Conjugated small organic molecules: synthesis and characterization of 4-arylpyrazole-decorated dibenzothiophenes

4-Arylpyrazole-decorated dibenzothiophenes have been synthesized. The synthesis involves the treatment of 2,8-dibromodibenzothiophene with pyrazole under Ullmann-type amination conditions for the dual C-N bond formation. The selective bromination of the resulting dual C-N bonded 2,8-dipyrazolyldibenzothiophene, and the subsequent Suzuki-Miyaura reaction furnished the target conjugated materials comprising small organic molecules. The electron-deficient dibenzothiophene-S,S-dioxide core was obtained in quantitative yield. UV-Vis absorption studies indicated changes in the positions of the peak maxima upon increasing the conjugation length. Electrochemical and theoretical investigations of selected synthesized materials are also included.