Structural Tuning and Sensitization of Uranyl Phosphonates by Incorporation of Countercations into the Framework

• Published in: Inorganic chemistry Vol. 58; no. 2; pp. 1382 - 1390
• Main Authors: Tang, Si-Fu, Hou, Xiaomin
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 22.01.2019
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.8b02904

By the introduction of terephthalic acid, tetramethylammonium chloride, and Zn2+ ions, three new uranyl triphosphonates with varying crystal structures, namely, [H3O]­[(UO2)2­(HL)]·​H2O (1), [NMe4]­[(UO2)2­(HL)­(H2O)]·​H2O (2), and [(UO2)3­Zn­(H2L)2­(H2O)2]·​3H2O (3), where H6L = benzene-1,3,5-triyltris­(methyl­ene) triphosphonic acid, have been successfully synthesized and characterized by means of powder and single crystal XRD, IR, EA, TGA, UV–vis, and luminescence. These three compounds all possess three-dimensional framework structures with hydrium, tetramethylammonium, and Zn2+ as the respective countercations. The uranium­(VI) center luminescence of compounds 1 and 2 is completely quenched. However, the incorporation of Zn2+ into the matrix of uranyl phosphonate in the case of compound 3 results in the emerging of the typical intense vibronic emissions of U­(VI), demonstrating that zinc phosphonate can behave as sensitizer of uranyl phosphonates. The quenching and sensitization mechanism were also discussed.