The synthesis, characterization, and new optical property of M(Co and Fe)-phenylalanine complexes

► Long flake-like Co(II)-PLL and sphere-like Fe(II)-PLL complexes were successfully synthesized by a refluxing method. ► The reaction time plays the key role during the whole process of the M-PLL complexes growth. ► The intensity of the peaks of M-PLL in photoluminscence spectra increased twice or more compared with that of pure PLL.