Synthesis, characterization, and fine turning of optical properties of soluble π-conjugated system with nitro-phenyl-activated 1, 3, 4-oxadiazole unit

A pi-conjugated polymer, with nitro group in the main chain, poly(2-nitro-p-phenylene-1, 3, 4-oxadiazole) [PNPO], has been synthesized and characterized. Unlike many oxadiazole derivatives with poor solubility, this product exhibited good solubility in DMF, DMSO, and formamide. Its characterization has been done by FT-IR, H-1 NMR, C-13-NMR, TGA, DSC, SEM, XRD, UV-Vis spectroscopy, fluorescence spectroscopy, and Z-scan measurement. PNPO showed excellent film-forming properties upon blending with 0.2 weight percentage of poly(methyl methacrylate)/poly(styrene). It has been observed to emit bluish green light with a maximum emission wavelength at 547-554 nm region. The further reduction of PNPO into nano-dimension has been found to enhance the emission maximum. Interestingly, PNPO exhibits good antimicrobial characteristics, under examination with E. coli and Staphylococcus. It has also been found to possess good thermal stability. PNPO has been proposed as an ideal candidate for making the active layers in polymer light-emitting diodes.