Two Octa-Nuclear {Ln₈} (Ln = Tb, Dy) Complexes with "4+4" Covalent Organic Macrocycles: Structure, Solution Behavior, Luminescence, and Magnetic Properties

In this study, two octa-nuclear lanthanide complexes consisting of a templated Ln(8) (Ln = Tb, Dy) cluster and a '' 4 + 4 '' type Schiff-base covalent organic macrocycle, named Ln(8)L(4+4), were constructed successfully. The stepwise solution assembly process of Tb8L4+4 from the initial organic subcomponents and metal templates was tracked as Tb1L1+2 -> Tb2L1+2 -> Tb3L1+2 -> Tb3L2+2 -> Tb4L2+2 -> Tb4L3+2 -> Tb5L3+2 -> Tb6L3+2 -> Tb8L4+4, through ESI-MS technology. Interestingly, Tb8L4+4 can be used as a sensitive and selective fluorescence-sensing material to determine the level of dipicolinic acid (DPA), and Dy8L4+4 has the characteristics of a single molecule magnet behavior.