Acoplamientos catalizados por paladio en cationes heteroaromáticos: síntesis y propiedades ópticas no lineales de cromóforos catiónicos

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The development of new organic materials with nonlinear optical properties (NLO) was one of the aims of research over the past decades due to their potential use in the field of telecommunications, optical computing and processing and optical data storage, among others. The advantages of organic compounds compared to inorganic crystals are its low cost, ease of processing and high number of structural variability, which makes them very attractive to industry. Most organic compounds with non-linear optical (NLO) properties are based on highly conjugated molecules with donors and acceptors substituted at the two ends of the molecule, called donor-acceptor (push-pull) systems, and these are amongst the most interesting structures for new compounds with efficient NLO responses. The PhD project presented in this report is framed in the context of a search for new molecules push-pull type, based on heteroaromatic cations as acceptors of the system (for these systems has been appointed a new name as NLO-catiophores), and partly in the development of the synthesis of new macrocyclic rigid cationic nature. First we describe the synthesis and study of nonlinear optical properties by Hyper-Rayleigh Scattering (HRS) of new push-pull system based on heteroaromatic cations. They were obtained through the development of the Suzuki, Heck and Sonogashira reactions. We have demonstrated that organotrifluroborates are better efficient partners than boronic acids for the Suzuki coupling reaction with pyridinium and, Moreover, the ease with which these potassium organotrifluoroborates reacted with azinium and quinolizinium salts in water and the coupling products can be isolated is a further advantage of the procedure and provides a new means for accessing to a great variety of substituted cations. It has proved possible to Heck coupling with aryl iodides with the four isomers of vinilquinolizinium. We have achived the synthesis of a series of D-A and D-A-D catio-phores by Sonogashira cross-coupling reaction from aziniun and quinolizinium bromoderivatives. Noting the overall study ONL values of selected molecules can be obtained the following conclusions: a) heteroaromatic cations type azinium and quinolizinium have good NLO properties (sHRS values between 25-500 10-30 esu). In general, for the pyridinium cation, substitution at the C4 produces best response NLO and in case of cation quinolizinium position C2 is best. b) electrodonating substituent favor the charge transfer on the system Donnor-Acceptor. Moreover it was found that the quinolizinium cation is better acceptor increasing the value of hyperpolarizability. On the other hand, in this context of development of new materials, we considered introducing the quinolizinium system on macrocyclic structures shape-persistent type, i.e. a rigid skeleton formed by aryl units linked together by triple bonds, which resulting in large molecular surfaces. These properties make the AEMs (arylene-ethynylene macrocycles), structures of interest in the field of organic materials.

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