Theoretical studies of actinide complexation with macrocyclic ligands: identifying synthetic targets and real-world applications

我建议研究铀酰和一系列卟啉之间的化学相互作用。铀酰是重元素铀的氧络合物，卟啉是大的环状碳基分子。这些化学复合物中有几种已经在实验室中被创造出来，我设想我的研究结果可以应用于核燃料浓缩、辐射检测、癌症治疗和太阳能等多种领域。此外，我的工作将确定研究化学家应该集中精力在实验室合成的配合物，以及证明最先进的理论方法可以而且必须应用于这些配合物，以便对其化学结构进行定量理解。卟啉可以被认为是分子环或大环，具有其他原子和分子可以驻留的中心腔，并且我所建议的各种应用是可能的，因为它们可以很容易地修改以改变它们的性质：-它们的大小可以改变，因此它们可以被量身定制，以在不同程度上“适合”铀酰。-它们可以被修改，使它们在加热时更容易蒸发。相关的大环使人们能够选择与铀酰直接相互作用的原子类型。-它们可以被改变，这样它们结合铀酰的强度就可以改变。我提议的工作的一个重要部分是它是计算性的：我所有的直接研究都将通过模拟。与其他化学领域相比，模拟在研究锕系元素（包括铀）方面发挥着更大的作用，因为所有锕系元素都具有放射性，其中一些具有极强的放射性，而世界上可供化学家使用的设施很少。这意味着可以执行较少的实验室工作，因此为了进一步了解这些元素，需要精确的模拟。为了研究铀酰卟啉复合物，我提出的研究采用了极其复杂的理论技术。虽然以前已经有一些关于这种复合物的模拟工作，但它使用的方法不太精确。我所概述的潜在应用的实现取决于卟啉和铀酰之间相互作用的具体细节。这些细节通常无法直接从实验中获得；因此，具有强大预测能力的理论技术是必要的。在我以前的研究中，我已经表明，流行的理论方法可能甚至不能定性地描述锕系元素复合物，特别是对于像钚这样较重的锕系元素，而且只有在今天，才有计算资源来进行能够对这种相对较大的复合物进行定量预测的模拟。作为我研究计划的一部分，我还打算研究卟啉与其他锕系元素的相互作用。其他锕系元素的表现可能与铀非常不同，了解它们何时以及如何不同是重元素化学的基本问题。我所描述的卟啉的性质允许我们考虑这些基本问题的许多不同方面。总之，我在这里提出的重要理论研究将补充美国大学和国家实验室正在进行的优秀实验工作。虽然这项工作的主要目标是实现我所概述的应用，但它也将为大分子系统的模拟设定新的标准，并加深我们对锕系元素化学的理解。

I propose to investigate the chemical interaction between uranyl and a series of porphyrins. Uranyl is an oxygen complex of the heavy element uranium and porphyrins are large, ringlike carbon-based molecules. Several of these chemical complexes have been created in laboratories, and I envisage the results of my research having applications as diverse as nuclear fuel enrichment, radiation detection, cancer therapy, and solar energy. In addition, my work will identify complexes that research chemists should focus their efforts on synthesising in the laboratory as well as demonstrating that state-of-the-art theoretical methods can and must be applied to these complexes in order to give a quantitative understanding of their chemical structure.The porphyrins can be considered as molecular rings, or macrocycles, with a central cavity in which other atoms and molecules can reside, and the variety of applications I have suggested is possible since they can be easily modified in order to change their properties:-Their size can be altered, so that they can be tailored to 'fit' with uranyl to varying degrees.-They can be modified so that they evaporate more readily when heated.-Related macrocycles enable one to choose the type of atom with which the uranyl directly interacts.-They can be altered so that the strength with which they bind uranyl can be varied.An important part of my proposed work is that it is computational: all of my direct research will be via simulation. Simulation plays a greater role in research into the actinide series of elements, which includes uranium, than in other areas of chemistry, since all actinides are radioactive, some of them extremely so, and there are very few facilities in the world where chemists can work with them. This means that less laboratory work can be performed, and so accurate simulation is a requirement in order to further our understanding of these elements.My proposed research employs extremely sophisticated theoretical techniques in order to study uranyl porphyrin complexes. Whilst there has been some previous simulation work on such complexes, it has been carried out using less accurate methods. The realisation of the potential applications that I have outlined are dependent on specific details of the interactions between the porphyrins and the uranyl. Such details are often unavailable directly from experiment; theoretical techniques with strong predictive capabilities are therefore a necessity. In my previous research I have shown that popular theoretical methods may not be capable of even qualitative descriptions of actinide complexes, particularly for the heavier actinides such as plutonium, and it is only in the present day that computational resources are available to conduct simulations capable of quantitative predictions on such relatively large complexes. As part of my proposed research I also intend to study the interactions of the porphyrins with other actinide elements. Other actinides can behave very differently to uranium, and understanding when and how they differ are fundamental questions in heavy element chemistry. The properties of the porphyrins that I have described allow many different aspects of these fundamental questions to be considered.In summary, the significant theoretical study that I propose here will complement the excellent experimental work being carried out both in universities and national laboratories in the United States. Whilst the primary goal of this work is the realisation of the applications I have outlined, it will also set new standards in the simulation of large molecular systems, and deepen our understanding of the chemistry of the actinide series.