Structures, and luminescence and magnetic properties of Ln(III)
- 저자
- 강*길
- 게재저널
- Journal of Luminescence 178.2016
- 키워드
- Ln(III) complex, X-ray crystallography, Sensitized luminescence, Quantum yield, Magnetic susceptibility
- 개요
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The single crystal structure, luminescence and magnetic susceptibility of Cs［Ln(DBM)4］ and Ln(DBM)3(phen) (Ln=Eu and Gd, DBM=dimenzoylmethanto and phen=1,10-phenanthroine) were characterized in detail. Apentanuclear Eu(Ⅲ) cluster with the formula, Eu5(DBM)10(OH)5, was obtained from Cs［Eu(DBM)4］ in ethanol, while from Cs［Gd(DBM)4］ in acetonitrile, a one-dimensional polymeric Gd(Ⅲ) assembly with the formula, ｛Cs［Gd(DBM)4］｝n, was achieved via a heterobimetallic backbone, composed of alternating Cs and Gd atoms bridged by DBM. Exciting the Eu(Ⅲ) complexes with ner-UV light produced sensitized red emission by energy transfer from the triplet excited state of DBM to the Eu(Ⅲ)ion.
Replacing DBM by phen increased the quantum yield from Q=8.3% for Cs[Eu(DBM)4] to Q=16.6%for Eu(DBM)3(phen). This was attributed to a reduction in the site-symmetry of Eu(III) from D4h to C2v. The magnetic susceptibilities of the synthesized Ln(III) complexes in the crystalline or powder states were measured using a SQUID magnetometer. The Eu(III) complexes illustrated magnetic anisotropy at low temperatures and temperature-dependent susceptibilities. The coercive field inducing the magnetic anisotropy of Eu5(DBM)10(OH)5 was more than 40-fold stronger than those of Cs[Eu(DBM)4] and Eu(DBM)3(phen). In particular, the calculation based on the Van Vleck's treatment confirmed that the thermal mixing between the excited and ground states played a key role in the temperature-dependent susceptibilities of Eu(III). The magnetic susceptibility of the Gd(III)ion in Gd(DBM)3(phen) was identical to that of the free Gd(III)ion, wheras that of the Gd(III)ion in Cs[Eu(DBM)4] was higher. The phen ligand with the π-conjugate rigid planar structure decreased the magnetic susceptibilities of the Eu(III) and Gd (III) ions.
- 첨부파일
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