Switchable Multifunctional Materials

随着能源需求的增长，对处理时间和数据量的预期也在呈指数级增长。解决这一问题的关键是用更少的资源做更多的事情，需要更快、更低功率的电子产品。分子(如纳米磁性)或二维(如石墨烯)材料已显示出巨大的磁性/导电性能；使用少量能量触发或利用这些材料可以大幅降低能源消耗。因此，其中可以切换物理特性的系统对寻求用作传感器、显示器等的优质下一代功能材料非常感兴趣。虽然可切换材料从根本上很有趣，但为了在商业上可行，响应部分必须在两个(或多个)状态之间可逆地相互转换，以确保双稳态(或多稳态)的存在(例如，二进制码中的0和1)。还必须开发一种耦合响应单元和功能单元的方法，以生产满足各种应用要求的可切换材料。由于其固有的双稳特性，自旋交叉(SCO)络合物可以在外界刺激(如光、温度、压力)引起低(LS)和高(HS)自旋磁态之间的切换，是实现基于分子的电子学和自旋电子学的有前途的候选者。这项提案旨在通过设计新材料来利用有机/无机系统的关键属性及其在分子电子学中的应用。虽然合理的设计允许获得具有新功能的新材料，这些材料结合了磁、光和传输特性，但物理特性对固态包装的依赖仍然是一个挑战。在上海合作组织系统中，这一点尤其相关，因为充分利用这些材料的努力表明了控制固态包装的重要性和难度，因此有针对性地控制宏观性能，以弥合实验室和现实之间的差距。上海合作组织材料的实际应用需要很强、突然或滞后的协作性。我们将通过配基设计加强分子间的相互作用，并在1)多核SCO络合物和2)氧化还原活性霍夫曼型骨架和普鲁士蓝-霍夫曼混合物的生成中使用共轭连接物；这些特征也有望通过加强响应和功能部分之间的通信以及固态中的受控组装而使SCO系统具有多功能性。由于光照射具有很高的空间和时间分辨率，可以通过光诱导自旋跃迁来实现LS态和HS态之间的高效率和良好的可逆性。设计具有磁性和光学双稳态的材料，并将这些特征与其他物理属性(如孔隙率)相结合，可以探索性能可通过外部刺激控制的智能多功能材料。

Expectations of processing times and volumes of data are increasing exponentially as are energy demands. Key to addressing this is to do more with less, requiring faster and lower power electronics. Molecular (e.g. nanomagnets) or two-dimensional (e.g. graphene) materials have shown tremendous magnetic/conducting properties; triggering or harnessing these with the use of a small amount of energy can drastically cut energy consumption. Thus, systems in which physical properties can be switched is of great interest in the quest for superior next-generation functional materials to be employed as sensors, displays, etc. While switchable materials are intriguing fundamentally, to be commercially viable the responsive moiety must reversibly interconvert between two (or more) states to ensure the existence of bistable (or multistable) states (e.g. 0 and 1 in binary code). A method to couple the responsive and functional units must also be developed to produce switchable materials that satisfy the requirements of various applications. Thanks to their inherent bistability, spin crossover (SCO) complexes in which external stimuli (e.g. light, temperature, pressure) can induce switching between low (LS) and high (HS) spin magnetic states are promising candidates for the realization of molecule-based electronics and spintronics.    This proposal targets new materials by design to exploit key attributes of organic/inorganic systems and their implementation into molecular electronics. While rational design permits access to novel materials with new functionalities that combine magnetic, optical and transport properties, the dependence of physical properties on solid-state packing remains a challenge. This is especially pertinent in SCO systems, as efforts to fully harness these materials reveal the importance and difficulty of controlling solid-state packing, and hence targeted macroscopic properties in order to bridge the gap between laboratory and reality. Practical application of SCO materials requires strong, abrupt or hysteretic cooperativity. We will achieve this by enhancing intermolecular interactions through ligand design and the use of conjugated linkers in the generation of 1) polynuclear SCO complexes and 2) redox active Hofmann-type frameworks & Prussian-blue-Hofmann blends; features that are also anticipated to render multifunctionality to SCO systems by strengthening communication between the responsive and functional moieties coupled with controlled assembly in the solid-state. Given the high spatial and temporal resolution afforded to photoirradiation, interconversion between LS and HS states can be realized with high efficiency and good reversibility via light-induced spin transitions. Designing materials with magnetic and optical bistabilities, and combining these features with other physical attributes (e.g. porosity), enables exploration of smart multifunctional materials where the properties can be controlled via external stimuli.