A series of Cu(I) complexes of bidentate or tetradentate Schiff base ligands bearing either 1-H-imidazole or pyridine moieties were synthesized. The complexes were studied by a combination of NMR and X-ray spectroscopic techniques. The differences between the imidazole-and pyridine-based ligands were examined by 1 H, 13 C and 15 N NMR spectroscopy. The magnitude of the 15 N imine coordination shifts was found to be strongly affected by the nature of the heterocycle in the complexes. These trends showed good correlation with the obtained CuÀ N imine bond lengths from single-crystal X-ray diffraction measurements. Variable-temperature NMR experiments, in combination with diffusion ordered spectroscopy (DOSY) revealed that one of the complexes underwent a temperaturedependent interconversion between a monomer, a dimer and a higher aggregate. The complexes bearing tetradentate imidazole ligands were further studied using Cu K-edge XAS and VtC XES, where DFT-assisted assignment of spectral features suggested that these complexes may form polynuclear oligomers in solid state. Additionally, the Cu(II) analogue of one of the complexes was incorporated into a metal-organic framework (MOF) as a way to obtain discrete, mononuclear complexes in the solid state.

The electrolyte is an essential constituent of the light-emitting electrochemical cell (LEC), since its operating mechanism is dependent on the redistribution of mobile ions in the active layer. Recent developments of new ion transporters have yielded high-performance devices, but knowledge about the interactions between the ionic species and the ion transporters and the influence of these interactions on the LEC performance is lacking. We therefore present a combined computational and experimental effort that demonstrates that the selection of the end group in a star-branched oligomeric ion transporter based on trimethylolpropane ethoxylate has a paramount influence on the ionic interactions in the electrolyte and thereby also on the performance of the corresponding LECs. With hydroxyl end groups, the cation from the salt is strongly coordinated to the ion transporter, which leads to suppression of ion pairing, but the penalty is a hindered ion release and a slow turn-on for the LEC devices. With methoxy end groups, an intermediate coordination strength is seen together with the formation of contact ion pairs, but the LEC performance is very good with fast turn-on. Using a series of ion transporters with alkyl carbonate end groups, the ion transporter:cation coordination strength is lowered further, but the turn-on kinetics are slower than what is seen for devices comprising the methoxy end-capped ion transporter.

Multidentate Schiff base ligands derived from a selection of biphenyl-and terphenyl polyamines were synthesized, and their reactivity towards divalent (Ni, Cu, Zn, Cd) and trivalent (Co, Y, Lu) metals was studied by single-crystal X-ray diffraction analysis, NMR spectroscopy, and UV/Vis spectroscopy for the Cu(II) complexes. Large variations in the resulting complexes were observed based on the relative position of the amine substituents in the parent triamines, as well as the electronic properties of the Schiff base ligand itself. Most notably, Schiff base ligands derived from a m-terphenyl-2,2',2''-triamine were found to coordinate in a tetradentate, pentadentate or hexadentate fashion, depending on the size and the valency of the corresponding metal center.

The Cover Feature shows Cu(I) complexes illustrated as extra‐terrestrial beings in space. The celestial bodies are the heterocyclic motifs of the ligands and the spectroscopic techniques that shed light on the coordination environment of copper. In analogy to the tale of two kids hiding under one trench coat in order to pass as a taller adult, two complexes are stapled, forming a dimer. Next to them sits a monomeric structure. The aggregation behavior of Cu(I) complexes was studied. The cover art was designed by Knut T. Hylland and Vincent Meier. More information can be found in the Full Paper by S. DeBeer, M. Amedjkouh and co‐workers.

A modular one-pot synthesis yielding tetracoordinated-N,N,N,N-copper(I) complexes bearing imine and diimine ligands was developed. Copper aids the condensation of a pyridine or imidazole carbaldehyde with a biphenyl amine and even stabilizes labile ligands. Tetradentate and bidentate ligands were formed, the latter forming homoleptic CuL2 complexes. The identity and purity of the compounds were assessed by NMR, elemental analysis and mass spectrometry. The interconversion of different species in solution was studied by variable temperature NMR. The complexes aim to mimic the histidine copper brace of lytic polysaccharide monooxygenases (LPMOs) and bond lengths obtained from XAS and single crystal XRD for the complexes were compared to reported photoreduced LPMOs.