Ion and molecule sensors using molecular recognition in luminescent, conductive polymers. 1998 annual progress report

摘要

The purpose of this project is to develop sensor technology for detecting specific heavy metal ions, such as transition metals, lead, lanthanides, and actinides in waste streams. The sensing strategy uses molecular recognition of the metal ions by polymers that change their luminescence and conductivity properties upon metal binding. Research problems that are being addressed by this project include: (1) designing molecular recognition sites that are highly selective for the metal ions of interest in the presence of a large background of other chemical species, (2) finding ways to incorporate many different selective groups into a single polymer, (3) fabricating polymer films, strips, sheets, and coatings that can be applied to other materials, such as fiber optics and surfaces, (4) developing interfaces between the polymers and substrates that can be used to produce prototype arrays of many sensor elements for rapid multi-contaminant detection and quantitation, and (5) developing multiplexed data collection techniques to rapidly process the data obtained from many polymer sensors into a chemical profile of a waste stream or waste site in real time. As of June 1, 1998, the authors have prepared several polymers based on the incorporation of 2,2(prime)-bipyridine into poly(phenylenevinylene) polymers. The central idea, illustrated in Figure 1, is to prepare a pseudoconjugated, ligand-containing polymer that upon incorporating metal ions undergoes a conformational change, thus converting the initial partially conjugated polymer to a fully or near fully conjugated one. Such conjugation enhancement,along with the simultaneous electron density change caused by incorporating metal ions onto the backbone of polymers, dramatically changes the optical and conductivity properties of the polymer. These property changes are used to signal the presence of the metal ion analyte. The authors have developed several synthetic routes to these polymers and have demonstrated that they exhibit selective binding properties when exposed to transition metals and lanthanides. In addition, the authors have developed a new polymer that gives us the versatility that they need for rapid attachment of ligands that bind heavy metals, such as lead and plutonium.