Synthesis, crystal structure, and photoluminescence of lanthanide fumarates (Ln = Sm, Eu, Nd, Er)
Synthesis, crystal structure, and photoluminescence of lanthanide fumarates (Ln = Sm, Eu, Nd, Er)
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富马酸镧系元素（Ln = Sm、Eu、Nd、Er）的合成、晶体结构和光致发光
DOI：
10.1016/j.poly.2015.08.037
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
P. Starynowicz
中科院分区：
文献类型：
--
作者：
Natalia Pawlak;G. Oczko;P. Starynowicz
研究了富马酸与三价镧系元素的络合作用。在适当的水溶液缓慢蒸发过程中，形成了Ln 2（C4 O 4 H2）3· 8H 2 O（Ln= Sm，Eu，Nd）和Er 2（C4 O 4 H2）3·12 H2O单晶。对富马酸钐（III）进行了光谱研究，并解析了钐（III）（1）、铕（III）（2）、钕（III）（3）和铒（III）（4）配合物的晶体结构。发现富马酸Nd、Eu和Sm是同构的（空间群P1 '），但Er化合物不同（空间群P2 1/c）。在前三种晶体中，有一个不依赖于水的Ln（III）阳离子，其采用9配位几何结构，其中6个氧原子来自羧酸根基团，3个氧原子来自水分子。在Er（III）络合物中，金属离子是八配位的（来自富马酸酯羧基的六个原子和两个水分子）。在所有四种晶体中，形成三维聚合物结构。对于Sm（III）富马酸盐，电子（吸收和发射）光谱记录在室温和低温下。在293 K和77 K的发射光谱中，峰对应于6 H J项的4个J能级（J= 5/2，7/2，9/2，11/2），这些跃迁在77 K分裂，表明Sm 3+离子的低对称性。紫外-可见光谱中最强的跃迁是超灵敏的4G 5/2→ 6 H9/2跃迁，并计算了I（4G 5/2→ 6 H9/2）/I（4G 5/2→ 6 H5/2）（η Sm）比值。根据吸收光谱计算出的电子云膨胀比β和Sinha参数σ，表明顺丁烯二酸钐到反丁烯二酸钐的Sm-O键的“共价度”降低。
The complexation of trivalent lanthanides with fumaric acid was studied. Monocrystals of Ln 2 (C 4 O 4 H 2) 3· 8H 2 O (Ln= Sm, Eu, Nd) and Er 2 (C 4 O 4 H 2) 3· 12H 2 O were formed during the slow evaporation of appropriate aqueous solutions. The spectroscopic investigations were performed for samarium (III) fumarate, and the crystal structures were solved for the samarium (III)(1), europium (III)(2), neodymium (III)(3), and erbium (III)(4) complexes. It was found that the Nd, Eu, and Sm fumarates were isostructural (space group P 1¯), but the Er compound was different (space group P2 1/c). In the three former crystals, there is one symmetry-independent Ln (III) cation, which adopts a 9-coordinate geometry with six oxygen atoms from the carboxylate groups and three oxygen atoms from water molecules. In the Er (III) complex, the metal ion is eight-coordinated (six atoms from the fumarate carboxyl groups and two water molecules). In all four crystals, 3-dimensional polymeric structures are formed. For Sm (III) fumarate, electronic (absorption and emission) spectra were recorded at room and low temperatures. In the emission spectra at 293 K and 77 K, peaks correspond to four J levels of the 6 H J term (J= 5/2, 7/2, 9/2, 11/2), and these transitions split at 77 K indicating the low symmetry of the Sm 3+ ion. The most intense transition in UV–Vis is the hypersensitive 4 G 5/2→ 6 H 9/2 transition, and the I (4 G 5/2→ 6 H 9/2)/I (4 G 5/2→ 6 H 5/2)(η Sm) ratio was calculated. The nephelauxetic ratio β and Sinha’s parameter σ, calculated on the basis of the absorption spectra, suggested the decrease in the “degree of covalency” of the Sm–O bond from Sm maleate to Sm fumarate.