Synthesis and physical property of uranium-containing porous coordination polymer

铀、镎和钚的多价配合物的颜色在很大程度上取决于金属离子的氧化状态，通常可以通过金属离子溶液的颜色来确定金属离子的氧化状态。由于铀的天然同位素的半衰期很长，所以它的放射性很弱，因此含铀化合物可以作为先进材料得到一些应用。在本研究中，采用不同的光谱方法研究了1-烷基-3-甲基咪唑阳离子的铀酰硫氰酸盐配合物的黄到红的温度依赖性变化，这种现象归因于铀酰离子的局部环境的变化，包括配位数，以及阳离子。离子相互作用。该结构包含3个NCS^-阴离子和1个C_2mim^+阳离子的无序性。U-O键距离(1.766（8),1.765(9)A）和O-U-O键角（171.2(9)1°）在铀酰部分的预期范围内。平均U-N距离为2.45 A，与[DPSH]_3[UO_2(SCN)_5]（DPSH=2-吡啶基硫代-2-吡啶）和Cs_3[UO_2(SCN)_5]的平均U-N距离为2.45 A接近。然而，在这个结构中，纯铀酰硫氰酸酯在77 K时的时间分辨发光光谱与平均值有很大的差异，距离较短（U-N=2.398(11) A）和距离较大（U-N=2.513(10) A），这是铀酰硫氰酸酯尚未发现的。各向异性结构可能在铬反应中起重要作用。由于硫氰酸盐和咪唑阳离子之间的弱相互作用，硫氰酸盐的配位几何形状是不稳定的和灵活的。

The colors of the multi-valent complexes of uranium, neptunium and plutonium strongly depend on the oxidation state of the metal ion, and it is often possible to determine the oxidation state of the metal ion from the color of its solutions. Given the fact that uranium is only weakly radioactive due to the long half-lives of its naturally occurring isotopes, uranium-containing compounds could find some applications as advanced materials.In the present study, temperature-dependent yellow-to-red colour changes of uranyl thiocyanate complexes with 1-alkyl-3-methylimidazolium cations have been studied by different spectroscopic methods and this phenomenon is attributed to changes in the local environment of the uranyl ion, including the coordination number, as well as to cation. anion interactions.The structure contained disorder in three of the NCS^-anions and one C_2mim^+cation. The U-O bond distances(1.766(8), 1.765(9) A) and the O-U-O bond angle(171.2(9) 1°) are in the range expected for the uranyl moiety. The mean U-N distance is 2.45 A which is close to that seen in[DPSH]_3[UO_2(SCN)_5](DPSH=2-pyridylthio-2-pyridinium) and Cs_3[UO_2(SCN)_5] which both have mean U-N distances of 2.45 A. However, in this structure there are large variations from the mean with much shorter distances(U-N=2.398(11) A) and large distances(U-N=2.513(10) A), Time-resolved luminescence spectra, at 77 K, of neat uranyl which have not been known for uranyl-thiocyanates. The anisotropic structure could play an important role in the chromic reactions. Due to the weak interaction between the thiocyanate and imidazolium cation, labile and flexible coordination geometries for thiocyanate are allowed.