An optical sensing platform for the dual channel detection of picric acid: The combination of rhodamine and metal-organic frameworks

Abstract For the present work, a dual channel optical sensing composite for the detection of picric acid (PA) was constructed, using luminescent lanthanide MOF as supporting substrate and a rhodamine-based dye as sensing probe, respectively. This composite material was discussed in detail by means of electron microscopy images, XRD, IR, TGA, absorption and emission spectra. These rod-liked composite nanocrystals had dual sensing channels towards PA, including colorimetric sensing and ratiometric fluorescent sensing. A linear working curve with limit of detection as low as 10 μM was obtained. Good selectivity towards PA was confirmed. Their sensing mechanism was discussed and found as the combination of proton-triggered rhodamine structural transformation and nitrophenyl-triggered Eu emission quenching. This composite material showed a superior sensing performance over literature ones owing to its dual sensing channels and the possibility of naked eye detection.