Synthesis of pyrene-1-carbaldehyde nanorods and emission tuning by the fluorescent ratiometric change

Pyrene-1-carbaldehyde (PyCHO) nanorods were prepared by a simple reprecipitation method. The morphologies and the structures of the as-prepared PyCHO nanorods were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Unlike pyrene, PyCHO has a preferable packing direction due to the hydrophilic group (CHO), facilitating the formation of one-dimensional structures. The photophysical properties of the as-prepared aqueous dispersions of PyCHO nanorods were investigated, and it is found that the aggregates and the solvated PyCHO coexist in the aqueous dispersion system. Upon increasing the concentration of PyCHO, the emission of the solvated PyCHO was quenched while the emission of the nanostructures gradually increased. Thus, an emission tuning was achieved by the fluorescent ratiometric change in the aqueous suspension and in the polymer film blended with PyCHO nanostructures, which may provide an alternative way to achieve tunable emission.