Trichromatic color tuning strategy for emission of heterometallic Eu^III/Tb^III coordination polymers with triazolyl-substituted 4-methyl-phenoxo ligand

This study presents the microwave-assisted synthesis and characterization of a series of heterometallic coordination polymers (HMCPs) with a 4-methyl-2,6-di[(1H-1,2,4-triazol-1-yl)]phenoxo ligand with varying Eu^III/Tb^III ratios. Single crystal X-ray diffraction reveals a double-chain structure bridged by triazolyl groups. Powder X-ray diffraction confirms the isostructural nature of the synthesized HMCPs. The photophysical properties depend on lanthanide ion concentration and excitation wavelength, leading to a color shift from green to blue as the proportion of Tb^III decreases and Eu^III increases. White light generation is achieved in the 8/2 Eu^III/Tb^III HMCP (CIE: 0.293, 0.326) under 335 nm excitation. The study suggests energy transfer from Tb^III to Eu^III, but both experimental and theoretical calculations indicate that this transfer is orders of magnitude lower than the sensitization through ligand states.