Atomic-Scale Quantum Sensing of Ensembles of Guest Molecules in a Metal-Organic Framework with Intrinsic Electron Spin Centers.

One of the exciting applications of electron-spin-based quantum sensing is the detection of distant nuclear spins of external molecular species. Here, we explore the application of a metal-organic framework (MOF) material as a host matrix for sensing spin centers. As a sensor, we employ inherent Cu ions in the structure of a Zn-doped HKUST-1 framework.

Proton and Electron Transfer in the Formation of a Copper Dithiolene-Based Coordination Polymer.

Metal bis(dithiolene) complexes are promising building blocks for electrically conductive coordination polymers. -Heterocyclic dithiolene complexes allow their cross-linking via the coordination of N-donor atoms to additional transition metal ions. In this study, we present the formal copper(II) and copper(III) 6,7-quinoxalinedithiolene complexes [Cu(qdt)] and [Cu(qdt)] (qdt: 6,7-quinoxalinedithiolate), as well as the 2D coordination polymer Cu[Cu(Hqdt)(qdt)] ().

Experimental Evidence for the Incorporation of Two Metals at Equivalent Lattice Positions in Mixed-Metal Metal-Organic Frameworks.

Metal-organic frameworks containing multiple metals distributed over crystallographically equivalent framework positions (mixed-metal MOFs) represent an interesting class of materials, since the close vicinity of isolated metal centers often gives rise to synergistic effects. However, appropriate characterization techniques for detailed investigations of these mixed-metal metal-organic framework materials, particularly addressing the distribution of metals within the lattice, are rarely available. The synthesis of mixed-metal FeCuBTC materials in direct syntheses proved to be difficult and only a thorough characterization using various techniques, like powder X-ray diffraction, X-ray absorption spectroscopy and electron paramagnetic resonance spectroscopy, unambiguously evidenced the formation of a mixed-metal FeCuBTC material with HKUST-1 structure, which contained bimetallic Fe-Cu paddlewheels as well as monometallic Cu-Cu and Fe-Fe units under optimized synthesis conditions.

Adsorption of Olefins at Cupric Ions in Metal-Organic Framework HKUST-1 Explored by Hyperfine Spectroscopy.

Metal-organic frameworks (MOFs) represent a promising platform for gas storage and separation. In this work, adsorption of olefins in Zn-doped HKUST-1 metal-organic framework is explored with hyperfine spectroscopy. By means of electron-nuclear double resonance and hyperfine sublevel correlation spectroscopy, we detect the interaction between the electron spins of the Cu sites of the MOF and the H nuclear spins of adsorbed CH and CH.

A combined continuous wave electron paramagnetic resonance and DFT calculations of copper-doped [CdCu(prz-trz-ia)] metal-organic framework.

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 Cu ions in the [CdCu(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 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 Cu ions.