Switchable Multifunctional Materials

对处理时间和数据量的预期随着能源需求呈指数级增长。解决这个问题的关键是用更少的资源做更多的事情，这需要更快、更低功耗的电子设备。分子（如纳米磁铁）或二维（如石墨烯）材料显示出巨大的磁性/导电性；用少量的能量触发或控制这些可以大大减少能源消耗。因此，可以切换物理性质的系统在寻求用作传感器，显示器等的优越下一代功能材料方面具有很大的兴趣。虽然可切换材料从根本上是有趣的，但要在商业上可行，响应部分必须在两个（或更多）状态之间可逆地相互转换，以确保双稳态（或多稳态）状态的存在（例如二进制代码中的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。由于其固有的双稳定性，外部刺激（如光、温度、压力）可以诱导低（LS）和高（HS）自旋磁态之间切换的自旋交叉（SCO）复合物是实现基于分子的电子学和自旋电子学的有希望的候选者。该提案旨在通过设计利用有机/无机系统的关键属性并将其应用于分子电子学的新材料。虽然合理的设计允许使用具有磁性、光学和输运性质的新功能的新材料，但物理性质对固态包装的依赖仍然是一个挑战。这在SCO系统中尤其重要，因为充分利用这些材料的努力揭示了控制固态包装的重要性和难度，因此有针对性的宏观性质，以弥合实验室与现实之间的差距。SCO材料的实际应用需要很强的、突然的或滞后的协同性。我们将通过配体设计和共轭连接体在生成1)多核SCO配合物和2)氧化还原活性霍夫曼型框架和普鲁士-蓝-霍夫曼共混物中增强分子间相互作用来实现这一目标；这些特性也有望通过加强响应部分和功能部分之间的通信以及固态受控组装来为SCO系统提供多功能。由于光照射具有较高的空间和时间分辨率，通过光诱导自旋跃迁可以实现LS态和HS态之间的高效转换和良好的可逆性。设计具有磁性和光学双稳定性的材料，并将这些特性与其他物理属性（例如孔隙率）相结合，可以探索智能多功能材料，其特性可以通过外部刺激控制。

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.