High Symmetry Paramagnetic Cages

含有大量(对)磁性过渡金属离子的分子化合物(笼状络合物)可以显示出令人着迷和根本重要的磁性性质。例如，他们可以对磁铁中的量子尺寸效应进行详细的洞察，这些效应与未来可能的技术直接相关，包括量子计算和分子自旋电子学。这样的分子笼通常是通过标准的配位化学技术制造的。参与这项提议的曼彻斯特和爱丁堡的小组开发了通过非标准方法合成此类材料的路线，即溶剂热(类似于高压锅)和微波法。这些非常不同的反应条件(在温度、压力和时间刻度上)可能导致非常不同的化学作用。我们观察到，强迫条件通常会导致高度对称的笼子。这种高度的对称性可以导致非常不寻常的磁现象：例如，我们已经发现了显示出巨大的低温磁热效应(磁场变化时的温度变化)的分子材料，以及通过以前未观察到的机制对异常高温的记忆效应。这项建议旨在通过系统地研究强迫条件在合成高对称性、高核度的d-块、f-块(稀土)和d-f混合过渡金属笼中的使用来建立在这些观察结果的基础上。我们将研究溶剂热和微波加热、笼形对称性和磁性之间的关系。我们希望发现不寻常的和潜在有用的低温物理，这是由高度受挫的自旋拓扑引起的，包括增强的磁热效应，以及其他已经预测但尚未观察到的基于柏拉图和阿基米德固体的笼子的影响。

Molecular compounds containing lots of (para)magnetic transition metal ions ( cage complexes ) can display fascinating and fundamentally important magnetic properties. They have allowed detailed insight into, for example, quantum size effects in magnets with direct relevance to possible future technologies including quantum computing and molecular spintronics. Such molecular cages are conventionally made by standard coordination chemistry techniques. The groups at Manchester and Edinburgh involved in this proposal have developed synthetic routes to such materials by non-standard methods, namely solvothermal (akin to a pressure cooker) and microwave methods. These very different (in temperature, pressure and timescale regimes) reaction conditions can lead to very different chemistry. We have observed that the forcing conditions often result in high symmetry cages. This high symmetry can lead to very unusual magnetic phenomena: for example, we have found molecular materials that display enormous low temperature magnetocaloric effects (temperature changes on changing a magnetic field) and also memory effects to unusually high temperature by a previously unobserved mechanism. This proposal seeks to build on these observations by systematically investigating the use of forcing conditions in the synthesis of high symmetry, high nuclearity d-block, f-block (rare earth) and d-f hybrid transition metal cages. We will examine the relationship between solvothermal and microwave heating, cage symmetry and magnetic properties. We expect to find unusual and potentially useful low temperature physics, resulting from highly frustrated spin topologies, including enhanced magnetocaloric effects, as well as other effects that have been predicted but as yet unobserved for cages based on Platonic and Archimedian solids.