Coordination-driven chiral self-assembly: Synthesis, structures and vapor adsorption properties of Zn(II) and Ag(I) complexes derived from two helical pyridylamide ligands

Two helical pyridylamide ligands N2,N6-bis(2-(nicotinamido)phenyl)pyridine-2,6-dicarboxamide (L1) and N2,N6bis(2-(isonicotinamido)phenyl)pyridine-2,6-dicarboxamide (L2) have been designed and synthesized. Four complexes, namely, {[Zn(L1)I2]center dot 2CH3OH center dot H2O}n (1), [Ag2(L1)2]center dot(NO3)2 (2), {[Ag(L2)NO3]center dot H2O}n (3), and {[Ag (L2)2]center dot 2H2O}n (4) were obtained via the solvent evaporation method from the reaction of the ligands with Zn(II) or Ag(I) ions respectively. The two ligands together with four complexes were structurally determined by singlecrystal X-ray diffraction and additionally characterized by infrared spectroscopy, element analysis and powder Xray diffraction. The crystal structures reveal different chiral self-assembly processes in the reaction of the helical liands with Zn(II) or Ag(I) ions. Complexes 1, 2 and 4 exhibit as a heterochiral coordination polymer or binuclear metallamacrocycle, while complex 3 exists as a homochiral coordination polymer. Besides, the structural differences between complexes 3 and 4 show that the reaction ratio of the ligand with metal ions has obvious influences on the coordination configuration. Furthermore, thermogravimetric analysis and methanol vapor adsorption properties of the synthesized complexes have been investigated, and cyclic voltammetric measurements of complexes 2-4 were carried out as well.