Oligosilanyl-Bridged Biscarbazoles: Structure, Synthesis, and Spectroscopic Properties.

Oligosilanyl-bridged systems are expected to give rise to unique optoelectronic properties because of sigma-pi conjugation between the Si-Si sigma orbital and the aryl pi orbital. Herein, we synthesized a small series of novel biscarbazoles bridged with permethylated oligosilanyl units (- [Si(CH3)(2)]n-, n = 1-4) and examined their spectroscopic properties in detail. In the target molecules BCzSin, n = 2-4, the efficient sigma-pi conjugation elevated the highest occupied molecular orbital energy level with no influence on the lowest unoccupied molecular orbital. In the solid state, the emission full width at half-maximum (fwhm) of all the compounds narrowed significantly, while the emission efficiency increased and the emission color of carbazole was retained. This research provided a very simple and general way of subtly manipulating the electronic properties of organic materials to construct an emissive color-retaining system for multifunctional applications.