Spielberg Eike T, Edengeiser Eugen, Mallick Bert, Havenith Martina, Mudring Anja-Verena
Inorganic Chemistry III, Ruhr-University Bochum, Universitätsstrasse 150, 44801 Bochum (Germany).
Chemistry. 2014 Apr 25;20(18):5338-45. doi: 10.1002/chem.201302777. Epub 2014 Mar 18.
The compound (C4C1py)[Cu(SCN)2], (C4C1py = 1-Butyl-4-methyl-pyridinium), which can be obtained from CuSCN and the ionic liquid (C4C1py)(SCN), turns out to be a new organic-inorganic hybrid material as it qualifies both, as a coordination polymer and an ionic liquid. It features linked Cu(SCN)2 units, in which the thiocyanates bridge the copper ions in a μ1,3-fashion. The resulting one-dimensional chains run along the a axis, separated by the C4C1py counterions. Powder X-ray diffraction not only confirms the single-crystal X-ray structure solution but proves the reformation of the coordination polymer from an isotropic melt. However, the materials shows a complex thermal behavior often encountered for ionic liquids such as a strong tendency to form a supercooled melt. At a relatively high cooling rate, glass formation is observed. When heating this melt in differential scanning calorimetry (DSC) and temperature-dependent polarizing optical microscopy (POM), investigations reveal the existence of a less thermodynamically stable crystalline polymorph. Raman measurements conducted at 10 and 100 °C point towards the formation of polyanionic chain fragments in the melt. Solid-state UV/Vis spectroscopy shows a broad absorption band around 18,870 cm(-1) (530 nm) and another strong one below 20,000 cm(-1) (<500 nm). The latter is attributed to the d(Cu(I))→π*(SCN)-MLCT (metal-to-ligand charge transfer) transition within the coordination polymer yielding an energy gap of 2.4 eV. At room temperature and upon irradiation with UV light, the material shows a weak fluorescence band at 15,870 cm(-1) (630 nm) with a quantum efficiency of 0.90(2) % and a lifetime of 131(2) ns. Upon lowering the temperature, the luminescence intensity strongly increases. Simultaneously, the band around 450 nm in the excitation spectrum decreases.
化合物（C4C1py）[Cu（SCN）2]（C4C1py = 1-丁基-4-甲基吡啶鎓）可由硫氰酸铜和离子液体（C4C1py）（SCN）制得，它被证明是一种新型有机-无机杂化材料，因为它兼具配位聚合物和离子液体的特性。它具有相连的[Cu（SCN）2]⁻单元，其中硫氰酸根以μ1,3-方式桥连铜离子。由此形成的一维链沿a轴延伸，被C4C1py抗衡离子隔开。粉末X射线衍射不仅证实了单晶X射线结构解析结果，还证明了配位聚合物可从各向同性熔体中重新形成。然而，该材料表现出离子液体常见的复杂热行为，例如形成过冷熔体的强烈倾向。在相对较高的冷却速率下，可观察到玻璃态的形成。当在差示扫描量热法（DSC）和变温偏光显微镜（POM）中加热该熔体时，研究揭示存在一种热力学稳定性较差的晶型。在10和100°C下进行的拉曼测量表明熔体中形成了多阴离子链片段。固态紫外/可见光谱在约18,870 cm⁻¹（530 nm）处显示出一个宽吸收带，在20,000 cm⁻¹以下（<500 nm）还有另一个强吸收带。后者归因于配位聚合物内d（Cu（I））→π*（SCN）-MLCT（金属-配体电荷转移）跃迁，产生的能隙为2.4 eV。在室温下用紫外光照射时，该材料在15,870 cm⁻¹（630 nm）处显示出一个弱荧光带，量子效率为0.90（2）%，寿命为131（2）ns。降低温度时，发光强度强烈增加。同时，激发光谱中约450 nm处的谱带减弱。
