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.