Nanoorganization of organic chromophores, with nlo and photoluminescent properties, on tetracyclosiloxane rings

During this PhD thesis, a series of sodium arylcyclotetrasiloxanolates properly functionalized in the para position of the aromatic ring, like [4-RC6H4Si(O)ONa]4 and the corresponding (trimethylsiloxy)cyclotetrasiloxanes [4-RC6H4Si(O)OSiMe3]4 (R = Cl, Br, CH=CH2, CH2Cl), were prepared as scaffolds for anchoring second order non-linear optical (NLO) active or fluorescent organic chromophores. The synthesis and the photophysical characterization of an ensamble of four NLO active organic tails nanoorganized on a cyclotetrasiloxane ring to produce various macrocyclic NLO chromophores have been studied, together with their conductimetric and second order NLO response. These macrocyclic NLO chromophores can be considered as a simple model of a monolayer of organic NLO chromophores on a silica surface. Their orientation under the action of a strong electric field, when blended with a poly(methyl methacrylate) matrix, was investigated using the Corona Poling technique. The development of straightforward routes from cyclotetrasiloxane to form fully condensed Janus silsesquioxanes with different moieties on each defined “face” of the cage was also investigated, and a new approach to nanocomposite materials that allows the catalytical and selective interconversion, at ambient temperatures, of a mixtures of polymethylsilsesquioxane (PMS) and polyvinylsilsesquioxane (PVS) to mixed functional group T10 and T12 silsesquioxane structures was developed.