A conjugated polyelectrolyte with symmetrically assembled hydrophilic and hydrophobic side groups along the backbone has been successfully synthesized and demonstrated significant photophysical tunability with 65 nm of wavelength shift and 10-fold of intensity enhancement for the emission maximum, through solvent composition adjustment. The highest fluorescence quenching effect (1/1(0) = 148) toward 10 mu M of Fe3+ was achieved in the solution having a THF/H2O ratio of 30/70, which could be attributed to a delicate balance among the influencing factors for the fluorescence quenching systems, the initial fluorescence, the rate of energy migration, and the accessibility of the receptors. The amplified symmetrical aggregation-nonaggregation inversion and the asymmetrical cation sensitivity across the whole range of H2O/THF composition were consistent with the molecular design.