Two new MOFs based on 5-((4-carboxypyridin-2-yl)oxy) isophthalic acid displaying unique selective CO2 gas adsorption and magnetic properties

Abstract

Herein, two new water-stable magnetic frameworks, [Cu_1.5(L)(H₂O)]·2H₂O (1) and [Co₄(L)₂(CH₃CN)(OH)₂(H₂O)₄]·3H₂O (2) (H₃L = 5-((4-carboxypyridin-2-yl)oxy) isophthalic acid), were synthesized by a solvothermal method in similar reaction systems and characterized by infrared spectroscopy, powder X-ray diffraction and thermogravimetric measurements. Due to their different metal ions, 1 shows a trinodal (4,4,4)-connected three-dimensional (3D) framework that possesses 1D channels based on [Cu₂(COO)₄] paddle-wheel secondary building units (SBUs), whereas 2 is a 2D layered network based on tetranuclear [Co₄(COO)₆(μ₃-OH)₂] SBUs and reveals a (3,6)-connected kgd topological structure. The gas adsorption explorations demonstrated that 1 exhibited commendable selectivity for CO₂ over CH₄. Moreover, both 1 and 2 showed different degrees of antiferromagnetic exchange action.