Authors: Leonardo Passerini | Eduard E. Bobylev | Felix de Zwart | Henrik Hintz | Adelheid Godt | Bas de Bruin | Joost Reek | Martina Hüber
Source:  (article, 2025-12-31)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Supplementary material to "Pulsed Electron Paramagnetic Resonance on two Cu(II)-Cage Compounds With Six, Respectively Eight Copper Ions" Meaning of geometric interpretation, Cu8: cube, Cu6: octahedronThe description of the arrangement of the Cu-ions in the cages as a cube (Cu8) or an octahedron (Cu6) facilitates the description of the arrangement of the Cu-ions, but does not imply that the ions form an idealized geometric body.The uncertainty range for the distances obtained from the models (Table 1, main text) gives the range of distances of individual pairs of Cu-ions.In an ideal cube or octahedron all distances between the specific types of Cu-ions should be identical.However, especially the model 2 structures show clear deviations from the shapes, as seen in figure SI1, where the distortions already can be seen in the figure .The corners of polyhedra also have specific relations between distances: In a cube, the relation between the shortest distance (distance a) along the edge of the cube and the face-diagonal (distance b) is b = 1/2 a, the same as the ratio between the shorter and the longer distance in an octahedron.As a result, the distances in Cu6 and Cu8 are expected to follow this ratio. Overview of measurementThe DEER traces presented here can be compared to those shown in Bobylev et al. [1].For Cu6, increasing the accumulation time and optimizing the pulse-excitation resulted in a better signal-to-noise ratio, increasing the confidence level for the distance-distribution shape compared to the traces shown in figure 8 and 10 of [1], while leading to the same distances as before.For Cu8, several attempts to improve the signal-to-noise ratio in a similar way did not improve the data due to a combination of factors, suggesting that the shorter T m time or other chemical factors cause the lower signal-to-noise ratio compared to what can be achieved for Cu6.In [1] DEER was one of several methods to verify the structure of the cages, so the focus was on the distances only.In the present manuscript, the number of interacting spins is determined by a direct comparison with a two-copper model compound (Cu2) enabling detailed analysis of this point in the multi-copper systems investigated.Additionally several different analysis methods were applied (Gaussian analysis of DEER traces, and DeerNet), see below, to quantitate the reliability of the analysis.Most of the differences observed with respect to [1], such as that the second distance peak in the Cu8 distance distribution centered at 2.6 nm, see figure 2, is reliable, result in a higher confidence in the interpretation and are due to the better signal to noise ratio of the data.Reproducibility was checked by measuring samples multiple times, and also measuring samples that had not been measured before.In between measurements, the EPR tubes with the samples were stored in liquid nitrogen, and introduced into the precooled resonator, to avoid accidental warming of the samples as much as possible. Copper ; Electron paramagnetic resonance ; Resonance (particle physics) ; Analytical Chemistry (journal) ; Paramagnetism Magnetism in coordination complexes ; Supramolecular Chemistry and Complexes ; Boron Compounds in Chemistry