complex formation and indicates the formation of metallo-supramolecular polymers. For the non-polymeric system, formed at room temperature, it could be shown that upon heating exchange takes place and that the thermodynamically favored product is formed. Using column chromatography, the first two major fractions of the mixture could be separated and analyzed. MALDI-TOF mass spectrometry and 1H NMR spectroscopy confirmed the formation of metallo-macrocyclic assemblies. For the chiral system, circular dichroism (CD) experiments showed the formation of an optically active material, with the spectra of the enantiomeric assemblies being mirror-symmetric.
桥接双三吡啶配体与铁(II)的配合作用产生了新的金属超分子组装体。双三吡啶配体通过4′-氯-2,2′:6′,2′′-三吡啶与不同二醇酸盐烷基和二硫醇酸盐烷基亲核试剂的亲核取代反应合成。加入铁(II)氯化物后,通过金属-配体配合作用形成了金属聚合结构。这里展示的金属聚合结构包含低摩尔质量的(环)烷基桥接双三吡啶配体,其中一种是消旋的,另外两种是手性对映体。对于这两种情况,NMR和UV/Vis光谱分析显示形成了复杂结构,并且表明形成了金属超分子聚合物。对于在室温下形成的非聚合物系统,可以证明在加热时发生了交换,并且形成了热力学上有利的产物。使用柱色谱法,可以将混合物的前两个主要部分分离和分析。MALDI-TOF质谱和1H NMR光谱证实了形成了金属大环结构。对于手性系统,圆二色性实验显示形成了光学活性材料,手性对映体的光谱是镜像对称的。