A series of water-soluble copolymers containing multi-fluorophore (PRNPHs) were synthesized for detecting Fe3+ in the existence of I-. Such copolymers can turn the fluorescent intensity response to the color change as a result of different fluorescence quenching degrees of each kind of fluorophores in the same copolymer chain. The color change based on PRNPH-4, one of the multi-fluorophore-containing copolymer, from near-white to red is observed by naked eyes after Fe3+ on 10(-6) M level was added into the aqueous solution. Fe3+ on 10(-7) M level can be detected by fluorescence spectra photometer. Other ions like Cu2+, Zn2+, Cd2+, Cr3+, Li+, Ca2+, and Pb2+ were also studied, and found almost no response. The proper concentration of PRNPH-4 for detecting Fe3+ in 10(-6) M is evaluated as 0.2 mg ml(-1) and the model curve of fluorescence intensity versus Fe3+ concentration is established. (C) 2010 Elsevier B.V. All rights reserved.