Homochiral coordination polymers from a chiral dicarboxylic acid and dipyridyl ligands: Structural diversity, photoluminescence and magnetic properties

Utilizing the mixed-ligand strategy, six new homochiral coordination polymers based on enantiopure (1R,2R)-1,2-cyclohexanedicarboxylic acid and varied auxiliary bipyridyl ligands, [Zn3(L)2(OH)2] (1), [Cu3(HL)2(L)2(bpy)3]·4H2O (2), [M(L)(bpe)2(H2O)2]·H2O (M = Co, 3; Ni, 4; Cd, 5), [Ni(L)(bpa)(H2O)3]·2H2O (6), [H2L = (1R,2R)-1,2-cyclohexanedicarboxylic acid, bpy = 4,4′-bipyridine, bpe = 1,2-bis(4-pyridyl)ethylene, bpa = 1,2-bis(4-pyridyl)ethane] have been hydrothermally synthesized. Compound 1 shows a 2D 63-hcb network in the absence of any bipyridyl ligand. Compound 2 is a 2D (4,4)-connected grid network in the presence of bpy. Compounds 3–5 are isomorphous and feature 1D staggered-sculls chains by using bpe instead of bpy. Compound 6 possesses a 1D left-handed helical chain sustained by flexible bpa ligand. Each type of these coordination structures is further extended into 3D supramolecular frameworks through different intermolecular interactions. Solid-state circular dichroism (CD) spectra of compounds 1–6 exhibit strong CD signals. Magnetic susceptibility measurement indicates weak antiferromagnetic interactions between the Cu(II) ions in compound 2. Compound 5 displays a strong fluorescent emission at 413 nm in solid state at room temperature.