Inorganic Chemistry, Vol.60, No.6, 3729-3740, 2021
Polyoxometalate-Templated Cobalt-Resorcin[4]arene Frameworks: Tunable Structure and Lithium-Ion Battery Performance
By employing a bowl-like tetra(benzimidazole)resorcin[4]arene (TBR4A) ligand, two new polyoxometalatetemplated metal-organic frameworks (POMOFs), [Co8Cl14(TBR(4)A)(6)]center dot 3[H3.3SiW12O40] center dot 10DMF center dot 11EtOH center dot 20H(2)O (1) and [Co3Cl2(TBR4A)(2)(DMF)4]center dot[SiW12O40]center dot 2EtOH center dot 3H(2)O (2), have been prepared under solvothermal conditions (DMF = N,N'dimethylformamide). 1 shows a 2D cationic layer, whereas 2 exhibits a 3D framework. Remarkably, the Keggin POMs in 1 and 2 were located in the cavities formed by two bowl-like resorcin[4]arenes in sandwich fashions. Their framework structures were highly dependent on the coordination modes of the TBR4A ligands. To increase the conductivity of POMOFs, the samples of 1 and 2 were loaded on the conductive polypyrrole-reduced graphene oxide (PPy-RGO) via ball milling (1@PG and 2@PG). Then, the obtained composites experienced calcination at a proper temperature to produce 1@PG-A and 2@PG-A. The resulting 1@PG-A and 2@PG-A composites, with improved conductivities, uniform sizes and micropores, exhibited promising electrochemical performance for lithium-ion batteries. We herein proposed a size-controlled route for the rational fabrication of functional POMOFs and their usage in energy fields.