室温宽滞Fe(II)系自旋转换纳米材料的设计、组装以及信息存储的潜在应用研究

As one kind of energetic molecular magnets with a long history, the spin-crossover (SCO) complex not only has various structures of molecular materials, but also the high-density storage of nano-magnets, especially the incomparable non-fatigue feature. Therefore, the SCO complex exhibits profound application in information storage, which makes it a research hotspot in chemistry of material. In this project, a series of bis(imidazole-pyridine) ligands are designed, which are deprived from 2-(imidazol-2-yl)pyridine by intensive elaborate modification. These ligands react with the Fe(II) ion to afford many complexes, and crystal structures are elucidated by X-ray single crystal diffraction. After studying the effects of terminal group and spacer on the topology and cooperativity, the principle of self-assembly will be concluded, which is beneficial to the rational design, directional assembly and precise synthesis of coordination polymer. Then a plenty of SCO complexes will be constructed, which possess very strong cooperativity and activity sites with medium ligand fields. Furthermore, monodisperse and high-purity nanocrystal materials could be prepared by the nano-technology, which could improve the morphology, size and purity of sample. Following, we will systematically study magnetic properties, interpret the elemental factor and mechanism of SCO, and summarize the regular rule on the magneto-structural correlation. The project throws light on the construction of SCO materials with abrupt transition and large hysteresis loops around room temperature under 1 atm, and provide innovation and development for the future information storage devices with high-density storage, long lifetime and light weight.

作为一种历久弥新的分子基磁体，SCO配合物既有分子材料结构多样性的特点，又兼具纳米磁体高存储密度的优点，尤其无与伦比的非疲劳特性，使得SCO材料在信息存储领域展现了广阔应用前景，正成为材料化学研究热点。本项目在2-(2-咪唑基)吡啶基础上，从不同角度依次拓展骨架，设计了一系列双(咪唑-吡啶)类配体。研究配体与FeII离子反应而成的配合物结构，考察配位端基和间隔基对拓扑网络以及协同作用的影响，阐明组装规律，逐步达到合理设计、定向组装和精确调控之目的。在把握组装规律基础上，构筑具有中等配体场活性中心和超强协同效应的SCO配合物，进一步采用纳米技术，优化合成路线，改善材料形貌、尺寸和品质，合成单分散高纯纳米晶材料。系统研究磁学性能，阐释SCO内在成因，期望在磁构关系方面获得规律性认识，力争合成室温常压下相变尖锐和宽滞回线的SCO材料，为新一代高密度、长寿命和轻质信息存储材料提供创新和发展的新动力。

超级电容器具有超高的功率密度和无与伦比的循环寿命，使得它成为独一无二的能源存储装置，极有可能在人类未来活动中大显身手，展现了广阔的应用前景。本项目根据咪唑基团的配位优势，设计了一系列具有不同配位端基和间隔基的长链刚性双咪唑类配体，并作为构筑单元与金属离子配位自组装，得到了26个MOFs材料。我们解析了它们的晶体结构，采用恰当纳米合成技术，富集了高品质粉晶样品作为前驱体。进一步通过煅烧-分解法，探索最佳煅烧策略和热解条件，制备了一系列高度有序、分散均一且高孔隙率的碳、金属化合物及其复合纳米材料，并揭示了MOFs和衍生材料之间的内在联系。最后遴选优质衍生材料制备电极，组装超级电容器，深入研究电容性能，不断改进器件制备工艺，逐渐提高能量密度，开发了多种在超级电容器领域具有应用价值的电极材料。具体研究内容主要包括如下几个方面：⑴首次采用Cd-MOFs前驱体，通过溶剂调控了MOFs衍生碳材料的比表面积和电容性能，诠释了镉离子的造孔效应；⑵采用Co-MOFs前驱体，通过简单煅烧方法快速制得了碳纳米管；⑶利用6种同构MOFs前驱体，揭示了金属离子对MOFs衍生碳材料的影响，包括造孔效应和石墨化效应；⑷利用二维Cu-MOF前躯体制得了具有超高比表面积(2491 m2 g-1)和质量比电容(260.5 F g-1)的碳纳米片材料，由其组装的双电层电容器能量密度为18.4 Wh Kg-1，超过了大部分碳材料，在超级电容器领域展现了广阔的应用前景；⑸借助ClO4-离子的爆炸造孔效应，利用Ni-MOF前驱体制备了单分散NiO纳米菜花，其电容量高达1863 F g-1，由其组装的超级电容器能量密度(38.4 Wh kg-1)能够媲美铅酸电池，在能源存储领域具有很大的市场价值。总体来说，本项目系统研究了MOFs衍生材料的影响因素，揭示了MOFs衍生材料成份、结构、形貌和性能的内在联系，为MOFs衍生材料的可控合成提供了新的理念。