Highly Luminescent and Thermally Stable Lanthanide Coordination Polymers Designed from 4-(Dipyridin-2-yl)aminobenzoate: Efficient Energy Transfer from Tb3+ to Eu3+ in a Mixed Lan
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- 作者：A. R. Ramya ; Debajit Sharma ; Srinivasan Natarajan ; M. L. P. Reddy
- 刊名：Inorganic Chemistry
- 出版年：2012
- 出版时间：August 20, 2012
- 年：2012
- 卷：51
- 期：16
- 页码：8818-8826
- 全文大小：404K
- 年卷期：v.51,no.16(August 20, 2012)
- ISSN：1520-510X
文摘
Herein, a new aromatic carboxylate ligand, namely, 4-(dipyridin-2-yl)aminobenzoic acid (HL), has been designed and employed for the construction of a series of lanthanide complexes (Eu3+ = 1, Tb3+ = 2, and Gd3+ = 3). Complexes of 1 and 2 were structurally authenticated by single-crystal X-ray diffraction and were found to exist as infinite 1D coordination polymers with the general formulas {[Eu(L)3(H2O)2]}n (1) and {[Tb(L)3(H2O)].(H2O)}n (2). Both compounds crystallize in monoclinic space group C2/c. The photophysical properties demonstrated that the developed 4-(dipyridin-2-yl)aminobenzoate ligand is well suited for the sensitization of Tb3+ emission (桅overall = 64%) thanks to the favorable position of the triplet state (3蟺蟺*) of the ligand [the energy difference between the triplet state of the ligand and the excited state of Tb3+ (螖E) = 3蟺蟺* 鈥?5D4 = 3197 cm鈥?], as investigated in the Gd3+ complex. On the other hand, the corresponding Eu3+ complex shows weak luminescence efficiency (桅overall = 7%) due to poor matching of the triplet state of the ligand with that of the emissive excited states of the metal ion (螖E = 3蟺蟺* 鈥?5D0 = 6447 cm鈥?). Furthermore, in the present work, a mixed lanthanide system featuring Eu3+ and Tb3+ ions with the general formula {[Eu0.5Tb0.5(L)3(H2O)2]}n (4) was also synthesized, and the luminescent properties were evaluated and compared with those of the analogous single-lanthanide-ion systems (1 and 2). The lifetime measurements for 4 strongly support the premise that efficient energy transfer occurs between Tb3+ and Eu3+ in a mixed lanthanide system (畏 = 86%).