Structure-property relationships of star-shaped blue-emitting charge-transporting 1,3,5-triphenylbenzene derivatives

Three star-shaped derivatives of 1,3,5-triphenylbenzene bonded to fluorene moieties with various linking groups were designed and synthesized. The three dendritic compounds are characterized by high values of decomposition temperature (up to 434 degrees C) and form glasses with glass transition temperatures ranging from 55 to 75 degrees C. The star-shaped compounds emit light in the deep blue region (385-412 nm) and their solutions exhibit moderately high fluorescence quantum yields in the range of 0.40-0.54. The obtained molecules show relatively small values of the optical gaps ranging from 2.50 to 3.08 eV. The layers of the compounds exhibit hole mobility values in the range of 4.9.10(-4)-2.4.0(-3) cm(2)/V s at electric field 1.10(5) V/cm. A comparative study of the experimentally estimated and theoretically calculated (DFT method) characteristics of the 1,3,5-triphenylbenzene showed that the geometry, optical and electrochemical properties of the star-shaped molecules depend on the degree of conjugation and the nature of the linking bridge. (C) 2015 Elsevier Ltd. All rights reserved.