Single-molecule magnetism in lanthanide organometallics

镧系有机金属中的单分子磁性

• 批准号: EP/K008722/1
• 负责人: Richard Layfield
• 金额: $ 44.15万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FK008722%2F1
• 关键词: Single; molecule; magnetism; lanthanide; organometallics

Molecules that have a magnetic memory are called single-molecule magnets (SMMs). In terms of their size and composition, SMMs have dimensions of a few nanometres and they consist of one or more metal atoms bonded to a group of non-metal atoms called a ligand. The interactions between neighbouring molecules are very weak, meaning that the magnetic properties of an SMM genuinely arise from within individual molecules.In stark contrast to SMMs, traditional 'bar' magnets used in everyday appliances are purely inorganic materials such as metal oxides or simply magnetic elements. A particularly important example of their application is in computer hard disk drives. In terms of their size and composition, rather than consisting of molecules traditional magnets feature much larger magnetic domains.Because one of the main differences between SMMs and traditional magnets relates to size, it is possible that SMMs represent the ultimate size limit for magnetic information storage. The properties of SMMs may one day allow them to be developed for use in quantum computers. A problem with SMMs is, however, that their magnetic memories function at temperatures of about -250oC, which can only be reached by cooling with liquid helium and is therefore impractical. Furthermore, the mechanisms by which SMMs relax their magnetization (i.e. the magnetic information is lost or 'wiped') are not clear, but it is likely that gaining an understanding of these processes will lead to enhanced performance at higher temperatures.We propose a new family of SMMs based on the lanthanide elements (Ln-SMMs). The lanthanides offer considerable potential for developing SMMs because these elements have particularly appealing magnetic properties. Ultimately, our Ln-SMMs will have magnetic memory effects observable above -196oC, which will be a major advance because this temperature can be reached by cooling with liquid nitrogen, a cryogen that is much cheaper than liquid helium, and easier to use.We will achieve our aims by using a molecular design tool available to us as synthetic chemists: we can make significant changes to the ways in which our ligands interact with our choice of lanthanide. This is important because the non-metal atoms used to interact with the lanthanides, and the symmetry with which the ligands are arranged around the lanthanides, allow us to influence the magnetism.A unique aspect of our approach to the design of Ln-SMMs is that our synthetic method gives access to an extremely broad range of chemical environments. Existing, conventional Ln-SMMs are almost entirely limited to ligands in which oxygen or nitrogen interacts with the lanthanide, however we can influence the magnetism using carbon, oxygen, sulphur, selenium, tellurium, nitrogen, phosphorus, arsenic, antimony or the halogens.By understanding the ways in which the different chemical environments influence the molecular magnetism we will be able to identify the optimum conditions for producing Ln-SMMs that function at unprecedentedly high temperatures.

具有磁记忆的分子称为单分子磁体（SMM）。就其尺寸和成分而言，SMM 的尺寸为几纳米，由一个或多个与一组称为配体的非金属原子键合的金属原子组成。相邻分子之间的相互作用非常弱，这意味着 SMM 的磁性真正来自于单个分子内部。与 SMM 形成鲜明对比的是，日常用品中使用的传统“条形”磁铁是纯无机材料，例如金属氧化物或简单的磁性元素。其应用的一个特别重要的例子是计算机硬盘驱动器。就其尺寸和成分而言，传统磁体不是由分子组成，而是具有更大的磁域。由于 SMM 和传统磁体之间的主要区别之一与尺寸有关，因此 SMM 可能代表了磁信息存储的最终尺寸限制。 SMM 的特性有一天可能会让它们被开发用于量子计算机。然而，SMM 的一个问题是，它们的磁存储器在大约 -250oC 的温度下工作，这只能通过液氦冷却才能达到，因此不切实际。此外，SMM 放松磁化强度（即磁信息丢失或“擦除”）的机制尚不清楚，但了解这些过程可能会导致在更高温度下增强性能。我们提出了一种基于稀土元素的新 SMM 系列（Ln-SMM）。镧系元素为开发 SMM 提供了巨大的潜力，因为这些元素具有特别吸引人的磁性。最终，我们的 Ln-SMM 将具有在 -196oC 以上可观察到的磁记忆效应，这将是一个重大进步，因为可以通过液氮冷却来达到这个温度，液氮是一种比液氦便宜得多的冷冻剂，并且更易于使用。我们将通过使用合成化学家可用的分子设计工具来实现我们的目标：我们可以对配体与我们选择的镧系元素相互作用的方式做出重大改变。这很重要，因为用于与镧系元素相互作用的非金属原子，以及配体在镧系元素周围排列的对称性，使我们能够影响磁性。我们设计 Ln-SMM 方法的一个独特方面是，我们的合成方法可以进入极其广泛的化学环境。现有的传统 Ln-SMM 几乎完全限于氧或氮与镧系元素相互作用的配体，但是我们可以使用碳、氧、硫、硒、碲、氮、磷、砷、锑或卤素来影响磁性。通过了解不同化学环境影响分子磁性的方式，我们将能够确定最佳的 生产可在前所未有的高温下发挥作用的 Ln-SMM 的条件。

项目成果

Iron- and Cobalt-Catalyzed Synthesis of Carbene Phosphinidenes.

• DOI: 10.1002/anie.201508303
• 发表时间: 2016-01-26
• 期刊: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
• 影响因子: 16.6
• 作者: Pal, Kuntal;Hemming, Oliver B.;Day, Benjamin M.;Pugh, Thomas;Evans, David J.;Layfield, Richard A.
• 通讯作者: Layfield, Richard A.

Reactivity of three-coordinate iron-NHC complexes towards phenylselenol and lithium phenylselenide.

• DOI: 10.1039/c3dt53203h
• 发表时间: 2014-02
• 期刊: Dalton transactions
• 影响因子: 4
• 作者: Thomas Pugh;R. Layfield

Influencing the properties of dysprosium single-molecule magnets with phosphorus donor ligands.

• DOI: 10.1038/ncomms8492
• 发表时间: 2015-07-01
• 期刊: Nature communications
• 影响因子: 16.6
• 作者: Pugh T;Tuna F;Ungur L;Collison D;McInnes EJ;Chibotaru LF;Layfield RA
• 通讯作者: Layfield RA

Strong Exchange Coupling in a Trimetallic Radical-Bridged Cobalt(II)-Hexaazatrinaphthylene Complex

三金属自由基桥联钴(II)-六氮杂萘配合物中的强交换耦合

• DOI: 10.1002/ange.201600694
• 发表时间: 2016
• 期刊: Angewandte Chemie
• 作者: Moilanen J

Strong Exchange Coupling in a Trimetallic Radical-Bridged Cobalt(II)-Hexaazatrinaphthylene Complex.

• DOI: 10.1002/anie.201600694
• 发表时间: 2016-04-25
• 期刊: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
• 影响因子: 16.6
• 作者: Moilanen, Jani O.;Chilton, Nicholas F.;Day, Benjamin M.;Pugh, Thomas;Layfield, Richard A.
• 通讯作者: Layfield, Richard A.