Near-infrared luminescent erbium complexes with 8-hydroxyquinoline-terminated hyperbranched polyester

- Two novel 8-hydroxyquinoline-terminated hyperbranched polyesters were synthesized.
- Erbium complexes based on modified hyperbranched polyesters were prepared.
- Erbium complexes show intense near-infrared luminescence and wide FWHM.

Novel 8-hydroxyquinoline-terminated hyperbranched polyesters (1-HBPQ and 2-HBPQ) were synthesized and characterized by 1H-NMR and UV-Vis analyses. Then, two erbium complexes (1-HBPQ-Er3+-HQ and 2-HBPQ-Er3+-HQ) were prepared by using 1-HBPQ or 2-HBPQ as the macromolecular ligand and 8-hydroxyquinoline (HQ) as a second ligand. The FTIR spectra and UV-Vis absorption spectra confirmed that both the macromolecular ligand and the second ligand were successfully coordinated with Er3+ ions. The erbium complexes emitted intense near-infrared luminescence at about 1530 nm, which corresponds to the 4I13/2-4I15/2 transition of Er3+ ions. Moreover, their full width at half maximum (FWHM) values were greater than 80 nm. The erbium complexes exhibited good solubility in conventional solvents and excellent near-infrared luminescence properties, indicating their promising potential as gain medium materials in optical amplification devices.

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