Simultaneous fluorescence and phosphorescence in Zn(ii)–zwitterionic coordination polymers with tunable colors

Abstract

Three similar ionic-type ligands which can provide ligand-centred charge transfer (LCCT) have been employed to synthesize three isostructural complexes, respectively. Due to the coordination of the ligands to the metal centres, all of the above mentioned complexes feature fluorescence and phosphorescence properties simultaneously. The mechanism of the luminous process is ligand-centred charge transfer (LCCT) combined with metal-to-ligand charge transfer (MLCT) processes. More interestingly, one compound manifests tunable colors from yellow to blue emissions involving white emission by varying the temperature and/or excitation wavelength directly. Experimental and computational results indicate that the differences in luminous properties originate from the ligand distortion combined with different electron states. Thus, this study provides a facile method to synthesize new single-component tunable-color luminescent coordination polymers with simultaneous fluorescence and phosphorescence.