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Atomic and Molecular Endofullerenes: Spins in a box

原子和分子内富勒烯：在盒子中旋转

基本信息

批准号：
EP/T004320/1
负责人：
Malcolm Levitt
金额：
$ 150.32万
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：
2020
资助国家：
英国
起止时间：
2020 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FT004320%2F1
关键词：
Atomic Molecular Endofullerenes Spins box

项目摘要

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 and denoted A@C60. A remarkable method is called "molecular surgery" in which a series of chemical reactions is used to open a hole in the fullerene, a small molecule or atom is inserted into each fullerene cage, and a further series of chemical reactions is used to "sew" the holes back up again to reform the pristine cage with the atom or molecule inside. Initial examples were hydrogen (H2@C60) and water (H2O@C60). Our team greatly improved the reported method and extended it to HF@C60. Our team recently achieved a breakthrough in encapsulating methane to give CH4@C60 - the first time an organic molecule has been put inside C60. The route developed, using a larger hole than before, opens the way to encapsulating other interesting molecules such as ammonia (NH3), oxygen (O2) and formaldehyde (CH2O).In the gas phase, ammonia (NH3) displays an unusual resonance in the microwave region of the electromagnetic spectrum. This resonance is associated with the "inversion" of the pyramid-shaped ammonia molecule, similar to an umbrella being inverted in a strong wind. This ammonia resonance is of great historical significance, since it was used for the very first MASER experiment (microwave amplification by stimulated emission of radiation), which was the precursor of the laser. This MASER resonance is quenched for ammonia in ordinary experimental conditions, by the interaction of the ammonia with neighbouring molecules. However it may exist for ammonia trapped inside the closed cavity of a C60 molecule. We intend to find out. Many small symmetrical molecules display a phenomenon called spin-isomerism. This means that they exist in several forms distinguished by the configurations of their magnetic atomic nuclei, and which convert only slowly into each other. We will study the spin-isomerism of confined molecules such as methane, ammonia, and formaldehyde by using techniques such as nuclear magnetic resonance (NMR), which detects radio frequency emissions from the atomic nuclei in a strong magnetic field. In some circumstances, spin-isomerism may be exploited to give strongly enhanced NMR signals. This is potentially important since NMR is widely used throughout science for examining the structure and motion of matter - the most famous example being MRI (magnetic resonance imaging). Any technique that increases the strength of NMR signals is potentially of great importance. Oxygen (O2) is an unusual molecule since it has two unpaired electron spins in the ground state. For this reason, oxygen is slightly magnetic. We will study the behaviour of the unpaired electron spins in fullerene-encapsulated oxygen by using a technique called electron paramagnetic resonance (EPR) in which the unpaired electrons are monitored for microwave emission in a strong magnetic field. We have reason to believe that oxygen molecules in which one of the oxygen atoms has atomic mass number 16, and the other one has atomic mass number 18, will have very unusual and useful EPR properties at low temperature. The element Helium (He) has two stable isotopes, called helium-3 and helium-4. Helium-3 (3He) is a very favourable nucleus for NMR, giving a strong, narrow signal. However it is a very rare and expensive gas. We will encapsulate 3He inside fullerene cages and greatly enhance the 3He NMR signals of the helium-endofullerene by exposing the solid material to 3He gas which has been brought into a strongly polarized state by using lasers. The polarized 3He-endofullerene solid may have applications as a tracer substance, for example in magnetic resonance imaging.

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，表示为A@C60。一种值得注意的方法被称为“分子外科”，在富勒烯上用一系列化学反应打开一个洞，在每个富勒烯笼子里插入一个小分子或原子，然后再用一系列的化学反应把小孔再次“缝合”起来，以改造里面有原子或分子的原始笼子。最初的例子是氢(H2@C60)和水(H2O@C60)。我们的团队极大地改进了已报道的方法，并将其扩展到HF@C60。我们的团队最近在封装甲烷以获得CH4@C60方面取得了突破--这是第一次将有机分子放入C60中。开发的路线使用了比以前更大的孔，为包裹其他有趣的分子开辟了道路，如氨(NH3)、氧(O2)和甲醛(CH2O)。在气相中，氨(NH3)在电磁光谱的微波区域显示出不寻常的共振。这种共振与金字塔形氨分子的“倒置”有关，类似于伞在强风中被倒置。这种氨共振具有重大的历史意义，因为它被用于第一次脉泽实验(通过辐射的受激发射进行微波放大)，这是激光的前身。在通常的实验条件下，由于氨与邻近分子的相互作用，这种脉塞共振对氨是猝灭的。然而，对于被困在C60分子封闭腔内的氨来说，它可能存在。我们打算找出答案。许多对称的小分子表现出一种称为自旋异构化的现象。这意味着它们以几种不同的形式存在，它们的磁性原子核的配置不同，它们彼此之间的转换速度很慢。我们将使用核磁共振(NMR)等技术来研究甲烷、氨和甲醛等受限分子的自旋异构性。核磁共振是指在强磁场中探测原子核的射频发射。在某些情况下，可以利用自旋异构性来给出强烈增强的核磁共振信号。这一点可能很重要，因为核磁共振在整个科学中被广泛用于检查物质的结构和运动--最著名的例子是核磁共振(MRI)。任何增加核磁共振信号强度的技术都可能是非常重要的。氧(O2)是一种不同寻常的分子，因为它在基态有两个不成对的电子自旋。由于这个原因，氧气具有轻微的磁性。我们将使用一种名为电子顺磁共振(EPR)的技术来研究富勒烯包裹的氧气中未配对电子的自旋行为。在EPR技术中，未配对电子在强磁场中被监测是否有微波发射。我们有理由相信，其中一个氧原子的原子质量数为16，另一个氧原子的原子质量数为18的氧分子，在低温下将具有非常不寻常和有用的EPR性质。氦元素(He)有两种稳定的同位素，分别称为氦-3和氦-4。氦-3(3He)是一种非常适合核磁共振的原子核，它给出了一个强而窄的信号。然而，它是一种非常稀有和昂贵的天然气。我们将3He封装在富勒烯笼内，通过将固体材料暴露在用激光使其进入强偏振态的3He气体中，大大增强了氦-内富勒烯的3He核磁共振信号。极化的~3He-内富勒烯固体可用作示踪物质，例如在磁共振成像中。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Synthesis of endohedral fullerenes by molecular surgery.

DOI：
10.1038/s42004-022-00738-9
发表时间：
2022-10-08
期刊：
COMMUNICATIONS CHEMISTRY
影响因子：
5.9
作者：
Bloodworth, Sally;Whitby, Richard J.
通讯作者：
Whitby, Richard J.

Atomic-Scale Time-Resolved Imaging of Krypton Dimers, Chains and Transition to a One-Dimensional Gas.

DOI：
10.1021/acsnano.3c07853
发表时间：
2024-01-30
期刊：
ACS NANO
影响因子：
17.1
作者：
Cardillo-Zallo, Ian;Biskupek, Johannes;Bloodworth, Sally;Marsden, Elizabeth S.;Fay, Michael W.;Ramasse, Quentin M.;Rance, Graham A.;Stoppiello, Craig T.;Cull, William J.;Weare, Benjamin L.;Whitby, Richard J.;Kaiser, Ute;Brown, Paul D.;Khlobystov, Andrei N.
通讯作者：
Khlobystov, Andrei N.

Electronic Spectroscopy of ${\bf{He}}@{ {\rm{C}}}_{60}^{+}$ for Astrochemical Consideration

${f{He}}@{ { m{C}}}_{60}^{ }$ 的电子光谱用于天体化学考虑