Mechanistic and Exploratory Photochemistry with Plane-Polarized Light

在化学系化学结构、动力学和机理B(CSDM-B)计划的支持下，北伊利诺伊大学的埃夫格尼·内斯特罗夫教授将研究一种新的方法，通过使用排列介质和平面偏振光来控制光化学反应的选择性。光化学本质上是“绿色化学”，因为它使用光(潜在的太阳光)作为能源和反应物。拟议的光化学研究计划旨在建立一种控制和提高光化学反应选择性的新范式，并有可能导致新的环境友好型化学过程。它还将有助于更好地理解光化学反应的机理，从而有助于将它们开发为实用的合成工具。参与该计划的学生将从多学科和协作培训中受益。内斯特罗夫小组还将通过参加对当地K-12学校的特别亲身实践活动来为社会做出贡献。这项研究的目标是建立和发展一种与平面偏振光调谐光化学有关的新范例。这有可能通过光反应化合物的均匀分子排列和通过使用平面偏振光对特定电子跃迁的空间选择性激发来控制光化学反应的过程和选择性。与以前通过对光反应分子施加一定的几何约束来控制光化学反应活性的方法不同，所提出的方法将不依赖于拓扑化学“反应腔”。相反，这里采取的方法是选择性地激发特定的电子跃迁，导致所需的光化学转变。如果成功，这些研究还将提供一种简单的方法，在实验上将光化学反应的结果与特定的电子跃迁联系起来，这可能是研究光化学反应机理的一个有价值的工具。该项目涉及以下具体目标：(1)设计和合成一系列具有光化学反应活性的化合物，这些化合物在液晶介质中具有增强的取向能力，使这些体系能够显示出激发选择性光化学反应活性；(2)详细研究这些体系利用平面偏振光进行的光化学反应；(3)研究在没有特别添加取向基团的情况下在光化学底物上进行类似反应的可能性；以及(4)开发不使用液晶溶剂来均匀排列光反应分子的替代方法。这将包括检查空气-水界面上的朗缪尔薄膜或使用分子“排列增强剂”，以及研究此类系统中的平面偏振光控制光化学。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Structure, Dynamics, and Mechanisms-B (CSDM-B) program of the Chemistry Division, Professor Evgueni Nesterov of Northern Illinois University will investigate a novel method to control selectivity of photochemical reactions through the use of aligning media and plane-polarized light. Photochemistry is intrinsically “green chemistry” as it uses light (potentially solar light) as both source of energy and reactant. The proposed research program in photochemistry aims to establish a new paradigm for controlling and enhancing selectivity of photochemical reactions, and can potentially lead to new environmentally benign chemical processes. It will also lead to better understanding of the mechanisms of photochemical reactions, thus helping to develop them as practically useful synthetic tools. Students participating in this program will benefit from multidisciplinary and collaborative training. The Nesterov group will also contribute to society through participation in special hands-on outreach activities to local K-12 schools.The goal of this research is to establish and develop a novel paradigm relating to the tuning of photochemistry with plane-polarized light. This has the potential to control the course and selectivity of photochemical reactions through the uniform molecular alignment of photoreactive compounds and through the use of spatially selective excitation of a particular electronic transition with plane-polarized light. In contrast to previous ways of controlling photochemical reactivity through imposing certain geometric constraints on the photoreactive molecule, the proposed approach will not rely on a topochemical “reaction cavity.” Rather the approach taken here is to selectively excite a particular electronic transition leading to a desired photochemical transformation. If successful, these studies would also deliver a simple method to experimentally correlate the outcome of a photochemical reaction with specific electronic transitions, a potentially valuable tool for the study of photochemical reaction mechanisms. The project involves the following specific aims: (1) design and synthesis of a series of photochemically reactive compounds with enhanced ability to align in liquid crystalline media, allowing these systems to display excitation-selective photochemical reactivity; (2) detailed investigation of the photochemistry of these systems using plane-polarized light; (3) investigation of the potential to carry out similar reactions on photochemical substrates without specially added aligning groups and (4) development of alternative methods for the uniform alignment of photoreactive molecules without using a liquid crystalline solvent. This will include examining Langmuir films on air-water interfaces or using molecular “alignment enhancers” and studying plane-polarized light controlled photochemistry in such systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.