Photothermal Catalysis: Using light to thermally generate reactive intermediates with temporal and spatial control

项目摘要 光子驱动的过程已经成为实现具有挑战性的键断裂的有力工具， 成键光催化提供了利用低能量光的时间和空间控制的益处，其具有 对于从简单的起始材料有效地构建分子复杂性具有广泛的优势。的 明智地选择光催化剂可以实现其他形式的催化剂很少能达到的反应精度 催化和加热。光热转换是一个未充分利用的领域。特定辐射 纳米颗粒或染料与可见光的接触在光热转换过程中产生强烈的热梯度。 与其中温度在整个反应介质上保持均匀的整体加热相反，衬底将 在瞬时加热下仅经历激发的几纳米内的热能。因此，委员会认为， 这一过程将利用辐射在高温下驱动化学过程， 控制空间控制使得能够选择性地形成高反应性物种，而无需竞争性双分子 副反应 拟议的研究包括三个基本项目，探索利用光热催化 以使得能够使用可见光照射合成复杂分子。一、高温热 重排将实现使用碳基纳米粒子和可见光照射下温和 条件这种策略将使合成复杂的产品，而没有热分解一般 与散装therapy有关。此外，还鉴定了各种光热剂和合成的 精细加工将产生更有效的催化剂。在第二个项目中，光热加热将产生 通过C-C键均裂形成碳中心自由基。拦截这些高活性的中间体， 扩环反应中的新C-C键，分子内环化。特定光热剂设计 将使分子间的环扩张，以建立分子的复杂性。在第三个项目中， 项目二中确定的均裂反应将用于原子经济的动态动力学拆分 对映体富集的药物化合物的合成。乳化液会将温度梯度限制在 胶束能够使热差向异构化反应与高选择性酶促反应偶联。 结合起来，这三个项目将发展光热催化和光的影响的理解 和强度对产生热梯度的影响。深入了解这些热梯度如何 利用可见光的空间和时间控制进行高温反应将使新的 以前未实现的合成键断开。

Project Summary Photon-driven processes have emerged as a powerful tool for achieving challenging bond cleavage and bond formation. Photocatalysis offers the benefit of temporal and spatial control with low energy light, which has been widely advantageous for efficiently building molecular complexity from simple starting materials. The judicious choice of photocatalysts enables the precision of reactivity that is rarely achieved with other forms of catalysis and heating. An underused area of photocatalysis is photothermal conversion. Irradiation of specific nanoparticles or dyes with visible light creates intense thermal gradients in a photothermal conversion process. In contrast to bulk heating, where the temperature remains uniform across a reaction medium, substrates would only experience thermal energy within a few nanometers of excitation under temporal heating. Consequently, this process would use irradiation to drive chemical processes at high temperatures with temporal and spatial control. Spatial control enables the selective formation of highly reactive species without competing bimolecular side reactions. The proposed research comprises three fundamental projects exploring the use of photothermal catalysis to enable the synthesis of complex molecules using visible light irradiation. First, high-temperature thermal rearrangements will be achieved using carbon-based nanoparticles and visible light irradiation under mild conditions. This strategy will enable the synthesis of complex products without thermal decomposition generally associated with bulk thermolysis. Additionally, the identification of various photothermal agents and synthetic elaborations will generate more efficient catalysts. In the second project, photothermal heating will generate carbon-centered radicals through C–C bond homolysis. Intercepting these highly reactive intermediates will forge new C–C bonds in ring expansion reactions, in intramolecular cyclizations. Specific photothermal agent design will enable intermolecular ring expansions to build molecular complexity. In a third project, the C–C bond homolysis reactions identified in project two will be used in dynamic kinetic resolutions for atom economical synthesis of enantioenriched pharmaceutical compounds. Emulsions will confine thermal gradients to within micelles enabling the coupling of thermal epimerization reactions with highly selective enzymatic reactions. Combined, these three projects will develop an understanding of photothermal catalysis and the effect of light and intensity on generation of thermal gradients. A thorough understanding of how these thermal gradients can be leveraged for high temperature reactions with the spatial and temporal control of visible light will enable new synthetic bond disconnections previously unrealized.