Cobalt Doping of the MOF-5 Framework and Its Effect on Gas-Adsorption Properties

Abstract

Partial isomorphic substitution of Zn in IRMOF metal clusters by cobalt ions is described for the first time. Specifically, different numbers of Co(2+) ions have been incorporated during solvothermal crystallization into the Zn-based MOF-5 (IRMOF-1) framework, which is one of the most studied MOF materials. The amount of Zn that can be substituted seems to be limited, being no more than 25% of total metal content, that is, no more than one Co atom inside every metal cluster formed by four transition-metal ions, on average. Several characterization techniques, including X-ray diffraction, DR UV-visible spectroscopy, N(2) adsorption isotherms, and thermogravimetrical analysis, strongly support the effective incorporation of Co into the material framework. As-synthesized CoMOF-5 has cobalt ions in octahedral coordination, changing to tetrahedral by simple evacuation, presumably by the removal of two diethylformamide molecules per Co ion. Moreover, the H(2), CH(4), and CO(2) uptake of MOF-5 materials systematically increases with the Co content, particularly at high pressure. Such an increase is moderate anyway, considering that Co is incorporated into unexposed metal sites that are less accessible to gas molecules.

Interplay of Linker Functionalization and Hydrogen Adsorption in the Metal–Organic Framework MIL-101

“…18,25 The reaction pathway for the indirect preparation route does not allow for the complete removal of the reactant from the pores to a small extent, which in turn may modify the material's hydrogen uptake. 26 In contrast, further analysis of the diffraction data reveals that pore narrowing can be excluded as the reason of the increase of the hydrogen uptake in the post-synthetically modified samples. The (0 2 2): (1 1 3) diffraction-peak ratio has been highlighted as a sensitive measure of pore filling.…”

Porphyrin-based metal-organic frameworks for solar fuel synthesis photocatalysis: band gap tuning via iron substitutions

“…19,20 Gascon et al 21 showed that by modifying the linker properties the overall bandgap of MOF-5 can be lowered. 21 Recently, we have predicted the possibility of nely controlling the electronic structure of zeolitic imidazolate frameworks (ZIFs), by following a linker mix-and-match approach.…”

Determination of heat capacities and thermodynamic properties of two structurally unrelated but isotypic calcium and manganese(II) 2,6-naphthalene dicarboxylate-based MOFs

“…Metal-organic frameworks (MOFs) are molecular architectures comprising metal ion nodes bridged by organic ligands, which have attracted much interest recently due to their potential interest for gas storage [1][2][3][4][5], gas separation [6][7][8][9][10], as catalytic active phases [11][12][13][14][15], and as luminescent materials [16][17][18]. Among the numerous synthetic routes leading to MOF materials, most of them involve the use of metal carboxylates as organic ligands that readily interact with various metal ions through their negatively charged ends.…”