Synthesis of highly emissive 1,8-diaryl anthracene derivatives and fabrication of their micro/nanostructures

Abstract

We report a new route for the synthesis of 1,8-diaryl anthracene derivatives (1–6) starting from anthraquinone. The reduction of 1,8-dichoroanthraquinone, followed by aryl–aryl coupling using modified Suzuki–Miyaura reaction conditions, furnished 1,8-diarylanthracene derivatives in a good yield. Detailed photophysical and electrochemical studies show that these anthracene derivatives emit in the blue region with a narrow FWHM and provide high quantum yields (upto 75%). The HOMO and LUMO energy levels of these compounds are in the ranges of −5.62 to 5.71 and 2.68–2.79 eV, respectively. Furthermore, anthracene derivative 5 was used for a surfactant assisted self assembling process to obtain micro/nanostructures. Compound 5 formed microplates in polyvinylpyrrolidone (PVP) and nanowires with an average diameter of ∼290 nm in cetyltrimethylammonium bromide (CTAB). The absorption and emission properties of the micro/nanoassemblies of compound 5 showed a red shift of about 12 nm. It was also noticed that the emission intensity of 5 was retained even in the nanoassemblies, and was found to be comparable with that of the solution of 5 in organic solvents. DFT calculations suggest that multiple hydrogen bonding interactions are possible between two interacting monomers of 5. We believe that the possibility of H-bonding interactions in 5 is one of the factors that may aid the formation of micro/nanoassemblies. The blue emitting properties, compatible HOMO and LUMO energy levels, and highly blue emitting micro/nanoassemblies of these compounds make them suitable materials for organic light emitting devices (OLEDs).