Abstract

With climate concerns consistently growing, the chemical industry must shift away from petrochemicals and turn to sustainable feedstocks derived from lignocellulosic biomass. There is urgency to develop new synthetic methodologies that effectively convert biomass-derived starting materials into useful consumer products. The production of multi-arylated furans and 2,5-furan-based oligomers, has gained popularity as organic candidates for light-emitting diodes or field-effect transistors, owing to their favourable optoelectronic properties found in highly conjugated furan-based materials. Hydroxymethylfurfural and furfural are biomass-derived platform chemicals that have received attention as raw materials due to their chemical functionality, renewability, and capability to produce various furan-containing building blocks. In this work, we aim to develop a synthetic methodology starting from biomass-derived chemicals to design potential optoelectronics. Hydroxymethylfurfural was studied to develop multi-arylated furans; however, a rigid diol monomer was synthesized instead. Working with methyl-5-bromofuran-2-carboxylate led to three different multi-arylated furans via regioselective halogenations followed by Pd-catalyzed cross-coupling reactions. 5-Bromofurfural, a close derivative of biomass-derived furfural, was an ideal candidate to produce ten 2,5-furan-based oligomers and one 2,5-furan-based push-pull chromophore. To rapidly extend the π-conjugation of each material, a double Pd-catalyzed decarboxylative cross-coupling (DCC) reaction was utilized. This strategy fuses two nucleophilic arylated furan acids with a dihalogenated aryl linker to produce highly planar furan-based oligomers. Regarding overall yields of the double DCC, electron-neutral and electron-donating furan acids exhibited higher yields (32 – 74%) than electron-withdrawing acid derivatives (18 – 21%). All furan-based compounds were then characterized by NMR and their absorbance, photoluminescence and quantum yields were studied in dilute solution.