SYNTHESIS AND CHARACTERIZATION OF SUBSTITUTED GROUP CONTROLLED PYRENE DERIVATIVES WITH RADICAL CATIONS

Two novel alkyl thiophene-modified pyrene derivatives (1)-(2) were created and synthesized using palladium-catalyzed Stille coupling processes and Friedel-Crafts reaction of pyrene. The polycyclic aromatic groups of the thiophene-modified pyrene were oxidized with Ag[Al(OC(CF₃)₃)₄] to provide the insensitive radical cations 1^•+-2^•+ based on the alkyl thiophene-modified pyrene derivatives. Nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), UV-Vis spectroscopy, and density functional theory (DFT) calculations, were used to investigate their structures and properties. The pyrene moieties were the primary location of the electron spin distribution, with a little overflow onto the outer thiophene moieties. Due to the different substituent groups, free radicals 1^•+ 2^•+ exhibit some different properties. Compound 1^•+ is the most extensive thiophene-modified pyrene radical cation that has been reported. These species are anticipated to have wide-ranging potential in the areas of optoelectronic materials and semiconductors.

Keywords:
thiophene; pyrene; radical; cation; aromatic hydrocarbon.