Exploiting chirality in mechanically interlocked molecules for new applications in nanotechnology

在《科学》(1)和J.Am上发表了开创性的出版物化学。(2)Leigh集团已经证明分子结具有良好的催化性能，这是因为它们有明确的空穴和良好表达的手性。(1，2)五元结特别是由于可以用于阴离子结合催化的多重氢键和库仑相互作用的组合结果，对卤化阴离子表现出非常强的亲和力。(3)此外，催化活性可以通过添加或移除以酶中变构控制为模板的形成空穴的金属离子来变构地开启和关闭。(1)本项目的目标是制备一系列包含光氧化还原活性Ir(III)中心的分子结，而不是先前使用的第一排过渡金属中心。(1，4)Ir中心将起双重作用：首先，Ir(III)的相对惰性允许将起始材料分离为单一对映体。(5)由于所需的圆形螺旋体的对称性，使用对映体Ir(III)络合物应导致结前体的立体选择性合成。其次，含有联吡啶辅助配体的环金属Ir(III)配合物是一种有效的可见光光氧化还原催化剂。(6)通过将光氧化还原活性成分引入到单手螺旋结构中，我们的目标是实现立体选择性的双光氧化还原/阴离子结合催化。例如，四氢异喹啉的两步亲核攻击可以通过光氧化还原催化剂和对映选择性氢键供体催化剂的组合来促进。(7)这个过程可以用Ir(III)结在一锅程序中实现。我们建议使用不同的金属离子作为信号系统，通过变构相互作用来控制反应。第一排过渡金属离子的去除将阻止该体系作为阴离子结合催化剂的作用，而光氧化还原性能将不受影响。将Fe(II)添加到模板腔中将允许阴离子结合，但会抑制光氧化还原过程。最后，锌(II)的加入应该允许光氧化还原和阴离子结合催化在丹德姆工作。该项目旨在合并一系列重要和新兴的领域，包括分子结、光氧化还原催化和可切换催化，以提供能够以生物系统的方式对立体化学和区域化学进行严格控制的催化反应途径的系统。分子结是一个新兴的领域，在可切换催化领域具有广阔的应用前景。化学拓扑学提供了一种在改变功能的同时保持分子连接性的迄今尚未开发的策略。利用化学拓扑学来改变反应路径的任何进展都将是该领域的前沿。虽然光氧化还原催化作为一种绿色温和的合成方法的使用正在迅速上升，但立体选择性光氧化还原过程仍处于起步阶段。使用光氧化还原催化实现的任何对映体选择性都将是对当前最先进技术的重大补充。自然界能够通过与各种不同的信号分子的变构相互作用来微调许多复杂途径的反应速度。改变合成反应路径的能力为创造能够对不同刺激做出反应的智能系统提供了可能性。该项目旨在结合一系列新兴技术，为未来的应用创造新的、令人兴奋的功能催化剂。V.Marcos et.《科学》，2016年，3521555-1559.2。G.Gil-Ramirez et.艾尔，J.Am化学。SoC。2016年，138%，13159-13162.3。J.-F.Ayme et.艾尔，J.Am化学。SoC。2015年，1379812-9815.4。D.A.Leigh，et.Al.，Nat.化学。2014年，6978-982.5。C.Chepelin et.艾尔，J.Am化学。SoC。2012年，134,19334-19337.6。C.K.Prier et.艾尔，化学。2013年版，1135322-5363.7。G.BerGonzini et.艾尔，化学。SCI。2014，5，1-60

In pioneering publications in Science(1) and J. Am. Chem. Soc.(2) molecular knots have been shown by the Leigh group to have promising catalytic properties due to their well-defined cavities and well-expressed chirality.(1,2) Pentafoil knots, in particular, show very strong affinities for halide anions as a combined result of the multiple hydrogen bond and coulombic interactions that can be utilised for anion binding catalysis.(3) Furthermore, the catalytic activity can be allosterically switched on and off by the addition or removal of metal ions that template the cavity formation in a manner reminiscent of allosteric control in enzymes.(1)This project will aim to prepare a range of molecular knots that contain photoredox-active Ir(III) centres in place of the previously used first row transition metal centres.(1,4 )The iridium centres will play a dual role: Firstly, the relative inertness of Ir(III) allows the isolation of the starting materials as single enantiomers.(5) Due to the required symmetry of the circular helicates, the use of an enantiopure Ir(III) complex should result in the stereoselective synthesis of the knot precursor. Secondly, cyclometallated Ir(III) complexes bearing a bipyridine ancillary ligand are well documented as effective visible light photoredox catalysts.(6)By incorporating photoredox active components into a helicate of single-handedness we aim to achieve stereoselective dual photoredox/anion binding catalysis. As an example, the two step nucleophilic attack of tetrahydroisoquinolines can be promoted by a combined mixture of a photoredox catalyst and an enantioselective hydrogen bond donor catalyst.(7) This process could be achieved in a one pot procedure using Ir(III) knots. We propose controlling the reaction via allosteric interactions using different metal ions as signalling systems. The removal of first row transition metal ions will prevent the system from acting as an anion binding catalyst whilst the photoredox properties will be unaffected. The addition of Fe(II) to template the cavity will allow anion binding but quench the photoredox process. Finally, the addition of Zn(II) should allow both photoredox and anion binding catalysis to work in tandem.This project aims to merge a range of important and emerging areas including molecular knots, photoredox catalysis and switchable catalysis to provide systems capable of catalysing reaction pathways with strict control over both the stereochemistry and regiochemistry in a manner reminiscent of biological systems. Molecular knots are an emerging field with promising potential for switchable catalysis. Chemical topology provides a to date untapped strategy for retaining molecular connectivity whilst altering function. Any progress in using chemical topology to alter reaction pathways would be at the forefront of the field. Whilst the use of photoredox catalysis as a green and mild synthetic method is rapidly on the rise, stereoselective photoredox processes are still in their infancy. Any enantioselectivity achieved using photoredox catalysis would be a significant addition to the current state-of-the-art. Nature is able to finely tune the reaction rate of many complex pathways via allosteric interactions with a wide range of different signalling molecules. The ability to alter synthetic reaction pathways opens the possibility of creating smart systems capable of responding to different stimuli. This project aims to combine a range of emerging technologies to create new and exciting functional catalysts for future applications.1. V. Marcos et. al., Science 2016, 352, 1555-1559.2. G. Gil-Ramirez et. al., J. Am. Chem. Soc. 2016, 138, 13159-13162.3. J.-F. Ayme et. al., J. Am. Chem. Soc. 2015, 137, 9812-9815.4. D. A. Leigh, et. al., Nat. Chem. 2014, 6, 978-982.5. O. Chepelin et. al., J. Am. Chem. Soc. 2012, 134, 19334-19337.6. C. K. Prier et. al., Chem. Rev. 2013, 113, 5322-5363.7. G. Bergonzini et. al., Chem. Sci. 2014, 5,1-60