8-hydroxyquinoline luminescence intensity

The luminescence properties of ligand 68 and its complexes have been examined.125 As shown in Figure 7, uncomplexed 68 exhibits a very weak luminescence band (d> < 5 X 10-5, t < 0.5 ns) centered at 540 nm in MeOH/H20 (1 1 v v), which is consistent with the luminescence behavior of 8-hydroxyquinoline in protic solvents. Also, no appreciable luminescence intensity increase was observed from pH 2 to 13 with uncomplexed 68. However, addition of Mg2+ to 68 (5 x 10 5 M) in a neutral (1 1 v v) MeOH/H20 solution (pH 7.2) results in a strong enhancement of the luminescence band ( = 0.042, t = 7.4 ns). Upon complexation with Mg2+ and excitation at 393 nm, the fluorescence intensity of 68 is increased by a factor of 1000. The excitation spectrum of the complex strictly matches the absorption spectrum of 68-Mg2+, suggesting that the observed fluorescence is due to neutral complex formation. 

NIR luminescence intensity for the Nd(III) or Yb(III) species. The most intense NIR emitting 8-hydroxyquinolinate lanthanide(III) complexes are the tetrakis complexes with 5,7-dihalo-8-hydroxyquinoline ligands. 

After this first report of NIR electroluminescence using Er hydroxyquinolinate, H. Suzuki et al. investigated the luminescence characteristics of this complex under different sample forms which can further be used as NIR emissive materials. Three types of samples have been prepared vacuum-deposited thin-films, doped spin-coated IR polymer films and doped polymer microparticles (Suzuki et al., 2003). Typical NIR luminescence of the Er ion was observed at 1.55 pm for each sample form and with higher intensities when excitation was performed in the ligand absorption bands instead of directly in the Er excited levels. This clearly indicates that sensitization of Er -centered luminescence occurs through ligand-to-metal energy transfer. For the doped monodispersed PMMA microparticles the lower lumi-... 

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