Organogel–quantum dots hybrid materials displaying fluorescence sensitivity and structural stability towards nitric oxide

Abstract

Nanoparticle doped hybrid organogels were prepared using the pseudopeptidic macrocycle 1 and CdSe/ZnS quantum dots (QDs). The new semi-solid materials show the same thermal stability and excellent optical transparency as compared to the parent organogel in the absence of the nanoparticles, but they are fluorescent due to the presence of embedded semiconductor nanocrystals. The fluorescence lifetime of a QD–organogel composite is reported for the first time, and it was found to be similar to that of the QDs in solution in a related solvent, independent of the concentration of gelator. The chemical sensing ability of the hybrid organogels towards gaseous nitric oxide was investigated by steady-state fluorescence spectroscopy. The gels show fluorescence sensitivity towards NO ranging from 0.05 to 0.5 (vol%). The results reported herein constitute a proof of principle of the potential of the hybrid supramolecular soft materials to develop nitric oxide sensor devices of practical application, especially because the semi-solid state of the organogel is preserved after interaction with the analyte. This is remarkable since, for the vast majority of organogels with analytical capabilities reported so far, the signaling mechanism relies upon the disassembly of the supramolecular structure.