Novel rare earth coordination polymers with greatly enhanced fluorescence by synergistic effect of carboxyl-functionalized poly(arylene ether nitrile) and 1,10-phenanthroline

Abstract

A series of novel rare earth coordination polymers were synthesized using carboxyl-functionalized poly(arylene ether nitrile) (CPEN) as a macromolecular ligand, europium and terbium ions as central ions, and 1,10-phenanthroline (Phen) as a small-molecule coligand. The experimental results confirmed that the rare earth ions were simultaneously coordinated with the carboxyl groups of CPEN and Phen in the ternary coordination polymers. It was worth noting that the fluorescence intensity of the ternary coordination polymers was greatly enhanced by the synergistic coordination of CPEN and Phen, which benefited from the efficient energy transfer from CPEN and Phen ligands to rare earth ions. Furthermore, it was found that the fluorescence intensity increased with increasing Eu3+ ion content in ternary coordination polymer, and the critical Eu3+ ion concentration when fluorescence quenching occurred was as high as 11.5 wt%. As a result, the ternary coordination polymers exhibit intense, characteristic red (Eu3+) and green (Tb3+) emission under UV excitation both in the powder and film state. In addition, the rare earth coordination polymers showed a high glass transition temperature (251 °C) and high thermal stability, offering great potential applications as light-emitting devices, fluorescence detectors and sensors in special environments (e.g., high-temperature environment, extreme environments).