Cerium-based triple-stranded helicates as luminescent chemosensors for the selective sensing of magnesium ions

Cerium-based triple-strand helicates Ce-CL1 and Ce-CL2 were achieved via self-assembly from malonohydrazone derived bis-tridentate ligands H2CL1 and H2CL2, respectively. Structure analysis of Ce-CL1 shows that six oxygen atoms of the beta-diketone groups on the ligands form a lantern-like cavity inside the helicate. Thus the helicates exhibit crown ether recognition behaviors and could work as luminescent magnesium chemosensors. The restricted geometry constraints of the internal cavities provide high selectivities of the helical probes towards Mg2+ ion over other alkaline and alkaline-earth ions such as Li+, Na+, K+, Ca2+ and Ba2+.