EAGER: Controlling Photochemistry via Spatially Selective Excitation

北伊利诺伊大学的Evgueni Nesterov教授在化学学部化学结构、动力学和机理- b （CSDM-B）项目资助下，研究了利用液晶介质和平面偏振光控制光化学反应的一种新的一般原理。液晶（lc）具有介于传统液体（它们可以流动）和固体晶体（它们以非常特定的方式定向）之间的特性。液晶显示器得到了广泛的应用，其中一个例子就是数字表盘。这项研究试图利用液晶捕捉光，并将光的能量定向到特定的化学反应中。该项目风险很大，因为这种概念尚未在实践中得到证实。如果成功，这项研究可能为控制光化学反应建立一个新的范例，从而产生非常特定的化学产物。这可能会导致新的无害环境的化学过程，它依赖于光作为化学转化的能量来源。参加该课程的学生受益于多学科和协作培训，这使他们在技术就业市场上具有很强的竞争力。他们还通过参与针对当地K-12教育的特殊实践活动为社会做出贡献。这个早期探索项目的最终目标是开发并通过实验证实一种新的范例，通过在液晶（LC）介质中光反应化合物的均匀分子排列和平面偏振光的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。与通过对光反应分子施加几何限制来控制光化学选择性的传统方法相反，这种方法依赖于特定电子跃迁的选择性激发，从而导致所需的光化学转化。本研究旨在设计和合成一系列光化学活性化合物，这些化合物在向列LC介质中具有增强的排列能力，可以显示激发选择性光化学反应性。研究小组提供了详细的实验分析和表征他们的lc施加的对准和过渡偶极矩取向使用紫外/可见极化光谱。本研究为控制和提高光化学反应的选择性提供了一个新的范例。这可能会导致新的无害环境的化学过程，它依赖于光作为化学转化的能量来源。除了这些实际利益之外，这项工作的更广泛影响还包括通过学生参与高级研究和参与旨在提高公众（特别是年轻一代）对现代科学技术的认识和欣赏的特殊外展活动，为STEM学科的学生提供多学科培训，从而为社会带来好处。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this project funded by the Chemical Structure, Dynamics, and Mechanisms-B (CSDM-B) Program of the Chemistry Division, Professor Evgueni Nesterov of Northern Illinois University investigates a new general principle to control photochemical reactions through the use of liquid crystalline media and plane polarized light. Liquid crystals (LCs) have properties between those of conventional liquids (in that they can flow) and those of solid crystals (in that they are oriented in a very specific way). Liquid crystal displays are widely used - one example is in digital watch faces. This research seeks to use liquid crystals in capturing light and specifically and uniformly redirecting the light's energy into specific chemical reactions. The project is high risk as such a concept has not yet been demonstrated in practice. If successful, this research may establish a new paradigm for controlling photochemical reactions so that very specific chemical products are made. This can potentially lead to new environmentally benign chemical processes which rely on light as a source of energy for chemical transformations. Students participating in this program benefit from multidisciplinary and collaborative training, which allows them to become highly competitive in the technical job market. They also contribute to society through participation in special hands-on activities targeting local K-12 education.The ultimate goal of this early-stage exploratory program is to develop and experimentally confirm a novel paradigm for controlling the course and selectivity of photochemical reactions through the uniform molecular alignment of photoreactive compounds in liquid crystalline (LC) media and spatially selective excitation of specific electronic transitions with plane-polarized light. In contrast to the conventional ways of controlling photochemical selectivity by imposing geometrical restrictions on the photoreactive molecule, this approach relies on selective excitation of the particular electronic transitions leading to a desired photochemical transformation. The research seeks to design and synthesize a series of photochemically reactive compounds with enhanced ability to align in nematic LC media, which can display excitation-selective photochemical reactivity. The research group provides detailed experimental analysis and characterization of their LC-imposed alignment and transition dipole moment orientation using UV/vis polarization spectroscopy. This research program may establish a new paradigm for controlling and enhancing selectivity of photochemical reactions. This can potentially lead to new environmentally benign chemical processes which rely on light as a source of energy for chemical transformations. In addition to these practical benefits, the broader impacts of this work include benefits to the society from multidisciplinary training of students in STEM disciplines, both through student involvement in advanced research and participation in special outreach activities developed with the goal of improving public awareness and appreciation of modern science and technology, particularly among younger generations.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.