Metal-Dependent Adsorption Mechanism in Perfluorinated MIL-140A Metal–Organic Frameworks

High Resolution Image Download MS PowerPoint Slide Perfluorinated metal–organic frameworks (MOFs) with MIL-140A topology display metal-dependent adsorption behavior: while the Ce IV analogue [F4_MIL-140A(Ce)] exhibits step-shaped CO 2 adsorption isotherms and strong affinity for H 2 O, both associated with a concerted structural rearrangement of the linkers, the Zr IV counterpart [F4_MIL-140A(Zr)] shows a classical type I CO 2 isotherm with a lower adsorption capacity and only weak affinity for H 2 O. A multitechnique approach, including solid-state nuclear magnetic resonance spectroscopy, in situ infrared spectroscopy, and variable temperature powder X-ray diffraction, provided clear evidence that this contrasting behavior arises from the absence of an open metal site on Zr IV and the inability of Zr IV to adopt an octacoordinated geometry, which prevent the establishment of strong metal-guest interactions.