Competitive Coordination of Heterometallic Ions for Synthetic Regulation of Mixed-Ligand Uranyl Coordination Compounds of Halogen-Substituted Isonicotinate

Abstract

In this work, second metal centers are introduced to regulate the coordination behavior of uranyl center in mixed-ligand uranyl compounds with halogen-substituted dichloroisonicotinic acid(H2, 6-dcpca) and 2, 2′-bipyridine(2, 2′-bpy). Through a strategy of diversified competitive coordination via a second metal center(Ag+, Zn2+ and Cu2+), the coordination environment of mixed-ligand uranyl complex was tuned, and six heterometallic uranyl compounds with different second ions, Ag+, Zn2+ or Cu2+, were successfully acquired by hydrothermal synthesis. Single-crystal structures show that these heterometallic nodes can coordinate with ［2, 6-dcpca］- and 2, 2′-bpy as the competitive candidate of uranyl center, and finally lead to different hydrothermal products with varying uranyl coordination patterns and molecular structures. Due to the difference in molecular structure, weak interactions and stacking modes in the supramolecular lattice of these compounds also show different changes. The regulation strategy based on diversified competitive coordination as well as the mixed-ligand method proposed here have been proved to be feasible to achieve the preparation of a diversity of heterometallic uranyl compounds and can be expected to be used for the synthesis and preparation of more valuable functional actinide-organic hybrid materials.

Keywords

• uranyl complexes
• chloroisonicotinic acid
• auxiliary ligands
• heterogeneous metals
• synthetic regulation