(Invited) Tuning Optoelectronic and Chiroptical Properties of Carbon Dots Based Hybrids
Authors: Herranz M. Ángeles , Ferrer-Ruiz Andrés , Vázquez-Nakagawa Mikiko , Rodríguez-Pérez Laura , Martín Nazario 
Published: September 2023

Carbon dots (CDs) are a rising star in carbon nanomaterials due to their easy preparation and numerous potential applications. With a diameter from a few to tens of nanometers, and a tunable structure, composition, and morphology, they integrate the merits of water solubility, low biological toxicity, and diversity of opto-electronic properties. Commonly, they are categorized into different subgroups, where graphene quantum dots (GQDs) and carbon nanodots (CNDs) can be found. GQDs are two-dimensional nanoparticles of one or few-layer graphene sheets formed during the exfoliation processes of graphitic materials, whereas CNDs are amorphous nanoparticles fabricated from easily affordable organic precursors, natural products, or waste.
In recent years, we have set-up methodologies for the synthesis of GQDs and CNDs, carried out a detailed characterization of the obtained structures, and explored the modulation of properties by chemical modification of these carbon nanostructures, as part of the objectives of our research.
Special attention was dedicated to customize the optoelectronic properties of GQDs and CNDs, and to investigate the electronic communication in related functional materials.1 Both, electron-donor and electron-acceptor character of GQDs and CNDs, make their charge-transfer chemistry rather versatile. Charge-separated states are observed in the photoexcitation of CNDs previously endowed with electron-donating extended tetrathiafulvalenes (exTTF) or electron-accepting 11,11,12,12-tetracyano-9,10-anthra-p-quinodimethanes (TCAQ).
In a different approach, the top-down synthesis of chiral GQDs by covalent functionalization of GQDs with chiral ligands has been explored.2 Chirality can actually be transferred to a supramolecular structure built with pyrene molecules, where the chiral-GQDs/pyrene ensembles show a characteristic chiroptical response depending on the configuration of the organic ligands introduced on the GQDs structure. Furthermore, amide hydrogen bonding and π-π stacking interactions could drive the self-aggregation process to construct supramolecular polymers at the nanoscale (Figure).
Within this contribution, we will present and discuss the most recent advances on the use of CDs in our group.

References

a) Ferrer-Ruiz, A.; Scharl, T.; Haines, P.; Rodríguez-Pérez, L.; Cadranel, A.; Herranz, M. A.; Guldi, D. M.; Martín, N. Angew. Chem. Int. Ed.
2018, 57, 1001-1005; b) Scharl, T.; Ferrer-Ruiz, A.; Saura-Sanmartín, A.; Rodríguez-Pérez, L.; Herranz, M. A.; Martín, N.; Guldi, D. M. Chem. Commun.,
2019, 55, 3223-3226; c) Ferrer-Ruiz, A.; Scharl, T.; Rodríguez-Pérez, L.; Cadranel, A.; Herranz, M. A.; Martín, N.; Guldi, D. M. J. Am. Chem. Soc.
2020, 142, 20324−20328.

a) Vázquez-Nakagawa, M.; Rodríguez-Pérez, L.; Herranz, M. A.; Martín, N. Chem. Commun., 2016, 52, 665-668, b) Vázquez-Nakagawa, M.; Rodríguez-Pérez, L:, Martín, N.; Herranz, M. A.; Angew. Chem. Int. Ed.,
2022, 61, e202211365.

Figure 1