Two-/three-dimensional open lanthanide–organic frameworks containing rigid/flexible dicarboxylate ligands: synthesis, crystal structure and photoluminescent properties
Two-/three-dimensional open lanthanide–organic frameworks containing rigid/flexible dicarboxylate ligands: synthesis, crystal structure and photoluminescent properties
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DOI：
10.1039/c3ce26684b
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发表时间：
2013-02
期刊：
影响因子：
3.1
通讯作者：
Ping Wang;Ruiqing Fan;Xinrong Liu;Li-yuan Wang;Yulin Yang;W. Cao;Bin Yang;W. Hasi;Q. Su
中科院分区：
文献类型：
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作者：
Ping Wang;Ruiqing Fan;Xinrong Liu;Li-yuan Wang;Yulin Yang;W. Cao;Bin Yang;W. Hasi;Q. Su
三个系列的二维和三维稀土配位聚合物{[Ln(Ox)1.5(H2O)3]·mH2O}n[Ln=Ce(1)，m=2和Pr(2)，m=3，H2ox=草酸]，{[Ln(Ox)2(H3O)]·Etoh·3H2O}n[Ln=Nd(3)，Sm(4)，Eu(5)，Gd(6)，Tb(7)，Dy(8)，Ho(9)，Er(10)和Yb(11)，乙醇]和{[LN_2(IMDC)_2(H_2O)_3]·mH_2O}n[Ln=Sm(12)，Eu(13)，Gd(14)，Tb(15)和Dy(16)，其中m=2.25，m=1.75，H3IMDC=咪唑-4，5-二元酸]。用元素分析、红外光谱和X-射线单晶衍射法对所有配位聚合物进行了表征。配位聚合物1-11表现出两种不同的结构类型：配位聚合物1-2的二维结构是一个(6，3)连接的HCB网络，配位聚合物3-11表现为具有66-网络拓扑结构的三维钻石结构。配位聚合物12-16是由IMDC3DNA的桥联羧基构筑而成的三维结构，其中IMDC3DNA桥联类−的双螺旋和三螺旋，相互缠绕连接成一维链，然后沿ab平面构象成三维结构。描述和讨论了两种不同结构的二羧酸盐配体(草酸为柔性配体，咪唑-4，5-二羧酸为刚性平面配体)。此外，配位聚合物在可见光区的发光性质和荧光寿命表现出相应的稀土离子的特征跃迁。研究发现，配位聚合物5和7具有较长的固体荧光寿命，分别为824.84和733.87μS。测定了Nd(3)、Sm(4和12)、Dy(8和16)和Yb(3)配位聚合物的固态近红外发射光谱。根据配体的紫外可见吸收边和Gd(III)配位聚合物6和14在77K的荧光光谱，分别计算了H_2OX和H_3IMDC的单重态激发态(草酸为30842 cm−1，H3IMDC为32258 cm−1)和最低三重态能级(草酸为23753 cm−1，H3IMDC为22371 cm−1)。讨论了Sm(III)、Eu(III)、Tb(III)和Dy(III)离子的最低三重态能级与最低共振能级之间的关系。结果表明，草酸配体的能量转移比H3IMDC更有效。
Three series of two-dimensional and three-dimensional lanthanide coordination polymers {[Ln(ox)1.5(H2O)3]·mH2O}n [Ln = Ce (1), m = 2 and Pr (2), m = 3, H2ox = oxalic acid], {[Ln(ox)2(H3O)]·EtOH·3H2O}n [Ln = Nd (3), Sm (4), Eu (5), Gd (6), Tb (7), Dy (8), Ho (9), Er (10) and Yb (11), EtOH = ethanol] and {[Ln2(IMDC)2(H2O)3]·mH2O}n [Ln = Sm (12), Eu (13), Gd (14), Tb (15) and Dy (16), where m = 2.25 except for 15 where m = 1.75, H3IMDC = imidazole-4,5-dicarboxylic acid] have been synthesized under hydrothermal conditions. All the coordination polymers have been characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. Coordination polymers 1–11 exhibit two different structural types: the 2-D structure of coordination polymers 1–2 are a (6,3)-connected hcb network, coordination polymers 3–11 appear as a 3-D diamond structure with 66-network topology. Coordination polymers 12–16 are 3-D structures constructed from the bridged carboxyl group of IMDC3−, in which IMDC3− bridged the DNA-like double-helix line and the triple-helix line, intertwined and connected into a 1-D chain and then conformed into a 3-D structure along the ab plane. The different structures of the two dicarboxylate ligands (oxalic acid as a flexible ligand and imidazole-4,5-dicarboxylic acid as a rigid planar ligand) were described and discussed. Furthermore, the luminescent properties in the visible region and the fluorescence lifetimes of the coordination polymers exhibited the characteristic transitions of the corresponding lanthanide ions. It was noted that coordination polymers 5 and 7 have long solid-state fluorescence lifetimes of 824.84 and 733.87 μs, respectively. The NIR emission spectra of the Nd (3), Sm (4 and 12), Dy (8 and 16) and Yb (3) coordination polymers in the solid-state were measured. The singlet excited state (30 842 cm−1 for oxalic acid, 32 258 cm−1 for H3IMDC) and the lowest triplet state energy level (23 753 cm−1 for oxalic acid and 22 371 cm−1 for H3IMDC) of the H2ox and H3IMDC ligand were calculated on the basis of the UV-Vis absorbance edges of the ligand and the phosphorescence spectrum of the Gd(III) coordination polymers 6 and 14 at 77 K, respectively. The relationship between the lowest triplet state energy level of the two dicarboxylate ligands and lowest resonance energy levels of the Sm(III), Eu(III), Tb(III) and Dy(III) ions were described and discussed. The results showed that the energy transfer from the oxalic acid ligands is much more effective than H3IMDC.