Construction of two lanthanide schiff base complexes: Chiral "triple-decker" structure and NIR luminescent response towards anions

Highlights: • The complexes show "triple-decker" and "cross" structures. • The complexes display typical NIR lanthanide luminescence. • The Zn–Nd complex exhibits lanthanide luminescent response towards anions. Two 4f and 3d-4f complexes [Yb₃L₃(OAc)₃] (1) and [Zn₂NdL₂(OAc)₃] (2) were constructed from Schiff base ligand N,N′-bis(3-methoxysalicylidene)(4-methylphenylene)-1,2-diamine (H₂L). 1 shows a chiral "triple-decker" structure with Yb³⁺ ions sandwiched between the alternating layers of Schiff base ligands, while 2 exhibits a "cross" structure with the Nd³⁺ ion clipped by two ZnL groups. Open 3D channel structures running along the a-axis are formed in the solid state of 1 and 2. Excited by ligand-centered absorption bands, 1 and 2 show typical NIR emission of Yb³⁺ and Nd³⁺, respectively. Interestingly, 2 exhibits lanthanide luminescent response towards anions, especially to CN⁻ and OAc⁻ at ppm level.