Organophosphate Detection by Multiphase Polydiacetylene Systems

Polydiacetylenes (PDAs) constitute a family of conjugated polymers exhibiting unique colorimetric and fluorescence transitions, and have attracted significant interest as chemo- and bio sensing materials.

The monomer of PDA can easily undergo polymerization upon irradiation with UV light leading to dramatic colorimetric transformations with a blue to red color shift. The advantage of PDA as sensor comes from the fact that PDA-based systems respond to a variety of environmental perturbations, such as temperature, pH, interfacial pressure, and some specific chemical bindings. In addition to its strong colorimetric change, PDA exhibits interesting fluorescent properties. The blue phase of PDA practically appears non-fluorescent while the red-phase of PDA exhibits strong fluorescence at 560 nm and at 640 nm. The chromatic transitions of PDA assemblies are believed to arise from the ene-yne topotactic polymerization process, made possible through self-assembly of the diacetylene monomers stabilized through a hydrogen bond network . This generic structural/chromatic feature of PDA systems has been attained in numerous morphologies; including vesicles, thin films, fibers, stacked domains, and others. In this project, we focused on PDA embedded thin films, vesicles and sol-gel.

In this project, we developed PDA-based sensing analytical platform capable of rapid detection of water pollutants, specifically organophosphates, through simple colorimetric analysis.

In order to improve the specificity of the systems, we have used PDA derivatives containing different head groups. Upon modifying the head group of PDA, we have observed changes in its sensitivity towards the organophosphates. The reason behind this is the determination of the sensor (blue to red) as a result of interactions with the organophosphates.