RNA templated water soluble Mg2+/PbSe porous nanostructures with dual fluorescence

This paper reports the synthesis and photophysics of quantized porous RNA mediated Mg2+/PbSe nanohybrids. These particles display an onset of absorption at 1.03 eV and dual fluorescence in both the red region and NIR range (700-1150 nm). The quantum efficiencies of fluorescence in the red and NIR regions are observed to be 0.02 and 0.38, respectively. The presence of Mg2+ induces new supramolecular interactions among the RNA matrix, Pb2+ and PbSe bringing a change in the morphology from spherical to porous. Interactions among different components have been analyzed by using electronic, IR and NMR spectroscopy and morphological changes have been investigated by performing AFM, FE-SEM and TEM analysis. Based on these investigations a scheme for the generation of porosity in these nanohybrids has been proposed. The presence of Mg2+ results in increased oscillator strength in PbSe enhancing the absorption coefficient in both the visible and NIR ranges, which makes them suitable for solar energy conversion devices. The confinement of PbSe in the porous nanostructures induces the non-radiative relaxation populating shallow traps resulting in the blue shifted fluorescence associated with a reduction in the intensity and fluorescence lifetime. The dual fluorescence observed in the red and NIR ranges, having fairly long lifetimes of 204 and 24 ns, respectively, makes them suitable for biomedical and clinical applications, specifically for the bioimaging of tissues.