Syntheses, crystal structures, and fluorescent properties of 2-D Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and 1,2,4,5-benzenetetracarboxylate ligands

Abstract

Two new complexes, {[Cd(btec)_0.5(imb)(CH₃OH)]·CH₃OH}_n (1) and {[Cd(btec)_0.5(H₂btec)]·(H₂imb)·2H₂O}_n (2) (H₄btec = 1,2,4,5-benzenetetracarboxylic acid, imb = 2-(1H-imidazol-1-methyl)-1H-benzimidazole), have been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. Both complexes exhibit 2-D network structures. In 1, each 1,2,4,5-benzenetetracarboxylate links four Cd²⁺ cations, and each Cd²⁺ cation connects two 1,2,4,5-benzenetetracarboxylates, to form a 2-D layer, with the imb ligands located on each side of the 2-D layer. In 2, there are two kinds of 1,2,4,5-benzenetetracarboxylates in the structure. One kind is completely deprotonated and acts as hexadentate linkers, leading to a 2-D layer. The other kind is only doubly deprotonated and decorates each side of the 2-D layer. In 2, imb is protonated, forming (H₂imb)²⁺ cations that only cocrystallize with the negatively charged Cd coordination polymer ({[Cd(btec)_0.5(H₂btec)]²⁻}_n), but does not coordinate to the Cd²⁺ cations. IR spectra, PXRD patterns, thermogravimetric analyses, and fluorescent properties of 1 and 2 have also been determined.

Keywords:

• 2-(1H-imidazol-1-methyl)-1H-benzimidazole
• 1,2,4,5-Benzenetetracarboxylate
• Cadmium complex
• Thermostability
• Fluorescent property

Acknowledgment

We gratefully acknowledge the financial support by the National Natural Science Foundation of China (No. J1210060).