| Abstract [eng] |
During this work, 8 new organic compounds were synthesized: three target derivatives of bis(N-carbazolyl)biphenyl baring cyano ant tret-butyl substituents, and 5 intermediate compounds used for their synthesis. The compounds were synthesized according to the reported procedures (Buchwald-Hartwig, Rosenmund-von Braun) but in the micro-wave reactor which allowed to shorten the processes by several times. The yields of 3,3'-disubstituted biphenyls were up to 70%. Unfortunately, 2,2'-biphenyl derivatives were not obtained by the methods tested. All the new compounds were characterized by means of nuclear magnetic resonance, infrared spectroscopy and mass spectrometry, their thermal, electrochemical and photophysical properties were investigated as well. 3,3'-bis(N-carbazolyl)biphenyls exhibited high thermal stability since changes in the weight of their samples were observed only above 350 °C. Two of these materials are capable of glass formation (existence in solid amorphous state) with glass-transition temperatures of 116 and 153 °C. A glass of the rest compound was not obtained since it melted at very high temperature together with chemical decomposition. The bis(N-carbazolyl)biphenyls discussed absorb ultraviolet (UV) radiation down to 355 nm, their fluorescence peaks are situated in the range of 344 – 373 nm (UV-violet light) and the ones of phosphorescence are in the range of 413 – 534 nm (violet-to-sky-blue light). Triplet energy values for these materials were estimated according to their phosphorescence spectra and were found to be 2.94 – 2.97 eV. The values of ionization potentials and electron affinities were estimated according to the data of electrochemical measurements as well electronic spectroscopy and were found to be in the range of 5.80 – 6.32 and 2.31 – 2.83 eV, respectively. According to the data obtained, the synthesized bis(N-carbazolyl)biphenyls can be regarded as suitable host materials for energy transfer to blue-light emitters in organic light-emitting devices. |
