(Invited) Synthetic Chiral Carbon Nanoforms

Abstract

Chirality is an important and fascinating concept which, however, has not been properly addressed in nanocarbon allotropes science.1 Recent results from our group support the basic idea that the chemistry of fullerenes, as probably the most studied carbon nanostructure from a synthetic point of view, is not fully developed. A variety of fundamental reactions, mainly involving transition metals and organocatalysts, would allow addressing issues such as the regio- and the stereo-selectivity in the fullerenes functionalization. We have recently reported on the synthesis of enantiomerically pure fullerenes with a total control of the stereochemical outcome. The suitable choice of the chiral metal catalyst ([Cu(II) or Ag(I)] – or organocatalyst – in combination with a variety of different chiral ligands) directs the 1,3-dipolar cycloaddition of N-metalated azomethyne ylides on C60, on C70 and on endohedral metallofullerenes with high levels of site-, regio-, diastereo- and enantio-selectivity.2 Chirality in graphene and, more specifically in graphene quantum dots (GQDs) has also been almost neglected despite the interest for potential further applications.3 We recently proof the concept that graphene quantum dots could become chiral and that this property can be transferred to a supramolecular structure built with pyrene molecules, where the CGQDs/pyrene ensembles show a characteristic chiroptical response depending on the configuration of the organic ligands introduced.4 Based on this simple approach, is it possible to envision the construction of more sophisticated chiral carbon-based GQDs supramolecular organizations where chirality could play an important role for practical applications. In this communication, the most significant and recent results involving synthetic covalent and non-covalent chiral GQDs will be discussed.References E. E. Maroto, M. Izquierdo, S. Reboredo, J. Marco-Martínez, S. Filippone, N. Martín "Chiral Fullerenes from Asymmetric Catalysis" Acc. Chem. Res. 2014, 47, 2660. a) Filippone, S., Maroto, E.E., Martín-Domenech, A., Suarez, M. and Martín, N., Nature Chem., 2009, 1, 578; b) Maroto, E. E.; de Cozar, A.; Filippone, S.; Martin-Domenech, A.; Suarez, M.; Cossio, F. P.; Martín, N. Angew. Chem. Int. Ed., 2011, 50, 6060; c) Sawai, K.; Takano, Y.; Izquierdo, M.; Filippone, S.; Martín, N.; Slanina, Z.; Mizorogi, N.; Waelchli, M.; Tsuchiya, T.; Akasaka, T.; Nagase, S. J. Am. Chem. Soc., 2011, 133, 17746; d) Maroto, E.E., Filippone, S., Martín-Domenech, A., Suarez, M. and Martín, N., J. Am. Chem. Soc. 2012, 134, 12936; e) E. E. Maroto, S. Filippone, M. Suárez, R. Martínez-Álvarez, A. de Cózar, F. P. Cossío, N. Martín, J. Am. Chem. Soc., 2014, 136, 705; J. Marco-Martínez, S. Vidal, I. Fernández, S. Filippone, N. Martín, Angew. Chem. Int. Ed., 2017, 56, 2136.a) L. Rodríguez-Pérez, M. A. Herranz, N. Martín, Chem. Commun. 2013, 49, 3721; b) G. Bottari, M. Á. Herranz, L. Wibmer, M. Volland, L. Rodríguez-Pérez, D. M. Guldi, A. Hirsch, N. Martín, F. D'Souza, T. Torres, Chem. Soc. Rev. 2017, 46, 4464.M. Vázquez-Nakagawa, L. Rodríguez-Pérez, M. A. Herranz, N. Martín, Chem. Commun., 2016, 52, 665; b) N. Suzuki, Y. Wang, P. Elvati, Z.-B. Qu, K. Kim, S. Jiang, E. Baumeister, J. Lee, B. Yeom, J. H. Bahng, J. Lee, A. Violi, N. A. Kotov, ACS Nano, 2016, 10, 1744.