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Determining Molecular Chirality with Femtosecond Lasers

用飞秒激光器测定分子手性

基本信息

批准号：
1786238
负责人：
金额：
--
依托单位：
Queen's University Belfast
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2016
资助国家：
英国
起止时间：
2016 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-1786238
关键词：
Determining Molecular Chirality Femtosecond Lasers

项目摘要

A molecule is chiral, having left and right handed types, if one type cannot be rotated so that it is superposed on the other. These molecules have very similar chemical and physical properties such as having the same infrared(IR) and nuclear magnetic resonance (NMR) spectra. However, left and right handed chiral molecules often taste, smell and interact with biological systems very differently. Most drugs are chiral compounds and often only one type is the active agent while the other can be poisonous. This was dramatically demonstrated in the 1950s and 1960s when thalidomide was given to pregnant woman to cure morning sickness but resulted in terrible birth defects. The reason for these catastrophic consequences is that the molecules of life are homochiral, for instance nearly all amino acids are left-handed while sugars are right-handed. The reasons for the existence of biological homochirality and if it is a pre-requisite for life remain a subject of intense debate.Chirality therefore has massive implications for the development of drugs and understanding life itself. However, present methods for identifying the different types of a chiral molecule are not very sensitive and mainly rely on the small differences in light absorption depending on whether the light is left or right circularly polarized. For this project a new conceptual approach based on asymmetry in the angular distribution of electrons emitted from photoionization of chiral molecules will be investigated. This phenomenon is several orders of greater in magnitude than current techniques and could provide a highly sensitive measurements of chirality in chemical samples. A prototype instrument is currently in development in our lab which uses femtosecond laser pulses to ionise the molecules. This device will be used for both fundamental studies and applications, such as to probe ultrafast changes in the structure of molecular motors and measuring the handedness of trace amounts of chiral compounds.

一个分子是手性的，有左手和右手类型，如果一种类型不能旋转，使其叠加在另一个。这些分子具有非常相似的化学和物理性质，例如具有相同的红外（IR）和核磁共振（NMR）光谱。然而，左手和右手手性分子的味道，气味和与生物系统的相互作用往往非常不同。大多数药物是手性化合物，通常只有一种类型是活性剂，而另一种可能是有毒的。这一点在20世纪50年代和60年代得到了戏剧性的证明，当时沙利度胺被用于治疗孕妇的晨吐，但却导致了可怕的出生缺陷。这些灾难性后果的原因是生命分子是同手性的，例如几乎所有的氨基酸都是左手性的，而糖是右手性的。生物同手性存在的原因以及它是否是生命的先决条件仍然是一个激烈争论的主题。因此，手性对药物的开发和理解生命本身具有巨大的意义。然而，目前用于识别不同类型的手性分子的方法不是非常灵敏，并且主要依赖于光吸收的小差异，这取决于光是左旋还是右旋圆偏振。在这个项目中，将研究一种新的概念方法，该方法基于手性分子光电离发射的电子角分布的不对称性。这一现象比现有技术在数量级上大几个数量级，可以提供化学样品中手性的高灵敏度测量。我们实验室目前正在开发一种原型仪器，它使用飞秒激光脉冲来电离分子。该装置将用于基础研究和应用，例如探测分子马达结构的超快变化以及测量微量手性化合物的旋向性。