Search results for "complexes"
showing 10 items of 875 documents
Side‐on Coordination in Isostructural Nitrous Oxide and Carbon Dioxide Complexes of Nickel
2021
Abstract A nickel complex incorporating an N2O ligand with a rare η2‐N,N′‐coordination mode was isolated and characterized by X‐ray crystallography, as well as by IR and solid‐state NMR spectroscopy augmented by 15N‐labeling experiments. The isoelectronic nickel CO2 complex reported for comparison features a very similar solid‐state structure. Computational studies revealed that η2‐N2O binds to nickel slightly stronger than η2‐CO2 in this case, and comparably to or slightly stronger than η2‐CO2 to transition metals in general. Comparable transition‐state energies for the formation of isomeric η2‐N,N′‐ and η2‐N,O‐complexes, and a negligible activation barrier for the decomposition of the lat…
Structurally simple complexes of CO2
2015
The ability to bind CO2 through the formation of low-energy, easily-broken, bonds could prove invaluable in a variety of chemical contexts. For example, weak bonds to CO2 would greatly decrease the cost of the energy-intensive sorbent-regeneration step common to most carbon capture technologies. Furthermore, exploration of this field could lead to the discovery of novel CO2 chemistry. Reduction of complexed carbon dioxide might generate chemical feedstocks for the preparation of value-added products, particularly transportation fuels or fuel precursors. Implementation on a large scale could help to drastically reduce CO2 concentrations in the atmosphere. However, literature examples of weak…
Придворные королевские церемонии и их рецепция в праздничной жизни Речи Посполитой
2020
The author traces the transition of the royal court of the Polish-Lithuanian Commonwealth to the Western European model of court ceremonies, which lasted for almost two centuries, from the sixteenth to the eighteenth centuries. Initially, they followed the ceremonial models of the House of Habsburg and, starting in the 1640s, the French ceremonial, refined at the Versailles of Louis XIV. Meant to extol the monarch in the eyes of subjects, such ceremonies became widespread under kings of the House of Vasa, Michał Korybut Wiśniowiecki, Jan III Sobieski, and the House of Wettin. Many etiquette elements and ceremonial patterns were borrowed and adapted to the needs of the wealthy Polish and Lit…
Firsts lysidinyl- and lysidinium-triphosphines Pd(II) complexes
2010
International audience; The preparation of first lysidinyl-triphosphine ligand (named Triphosline) is described in three steps which are first a Michael type addition of imidazolidine (or lysidine) to diethylvinylphosphonate, second a phosphonate reduction with LiAlH4 and third an anti-Markovnikov radical addition of the primary phosphine to diphenylvinylphosphine. The Triphosline behaves as a tridentate P-coordinating ligand in palladium(II) complexes. The dangling lysidine function is then cleanly and totally alkylated by methyl iodide to lead to a new kind of lysidinium-triphosphine complexes. Subsequent anion exchange with TlPF6 affords the first example of a chloride free lysidinium-tr…
Nuclear entry and egress of parvoviruses.
2022
Parvoviruses are small non-enveloped single-stranded DNA viruses, which depend on host cell nuclear transcriptional and replication machinery. After endosomal exposure of nuclear localization sequence and a phospholipase A2 domain on the capsid surface, and escape into the cytosol, parvovirus capsids enter the nucleus. Due to the small capsid diameter of 18–26 nm, intact capsids can potentially pass into the nucleus through nuclear pore complexes (NPCs). This might be facilitated by active nuclear import, but capsids may also follow an alternative entry pathway that includes activation of mitotic factors and local transient disruption of the nuclear envelope. The nuclear entry is followed b…
Azonia spiro polyaza macrocycles containing biphenyl subunits as anion and cation receptors
2011
Abstract The reaction of N-Boc triprotected cyclam with bis(chloromethyl)biphenyl followed by the corresponding deprotection of the nitrogen atoms allows the preparation of receptor 3 containing an azonia spiro subunit. This receptor shows slightly increased basicity than cyclam, in particular for the formation of the appropriate triply charged species as a consequence of the reduced capacity of the structure present in 3 to stabilize the species with lower protonation degrees through the formation of intramolecular hydrogen bonds. The properties of 3 as a receptor for Cu2+ and Zn2+ and the anions derived from PO 4 3 − ( Pi ) , P 2 O 7 4 − ( PPi ) , P 3 O 10 5 − ( TPP ) and ATP have been st…
An Off-On-Off Fluorescent Sensor for pH Windows Based on the 13aneN4-Zn 2+ System
2016
International audience; The new ligand L was prepared and features a 13-membered tetraaza macrocyclic ring with a 1,8-naphthalimide fluorophore appended to a C atom of its backbone. The protonation constants of L as well as its complexation constants with Zn2+ ions were determined in 1:1 water/methanol solutions by potentiometric titrations. Fluorimetric pH titrations were performed with L alone and L in the presence of Zn2+ ions (1:1), and the species distributions (%) versus pH were compared. A window-shaped fluorescence trend was observed with pH for the L/Zn2+ system, which behaves as an off-on-off pH sensor. The on window is centred in the 6.5-7.5 pH range, in correspondence with the f…
Synthesis, Characterization, and Cu(2+) Coordination Studies of a 3-Hydroxy-4-pyridinone Aza Scorpiand Derivative.
2016
The synthesis, acid-base behavior, and Cu(2+) coordination chemistry of a new ligand (L1) consisting of an azamacrocyclic core appended with a lateral chain containing a 3-hydroxy-2-methyl-4(1H)-pyridinone group have been studied by potentiometry, cyclic voltammetry, and NMR and UV-vis spectroscopy. UV-vis and NMR studies showed that phenolate group was protonated at the highest pH values [log K = 9.72(1)]. Potentiometric studies point out the formation of Cu(2+) complexes of 1:2, 2:2, 4:3, 1:1, and 2:1 Cu(2+)/L1 stoichiometries. UV-vis analysis and electrochemical studies evidence the implication of the pyridinone moieties in the metal coordination of the 1:2 Cu(2+)/L1 complexes. L1 shows …
Accelerated Light-Induced Defect Transformation Study of Elkem Solar Grade Silicon
2012
AbstractSolar cells made of silicon feedstock from a metallurgical route must qualify not only the initial efficiency, but must also be comparable to the solar cells made from reference polysilicon on the spectral response after light induced degradation. A detailed comparative study of light induced defects and its impact on cell performance is necessary for both materials. We have studied accelerated light induced degradation (ALID) defect transformation for Elkem Solar Silicon and polysilicon solar cells by selecting wafers from different positions from respective silicon bricks. Active boron-oxygen complexes and iron ions in multicrystalline silicon solar cells have been analyzed, and t…
Truncated recombinant light harvesting complex II proteins are substrates for a protein kinase associated with photosystem II core complexes
1998
AbstractPrevious studies directed towards understanding phosphorylation of the chlorophyll a/b binding proteins comprising light harvesting complex II (LHC II) have concentrated on a single phosphorylation site located close to the N-terminus of the mature proteins. Here we show that a series of recombinant pea Lhcb1 proteins, each missing an N-terminal segment including this site, are nevertheless phosphorylated by a protein kinase associated with a photosystem II core complex preparation. An Lhcb1 protein missing the first 58 amino acid residues is not, however, phosphorylated. The results demonstrate that the LHC II proteins are phosphorylated at one or more sites, the implications of wh…