Conjugated silane-based arylenes as luminescent materials

Symetric (4a,b) and asymmetric (7b,c) silane-containing conjugated compounds comprising electron rich benzofurazane, 10-hexylphenothiazine and ethylenedioxytiophene moiety were designed and successfully synthesized by the palladium-catalyzed Suzuki coupling. These compounds have a relatively small band gaps and show strong absorption in the region 300–340 nm. Furthermore, compounds 7b and 7c show light emission in almost the entire visible light (from blue to red region) when symetric compounds emit blue and green light. of synthesized structures The electrochemical study revealed the onset of the oxidation wave was found at rather low potentials. The optical band gap (1.8 eV - 3.39 eV) makes the structures potentially useful as an hosting material for emitters. The lowest electrochemical and optical band gap characterizes asymmetric structure containing silane unit, the largest - structure with benzofurazane moiety. The electrochemical behavior of tetraphenylsilane derivatives was also confirmed by EPR as well as theoretical (density functional theory (DFT)), and time dependent density DFT techniques. The calculations rationalize the difference between electrochemical and optical experimentally measured energy gaps.