Synthesis of NIR-harvesting hybrid nanomaterials

This PhD thesis describes the design, the study and the synthesis of NIR-harvesting hybrid nanomaterials, consisting of an inorganic (noble metal) and an organic component. Indeed, this strategy can be applied to enhance the emission of proper NIR dyes by exploitation the plasmon-enhanced fluorescence (PEF). This phenomenon rises from the coupling of the organic dyes with plasmonic nanostructures, such as nanoparticles (NPs), and nanorods (NRs). In the first part of the thesis, a host-guest approach was studied and exploited in order to have a control on the aggregation of nanostructures and, in principle, to modify their properties. In particular, the attention was focused on the synthesis of calix[n]arene derivatives used either as multivalent hosts for the decoration of noble metal NPs and NRs or as aggregators for properly functionalized NPs. In the second part of the thesis, the work was focused on the design and the synthesis of the organic part of the hybrid nanomaterial. Firstly, cyanine-type dyes characterized by a D-A-D structure (D = donor, A = acceptor) were prepared. The central acceptor core is represented by the croconic acid and for this reason these dyes are called croconates or croconaines. In order to have a better interaction and a major control on the effective coupling between the dye and the surface, the introduction of linker units, basically on the donor, was design. The linkers are characterized by the presence of a functional group in order to have a covalent grafting of the dyes on the metal (e.g. thiol, amine, carboxylic acid). Another type of NIR-compound is represented by acene class. On this topic, a research period of three months was spent in the laboratories of CEMES-CNRs of Toulouse (France) with the aim to obtain suitable precursors for the construction of long acenes and [16]starphene(5.5.5).