Sensory response of pegylated and siloxanated 4,8-dimethylcoumarins: A fluorescence quenching study by nitro aromatics

Coumarins comprise a very large class of phenolic compounds and are well known for their optical properties. Co-polymers of 4,8-dimethylcoumarins with poly(ethylene glycol) (PEG) and polydimethylsiloxane (PDMS) have been synthesized using Candida antarctica lipase as a catalyst under solventless condition. These co-polymers can be coated as thin films without significant aggregation of the chromophores. The low Tg of PEG and PDMS may facilitate porous structure in solid thin films which allows quencher molecules to easily diffuse in and out of these films. Fluorescence quenching of these co-polymers containing 4,8-dimethylcoumarin and their response to electron-deficient aromatic compounds, 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT), have been investigated in both solution and thin film. The response of these polymeric sensors is promising and can easily detect DNT and TNT at few parts per billion levels.