The ionothermal synthesis of a new 3-D framework based on classic β-[Mo₈O₂₆]⁴⁻ anions

Abstract

An unusual metal-organic framework, {H[Ag(I)L][Mo(VI)₄O₁₃]}_n (1) (L=(4-((1H-1,2,4-triazol-1-yl)methyl)phenyl)methanol)), has been obtained under ionothermal conditions. According to the single-crystal X-ray diffraction analysis, 1 is a new 3-D framework based on β-[Mo₈O₂₆]⁴⁻ type polymolybdate anions with two kinds of channels (A and B) along the b-axes and c-axes in the framework. The neighboring inorganic Mo₈-Ag chains are linked by the organic ligands through the Ag centers resulting in 2-D layers. These adjacent 2-D layers extend into a 3-D framework through Ag1 nodes and β-[Mo₈O₂₆]⁴⁻ anions, respectively, resulting in a topological symbol (6⁴ · 8²)₂(6⁴ · 8²). In addition, the gas adsorption, proton conduction and luminescent properties of 1 are also discussed in detail. Moreover, the electrochemical impedance spectroscopy (EIS) measurements show a conductivity (1.9 × 10⁻⁴ S cm⁻¹ at 65 °C and 95% relative humidity (RH)), with an activation energy of 0.41 eV for 1. The mechanism of proton conduction for 1 is proved to be the vehicular mechanism.

Graphical Abstract

Keywords:

• Ionothermal synthesis
• 3-D framework
• adsorption
• proton conduction
• luminescence

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the National Nature Science Foundation of China (Nos. 21301019 and 21503022), the Nature Science Foundation of the Technology Department of Jilin Province, China (Nos. 20160101299JC and 20160520136JH), the National Science Foundation for Post-doctoral Scientists of China (No. 2013M530135), China Scholarship Council (No. 201708220042) and Science Research Project of the Education Department of Jilin Province, China (No. jjkh20170546kj).