Hyperbranched microspheres formed by an EDTA-based coordination polymer with ternary architectures assembled by ultrathin nanoribbons and their tricolor luminescent properties

Here we report a novel structure of hierarchical coordination polymers with hyperbranched microspheres. The microspheres were formed by the automatic piling of ultrathin nanoribbons with a thickness of 3.5 +/- 0.1 nm, which resulted from the prior self-assembly of the molecules in a ternary architecture. Briefly, the ultrathin nanoribbons of the lanthanide-EDTA coordination polymers were prepared via an Ostwald ripening process, by a simple hydrothermal treatment in an aqueous mixture of lanthanide cations and EDTA-2Na ligands. To satisfy the requirement of a low surface/interface energy, these ultrathin nanoribbons were then self-assembled into multi-layer nanoribbons, followed by the formation of hyperbranched microspheres. Finally, tricolor (red, green and blue, known as RGB) fluorescent hyperbranched microspheres were also prepared by doping with Eu3+, Tb3+ and Zn2+ as luminescent centers, respectively. Our work shows a simple method to fabricate complex structures of coordination polymers and may inspire further studies on hierarchical architectures of coordination polymers.