A Different Perspective on Tuning the Photophysical and Photochemical Properties: The Influence of Constitutional Isomers in Group 6 Carbonyl Complexes with Pyridyl-Mesoionic Carbenes.

Exploring novel and existing design principles to tune the photochemical and photophysical properties of transition-metal complexes is an important goal in contemporary research. Here, we highlight the influence of constitutional isomers of pyridyl-1,2,3-triazolylidene mesoionic carbene (MIC) ligands on the photophysical and photochemical properties of the corresponding tetracarbonyl group 6 metal complexes (M = Cr, Mo, W). All new complexes [M()] presented herein incorporate a linked pyridyl-MIC ligand and were fully characterized by X-ray diffraction analysis, elemental analysis, and H NMR and IR spectroscopy.

Cooperativity-Driven Reactivity of a Dinuclear Copper Dimethylglyoxime Complex.

In this report, we present the dinuclear copper(II) dimethylglyoxime (H dmg) complex [Cu (H dmg)(Hdmg)(dmg)] (1), which, in contrast to its mononuclear analogue [Cu(Hdmg) ] (2), is subject to a cooperativity-driven hydrolysis. The combined Lewis acidity of both copper centers increases the electrophilicity of the carbon atom in the bridging μ -O-N=C-group of H dmg and thus, facilitates the nucleophilic attack of H O. This hydrolysis yields butane-2,3-dione monoxime (3) and NH OH that, depending on the solvent, is then either oxidized or reduced.

Mechanistic and Kinetic Investigations of ON/OFF (Photo)Switchable Binding of Carbon Monoxide by Chromium(0), Molybdenum(0) and Tungsten(0) Carbonyl Complexes with a Pyridyl-Mesoionic Carbene Ligand.

Invited for the cover of this issue are Gereon Niedner-Schatteburg, Biprajit Sarkar and co-worker at TU Kaiserslautern and the University of Stuttgart. The image depicts the selective dissociation of an axial CO from a metal complex. Read the full text of the article at 10.

Unexpected Boost in Activity of a Cu(I) Photosensitizer by Stabilizing a Transient Excited State.

In this study, we present a slight but surprisingly successful structural modification of the previously reported heteroleptic Cu(I) photosensitizer ([(xantphos)Cu(biipo)]PF; = 16-benzo-[4',5']-isoquinolino-[2',1':1,2]-imidazo-[4,5-]-[1,10]-phenanthrolin-16-one). As a key feature, bears a naphthalimide unit at the back, which is directly fused to a phenanthroline moiety to extend the conjugated π-system. This ligand was now altered to include two additional methyl groups at the 2,9-positions at the phenanthroline scaffold.

Mechanistic and Kinetic Investigations of ON/OFF (Photo)Switchable Binding of Carbon Monoxide by Chromium(0), Molybdenum(0) and Tungsten(0) Carbonyl Complexes with a Pyridyl-Mesoionic Carbene Ligand.

This work tackles the photochemistry of a series of mononuclear Cr , Mo and W carbonyl complexes containing a bidentate mesoionic carbene ligand of the 1,2,3-triazol-5-ylidene type. FTIR spectroscopy, combined with density functional theory calculations, revealed a clean photo-induced reaction in organic solvents (acetonitrile, pyridine, valeronitrile) to give mainly one photoproduct with monosubstitution of a carbonyl ligand for a solvent molecule. The highest photodissociation quantum yields were reached for the Cr complex under UV irradiation (266 nm).

NIR-Emissive Chromium(0), Molybdenum(0), and Tungsten(0) Complexes in the Solid State at Room Temperature.

The development of NIR emitters based on earth-abundant elements is an important goal in contemporary science. We present here Cr(0), Mo(0), and W(0) carbonyl complexes with a pyridyl-mesoionic carbene (MIC) based ligand. A detailed photophysical investigation shows that all the complexes exhibit dual emissions in the VIS and in the NIR region.

Thermally Activated Delayed Fluorescence and Phosphorescence Quenching in Iminophosphonamide Copper and Zinc Complexes.

The synthesis of copper and zinc complexes of four variably substituted iminophosphonamide ligands is presented. While the copper complexes form ligand-bridged dimers, the zinc compounds are monomeric. Due to different steric demand of the ligand the arrangement of the ligands within the dimeric complexes varies.

Investigation of Luminescent Triplet States in Tetranuclear Cu Complexes: Thermochromism and Structural Characterization.

To develop new and flexible Cu containing luminescent substances, we extend our previous investigations on two metal-centered species to four metal-centered complexes. These complexes could be a basis for designing new organic light-emitting diode (OLED) relevant species. Both the synthesis and in-depth spectroscopic analysis, combined with high-level theoretical calculations are presented on a series of tetranuclear Cu complexes with a halide containing Cu X core (X=iodide, bromide or chloride) and two 2-(diphenylphosphino)pyridine bridging ligands with a methyl group in para (4-Me) or ortho (6-Me) position of the pyridine ring.

Highly soluble fluorine containing Cu(i) AlkylPyrPhos TADF complexes.

Luminescent Cu(i) AlkylPyrPhos complexes with a butterfly-shaped CuI core and halogen containing ancillary ligands, with a special focus on fluorine, have been investigated in this study. These complexes show extremely high solubilities and a remarkable (photo)chemical stability in a series of solvents. A tunable emission resulting from thermally activated delayed fluorescence with high quantum yields was determined by luminescence and lifetime investigations in solvents and solids.