Vapochromism of iridium(III) bis-terpyridine complex based on modulation of halide-to-ligand charge transfer transition
Vapochromism of iridium(III) bis-terpyridine complex based on modulation of halide-to-ligand charge transfer transition
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基于卤化物到配体电荷转移跃迁调节的铱(III)双三联吡啶络合物的气致变色
DOI：
10.1039/d2dt00368f
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发表时间：
2022
影响因子：
4
通讯作者：
Kazuteru Shinozaki
中科院分区：
文献类型：
--
作者：
Shingo Hattori;Mio Kondo;Akiko Sekine;Kazuteru Shinozaki
我们首次报道了由于 Ir(III) 双三联吡啶络合物晶体的卤化物到配体电荷转移 (XLCT) 带的移动响应结晶水的吸附/解吸而产生的颜色变化。红色和橙色分别通过热处理和冷处理可逆地发生。单X射线晶体学表明，Ir(III)配合物具有两个结晶水，通过氢键构建二聚体结构，rO-O = 2.911 Å。研究发现，水二聚体通过氢键连接到一个 rO-I = 3.664 Å 的碘离子，并与另一个 rO-I = 3.747 Å 的碘离子接触，这表明晶体中的水解吸很容易改变碘离子 5p 轨道与 tpy π* 轨道之间相互作用产生的 XLCT 跃迁。热重测量揭示了晶体中水的逐步解吸，粉末 X 射线衍射显示了 Ir(III) 络合物晶体骨架在吸附/解吸循环过程中的稳健性。氮气流或极性有机溶剂的存在会导致 XLCT 吸收带的红移，这是由于晶体中的水分子与蒸发的水分子之间的平衡移动导致水分子的解吸。研究发现，暴露于 25% 氨水中的氨蒸气不会导致 Ir(III) 络合物晶体的颜色变化。
We report, for the first time, a color change originating from the shift of the halide-to-ligand charge transfer (XLCT) band of the Ir(III) bis-terpyridine complex crystal in response to the sorption/desorption of water of crystallization. Red and orange coloration reversibly takes place by heat and cool treatments, respectively. Single X-ray crystallography shows that the Ir(III) complex possesses two waters of crystallization constructing a dimer structure, rO–O = 2.911 Å, by hydrogen bonding. It was found that the water dimer connects to one of the iodide ions with rO–I = 3.664 Å by hydrogen bonding and comes into contact with another iodide ion with rO–I = 3.747 Å, suggesting that water desorption from the crystal easily changes the XLCT transition arising from the interaction between the iodide ion 5p orbital and tpy π* orbital. Thermogravimetry measurement reveals the stepwise water desorption from the crystal, and powder X-ray diffraction shows the robustness of the Ir(III) complex crystal framework during the sorption/desorption cycles. Nitrogen gas flow or presence of a polar organic solvent contributes to the red-shift of the XLCT absorption band due to the desorption of water molecules resulted by the shift of equilibrium between water molecules in the crystal and vaporized water molecules. Exposure to ammonia vapor from 25% aqueous ammonia is found not to contribute to the color change of the Ir(III) complex crystal.