Theoretical study of fullerene encapsulation by cycloparaphenylene-based carbon nanorings

Resumo

Since the discovery of fullerene in 1985, a large number of investigations were performed about this carbon curved molecule. During these researches some important electronic properties were found. These properties led to study the possible employment of fullerenes in organic photovoltaic cells due to their low cost, lightweight and they allow us to obtain flexible devices. The problem of these photovoltaic cells is that they have to present highly ordered structures, for this reason the study of the intermolecular forces to sort these structures may be very important. One of the possible applications of these forces is to place the receptors on a surface forming a layer to capture the fullerene through π···π interactions and keep neat the molecules. In the last years a higher number of carbon nanorings were synthesized and due their concave hole there are very promising molecules to use as fullerene receptors. This thesis was realized with different computational techniques and especially remarkable is the use of density functional theory. This thesis is possible to split in two purpose although they are not totally separable: in the first place the interaction between carbon nanorings and fullerenes of different types and size was studied. To carry out this study, different types of fullerenes have been used, including the most abundant C60 and C70, as well as other less abundant fullerenes such as C50, C76 or C78. In addition, it has been considered other fullerenes known as endofulerenos, fullerenes that contain some species inside. These species may contain one or several metallic species or even a small atomic cluster, as in the case of Sc3N@C80, the third most abundant fullerene after C60 and C70. The complexes of these fullerenes with various carbon nanorings have been studied, mainly considering [n]cycloparaphenylenes of different sizes ([n] CPP). Apart from these, other nanorings have been considered, such as [6]CPPA, which was the first synthesized carbon nanoring and it alternates paraphenylene and ethynyl groups, furthermore some other modifications of CPPs like the inclusion of anthracene units was considered too. According to the interaction studies in this block, we would pretend to predict the stability of complexes and obtain information about which are the keys that control the stability in this type of systems.