Chemically Modified Graphene and Carbon Quantum Dots: Structural, Electronic and Chiroptical Characterization

Abstract

Graphene Quantum Dots (GQDs) and Carbon Quantum Dots (CQDs) are nanomaterials with rising popularity as an alternative to traditional semiconductor quantum dots and organic dyes.1 In addition to simple fabrication methods and low production costs, GQDs and CQDs exhibit a good chemical stability and solubility, unique photophysical properties, photochemical stability, and biocompatibility. These are remarkable properties for applications in fields such as catalysis, photovoltaic devices, bioimaging or medical diagnosis.2 With the objective of constructing versatile and functional ensembles for nanoelectronics and optoelectronics, we lately embarked in the synthesis of these carbon nanomaterials and their covalent or supramolecular modification with ligands that modify their fundamental properties. For instance, adding a chiroptical response to the semiconductor properties of GQDs will provide the extra value of their potential application in photonics. In this sense, we recently proof the concept that GQDs are able to become chiral and that this property can 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 introduced organic ligands.3 We have also combined GQDs and CQDs materials with p-quinonoid π-extended tetrathiafulvalenes (exTTFs)4 in the search for new electron donor-acceptor systems (Figure). The electronic interactions between the CQDs and exTTF have been investigated in the ground and excited states. The characterization of the obtained GQDs and CQDs nanomaterials by a combination of analytical, microscopic and spectroscopic techniques will be presented and discussed, along with the photophysical properties of some of the aggregates formed.