(Invited) The Mechanical Bond As a New Tool to Revisit Old Problems in Swnt Chemistry
Authors: Perez Emilio M 
Published: May 2020

The chemical mofidication of SWNTs typically aims at modifying their surface properties (to make them more processible, or to improve interface with other materials) and/or their electronic properties (to fine tune them for specific applications). Both covalent and supramolecular strategies have been explored towards those ends.[1]

We will present strategies towards the synthesis of mechanically interlocked derivatives of SWNTs (MINTs), which are rotaxane-type materials in which the SWNTs are threaded through organic macrocycles, so that they are interfaced through mechanical bonds (see image, for a cartoon and a HRTEM of a MINT).[2] With the synthetic strategies established, we will focus on the the effect of the mechanical bond on the properties of SWNTs and show that such effect is unique, and clearly different from the noninterlocked, supramolecular compounds.[3] More specifically, we will report how to use the mechanical bond to improve the interface between SWNTs and polymeric materials, to achieve significantly improved mechanical properties.[4] We will also show that the organic macrocycles can be used to modulate the electronic properties of SWNTs, which in turn influence their catalytic properties.[5]

[1] Rao, R.; Pint, C. L.; Islam, A. E.; Weatherup, R. S.; Hofmann, S.; Meshot, E. R.; Wu, F.; Zhou, C.; Dee, N.; Amama, P. B.; Carpena-Nuñez, J.; Shi, W.; Plata, D. L.; Penev, E. S.; Yakobson, B. I.; Balbuena, P. B.; Bichara, C.; Futaba, D. N.; Noda, S.; Shin, H.; Kim, K. S.; Simard, B.; Mirri, F.; Pasquali, M.; Fornasiero, F.; Kauppinen, E. I.; Arnold, M.; Cola, B. A.; Nikolaev, P.; Arepalli, S.; Cheng, H.-M.; Zakharov, D. N.; Stach, E. A.; Zhang, J.; Wei, F.; Terrones, M.; Geohegan, D. B.; Maruyama, B.; Maruyama, S.; Li, Y.; Adams, W. W.; Hart, A. J. Carbon Nanotubes and Related Nanomaterials: Critical Advances and Challenges for Synthesis toward Mainstream Commercial Applications.
ACS Nano 2018, 12, (12), 11756-11784.

[2] a) de Juan, A.; Pouillon, Y.; Ruiz-Gonzalez, L.; Torres-Pardo, A.; Casado, S.; Martin, N.; Rubio, A.; Perez, E. M. Mechanically Interlocked Single-Wall Carbon Nanotubes.
Angew. Chem., Int. Ed. 2014, 53, 5394-5400; b) Lopez-Moreno, A.; Perez, E. M. Pyrene-based mechanically interlocked SWNTs. Chem. Commun. 2015, 51, 5421-5424; Leret, S.; Pouillon, Y.; Casado, S.; Navio, C.; Rubio, A.; Perez, E. M. Bimodal supramolecular functionalization of carbon nanotubes triggered by covalent bond formation. Chem. Sci. 2017, 8, 1927-1935; c) de Juan-Fernandez, L.; Munich, P. W.; Puthiyedath, A.; Nieto-Ortega, B.; Casado, S.; Ruiz-Gonzalez, L.; Perez, E. M.; Guldi, D. M. Interfacing porphyrins and carbon nanotubes through mechanical links. Chem Sci 2018, 9 (33), 6779-6784; d) For reviews, see: Perez, E. M. Putting Rings around Carbon Nanotubes. Chem. Eur. J. 2017, 23 (52), 12681-12689; Mena-Hernando, S.; Perez, E. M., Mechanically interlocked materials. Rotaxanes and catenanes beyond the small molecule. Chem. Soc. Rev. 2019, 48, 5016-5032.

[3] Martinez-Perinan, E.; de Juan, A.; Pouillon, Y.; Schierl, C.; Strauss, V.; Martin, N.; Rubio, A.; Guldi, D. M.; Lorenzo, E.; Perez, E. M. The mechanical bond on carbon nanotubes: diameter-selective functionalization and effects on physical properties. Nanoscale 2016, 8 (17), 9254-9264.

[4] Lopez-Moreno, A.; Nieto-Ortega, B.; Moffa, M.; de Juan, A.; Bernal, M. M.; Fernandez-Blazquez, J. P.; Vilatela, J. J.; Pisignano, D.; Perez, E. M. Threading through Macrocycles Enhances the Performance of Carbon Nanotubes as Polymer Fillers. ACS Nano 2016, 10 (8), 8012-8018.

[5] Blanco, M.; Nieto-Ortega, B.; de Juan, A.; Vera-Hidalgo, M.; López-Moreno, A.; Casado, S.; González, L. R.; Sawada, H.; González-Calbet, J. M.; Pérez, E. M. Positive and negative regulation of carbon nanotube catalysts through encapsulation within macrocycles. Nat. Commun. 2018, 9 (1), 2671.

Figure 1