Abstract
A new family of lanthanide/Schiff base complexes have been synthesized and fully characterized from the novel Schiff base ligand: L1, (E)-N′-(dipyridin-2-ylmethylene)acetohydrazide and L2, (E)-N′-(pyridin-2-ylmethylene)acetohydrazide. The single crystal X-ray structure and mass spectroscopy reveal the isostructural mononuclear complexes: [LnL2(NO3)2]NO3and [LnL(HFAC)3]3where Ln = La, Eu, Gd and Tb and HFAC = hexafluoroacetylacetonate. Upon excitation of the Ln(III) complexes in solution, their luminescence spectra display the broad ligand-centred (LC) emission centred at ∼435 nm as well as the narrow f–f transitions. Generally, the ligands can efficiently sensitize the Tb(III) complexes because of the better triplet state energy match to the Tb(III)–5D0excited states. The luminescence lifetimes of the Ln(III)-nitrate chelates are found shorter than those from the corresponding HFAC complexes. The nitrate chelates can quench the luminescence through energy transfer pathways involving π∗–n transitions. The intrinsic quantum yields for the Eu(III) complexes have also been investigated. The ϕEuvalue for the complex Eu1N is found the lowest, 2.9% due to deactivation from intramolecular H-bonding NH⋯N involving the pyridine and amine units in the ligand as proved by X-ray crystallography.
Original language | English |
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Pages (from-to) | 552-560 |
Number of pages | 9 |
Journal | Polyhedron |
Volume | 117 |
DOIs | |
Publication status | Published - 2016 |
Externally published | Yes |
Keywords
- Coordination chemistry
- Crystal structure
- Emission
- Lanthanides
- Photophysics
ASJC Scopus subject areas
- Materials Chemistry
- Inorganic Chemistry
- Physical and Theoretical Chemistry