Search results for "LIGA"

CO2 Fixation by Copper(II) Complexes of a Terpyridinophane Aza Receptor

2004

CO2 is fixed by a Cu2+ complex of a macrocyclic terpyridinophane ligand forming a carbamate group. Several features of the structure mimic the enzyme rubisco.

Mass spectrometric studies on pyridine-piperazine-containing ligands and their complexes with transition metals formed in solution.

2001

Electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) methods were used to study open-chain piperazine-containing ligands (L) and their complexes formed with transition-metal salts. ESI and MALDI measurements were performed with a Fourier transform ion cyclotron resonance (FT-ICR) and a time-of-flight (TOF) mass spectrometer, respectively. Only singly charged complexes, between one ligand and one or several metal ions, were formed in the ESI measurements. Because the net charge was always one, one or several counterions were attached to the complex. Under ESI conditions, the complexes formed between the ligands and metal (Co, Ni, Cu, and Cd) salts were [L + M…

Soluble/MOF-Supported Palladium Single Atoms Catalyze the Ligand-, Additive-, and Solvent-Free Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids.

2021

Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cystein…

Direct arylation of heteroaromatic compounds with congested, functionalised aryl bromides at low palladium/triphosphane catalyst loading.

2011

International audience; A new ferrocenyl triphosphane ligand associated to palladium was found to be an efficient catalyst for the direct coupling of highly congested, functionalised aryl bromides with a variety of heteroarenes. These coupling reactions can generally be performed by using a low-loading (0.1-0.5 mol%) of the catalyst. The present protocol tolerates important and useful functional groups, which allows for further elaboration into more sophisticated heterocyclic molecules. The straightforward arylation of heteroaromatic compounds with congested ortho-substituted aryl bromides may permit further convergent syntheses of diverse ligands, biologically active molecules and molecula…

Study of the role of sulfur functionalities in humic acids for uranium(VI) complexation

2009

Humic substances influence the speciation and migration behavior of toxic and radiotoxic metal ions, such as actinides, in the environment. Depending on their origin, humic substances contain different amounts of sulfur ranging from 0.1 to 3.6% and 0.5 to 1.43% in soil and aquatic humic substances, respectively [1]. Reduced, intermediately oxidized and highly oxidized sulfur functionalities occur in humic substances [1]. Although sulfur functionalities occur in small concentrations, they can play an important role in the complexation of selected metal ions. Knowledge about the impact of sulfur functionalities on the metal ion complexation by humic substances and their significance compared …

Motivos por los que los emigrantes españoles se inscriben en el registro consular

2018

La inscripción en el registro consular no es obligatoria para los emigrantes españoles. Conlleva, no obstante, una serie de ventajas que propician, antes o después, su realización. En este artículo se identifican y analizan los principales motivos que animan a ello a los emigrantes españoles. Se toman como base fundamental los datos e informaciones obtenidos a través de una encuesta cuantitativa y entrevistas semiestructuradas realizadas a más de cuatro mil españoles residentes en el extranjero. Se concluye que los principales motivos para llevar a cabo esta inscripción son los relacionados con el ejercicio de derechos y deberes ciudadanos (especialmente el de sufragio en elecciones español…

Kungliga Vetenskapsakademien och det svenska samhället på 1700-talet

2022

Diastereomeric control of enantioselectivity: evidence for metal cluster catalysis

2014

Enantioselective hydrogenation of tiglic acid effected by diastereomers of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P–P*)] (P–P* = chiral Walphos diphosphine ligand) strongly supports catalysis by intact Ru3 clusters. A catalytic mechanism involving Ru3 clusters has been established by DFT calculations. peerReviewed

DOSY NMR, X-ray Structural and Ion-Mobility Mass Spectrometric Studies on Electron-Deficient and Electron-Rich M6L4 Coordination Cages.

2015

A novel modular approach to electron-deficient and electron-rich M6L4 cages is presented. From the same starting compound, via a minor modulation of the synthesis route, two C3-symmetric ligands L1 and L2 with different electronic properties are obtained in good yield. The trifluoro-triethynylbenzene-based ligand L1 is more electron-deficient than the well-known 2,4,6-tri(4-pyridyl)-1,3,5-triazine, while the trimethoxy-triethynylbenzene-based ligand L2 is more electron-rich than the corresponding benzene analogue. Complexation of the ligands with cis-protected square-planar [(dppp)Pt(OTf)2] or [(dppp)Pd(OTf)2] corner-complexes yields two electron-deficient (1a and 1b) and two electron-rich …

Ligand-Centred Fluorescence and Electronic Relaxation Cascade at Vibrational Time Scales in Transition-Metal Complexes

2015

Using femtosecond-resolved photoluminescence up-conversion, we report the observation of the fluorescence of the high-lying ligand-centered (LC) electronic state upon 266 nm excitation of an iridium complex, Ir(ppy)(3), with a lifetime of 70 +/- 10 fs. It is accompanied by a simultaneous emission of all lower-lying electronic states, except the lowest triplet metal-to-ligand charge-transfer ((MLCT)-M-3) state that shows a rise on the same time scale. Thus, we observe the departure, the intermediate steps, and the arrival of the relaxation cascade spanning similar to 1.6 eV from the (LC)-L-1 state to the lowest 3MLCT state, which then yields the long-lived luminescence of the molecule. This …