A new Schiff base fluorescent chemosensor (L1) and its reduced form (L2) have been designed and synthesized. Nanoparticles of L2 were also prepared by using a nanoprecipitation method. The nano-chemosensor of L2 shows very high selectivity and sensitivity towards Fe3+ and I- ions in aqueous buffer solution. L2 also shows selective detection and discrimination of Fe3+ and Fe2+ in an aqueous environment. The lowest detectable concentration of Fe3+ ions by L2 was found to be 68 nM.