Construction of a series of mercury(II) complexes based on a bis-pyridyl-bis-amide ligand: Effect of counter anions, interactions on the supermolecular structures

Four new complexes, [Hg(L)Cl2]2 (1), [Hg(L)Br2]2 (2), [Hg(L)I2(DMF)2]n (3), and [HgLCl(SCN)]n (4) (L = N,N-bis-(3-pyridyl)isophthalamide) were obtained through the self-assembly of a rigid conjugated clamp-like bis-pyridyl-bis-amide ligand L with HgX2 (X = Cl for 1, Br for 2, I for 3, and Cl for 4 with the addition of KSCN) and characterized by single crystal X-ray diffraction, elemental analysis, IR spectrum, etc. Employments of different anions result in different structures. Complexes 1 and 2 feature bimetallic macrocycle formed by coordinating two Hg(II) metal centers by two ligands which are in syn–syn conformation. The macrocyclic subunits further self-assemble into a porous macrocycle structure via the hydrogen-bonding and π–π stacking interactions. Introduction of I− and SCN− ions bring about stronger steric hindrance effect. Complexes 3 and 4 are polymers with infinite 1D polymeric chain in herringbone fashion and the hydrogen-bonding interactions and π–π stacking interactions between the parallel benzene rings and the pyridyl rings stabilize the supromolecular framework. Furthermore, we measured their fluorescent properties in the solid state at room temperature and XRD properties also have been determined.