Polycyclic aromatic hydrocarbons (PAHs) are an environmentally relevant class of molecules that have been repeatedly introduced into waterways. The EPA has listed 16 priority PAHs for study, which were selected considering abundance and perceived harmfulness. These molecules have characteristic absorption and fluorescence spectra; however, low concentrations can make differentiation and quantitation challenging.  The conjugated core of these hydrocarbons can interact with fluorescent moieties containing complementary aromatic systems to afford a method of detection through the modulation of their fluorescence emission. We developed a series of aromatic polymers that can interact with small PAHs. These polymers contain a fluorene backbone, with variations occurring in the spacing of the aromatic core, as well as different substituents branching off the backbone. In this study we focus on polymers including phenylbenzimidazole groups or polyethylene glycol chains as pendant chains.  Introducing aliquots of PAH into polymer solutions in DMF gradually quenches the fluorescence of these polymers, to different extents and at different molar ratios. The ability of small PAH molecules to quench the fluorescence of these polymers is not only a function of adventitious donor-acceptor interactions, but also of the relative sizes of the binding sites provided by the polymers.  These polymers have been used to differentiate PAHs in solution via optical spectroscopy. Data interpretation was carried out by linear discriminant analysis (LDA). The interaction patterns between these polymers and the structurally similar 16 PAHs is sufficiently rich and nuanced that it contains sufficient information for chemical differentiation of these species.

Chemical fingerprinting of polycyclic aromatic hydrocarbons by fluorescent conjugated polymers

256th National Meeting (2018)

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