Zheng Xiu-Ying, Du Ming-Hao, Amiri Mehran, Nyman May, Liu Qiang, Liu Tao, Kong Xiang-Jian, Long La-Sheng, Zheng Lan-Sun
Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
Institutes of Physical Science and Information Technology, Key Laboratory of Structure and Functional Regulation of, Hybrid Materials of Ministry of Education, Anhui University, Hefei, 230601, P. R. China.
Chemistry. 2020 Jan 27;26(6):1388-1395. doi: 10.1002/chem.201904636. Epub 2020 Jan 9.
Atomically precise molecular metal-oxo clusters provide ideal models to understand metal oxide surfaces, self-assembly, and form-function relationships. Devising strategies for synthesis and isolation of these molecular forms remains a challenge. Here, the synthesis of four Ln-Fe oxo clusters that feature the ϵ-{Fe } Keggin cluster in their core is reported. The {Fe } metal-oxo cluster motif is the building block of two important iron oxyhydroxyide phases in nature and technology, ferrihydrite (as the δ-isomer) and magnetite (the ϵ-isomer). The reported ϵ-{Fe } Keggin isomer as an isolated molecule provides the opportunity to study the formation of ferrihydrite and magnetite from this building unit. The four currently reported isostructural lanthanide-iron-oxo clusters are fully formulated Y Fe (TEOA) (Hyp) (μ -OH) (μ -O) (H O) ⋅50 H O (1, Y Fe ), Gd Fe (TEOA) (Hyp) (μ -OH) (μ -O) (H O) ⋅50 H O (2, Gd Fe ) and Ln Fe (TEOA) (Hyp) (μ -OH) (μ -O) (H O) (NO ) ⋅n H O (Ln=Y for 3, Y Fe , n=37 and Ln=Gd for 4, Gd Fe n=25; Hyp=trans-4-Hydroxyl-l-proline and TEOA=triethanolamine). The next metal layer surrounding the ϵ-{Fe } core within these clusters exhibits a similar arrangement as the magnetite lattice, and Fe and Ln can occupy the same positions. This provides the opportunity to construct a family of compounds and optimize magnetic exchange in these molecules through composition tuning. Small-angle X-ray scattering (SAXS) and high-resolution electrospray ionization mass spectrometry (HRESI-MS) show that these clusters are stable upon dissolution in both water and organic solvents, as a first step to performing further chemistry towards building magnetic arrays or investigating ferrihydrite and magnetite assembly from pre-nucleation clusters.
原子精确的分子金属氧簇为理解金属氧化物表面、自组装以及结构与功能关系提供了理想模型。设计这些分子形式的合成和分离策略仍然是一项挑战。在此，报道了四种以核心为ϵ-{Fe } 凯gin簇的镧系 - 铁氧簇的合成。{Fe } 金属氧簇基序是自然界和技术中两种重要的羟基氧化铁相——水铁矿（作为δ - 异构体）和磁铁矿（ϵ - 异构体）的构建单元。所报道的作为分离分子的ϵ-{Fe } 凯gin异构体为研究从该构建单元形成水铁矿和磁铁矿提供了机会。目前报道的四种同构镧系 - 铁 - 氧簇的完整化学式为Y Fe (TEOA) (Hyp) (μ -OH) (μ -O) (H O) ⋅50 H O（1，Y Fe ）、Gd Fe (TEOA) (Hyp) (μ -OH) (μ -O) (H O) ⋅50 H O（2，Gd Fe ）以及Ln Fe (TEOA) (Hyp) (μ -OH) (μ -O) (H O) (NO ) ⋅n H O（Ln = Y时为3，Y Fe ，n = 37；Ln = Gd时为4，Gd Fe ，n = 25；Hyp =反式 - 4 - 羟基 - l - 脯氨酸，TEOA =三乙醇胺）。这些簇中围绕ϵ-{Fe } 核心的下一层金属表现出与磁铁矿晶格相似的排列，并且Fe和Ln可以占据相同位置。这为构建一系列化合物并通过组成调整优化这些分子中的磁交换提供了机会。小角X射线散射（SAXS）和高分辨率电喷雾电离质谱（HRESI - MS）表明，这些簇在溶解于水和有机溶剂中时都是稳定的，这是朝着构建磁性阵列或研究从预成核簇组装水铁矿和磁铁矿进行进一步化学研究的第一步。
