p-Oligophenylene-based polymeric fluorescent nanofilms: Synthesis, electrooptical characterization and application in aqueous phase nitroaromatic detection

Abstract

Model compounds and new polymeric materials bearing p-terphenylene and p-quaterphenylene units tethered by their para-positions were synthesized. PTF, with terphenylene groups tethered with C(CF3)2 groups, reached the higher polymerization degrees. All these materials, except PTF, show variable amounts of local ordering in the form of J- and H-aggregates. The insensibility of the fluorescence response of PTF films to casting conditions or the excitation wavelength makes it a good candidate for thin-film chemosensory applications. Thus, thin films of PTF and its biphenylene homolog PBF were used as fluorescent active layers for sensitive detection of nitroaromatics in water media. PTF films are quite sensitive to nanomolar concentrations of TNT, the quenching being a combination of PET and IFE contributions. PBF presents a weaker response to TNT that arises from hindered TNT diffusion into the polymeric film. On the contrary, PBF is very sensitive towards picric acid, PA. The sensing configuration polymeric film/aqueous solution studied here demonstrated promising potential for the direct sensing of nitroaromatics in water bodies of industrial and city areas.