Design, synthesis and optoelectronic properties of aminoacid derivatives of poly(Arylene ethynylene) platforms: Hybrid bio-synthetic systems for sensoring applications

By means of the modular construction of a large series of poly(arylene ethynylene)s (PAEs) employing Pd-promoted synthetic routes, molecular models of type A-CºC-B-CºC-A and B-CºC-A-CºC-B, and polymers of type [-CºC-A-]<inf>n</inf> and [-CºC-A-CºC-B-]<inf>n</inf> carrying a variety of aminoacidic side arms, have been prepared and fully characterized towards their application as sensing materials. The introduction of different aminoacidic groups as side substituents on the conjugated backbone may allow the tuning of the recognition ability of the receptor site towards given analytes. The luminescent sensing properties of these materials towards metal ions were investigated. The flexibility of the synthetic route allows tuning of binding activity, molecular recognition and opto-and electro-properties of the materials, as well as the responses upon exposure to metal ions. All compounds showed high selectivity towards Hg(II) ions, and a signal amplification in Hg(II) detection was observed for the polymeric compound in comparison with small molecule analogues. Further functionalization of aminoacid substituted PAEs with ferrocene moieties allows the electrochemical sensing by change in the oxidation potential of Fe(II)/Fe(III) redox couple, and its dependence with the interaction of aminoacidic side arms with given analytes.