Four 1D and 2D Cadmium(II) Complexes Based on Different Anions and Two Modified Bipyridyl Ligands: Syntheses, Structures, Thermogravimetric, and Fluorescent Properties

A series of cadmium(II) coordination polymers constructed from 1, 3-bis(pyridine-3-carbonyl)imidazolidin-2-thioxo (3-bpit) and 1, 3-bis(pyridine-4-carbonyl)imidazolidin-2-thioxo (4-bpit), namely,{[Cd(SCN)(2)(3-bpit)(2)]center dot 2(CH3OH)}(n) (1), {[Cd(NO3)(2)(3-bpit)(2)]center dot 2(CH3OH)}(n) (2), [CdI2(4-bpit)](n) (3), and [CdCl2(4-bpit)(4)](n) (4) were prepared and characterized by single-crystal X-ray diffraction. Complexes 1 and 2 display different types of infinite 1D helical chain structures, both of which contain 24-membered metallocyclic rings. Complex 3 is composed of 1D zigzag chains, which further form a 3D supramolecular architecture by weak C-H center dot center dot center dot S and S center dot center dot center dot I interactions. Complex 4 also features a 3D supramolecular network assembled from 2D rhombus-shaped layer through intermolecular hydrogen bonding. These structures indicate that the conformation of the ligand and the diverse anions take important roles in the formation of different frameworks. Thermogravimetric and fluorescent properties over complexes are also discussed.