Significant enhancement of curcumin photoluminescence by a photosensitizing organogel: An optical sensor for pyrrole detection

A curcumin organogel was prepared using an organogelator of N′1,N′6-bis(3-(1-pyrrolyl)propanoyl) hexanedihydrazide (DPH), and its photoluminescence properties were examined for sensor applications. The organogelator created a yellow curcumin organogel and considerably enhanced curcumin photoluminescence through the photosensitization effect. Specifically, the DPH organogel allowed the curcumin organogel to be excited over a wider range of visible light. Due to the organogelator, the quantum yield of curcumin photoluminescence increased to around 50%. A series of control experiments with variations in solvent composition and concentrations of organogelator verified that both the solvent composition and the phase transition from solution to organogel remarkably enhanced photoluminescence. The curcumin organogel was exploited as a sensor material that selectively recognizes pyrrole among heterocyclic compounds because of the molecular similarity of DPH with pyrrole. Due to the properties of a gel, nonlinear photoluminescence quenching behavior suggests both static and dynamic quenching mechanisms. In summary, the curcumin organogel showed significantly enhanced photoluminescence due to the DPH organogelator, and this material could be utilized as a soft solid platform for optical pyrrole detection.