Self-Assembly of Discrete Metallocycles versus Coordination Polymers Based on Cu(I) and Ag(I) Ions and Flexible Ligands: Structural Diversification and Luminescent Properties.

Three new Ag(I) and one Cu(I) coordination compounds with two different positional isomers, propane-1,3-diyl bis(pyridine-4-carboxylate) (L1) and propane-1,3-diyl bis(pyridine-3-carboxylate) (L2), of a bis-(pyridyl-carboxylate) ligand have been synthesized. X-ray diffraction analysis revealed that the self-assembly of L1 with AgCF₃SO₃ and AgClO₄ salts leads to the formation of discrete binuclear metallocycles {Ag(L1)CF₃SO₃}₂ (1) and {Ag(L1)ClO₄}₂ (2), respectively. However, self-assembly of the other ligand, L2, with AgCF₃SO₃ and CuCl salts, results in a 1-D zig-zag chain {Ag(L2)CF₃SO₃}∞ (3) and a 1-D double-stranded helical chain {Cu₂Cl₂(L2)₂}∞ (4) coordination polymers, respectively. Solid emission spectra recorded at room temperature show interesting luminescence properties for all four compounds in the range from 438 to 550 nm, especially for compound 4 that was found to change its emission color when the wavelength of the excitation radiation is switched from 332 to 436 nm.