Three keggin-templated compounds constructed by flexible ligands: syntheses and electrochemical properties

Abstract

By using the Keggin anion [SiMo₁₂O₄₀]⁴⁻ as a template and bis(triazole) derivatives as organic ligands, three compounds were synthesized, [Zn₂(bte)₄(SiMo₁₂O₄₀)]·H₂O (1), [Zn₄(btb)₈(SiMo₁₂O₄₀)₂] (2) and [Zn₂(bth)₄(SiMo₁₂O₄₀)] (3) (bte = 1,2-bis(1,2,4-triazol-1-yl)ethane, btb = 1,2-bis(1,2,4-triazol-1-yl)butane and bth = 1,2-bis(1,2,4-triazol-1-yl)hexane). Compound 1 has a cross-shaped cycle-connecting-cycle chain, with two Keggin anions locating above and below for each cycle. By increasing the spacer length of the ligands, a 2D double-layer is formed in 2. The Keggin anions are embedded in the grids of the double-layer. Compound 3 exhibits a wave-like 2D layer with large grids. The two layers penetrate in the form of crests to crests. The anions are covered by these two penetrated layers. The Keggin anions induce distinct metal-organic subunits in 1–3 as the templates. We found that these compounds show electrocatalytic activity for ascorbic acid, bromate and nitrite. All these compounds can be used as electrochemical sensors for nitrite and show good selectivity for NO₂⁻ ions.

Keywords:

• Polyoxometalate
• flexible ligands
• electrochemical properties
• fluorescence property

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Financial supports of this research by the National Natural Science Foundation of China (Nos. 21571023, 21401010, and 21471021), LiaoNing Revitalization Talents Program (XLYC1807049) and Program of Innovative Research Team in University of Liaoning Province (LT2012020).