Synthesis of alkylated π-extended heterocyclic for applications as advanced molecular materials
quinoxaline; benzimidazole; phenazine; advanced molecular materials
In the last years, advanced molecular materials has boosted the development of organo-eletronics fields, with detachment to OLED and liquid crystal devices, especially due their semiconductor properties. In this context, this work present the synthesis and characterization of new organic materials based on three aza-heteroyclcic nuclei: quinoxaline, benzimidazole and phenazine, functionalized with dodecyl groups. Reaction of oxalic acid and o-phenylenodiamine afforded 1,4-dihydroquinoxaline-2,3-dione, which reacted with dodecylbromide under controlled conditions to produce mono- and disubstituted targets 1-dodecyl-1H-quinoxaline-2,3-dione e 1,4-didodecylquinoxalina-2,3-dione, respectively. Benzimidazole derivatives were obtained via reaction of o-phenylenediamine and 4-dodecyloxybenzaldehyde, affording target 2-(4-dodecylocy-phenyl)1H-benzimidazole, which underwent alkylation for produce other compound of interest, 1-dodecyl-2-(4-dodecylocy-phenyl)1H-benzimidazole. Lastly, phenazine derivative was obtained by a three-step protocol, including oxidation of hydroquinone to 2,5-dihydroxy-[1,4]benzoquione, which react with o-phenylenediamine to afford 2,3-dihydroxyphenazine. Alkylation of this latter with two equivalents of dodecyl bromide led to the target 2,3-didodecyloxyphenazine. In general, target-compounds were obtained in good yields, and were adequately characterized by melting point as well as infrared and NMR (1H and 13C) spectroscopies. Addition of long alkyl chains (C12) led to lowering melting points of the compounds of interest. We are currently investigating additional thermal properties of this new heteroyclces by thermogravimetric analyses, differential scanning calorimetry and polarized optical microscopy. Additionally, optical behavior of target-molecules are being studied by TV-Vis and fluorescence spectroscopies. These new compounds are expected to present features that make them proper for applications as advanced molecular materials.