以自組裝方法合成無機骨架之多芽氮異環碳烯

Abstract

由近三、四十年的科學發展中可知，氮異環碳烯的合成與應用已經愈來愈廣泛，除常見的使用其作為有機金屬化合物的配基之外，近期也被利用在孔洞材料的合成。目前多芽的氮異環碳烯都以有機分子為骨架，其合成多仰賴多步驟的有機合成反應，而且每改變骨架結構就必須更改新的合成步驟，所以多芽的氮異環碳烯的研究就仍屬少數。在本篇研究報告中，我們利用自組裝的概念，以具有氮異環碳烯與酸根的有機配基為組裝單體，並以金屬簇或金屬氧化物作為多芽氮異環碳烯的骨架，合成出多種具不同對稱性的多芽氮異環碳烯。這些金屬簇團的選擇包含了鋅、銅、鈷、鐵的化合物，其結構則可為水車狀的四芽氮異環碳烯與正八面體的六芽氮異環碳烯等。這些具高對稱性的多芽氮異環碳烯將可做為金屬有機骨架材料（Metal-Organic Framwork）中非常具有潛力的配基。

For more than decades, the syntheses and coordination chemistry of N-heterocyclic carbenes remain one of the most popular fields of chemical research. Recent development in NHCs showed that the role of NHC has shifted from a strong donating ligand in metal complexes to the bridging unit in oligomeric and polymeric materials. Nowadays all of the reported poly-NHCs are synthesized via stepwise procedures with organic molecular backbones. When one would like to change the symmetry of poly-NHCs, a new molecular backbone and, possibly, new synthetic route has to be applied. This may be the reason why the research of poly-NHCs is still limited. In this work, we synthesized a bifunctional ligand, which features an imidazolium unit on one side of the molecule and a carboxylic acid group on the other side, and investigated its potential in forming poly-NHCs via assembly approach. The resulting poly-NHC ligands are envisioned to possess numerous geometries with metal-cluster or metal-oxide cluster as molecular backbone. The selection of metal ions includes zinc, copper, cobalt and iron, and the structure of poly-NHCs can range from low-symmetric C2 ligand to highly symmetric paddle wheel and octahedral geometry. All of these poly-NHCs are potential bridging ligands for metal-organic framework.