Developing electron transfer from chiral circularly polarized luminescence-based photocatalysts towards selective radical cross-coupling reactions

摘要 拟议项目的长期目标是开发下一代交叉偶联反应。我们 旨在消除在耦合伙伴之间进行区分的需要，同时保持高反应性和 利用极化自由基物种的选择性。我们将利用这样一个事实，一个两极分化的激进分子 物种只会与另一个极化相反的自由基物种发生反应。中心假设是 强圆偏振发光(CPL)的配合物具有较高的高能级布居 可用于反应的极化激子。CPL是具有优先圆形的光发射 偏振，已成为下一代光源。稀土络合物是最好的CPL 发射体和铈的络合物是已知的能够产生自由基物种的光敏剂。我们会 合成了显示CPL的发光对映体手性配合物，并考察了它们的转移能力 极化电子。为了获得较强的cpl和光敏化能力，我们将目标对手性刚性胍酸盐。 配基。我们还将研究这些络合物转移极化电子并产生 极化自由基与猝灭研究配合物的光激发态。我们还将评估 极化自由基对CSP3-CSP3交叉偶联反应的反应性 荧光研究和流动化学。在拟议的供资期间，我们预计将交付第一个 CPL活性的Ce络合物的例子，以及极化电子转移的原理证明。我们还将 为极化的基于自由基的交叉偶联反应开发早期概念验证。

Summary The long-term goal of the proposed project is to develop the next generation of cross-coupling reactions. We aim at eliminating the need of differentiation between coupling partners, while retaining high reactivity and selectivity by utilizing polarized radical species. We will take advantage from the fact that a polarized radical species will only react with another radical species with the opposite polarization. The central hypothesis is that complexes emitting strong circularly polarized luminescence (CPL) possess a high population of high energy polarized excitons that can be harvested for reactivity. CPL is the emission of light with preferential circular polarization and has emerged as the next generation light source. Lanthanide complexes are the best CPL emitters, and cerium complexes are known to be photosensitizers capable of generating radical species. We will synthesize luminescent enantiopure chiral complexes exhibiting CPL, and will examine their ability to transfer polarized electrons. To attain strong CPL and photosensitizing ability, we will target chiral rigid guanidinate ligands. We will also examine the ability of these complexes to transfer polarized electrons and generate polarized radicals with quenching studies of the complexes in their photoexcited states. We will also evaluate the reactivity of polarized radicals toward Csp3-Csp3 cross-coupling reactions using a combination of fluorescence studies and flow chemistry. During the proposed funding period, we expect the delivery of the first examples of CPL-active cerium complex, as well as proof-of-principle for polarized electron transfer. We will also develop early stage proof-of-concept for the polarized radical-based cross-coupling reactions.