多酸模板导向金属有机超分子组装及其电子与质子传导

Polyoxometalates as a result of their intrinsic structure feature and revisable redox activity are wildly used in the field of catalysis, medicine and molecular electric devices. However, the highly soluble in water and alcohol and the low specific surface area largely restricted their applications. Therefore, the exploitations of the function-directed crystalline materials is one of the most intriguing research field. This program aims at design and synthesis of a new type of polyoxometalates template directed metal-organic frameworks supramolecular crystalline materials in which impregnating polyoxometalates as electron acceptors or proton carries into the porous coordination polymers. In the last decades, great progress about the polyoxometalate and tetrathiafulvalene cocrystal materials had been achieved, however, the polyoxometalate directed metal and N containing ligands in which the tetrathiafulvalene as core supramolecular assemblies had not been developed. So it will be desirable to synthesis of these crystalline materials and study their electron transport property. In addition, Proton exchange membrane fuel cells are widely used in energy materials, however, this materials based on state-of-the-art perfluorosulfonic acid membranes from Dupone company generally operated at low temperature and high humility. Therefore, it is pressing to develop a new generation of proton exchange membrane fuel cells at high temperature and low humility. The impregnation of proton carries polyoxometalate into the porous triazole metal-organic frameworks will be an ideal proton conduction materials at high temperature and low humidity. Most importantly, it provides an ideal model for study their relationship among the structure, properties and mechanism.

多酸由于其独特的结构特征及其可逆的氧化还原性广泛应用于催化、医药、分子电子等领域。但是由于其极高的溶解性以及低的比表面积极大的限制了其使用。开发具有功能导向的晶态材料是目前研究热点之一。本项目致力以多酸为阴离子模板组装金属有机框架材料，多酸作为电子受体或者质子载体负载在孔洞的金属有机框架中。四硫富瓦烯作为电子给体广泛应用于分子电子学领域，将四硫富瓦烯为核的含氮配体与多酸形成给/受体金属有机框架目前尚未见报道，通过研究其电荷转移相互作用探索其在电子传导机制。另外质子交换膜燃料电池广泛应用于能源材料领域，目前使用的杜邦公司全氟磺酸型质子交换膜只能在低温高湿度的条件下适用。因此提高质子交换膜的操作温度与环境耐受性对于开发新一代质子交换膜燃料电池至关重要。将具有质子传导的多酸负载在三氮唑的金属有机框架中将是一类理想的高温低湿度的质子导体材料，并为研究质子传导的结构-性能-机理构效关系提供良好模型。

金属有机框架由于其独特的结构特征和孔洞可调性广泛应用于气体储存与分离、催化、荧光和药物释放等领域。然而，由于这类材料缺乏金属与配体的电子耦合以及配体之间电子传输的路径导致其极低的电导率，从而限制了它们在电子器件与能源材料等领域的应用。我们首次将具有氧化还原活性和π-共轭平面的的萘酰亚胺作为基本建筑单元引入到这一体系中，采取网格化学设计的思想，线性的萘酰亚胺与一价铜配位后得到了一例具有六重穿插的金刚烷结构的金属有机框架。正是由于这种π…π堆积形成的穿插结构形成了沿着萘酰亚胺π平面的J-聚集，从而提供电子跳跃的路径。两探针电子导体测试表明该化合物展现出卓越的室温电子传输性能，为1.2×10-3 S·m−1。紫外漫反射光谱表明该化合物是一个窄波段的金属有机半导体，其带隙为1.2电子伏。理论计算表明一价铜中心和吡啶氮原子d-π电子耦合以及π…π堆积形成的J-聚集提供了电子传输的路径。该化合物的成功合成和电子结构分析，为金属有机框架材料在分子电子与能源材料等领域铺开了新的道路。