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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Novel bimetallic MOF phosphors with an imidazolium cation: structure, phonons, high-pressure phase transitions and optical response
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Novel bimetallic MOF phosphors with an imidazolium cation: structure, phonons, high-pressure phase transitions and optical response

机译：具有咪唑鎓阳离子的新型双金属MOF磷光体：结构，声子，高压相转变和光学响应

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We report the synthesis, crystal structure, phonons and luminescence properties of three novel heterometallic metal organic frameworks (MOFs) with perovskite-like topology of the following formulas: [C3H5N2] Na0.5Cr0.5(HCOO)(3) (ImNaCr), [C3H5N2] Na0.5Al0.5(HCOO)(3) (ImNaAl) and [C3H5N2] Na0.5Al0.475Cr0.025(HCOO)(3) (ImNaAlCr with 5 mol% of Cr3+). ImNaCr crystallizes in a monoclinic system (P2/n space group) with one imidazolium cation (Im(+)) in an asymmetric unit forming six N-H center dot center dot center dot O and four C-H center dot center dot center dot O hydrogen bonds. In contrast to other known heterometallic MOFs, the complete substitution of Cr3+ ions with smaller Al3+ ions leads to a change of the crystal symmetry. ImNaAl adopts a monoclinic P2(1)/n space group with two distinct Im(+) cations and different H-bonding patterns. The DSC measurements and XRD single-crystal studies show that the studied crystals do not undergo structural phase transitions in the 80-400 K range. The high-pressure Raman studies of ImNaCr reveal the presence of two reversible structural instabilities, first in the 0.4-1.1 GPa range and second near 4 GPa. The first pressure-induced phase transition involves weak distortion of the metal-formate framework, while the second one is associated with partial and reversible amorphization of the sample. We discuss the stability of heterometallic formate MOFs depending on their building blocks. The luminescence measurements show that both the fully concentrated crystal (ImNaCr) and the diluted one (ImNaAlCr) exhibit a Cr3+-based emission characteristic of intermediate ligand field strength. We also show that the spectroscopic properties of heterometallic MOFs depend strongly on the templated cation, i.e. the decreasing size of the organic cation leads to an increase in the crystal field.
机译：我们用以下式的钙钛矿状拓扑报告三个新型杂象金属有机骨架（MOF）的合成，晶体结构，声子和发光性质：[C 3 H 5 N 2] Na0.5CR0.5（HCOO）（3）（IMNACR）， [C3H5N2] Na0.5Al0.5（HCOO）（3）（3）（IMAO）和[C 3 H 5 N 2] Na0.5Al0.475CR0.025（HCOO）（3）（癌症5mol％CR3 +）。 IMNACR在单斜替碘（P2 / N空间组）中结晶，在非对称单元中，在不对称单元中形成六个N-H中心点中心点中心点O和四个C-H中心点中心点中心点O氢键。与其他已知的杂机MOF相反，CR3 +离子的完全取代具有较小的Al3 +离子导致晶体对称的变化。血肿性采用具有两个不同IM（+）阳离子和不同H键合图案的单斜晶型P2（1）/ N个空间组。 DSC测量和XRD单晶研究表明，研究的晶体在80-400k范围内不会经过结构相变。 IMNACR的高压拉曼研究揭示了两种可逆结构稳定性的存在，首先在0.4-1.1GPA范围和第二近4GPa附近。第一压力诱导的相变涉及金属甲酸酯框架的弱变形，而第二个压力诱导的畸变与样品的部分和可逆的杂化相关。我们讨论了根据其构建块的杂象夹层MOF的稳定性。发光测量结果表明，全浓缩晶体（IMNACR）和稀释的一种（IMNAALCR）都表现出中间配体场强的CR3 +基于发射特性。我们还表明，异常机制MOF的光谱性质在模板阳离子上强烈地依赖于模板阳离子，即有机阳离子的减小尺寸导致晶体场的增加。

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