Vibrational Spectral Studies

范德堡大学的Prasad Polavarapu在实验物理化学项目和多学科活动办公室的支持下，(i)开发了一种具有双偏振调制和数字信号处理能力的步进扫描偏振分裂干干仪，（ii）使用该仪器研究包裹在环糊精腔中的致癌物的蛋白质-麻醉相互作用和主客体相互作用。手性分子的对映异构体作为麻醉剂的效果不同。为了更好地理解分子水平上的立体定向相互作用，PI将研究手性对映体的绝对构型和麻醉分子存在的构象。为了阐明客-主相互作用，一系列取代的氧烷将作为被困在环糊精腔中的客分子。同位素取代将被用来分离由于客分子引起的光谱带，并确定由宿主施加的扰动。PI将利用圆偏振光探测手性分子的振动跃迁。这些研究在药物设计领域具有极其重要的意义，对映体的有效性差异可能相当显著。例如，众所周知，臭名昭著的药物沙利度胺的一种对映体是镇静剂，而另一种对映体会导致严重的先天缺陷。为什么两个结构“几乎”相同的分子会对人体产生如此完全不同的影响，目前还完全不清楚。这是基础化学，其结果将对生物技术领域产生重大影响。

Prasad Polavarapu of Vanderbilt University is supported by the Experimental Physical Chemistry Program and the Office of Multidisciplinary Activities to (i) develop a step-scan polarization division interferometer with double polarization modulation and digital signal processing capabilities, and (ii) use this instrument to investigate protein-anesthetic interactions and host-guest interactions for carcinogens encapsulated in cyclodextrin cavities. Enantiomers of chiral molecules show differences in their effectiveness as anesthetics. To better understand the stereospecific interactions at the molecular level, the PI will study the absolute configurations of chiral enantiomers and the conformations in which the anesthetic molecules exist. For elucidating guest-host interactions, a series of substituted oxiranes will serve as guest molecules trapped in cyclodextrin cavities. Isotopic substitution will be exploited to isolate the spectral bands due to the guest molecule, and to determine the perturbations imposed by the host. The PI will probe the vibrational transitions of chiral molecules using circularly polarized light. These studies have tremendously important implications in the area of drug design, where differences in the effectiveness of enantiomers can be quite dramatic. For example, one enantiomer of the infamous drug, thalidomide, is known to be a sedative while the other causes severe birth defects. Why two molecules of `nearly` identical structure could have such completely different effects on the human body is not at all clear. This is fundamental chemistry, the results of which will have a significant impact in the area of biotechnology.