Anion-tunable architectures of Zn(II) complexes of a bis-pyridyl-bis-amide ligand: Syntheses, crystal structures and properties

Abstract Through natural evaporation of the reaction solutions of ZnX 2 (X = Cl − , CH 3 COO − and SCN − ) and the ligand 2,6-bis(pyridine-4-carboxamido)pyridine ( L ), three new coordination compounds, [Zn( L )(Cl) 2 ] n · n CH 3 OH· n H 2 O ( 1 ), [Zn( L )(CH 3 COO) 2 ] 2 ( 2 ) and [Zn( L ) 3 (SCN) 2 ] n ( 3 ) have been obtained. In these zinc(II) complexes, ligand L displays various conformers and coordination modes to fabricate the helical chain of 1 , the discrete dimer of 2 and the zigzag chain of 3 , with the coordination number of Zn II varying from 4 for 1 , 5 for 2 to 6 for 3 . Through complementary amide hydrogen bonds, their structures are extended into chiral layers, 1D ribbons and a 3D supramolecular network, respectively. Interestingly, the coordination numbers of Zn II , as well as the molecular and supramolecular structures of the resulting coordination complexes, are obviously tuned with the X anion used. Additionally, the TGA of 1 and 2 as well as the fluorescence of the free ligand L and 1 were measured in the solid state.