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

1. 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.
2. 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.
3. 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.
4. 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.