Transformation of a Luminescent Benzimidazole-Based Yb₃ Cluster into a One-Dimensional Coordination Polymer

Reaction of the benzimidazole-based ligand 2-(1H-benzoimidazol-2-yl)-4-bromo-6-methoxy-phenol (HL) with LnCl3·6H2O in a 4:3 mol ratio in refluxing EtOH gave the trinuclear complexes [Ln3L4Cl4(H2O)2]·Cl·H2O·EtOH (1) (Ln = Tb (a), Er (b), Yb (c)) in 40−59% yields. Under similar conditions, but with the subsequent addition of Zn(OAc)2·2H2O to the reaction mixture, complex {[Yb3L4(OAc)4]·Cl·EtOH}n (2) can be isolated in 48% yield. 2 has a one-dimensional coordination structure in the solid state. All complexes display intramolecular π−π stacking and hydrogen bonded interactions in the solid state as well as lanthanide ion based luminescence in both solution and the solid.