A combined continuous wave electron paramagnetic resonance and DFT calculations of copper-doped 3∞[Cd0.98Cu0.02(prz-trz-ia)] metal–organic framework

Abstract

Continuous wave X-band electron paramagnetic resonance (EPR) and density functional theory (DFT) were successfully applied to explore the incorporation and coordination state of the Cu²⁺ ions in the ³_∞[Cd_0.98Cu_0.02(prz-trz-ia)] porous metal–organic frameworks. EPR measurements on powder samples and single crystals provided the full electron Zeeman g and copper hyperfine A^Cu interaction tensors including the orientation of their principal axes frames. DFT computations allowed for a detailed interpretation of the experimental results in terms of coordination symmetry and binding properties of the paramagnetic Cu²⁺ ions. Cupric ions were found to substitute Cd²⁺ ions in the dinuclear Cd–Cd units where they experience a noticeably distorted elongated pyramidal coordination environment formed by three nitrogen and two oxygen atoms from three linker molecules.