Concave–Convex π–π Template Approach Enables the Synthesis of [10]Cycloparaphenylene–Fullerene [2]Rotaxanes

• DOI: 10.1021/jacs.8b08244
• Publication Date: 2018-09-20T18:38:32Z
• Authors: Youzhi Xu; Ramandeep Kaur; Bingzhe Wang; Martin B. Minameyer; Sebastian Gsänger; Bernd Meyer; Thomas Drewello; Dirk M. Guldi; Max von Delius
• Keywords: Rotaxane; Heteroatom; Molecular machine; Structural isomer

The cycloparaphenylenes (CPPs) are a class of strained macrocycles that until 2008 were considered beyond the reach organic synthesis. With its cyclic array ten para-substituted phenylene rings, [10]CPP possesses concave π-system is perfectly preorganized for strong supramolecular association convex fullerenes such as C60. Although mechanically interlocked CPP architectures have been observed in gas phase, rational synthesis bulk quantities has not achieved yet, which likely due to fact conventional template strategies amenable rings lack heteroatoms. Here, we report two [2]rotaxanes ring binds central fullerene bis-adduct and prevented from dethreading by presence bulky hexakis-adduct stoppers. final step rotaxane surprisingly efficient (up ca. 40% yield) regioselective because acts an template, while directing group, steering reaction at exclusively toward trans regioisomers. Comprehensive physicochemical studies confirmed structure, shed light on dynamic nature CPP-fullerene interaction, revealed intriguing consequences mechanical bond charge transfer processes. In recent advances nanohoops nanobelts, our concave-convex π-π templating strategy may be broadly useful enable applications molecular electronics or complex machinery.