Mei Lei, Wang Cong-Zhi, Zhu Liu-Zheng, Gao Zeng-Qiang, Chai Zhi-Fang, Gibson John K, Shi Wei-Qun
School of Radiological and Interdisciplinary Sciences and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University , Suzhou 215123, China.
Chemical Sciences Division, Lawrence Berkeley National Laboratory (LBNL) , Berkeley, California 94720, United States.
Inorg Chem. 2017 Jul 17;56(14):7694-7706. doi: 10.1021/acs.inorgchem.7b00312. Epub 2017 Jun 23.
The reaction of uranyl nitrate with terephthalic acid (HTP) under hydrothermal conditions in the presence of an organic base, 1,3-(4,4'-bispyridyl)propane (BPP) or 4,4'-bipyridine (BPY), provided four uranyl terephthalate compounds with different entangled structures by a pH-tuning method. UO(TP)·2HO (1) obtained in a relatively acidic solution (final aqueous pH, 4.28) crystallizes in the form of a noninterpenetrated honeycomb-like two-dimensional network structure. An elevation of the solution pH (final pH, 5.21) promotes the formation of a dimeric uranyl-mediated polycatenated framework, (UO)(μ-OH)(TP)·4.5HO (2). Another new polycatenated framework with a monomeric uranyl unit, (UO)(TP) (3), begins to emerge as a minor accompanying product of 2 when the pH is increased up to 6.61, and turns out to be a significant product at pH 7.00. When more rigid but small-size BPY molecules replace BPP molecules, UO(TP) (4) with a polycatenated framework similar to 3 was obtained in a relatively acidic solution (final pH, 4.81). The successful preparation of 2-4 represents the first report of uranyl-organic polycatenated frameworks derived from a simple HTP linker. A direct comparison between these polycatenated frameworks and previously reported uranyl terephthalate compounds suggests that the template and cavity-filling effects of organic bases (such as BPP or BPY), in combination with specific hydrothermal conditions, promote the formation of uranyl terephthalate polycatenated frameworks.
在水热条件下，硝酸铀酰与对苯二甲酸（HTP）在有机碱1,3-(4,4'-联吡啶基)丙烷（BPP）或4,4'-联吡啶（BPY）存在下反应，通过pH调节法得到了四种具有不同缠结结构的铀酰对苯二甲酸化合物。在相对酸性溶液（最终水溶液pH为4.28）中获得的UO(TP)·2HO（1）以非互穿蜂窝状二维网络结构的形式结晶。溶液pH升高（最终pH为5.21）促进了二聚铀酰介导的多链框架(UO)(μ-OH)(TP)·4.5HO（2）的形成。当pH升高到6.61时，另一种具有单体铀酰单元的新型多链框架(UO)(TP)（3）开始作为2的次要伴随产物出现，而在pH为7.00时成为主要产物。当更刚性但尺寸较小的BPY分子取代BPP分子时，在相对酸性溶液（最终pH为4.81）中获得了具有与3类似的多链框架的UO(TP)（4）。2-4的成功制备代表了源自简单HTP连接体的铀酰-有机多链框架的首次报道。这些多链框架与先前报道的铀酰对苯二甲酸化合物之间的直接比较表明，有机碱（如BPP或BPY）的模板和空穴填充效应，与特定的水热条件相结合，促进了铀酰对苯二甲酸多链框架的形成。
