Syntheses,Structures, and Photoluminescence Properties of a Series of 3D Zn‐Ln Heterometallic Complexes with 2,3‐Pyrazine Dicarboxylic Acid as a Bridging Ligand

A series of 3D d–f heterometallic coordination polymers, {[Ln₂Zn(Pzdc)₄(H₂O)₆] · 2H₂O}_n [Ln = La ( 1 ), Pr ( 2 ), Nd ( 3 ), Sm ( 4 ), Eu ( 5 ), Gd ( 6 ), Tb ( 7 ), Dy ( 8 )] (H₂Pzdc = 2,3‐pyrazine dicarboxylic acid), were synthesized by one‐pot reactions under hydrothermal conditions. X‐ray crystallographical analysis and powder X‐ray diffraction analysis reveal that the complexes 1 – 8 are isostructural and adopt a multi‐parallel quadrilateral channel network structure with {4.6 · 2}₂{4 · 2.6 · 2.8 · 2}{6 · 3}2{6 · 5.8}₂ topology, in which the central Ln^III ion is nine‐coordinate by four oxygen atoms and two nitrogen atoms from four ligands and three oxygen atoms from three coordinated H₂O molecules and the central Zn^II ion is six‐coordinate by four oxygen atoms and two nitrogen atoms from four ligands. Moreover, the photophysical properties related to the electronic transition for complexes 4 , 5 , 7 , and 8 were investigated by the excitation and emission spectra as well as the emission lifetimes.