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Quantitative scale for halogen bonding and hydrogen bonding: a foundation for self-assembly

卤素键和氢键的定量尺度：自组装的基础

基本信息

批准号：
EP/J012998/1
负责人：
Lee Brammer
金额：
$ 46.32万
依托单位：
University of Sheffield
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2012
资助国家：
英国
起止时间：
2012 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FJ012998%2F1
关键词：
Quantitative scale halogen bonding hydrogen

项目摘要

This project will provide quantitative experimental data on interactions between molecules that will underpin future research in self-assembly. The pre-eminent class of intermolecular interaction is the hydrogen bond. More recently established are halogen bonds, highly important interactions which parallel hydrogen bonds. The atoms within molecules are usually held together by strong chemical bonds (150-1000 kJ/mol), but their molecular structures are often strongly influenced by forces that are about 10 times weaker, of which the most famous is the hydrogen bond. It is the hydrogen bond that provides the means for DNA to encode genetic information and for proteins to acquire their specificity. These weaker forces also underlie interactions between molecules, and hence determine how small molecules assemble into larger structures. Self-assembly is the process of forming the larger structures: it pervades research and technology in areas ranging from materials chemistry to catalysis to structural biology. For instance, it is the interaction of a drug with a protein that determines its activity, or the interaction of a catalyst with a substrate that determines its specificity.When strong chemical bonds are formed, for instance between nitrogen and hydrogen atoms, the electrons are distributed unevenly; the nitrogen acquires a slight negative charge and the hydrogen acquires a slight positive charge. A hydrogen bond is formed when a hydrogen atom with a slight positive charge interacts with another atom with a slight negative charge: e.g. N-H...OC, where O has a partial negative charge. In this project we will also focus on the halogen bond, in which the role of the hydrogen is replaced by a halogen (iodine, bromine or chlorine) with the partial positive charge. This situation arises when these halogens are attached to other groups that pull the electrons away, for instance fluorine-containing groups. In 2004, Hunter presented a quantitative approach to understanding the impact of molecular interactions that has unified all classes of intermolecular interaction in all solvents. The basic principles have now been experimentally validated for simple systems that form hydrogen bonds, but the challenge is to implement this approach in systems that are more complicated and feature different types of intermolecular interaction. The research programme will examine hydrogen bonds to transition metal complexes and halogen bonds in general. The resulting quantitative measurements will be placed on a common scale with existing knowledge of organic hydrogen bonds.The dominant techniques for quantitative probing of molecular interactions in solution will be nuclear magnetic resonance spectroscopy (especially appropriate to the transition metal compounds) and automated ultraviolet/visible spectroscopy (especially for the organic molecules). The interaction energies will often be determined at many temperatures, giving a full range of energetic information. The geometry of the interactions will be studied by X-ray crystallography, supported by solid-state nuclear magnetic resonance. The experimental studies will be underpinned by computational methods based on quantum mechanics that can predict the site of interaction and its strength. The Brammer-Hunter-Perutz team bring great experience of studying intermolecular interactions and an established record of collaboration. The project is divided into three sections: (A) studies of transition metal compounds, (B) studies of interactions of organic molecules, (C) development of quantitative scales for hydrogen-bond and halogen-bond donor and acceptor strengths. Brammer provides the lead in crystallography, Perutz in NMR spectroscopy especially of transition metal complexes, and Hunter in automated UV/visible spectroscopy of organic molecules. Hunter also is the leader in data analysis methods and in computational methods.

该项目将提供分子之间相互作用的定量实验数据，这些数据将支持未来的自组装研究。分子间最主要的相互作用是氢键。最近建立的是卤键，这是与氢键平行的非常重要的相互作用。分子中的原子通常通过强化学键（150-1000 kJ/mol）结合在一起，但它们的分子结构通常受到弱约10倍的力的强烈影响，其中最著名的是氢键。正是氢键提供了DNA编码遗传信息和蛋白质获得特异性的手段。这些较弱的力也是分子之间相互作用的基础，因此决定了小分子如何组装成更大的结构。自组装是形成更大结构的过程：它贯穿于从材料化学到催化到结构生物学等领域的研究和技术。例如，药物与蛋白质的相互作用决定了其活性，催化剂与底物的相互作用决定了其特异性。当氮原子和氢原子之间形成强化学键时，电子分布不均匀，氮原子带轻微的负电荷，氢原子带轻微的正电荷。当一个带轻微正电荷的氢原子与另一个带轻微负电荷的原子相互作用时，就会形成氢键：例如N-H.其中O具有部分负电荷。在这个项目中，我们还将关注卤键，其中氢的作用被带部分正电荷的卤素（碘，溴或氯）取代。当这些卤素连接到其他将电子拉开的基团（例如含氟基团）时，就会出现这种情况。2004年，Hunter提出了一种定量方法来理解分子相互作用的影响，统一了所有溶剂中所有类型的分子间相互作用。基本原理现在已经在形成氢键的简单系统中得到了实验验证，但挑战是在更复杂且具有不同类型分子间相互作用的系统中实施这种方法。该研究方案将研究过渡金属络合物的氢键和一般的卤键。由此产生的定量测量将被放置在一个共同的规模与现有的有机氢键的知识。在溶液中的分子相互作用的定量探测的主要技术将是核磁共振光谱（特别是适用于过渡金属化合物）和自动紫外/可见光谱（特别是对有机分子）。相互作用能通常可以在许多温度下测定，从而提供全方位的能量信息。相互作用的几何形状将通过X射线晶体学研究，并得到固态核磁共振的支持。实验研究将得到基于量子力学的计算方法的支持，这些计算方法可以预测相互作用的位置及其强度。Brammer-Hunter-Perutz团队带来了研究分子间相互作用的丰富经验和既定的合作记录。该项目分为三个部分：（A）过渡金属化合物的研究，（B）有机分子相互作用的研究，（C）氢键和卤素键供体和受体强度的定量尺度的发展。Brammer在晶体学方面领先，Perutz在NMR光谱学方面领先，特别是过渡金属络合物，Hunter在有机分子的自动紫外/可见光谱学方面领先。亨特也是数据分析方法和计算方法的领导者。