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Mechanically interlocked single-wall carbon nanotubes

Abstract:

Extensive research has been devoted to the chemical manipulation of carbon nanotubes. The attachment of molecular fragments through covalent-bond formation produces kinetically stable products, but implies the saturation of some of the C-C double bonds of the nanotubes. Supramolecular modification maintains the structure of the SWNTs but yields labile species. Herein, we present a strategy for the synthesis of mechanically interlocked derivatives of SWNTs (MINTs). In the key rotaxane-forming step, we employed macrocycle precursors equipped with two π-extended tetrathiafulvalene SWNT recognition units and terminated with bisalkenes that were closed around the nanotubes through ring-closing metathesis (RCM). The mechanically interlocked nature of the derivatives was probed by analytical, spectroscopic, and microscopic techniques, as well as by appropriate control experiments. Individual macrocycles were observed by HR STEM to circumscribe the nanotubes. Nanotubes in MINT condition! In a clipping reaction, macrocycles were formed by ring-closing metathesis around single-wall nanotubes (SWNTs) as "threads" to produce rotaxane-type species: mechanically interlocked derivatives of carbon nanotubes (MINTs; see picture). Extensive characterization, including high-resolution STEM and control experiments, proved the interlocked nature of the products. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.