A series of luminescent
phenoxo-bridged dinuclear TbIII complexes with tripodal
ligands, 2,2′-[[(2-pyridinylmethyl)imino]di(methylene)]-bis(4-R-phenol),
where R = CH3 (LCH3) (I), Cl (LCl) (II), CH3O (LCH3O) (III), COOCH3 (LCOOCH3) (IV), were prepared to probe the effect of para-substitution
on the phenol ring of the ligand on the TbIII luminescence.
For these TbIII complexes a complete suppression of the
ligand-centered fluorescence is observed, which demonstrates an efficient
ligand-to-metal energy transfer. Complex IV was found
to be the one that shows the greater intensity of the emission at
room temperature. The obtained quantum yields follow the trend IV > II ≫ I > III. The quantum yield for II and IV is approximately
five times greater than those obtained for I and III, indicating that the LCl and LCOOCH3 are better sensitizers of the TbIII ions. These results
were rationalized in terms of the variation of the energy gap between
the triplet level (T1) of the ligand and the emissive 5D4 level of TbIII, due to the electron-acceptor
or electron-donor properties of the substituents. The τav values are in the millisecond range for all the studied
complexes and resulted independent of temperature. The Commission
International d’Eclairage coordinates (CIE) for all complexes
are in the green color region, being insensitive to the variation
of temperature. Moreover, the color purity (CP) is ca. 90% for all
complexes, being ca. 100% for IV. Thus, the introduction
of electron-acceptor substituents on the ligand permitted us to improve
the luminescent properties of the TbIII complexes.
We report the intercalation of PrIII and NdIII macrocyclic complexes into the layered hexahypothiophosphate MnPS3 and the effect of this process on the optical and magnetic properties of the layered...
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