Molecular Magnets: From Cages to Supramolecular Assemblies

磁性材料在现代社会中的应用范围非常广泛，从计算机中的信息存储，安全和天文仪器中的制冷，用作磁共振成像（MRI）和诊断中的对比剂和偏振剂的生物相容性试剂，以及作为磁热疗剂。在学术上，基于分子的磁体也在其重要的基础化学和物理学方面进行了深入研究，因为它们有可能在纳米级电子器件中被利用，正如最近单分子自旋电子器件（自旋阀和晶体管）的构建所展示的那样。基于分子的材料提供了通过合成化学可设计和可操作的巨大优势。也就是说，它们可以一个原子接一个原子、一个分子接一个分子地构建，具有可溶性、尺寸、形状和物理性质单分散以及在原子尺度上可调节的无与伦比的优点。事实上，这种“自下而上”的研究视野并不局限于学术界- IBM最近报告了在液态He温度下Fe原子的表面隔离（2x 6）阵列中的信息存储，并正在积极研究自旋电子学和数据存储，以期最终实现这些技术。然而，在任何分子或基于分子的材料可以具有商业应用或价值之前，必须理解结构和磁性行为之间的基本和内在关系。这需要化学家设计和构建相关复合物的家族，在结构和磁性上对它们进行优化，并通过与世界级凝聚态物理学家和理论家网络的广泛合作，了解它们的基本物理性质。当前的提案通过将分子磁体受控聚集和组织成固态设计的0-3D架构来直接解决这些基本问题。具体来说，它应用超分子化学的基本原理，通过利用简单的配位驱动的自组装过程将单分子磁体组装成新颖的拓扑结构。我们将采用分子磁体作为构建块，用于形成超分子组装体和配位聚合物，其中分子构建块的自旋动力学通过与其他顺磁性部分的连接和相互作用来调制。为了实现这一目标，我们将：设计和构建一系列金属配体，从简单的各向同性分子到更复杂和奇异的各向异性分子，并将它们附着到预制的SMM上;从SMM和氰酸酯构建块构建混合磁性材料;设计和合成能够指导SMM形成并同时将它们连接成更高阶（O-3D）材料的双功能配体;并通过一系列技术，从结构和磁性上将所有材料包裹起来。

Magnetic Materials are employed in an enormous range of applications in modern society, from information storage in computers, refrigeration in security and astronomical instrumentation, biocompatible agents for use as both contrast and polarizing agents in magnetic resonance imaging (MRI) and diagnosis, and as agents for magnetic hyperthermic treatments. Academically, molecule-based magnets are also studied intensively with regard to their important fundamental chemistry and physics, since they have the potential to be exploited in nanoscale electronics devices, as beautifully demonstrated recently by the construction of single-molecule spintronic devices (spin valves and transistors). Molecule-based materials offer the great advantage of being designable and manipulable by synthetic chemistry. That is, they can be constructed atom by atom, molecule by molecule with the unparalled advantages of being soluble, monodisperse in size, shape and physical properties, and tuneable at the atomic scale. Indeed, this "bottom-up" research vision is not restricted to academia - IBM recently reported information storage in surface-isolated (2x6) arrays of Fe atoms at liquid He temperatures and are actively investigating spintronics and data storage with a view to the ultimate miniaturisation of such technologies. However, before any molecule or molecule-based material can have commercial application or value, the fundamental and intrinsic relationship between structure and magnetic behaviour must be understood. This requires the chemist to design and construct familes of related complexes, characterise them structurally and magnetically, and through extensive collaboration with a network of world-class condensed matter physicists and theoreticians, understand their underlying physical properties. The current proposal directly addresses these fundamental questions through the controlled aggregation and organisation of molecular magnets into designed 0-3D architectures in the solid state. Specifically it applies the fundamental principles underpinning supramolecular chemistry to assemble single-molecule magnets into novel topologies by taking advantage of simple coordination-driven self-assembly processes. We will employ molecular magnets as building blocks for the formation of supramolecular assemblies and coordination polymers in which the spin dynamics of the molecular building blocks are modulated through the attachment of, and interaction with, other paramagnetic moieties. In order to achieve this we will: design and build a range of metalloligands, ranging from simple isotropic molecules to more complex and exotic anisotropic molecules and attach them to pre-made SMMs; construct hybrid magnetic materials from SMMs and cyanometalate building blocks; design and synthesise dual-functioning ligands which are capable of directing the formation of SMMs and simultaneously linking them into higher order (O-3D) materials; and characterise all materials, structurally and magnetically, through a battery of techniques.