• Callens, Freddy
• Vrielinck, Henk
• Maes, Kwinten

Abstract

Electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) provide detailed information on the nearest environment of paramagnetic ions through symmetry and hyperfine interactions. They are thus perfectly suited for determining the location of paramagnetic states of transition metal and lanthanide ions in insulating materials.In recent years our EPR and ENDOR research has mainly focused on understanding how metal dopant ions get incorporated in metal organic frameworks (MOFs). These crystalline, highly porous materials, consisting of metal-inorganic nodes connected by organic struts, have a wide range of potential applications, e.g. in gas storage, separation, sensing and heterogeneous catalysis. Combining various metals in the same framework may lead to new or improved functionality, or allow to build in an metal ion with desired properties in an inert and highly stable host.1 The rationale behind doping of MOFs is thus similar as for classical oxide and halide materials.MOFs are most often synthesized via solvothermal methods. Metal doping occurs by adding dopants to the solution during synthesis or via post-synthesis ion exchange reactions in solution. These procedures do not necessarily only lead to simple metal substitution. In this presentation, we illustrate this with our recent work on vanadium doping of a (Al-OH)-biphenyl-dicarboxylate MOF (DUT-5),2 where we combine EPR and ENDOR with infrared spectroscopy, X-ray diffraction and electron microscopy.1. S. Abednatanzi, P. Gohari Derakhshandeh, H. Depauw, F.-X. Coudert, H. Vrielinck, P. Van Der Voort,and K. Leus, Chem. Soc. Rev. (2019) 48, p. 2535-2565.DOI: 10.1039/c8cs00337h2. K. Maes, I. Nevjestić, H. Depauw, K. Leus, P. Van Der Voort, H. Vrielinck, F. Callens, Opt. Mater. (2019) 94, p. 217-223.DOI: 10.1016/j.optmat.2019.05.050

Topics

• porous
• impedance spectroscopy
• x-ray diffraction
• electron microscopy
• electron spin resonance spectroscopy
• Lanthanide
• vanadium
• infrared spectroscopy
• microwave-assisted extraction
• electron nuclear double resonance spectroscopy