Renewing the Warwick 600 MHz Solid-State NMR System: Enabling State of the Art Technique Development and Novel Structural Applications

当科学家调查问题时，就像所有优秀的侦探一样，他们需要关于正在发生的事情的线索。对于一系列关键问题，能够揭示原子周围局部环境的技术对于深入了解这一水平的结构至关重要，这通常决定了材料或分子的行为。核磁共振（NMR）光谱在整个科学中的重要性越来越高，因为它是一种元素特异性探针，可以区分不同位点周围的微小变化（例如，SiO 4单元在结构中连接的角的数量，或碳的不同键合，例如CH 3和CH 2之间的差异）。核磁共振利用了原子核的固有磁性：就像指南针在地球磁场中的排列一样，当放置在强磁场中时，核磁体具有优先方向。然而，这种偏好是弱的，并且可以通过施加谐振无线电波，即，其频率和能量与翻转核磁体所需的能量精确匹配。原子核周围的电子也受到磁场的影响。重要的是，特定原子核的共振频率非常敏感地依赖于电子的这种附加响应，使得原子核充当局部电子环境的间谍，因此特定的化学键合允许其用于探测如上所述的环境。不同核同位素的共振频率被很好地分离，使得NMR谱对特定选择的同位素是特定的。(An一种元素可以以不同的同位素存在，因此在原子核中有相同数量的质子，但不同数量的中子-数量是指质子和中子的总数。这个项目将利用元素周期表的大部分内容。有些原子核很容易被发现（如13 C和29 Si），但其他原子核很少被NMR观察到（如33 S，47，49 Ti）。该项目将提供最先进的设备，以便进行最新的现代实验和设计新的实验。该设备将与高磁场结合使用，这使得一些实验成为可能，而这些实验在较低的磁场下是不可能的，因为该系统将提供更高的分辨率和更大的信号。核磁共振的一个关键优点是，原子核经历的相互作用传递了有关其周围环境的精确信息。作为一个例子，偶极相互作用的出现是因为核磁体不是孤立的，而是它们以类似于两个条形磁体在靠近时如何吸引或排斥的方式相互作用。重要的是，这种所谓的偶极相互作用的大小与两个核自旋之间的立方距离成反比。因此，测量一对17 O和1H核之间的偶极相互作用直接给出了氧原子和氢原子之间的距离。这样的距离可以用于量化氢键的程度-一种在确定，例如，蛋白质的三维结构。一项好的技术的检验是它适用于广泛的问题。作为该项目一部分开发的设备和技术将应用于物理和生命科学。原子尺度结构信息将应用于的问题包括：药物、碳氢化合物转化催化剂、火山物质、放射性废物储存玻璃、新的组织替代材料、了解疾病和酶途径以及新的电子材料。正是通过以问题为基础和以技术为基础的科学家之间的伙伴关系，才取得了真实的进展。

When scientists investigate problems, like all good detectives they need clues as to what is happening. For a whole range of key problems, techniques that can reveal the local environment around an atom are crucial to provide insight into the structure at this level, which often governs how a material or molecule behaves. Nuclear Magnetic Resonance (NMR) spectroscopy has increased in importance throughout the sciences as it is an element specific probe that can distinguish very small changes in the surroundings of different sites (e.g. the number of corners by which an SiO4 unit is connected in a structure, or the different bonding of carbon, such as the differences between CH3 and CH2). NMR exploits the inherent magnetism of atomic nuclei: like the alignment of a compass needle in the Earth's magnetic field, nuclear magnets have a preferred direction when placed in a strong magnetic field. This preference, however, is weak and a nuclear magnet can be made to change its direction from e.g. aligned with to aligned against the magnetic field, by applying a resonant radio wave, i.e., one whose frequency and hence energy matches precisely the energy required to flip the nuclear magnet. The electrons surrounding the atomic nucleus are also affected by the presence of a magnetic field. Importantly, the resonant frequency of a particular nucleus depends very sensitively on this additional response of the electrons, such that the atomic nuclei act as spies of the local electron environment and hence the specific chemical bonding allowing it to be used to probe environments as described above.The resonant frequencies of different nuclear isotopes are well separated such that an NMR spectrum is specific to a particular chosen isotope. (An element can exist as different isotopes whereby there is the same number of protons but a different number of neutrons in the nucleus - the number refers to the total number of protons and neutrons.) This project will make use of much of the Periodic Table. Some nuclei are easy (such as 13C and 29Si) but others have been rarely observed by NMR (e.g. 33S, 47,49Ti). The project is to provide the state of the art equipment to allow the latest, modern experiments to be implemented and new ones designed. The equipment will be used in conjunction with a high magnetic field, and this makes possible some experiments that are not possible at lower fields because of the increased resolution for some nuclei and larger signal that the system will provide. One of the key plus points for NMR is that nuclei experience interactions that convey precise information about their surroundings. As an example the dipole interaction arises as the nuclear magnets are not isolated, but rather they interact in an analogous way to how two bar magnets either attract or repel when brought close together. Importantly, the magnitude of this so-called dipolar interaction is inversely proportional to the cubed distance between the two nuclear spins. Thus, the measurement of such dipolar interactions between a pair of say 17O and 1H nuclei directly gives the distance between an oxygen and a hydrogen atom. Such a distance can be used to quantify the degree of hydrogen bonding - an interaction that plays a key role in determining, e.g., the three-dimensional structure of a protein.A test of a good technique is that it is applicable to a wide range of problems. The equipment and the techniques developed as part of this project will be applied to both physical and life sciences. Problems to which the atomic scale structural information will be applied include: pharmaceuticals, catalysts for hydrocarbon conversion, volcanic materials, radioactive waste-storage glasses, new tissue replacement materials, understanding diseases and enzyme pathways and new electronic materials. It is through the partnership between problem-based and technique-based scientists that real progress is made.