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Structural, Thermal, and Fluorescence Properties of Eu(DBM)3Phenx Complex Doped in PMMA

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journal contribution
posted on 2010-10-21, 00:00 authored by A. K. Singh, S. K. Singh, H. Mishra, R. Prakash, S. B. Rai
Tris (dibenzoylmethanido) (o-phenanthroline)-europium(III) complexes [Eu(DBM)3(Phen)x] have been synthesized, and their structural, thermal, and fluorescence properties have been investigated both as an independent complex and also after embedding it in poly(methyl methacrylate) (PMMA) polymer matrix. X-ray analysis reveals an unusual crystalline to amorphous transformation in structure of the Eu(DBM)3Phenx complexes when x exceeds 1.0 (mole %). Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) analysis depict the interaction between the Eu(DBM)3Phenx complex and the PMMA matrix. The fluorescence intensity of Eu3+ ion in the Eu(DBM)3Phen1·5 complex is an order of magnitude larger compared to the Eu(DBM)3·2H2O complex. In addition to the transition 5D07F2, which has a rise time of 83 μs, transitions from the 5D1 and 5D2 levels are also observed, along with several ligand field splittings in the Eu(DBM)3Phen1·5 complex. Appearance of a rise time (∼0.76 ns) in the decay of the fluorescence from DBM in the presence of Phen and a simultaneous large decrease in the fluorescence intensity (both the singlet and triplet emission) of DBM along with a decrease in fluorescence decay time, in the presence of Eu3+, indicates a cascading excitation energy transfer from Phen to DBM and finally to the 5D0 state of Eu3+ ion in Eu(DBM)3Phen1.5 through short-range excitation energy transfer. A systematic and significant improvement in the thermal and fluorescence properties of the complex is observed with an increase in the mole concentration of Phen. The maximum fluorescence is observed for Eu(DBM)3Phen1·5, which is a new composition as compared with the usual composition reported earlier. This finding indicates the possibility for the development of brighter luminescent lanthanide photonic materials.

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