Synthesis, Properties and Fundion of Cage-shaped Oligothiophenes

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Unfortunately, we could not obtain the target compounds, which is cage molecules contsracted with oligothiophene chains, we prepared a cage compound bridged with diacetylene units, a precursor of the target, and got several new findings during the synthetic studuies.The most bothering feauture is a unexpected high reactivity of bond between silicon and carbon on thiophen ring. To functionalize thiophene rings of tris (2-thienyl) silane derivatives, the selection of the fourth substituent on the silicon atom is important. Sterically hindered substituent is requared for protection of carbon-silicon bond from reactants. We found that isobutyl group is bearable to some reactions, but it is still nessesary for searching better substituent.The cage compound bridged with diacetylene units is prepared by Pd-catalyzed oxidative coupling of triethynyl derivative, though the yield was low. The structure of the compound was determined by X-ray crystallography. In crystal, it has C3 symmetry, propably due to the long carbon-silicon bond. Furthermore, the UV-Vis and fluorescence spectra reflect the effect of silicon atom. While significant bathochromic shift was not observed by comparison with non-caged analoge, absorption coefficients were remarkably increased. Relatively strong fluorescent was shown on the cage compound.