1D and 2D Zn–Ln coordination polymers based on compartment compounds: [ZnLn(L)(NO3)2(4-ppa)(EtOH)] and [ZnLn(L)(NO3)2(4-pca)(H2O)] (Ln = Eu, Tb; H2 L = 1,3-bis((3-methoxysalicylidene)amino)propane; 4-Hppa = 4-pyridinepropionic acid; 4-Hpca = 4-pyridinecarboxylic acid)

Abstract

This paper describes the preparation of four 3d–4f (3d=Zn; 4f=Eu, Tb) coordination polymers and their emission quenching of the lanthanide ions. Two dinuclear Zn–Ln compartment compounds, [ZnLn(L)(NO3)(CH3CN)(H2O)4](NO3)2(H2O) (Ln=Eu, Tb), were prepared at room temperature by stirring an acetonitrile solution containing [Zn(L)] (H2L=1,3-bis((3-methoxysalicylidene)amino)propane) and Ln(NO3)3·n(H2O). When these compounds were treated with 4-pyridinepropionic acid (4-Hppa) under microwave-heating conditions, one-dimensional Zn–Ln coordination polymers were formed: [ZnLn(L)(NO3)2(4-ppa)(EtOH)] (Ln=Eu (1), Tb (2)). By contrast, these compounds reacted with pyridine-4-carboxylic acid (4-Hpca) to give two-dimensional Zn–Ln coordination polymers: [ZnLn(L)(NO3)2(4-pca)(H2O)] (Ln=Eu (3), Tb (4)). All the compounds (1–4) exhibited the emission quenching of the Ln3+ ion, probably due to the Ln3+→Zn2+ energy transfer.