Solution studies of lanthanide (III) complexes based on 1,1,1,5,5,5-hexafluoro-2,4-pentanedione and 1,10-phenanthroline Part-I: Synthesis, H NMR, 4f-4f absorption and photoluminescence |
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Authors: | Zubair Ahmed |
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Institution: | Department of Chemistry, Jamia Millia Islamia, New Delhi 110 025, India |
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Abstract: | Solution studies on the complexes of the type Ln(hfaa)3(phen)2] (Ln = La, Pr and Nd) and Ln(hfaa)3phen] (Ln = Nd, Ho, Er and Yb; hfaa stands for the anion of 1,1,1,5,5,5-hexafluoro-2,4-pentanedione and phen stands for 1,10-phenanthroline) are presented. These complexes are synthesized in high yields by an in situ method in which hfaa, ammonium hydroxide, lanthanide chlorides and phen were allowed to react in 3:3:1:1 molar ratio in ethanol. In the case of neodymium both eight- and ten-coordinate complexes are isolated. The paramagnetic shifts of the methine protons of β-diketone have their sign opposed to those of paramagnetic shifts of phen protons and the shifts are dominated by dipolar interactions. The inter- and intramolecular shift ratios have been calculated and discussed. The 4f-4f absorption spectra of the complexes of Pr, Nd, Ho and Er are analyzed. The eight- and ten-coordinate neodymium complexes display distinctively different band shapes of the 4G5/2,2G7/2 ← 4I9/2 hypersensitive transition. The efficient energy transfer from ligand to Pr(III) is reflected by strong red luminescence of this complex at room temperature. |
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Keywords: | Lanthanides Hexafluoroacetylacetone NMR Luminescence 4f-4f Absorption Hypersensitivity |
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