Wassy Daniel, Hermann Mathias, Wössner Jan S, Frédéric Lucas, Pieters Grégory, Esser Birgit
Institute for Organic Chemistry, University of Freiburg Albertstraße 21 79104 Freiburg Germany
Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SCBM 91191 Gif-sur-Yvette France.
Chem Sci. 2021 Jun 22;12(30):10150-10158. doi: 10.1039/d1sc02718b. eCollection 2021 Aug 4.
Strained conjugated nanohoops are attractive synthetic targets due to the bending of their π-system, which leads to intriguing optoelectronic properties, among others. By incorporating non-mirror-symmetric aromatic panels, chiral nanohoops can be obtained. We herein present a strategy to enantiopure nanohoops by racemic resolution through chiral derivatization of diketone-embedded hoops. The resulting diketo[]CPPs ( = 6, 7) contain two stereogenic carbon atoms each and possess high fluorescence quantum yields paired with circularly polarized luminescence. These are versatile precursors to chiral dibenzo[,]pentalene-based nanohoops DBP[]CPPs with antiaromatic character and ambipolar electrochemical behavior. Due to their strained structures the DBP[]CPPs do not racemize at room temperature, which is supported by high calculated isomerization barriers. X-ray crystallographic investigations on the DBP[]CPPs and their precursors as well as DFT calculations provide insight into the build-up of strain energy during the synthetic transformations.
由于其π体系的弯曲，受应变的共轭纳米环是引人注目的合成目标，这导致了有趣的光电特性等。通过引入非镜像对称的芳香面板，可以获得手性纳米环。我们在此提出一种通过对嵌入二酮的环进行手性衍生化的外消旋拆分来制备对映体纯纳米环的策略。所得的二酮[]CPPs（ = 6, 7）每个都含有两个手性碳原子，并具有高荧光量子产率以及圆偏振发光。这些是具有反芳香特性和双极性电化学行为的基于手性二苯并[,]戊搭烯的纳米环DBP[]CPPs的通用前体。由于其受应变的结构，DBP[]CPPs在室温下不会消旋，这得到了高计算异构化势垒的支持。对DBP[]CPPs及其前体的X射线晶体学研究以及DFT计算提供了对合成转化过程中应变能积累的深入了解。
