CAREER: CAS: Organic Photochemistry for Light-Driven CO2 Capture and Release

在化学系化学结构、动力学和机理B(CSDM-B)计划的支持下，哈佛大学化学和化学生物系的Richard Liu正在开发新型的可光开关有机化合物，以实现对二氧化碳(CO2)结合和可见光释放的控制。这一基本知识可以用来开发利用来自阳光的能量来将二氧化碳从排放流中分离出来，或者直接从大气中分离出来，然后根据需要释放捕获的二氧化碳以供利用或储存的设备。该项目将这些研究目标与旨在促进更广泛参与科学事业的教育活动结合起来，特别是旨在吸引波士顿地区的K-12学生以及成人和非传统学习者的教育活动。还将开发向盲人和低视力学生教授有机化学概念的工具，重点放在与研究目的相关的分子几何、立体化学和异构化反应等主题上。光致变色有机分子是一种很有前途的直接光驱动分离材料，因为它们可以有效地在两种或多种化学性质显著不同的异构体之间切换。拟议的研究概述了将这些光控平衡耦合到下游光无关平衡的一般方案，这些平衡涉及二氧化碳吸收到溶液中。在一种模式中，在辐射后进入亚稳态、高度酸性状态的新化合物将被用于被动捕获和按需释放二氧化碳。在第二种互补模式中，可逆光碱--一类被忽视的化合物，鲜有已知的例子--将被用来实现光触发捕获和逐渐被动释放。还将探索涉及将光酸或光碱与传统的胺类吸附剂相结合的合作机制。对于每一类化合物，将使用原位分光光度法、pH和CO2测量以及超快光谱来表征关键的光化学机制。有效光开关的热力学要求将通过对光开关的系统综合和评估来揭示。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 & Mechanisms-B (CSDM-B) Program of the Chemistry Division, Richard Liu of the Department of Chemistry and Chemical Biology at Harvard University is developing new classes of photoswitchable organic compounds to enable control of carbon dioxide (CO2) binding and release with visible light. This fundamental knowledge may be used to develop devices that harness energy from sunlight to separate CO2 from emission streams or directly from the atmosphere and then release that captured CO2 on demand for utilization or storage. This project integrates these research goals with educational activities intended to promote broader participation in scientific careers, specifically aimed at engaging K-12 students in the Boston area as well as adult and non-traditional learners. Tools for teaching organic chemistry concepts to blind and low-vision students will also be developed, focusing on topics such as molecular geometry, stereochemistry, and isomerization reactions related to the research aims.Photochromic organic molecules are promising materials for directly light-driven separations, as they may be efficiently switched between two or more isomeric forms that can differ significantly in their chemical properties. The proposed research outlines general schemes for coupling of these optically controlled equilibria to downstream light-independent equilibria involving CO2 uptake into solution. In one mode, new compounds that enter a metastable, highly acidic state upon irradiation will be used for passive capture and on-demand release of CO2. In a second, complementary mode, reversible photobases – a neglected class of compounds with few known examples – will be employed to enable light-triggered capture and gradual passive release. Co-operative mechanisms involving the combination of photoacids or photobases with traditional amine sorbents will also be explored. For each class of compounds, in situ spectrophotometry, pH and CO2 measurement, and ultrafast spectroscopy will be used to characterize key photochemical mechanisms. The thermodynamic requirements for effective photoswitching will be revealed through systematic synthesis and evaluation of photoswitches.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.