Synthesis and characterization of luminescent 2,7-disubstituted silafluorenes

The synthesis and characterization of a series of six new highly fluorescent 2,7-alkynyl(aryl)-3,6-dimethoxy-9,9-diphenylsilafluorenes was investigated utilizing a modified multi-step synthetic pathway in which the final step utilizes palladium-catalyzed cross-coupling conditions to incorporate a variety of conjugated – alkynyl(aryl) groups at the 2,7-positions. These new compounds were characterized utilizing X-ray crystallography as well as multinuclear NMR, EA, TGA, DSC, UV–Vis, and fluorescence spectroscopic techniques. The new silafluorene compounds show a strong absorption band in the visible region with a maximum in the region of 374–388 nm and an emission maximum in the range of 403–420 nm. The solution-state quantum efficiencies for the luminescence are high and range from 0.80 to 0.89. All of the compounds show high thermal stability as determined by DSC and TGA analysis.

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