Syntheses, structures, and photoluminescence of three cadmium(II) coordination polymers with flexible bis(benzimidazole) ligands

Abstract

Three cadmium(II) coordination polymers, [CdBr₂(L₁)] _n (1), [CdI₂(L₂)] _n (2), and Cd₂Br₄(L₃)₂ (3), where L₁ = 1,3-bis(5,6-dimethylbenzimidazole)propane, L₂ = 1,4-bis(5,6-dimethylbenzimidazole)butane, and L₃ = 1,6-bis(5,6-dimethylbenzimidazole)hexane, have been synthesized by hydrothermal methods and characterized by elemental analyses, IR spectra, TGA, PXRD, and X-ray crystallographic diffraction. Complex 1 contains a 1-D helical chain in which CdBr₂ units are linked by L₁. For 2, each CdI₂ is connected by two different conformations of L₂ to form a 1-D zigzag chain. For 3, each CdBr₂ is linked by L₃ bridges to afford a binuclear structure. These results indicate that the spacer length of the ligands play important roles in assembly of Cd(II) coordination polymers. Thermogravimetric analyses and solid-state luminescent properties of the complexes have also been investigated.

Keywords:

• Cadmium(II) coordination polymers
• Crystal structure
• Flexible bis(benzimidazole)
• Luminescent properties