Molecular Endofullerenes: Nanoscale dipoles, rotors and oscillators

分子内富勒烯：纳米级偶极子、转子和振荡器

• 批准号: EP/M001962/1
• 负责人: Malcolm Levitt
• 金额: $ 105.3万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FM001962%2F1
• 关键词: Molecular; Endofullerenes; Nanoscale; dipoles; rotors

Fullerenes are football-shaped cages of carbon atoms, for the discovery of which the British scientist Harry Kroto won the Nobel prize in 1996. Inside the cage is an empty space. Chemists and physicists have found many ingenious ways of trapping atoms or molecules inside the tiny fullerene cages. These encapsulated compounds are called endofullerenes. A remarkable method was pioneered by the Japanese scientists Komatsu and Murata, one of whom is a project partner on the current proposal. They performed "molecular surgery". First, a series of chemical reactions was used to open a hole in the fullerene cages. A small molecule such as water (H2O) was then inserted into each fullerene cage by using high temperature and pressure. Finally, a further series of chemical reactions was used to "sew" the holes back up again. The result was the remarkable chemical compound called water-endofullerene, denoted H2O@C60. Our team has succeeded in developing a new synthetic route which requires milder conditions and has improved yield for the production of H2O@C60. In addition we will encapsulate other small molecules in the fullerene cage, including ammonia (NH3) and methane (CH4). Molecules of ordinary water have two forms, which are called ortho and para-water, which are distinguished by the way the magnetic hydrogen nuclei point: in opposite sense for para-water, and in the same sense for ortho-water. In ordinary conditions, these two forms interconvert rapidly, and cannot be isolated. However, by trapping water molecules inside fullerene cages, the two forms are isolated and may be studied separately. We recently observed that these two forms of water have different electrical properties. At low temperatures, the two forms interconvert over a period of tens of hours. We will study the interconversion of the two forms of water, and develop a theory of why this conversion changes the electrical properties. In order to understand how these molecules behave, we will use several techniques. These methods include nuclear magnetic resonance (which involves a strong magnet and radiowaves), neutron scattering (in which the material is bombarded with neutrons from a nuclear reactor) and infrared spectroscopy (which involves the absorption of low-energy light waves). By combining the information from these different techniques, we will build up a complete picture of the quantum-mechanical behaviour of the trapped molecules. Since ortho and para-water have different electrical properties, we expect to distinguish between single H2O@C60 molecules in the ortho and para states, by measuring the electrical response of single molecules. This will be done scanning over a surface loaded with the fullerenes, using a very sharp tip. In this way, we hope to observe the ortho to para transition of single molecules - something that has never been done before. Although most of this project concerns basic science, this project could lead to technological and even medical advances in the future. For example, the ortho and para states of the individual H2O@C60 molecules could allow the storage of one bit of information inside a single molecule, without damaging it in any way. This might lead to a new form of very dense data storage. Since a single gram of H2O@C60 contains about 10^19 molecules, this single gram could in principle store 1 million terabytes of information, sufficient to store the DNA sequences of everyone on the planet (although it will be very difficult to store and retrieve this information). In addition, the quantum behaviour of the encapsulated molecules is expected to give rise to greatly enhanced magnetic resonance signals, leading to the possibility of greatly enhanced MRI images, with considerable medical benefits.

富勒烯是由碳原子组成的足球形状的笼子，英国科学家哈里·克罗托因这一发现于1996年获得诺贝尔奖。笼子里是一片空地。化学家和物理学家已经发现了许多巧妙的方法来将原子或分子困在微小的富勒烯笼子里。这些被包裹的化合物被称为内富勒烯。一种非凡的方法是由日本科学家小松和村田开创的，他们中的一人是当前提案的项目合作伙伴。他们进行了“分子手术”。首先，通过一系列化学反应在富勒烯笼子上开一个洞。然后，通过高温高压将水等小分子插入每个富勒烯笼子中。最后，进一步的一系列化学反应被用来将这些洞再次“缝合”起来。结果产生了一种引人注目的化合物，称为水-内富勒烯，表示为H2O@C60。我们的团队成功地开发了一条新的合成路线，该路线需要更温和的条件，并提高了生产H2O@C60的产率。此外，我们还将在富勒烯笼子中封装其他小分子，包括氨(NH3)和甲烷(CH4)。普通水的分子有两种形式，它们被称为邻水和副水，这两种形式通过磁性氢核指向的方式来区分：对于副水来说是相反的，对于正水来说是相同的意义。在正常情况下，这两种形式相互作用很快，不能孤立。然而，通过将水分子捕获在富勒烯笼子内，这两种形式是分离的，可以单独研究。我们最近观察到，这两种形式的水具有不同的电学性质。在低温下，这两种形式会在数十小时内相互转换。我们将研究这两种形式的水的相互转化，并提出为什么这种转化会改变电学性质的理论。为了了解这些分子的行为，我们将使用几种技术。这些方法包括核磁共振(包括强磁铁和无线电波)、中子散射(材料被来自核反应堆的中子轰击)和红外光谱(涉及吸收低能光波)。通过结合来自这些不同技术的信息，我们将建立起被捕获分子的量子力学行为的完整图景。由于邻位和对位水具有不同的电学性质，我们希望通过测量单分子的电学响应来区分处于邻位和对位状态的单个H2O@C60分子。这将用一个非常锋利的尖端在富勒烯表面上进行扫描。通过这种方式，我们希望观察到单分子从邻位到对位的转变--这是以前从未做过的事情。尽管这个项目的大部分涉及基础科学，但这个项目可能会在未来带来技术甚至医学上的进步。例如，单个H2O@C60分子的邻位和对位状态可以允许在单个分子内存储一比特信息，而不会以任何方式破坏它。这可能会导致一种新的非常密集的数据存储形式。由于一克H2O@C60含有大约10^19个分子，原则上这一克可以存储100万TB的信息，足以存储地球上每个人的DNA序列(尽管存储和检索这些信息将非常困难)。此外，被包裹的分子的量子行为有望产生极大增强的磁共振信号，从而有可能极大地增强磁共振图像，具有相当大的医疗效益。

项目成果

A Solid-State Intramolecular Wittig Reaction Enables Efficient Synthesis of Endofullerenes Including Ne@C 60 , 3 He@C 60 , and HD@C 60

固态分子内 Wittig 反应可有效合成内富勒烯，包括 Ne@C 60 、 3 He@C 60 和 HD@C 60

• DOI: 10.1002/ange.202100817
• 发表时间: 2021
• 期刊: Angewandte Chemie
• 作者: Hoffman G

Synthesis and Properties of Open Fullerenes Encapsulating Ammonia and Methane.

• DOI: 10.1002/cphc.201701212
• 发表时间: 2018-02-05
• 期刊: Chemphyschem : a European journal of chemical physics and physical chemistry
• 作者: Bloodworth S;Gräsvik J;Alom S;Kouřil K;Elliott SJ;Wells NJ;Horsewill AJ;Mamone S;Jiménez-Ruiz M;Rols S;Nagel U;Rõõm T;Levitt MH;Whitby RJ
• 通讯作者: Whitby RJ

First Synthesis and Characterization of CH 4 @C 60

CH 4 @C 60 的首次合成与表征

• DOI: 10.1002/ange.201900983
• 发表时间: 2019
• 期刊: Angewandte Chemie
• 作者: Bloodworth S