196,562 research outputs found
Mononuclear and polynuclear Cu(I) complexes with N2S ligands based on the pyrazole-pyridine framework.
No full textCu-complexes with scorpionate ligands as models for the binding sites of copper proteins
No full textThe bioinorganic relevance of copper is made evident by its involvement in many crucial biological functions, which include: (1) dioxygen activation (copper oxidases and oxygenases) and transport (hemocyanin), (2) electron transfer (cupredoxins), and (3) nitrite reduction to nitric oxide (copper nitrite reductases). As metalloprotein chemistry is governed by the environment close to the metal center(s), a fertile field of investigation is concerned with the preparation of low molecular weight complexes that mimic the structural or functional features of protein active sites. Trofimenko's scorpionate ligands have been extensively used in biomimetic chemistry as "spectator ligands", which modulate the electronic and steric properties of the metal ion and of the co-ligands ("actor ligands"), but are not directly involved in the metal-based reactivity. The structural and functional properties of copper complexes with scorpionate ligands used as synthetic analogs for the binding sites of copper proteins are the subject of the present review. The specific Cu-binding sites examined are: the T3 binuclear and the T2 mononuclear sites of dioxygen-binding proteins, the T1 sites of electrontransfer in blue copper proteins, and the T2 site of nitrite reductase. © 2009 Bentham Science Publishers Ltd
Special issue: Molecular biomarkers in solid tumors
No full textDiagnostic strategies using a next-generation systematic approach have the potential to radically improve the outcome and subsequent quality of life of patients with cancer [...]
Electrochromic second-order NLO chromophores based on M-II (M = Ni, Pd, Pt) complexes with diselenolato-dithione (donor-acceptor) ligands
No full textThe donor-acceptor type mixed-ligand complexes [M(Bz(2)pipdt)(dsit)]; dsit = 2-thioxo-1,3-dithiole-4,5-diselenolato (donor); Bz(2)pipdt = 1,4-dibenzyl-piperazine-2,3-dithione (acceptor); M(II) = Ni (1), Pd (2), and Pt (3) were prepared and characterized to investigate the variation of the properties by substituting selenium for sulfur in the donor ligand dmit = 2-thioxo-1,3-dithiole-4,5-dithiolato of the corresponding known complexes. Both these classes of complexes exhibit large negative second-order polarizabilities, amongst the highest values determined so far for metal-complexes, and are potential candidates for redox switchability of the molecular first hyperpolarizability due to the bleaching/restoring of the solvatochromic peak for mono-reduction/oxidation. DFT and TD-DFT calculations on 1-3 allow one to correlate geometries and electronic structures and are in agreement with the observed minor changes following the substitution of selenium for sulfur atoms in the dichalcogenolato ligand. The observed differences can be ascribed to the increased size of the selenium atom leading to increased M-X distances and dipolar moments of the ground state, which are highest for the Pd-derivative in the tria
Dei Gratia Augustus Dux Saxoniae, Landgravius Thuringiae, Marchio Misniae Etc. Rector Academiae Witebergensis Lecturis gratiam & favorem ... Actum 23. Aprilis Anno Christiano M. DCII.
No full textDEI GRATIA AUGUSTUS DUX SAXONIAE, LANDGRAVIUS THURINGIAE, MARCHIO MISNIAE ETC. RECTOR ACADEMIAE WITEBERGENSIS LECTURIS GRATIAM & FAVOREM ... ACTUM 23. APRILIS ANNO CHRISTIANO M. DCII.
Dei Gratia Augustus Dux Saxoniae, Landgravius Thuringiae, Marchio Misniae Etc. Rector Academiae Witebergensis Lecturis gratiam & favorem ... Actum 23. Aprilis Anno Christiano M. DCII. ([1]
New ligand behavior of 4-amino-3-R-1,2,4-Δ2-triazoline-5-thione. Crystal structures of silver(I) [R = H] and copper(I) [R = CH2CH3] complexes
No full textThe molecular structures of [Ag(HL1)2]NO3 and [CuCl(HL2)3] (HL1 = 4-amino-1,2,4-Δ2-triazoline-5-thione; HL2 = 4-amino-3-ethyl-1,2,4-Δ2-triazoline-5-thione) have been determined by single crystal X-ray analyses. Unusual dimeric and polymeric species are present in the silver compound due to the versatile coordination ability of the ligand. The tetrahedral copper(I) complex (C3 symmetry) is chiral owing to the conformational helicoidal disposition of the three S-coordinated triazoline molecules interacting via hydrogen bonds with the coordinated chlorine atom and, in a head-to-tail fashion, with other complexes forming chains running parallel to c. A spontaneous resolution is observed and in the crystal structure only A conformers are present. (C) 2000 Elsevier Science S.A
Distribuzione selettiva, esaurimento del marchio e difesa dell'immagine di lusso nella giurisprudenza europea
No full textLo studio esamina come le norme in tema di esaurimento del marchio e quelle disciplinanti la distribuzione selettiva nell'ambito del diritto antitrust siano state interpretate ed applicate dalla giurisprudenza europea con riguardo al diritto del titolare del marchio di prodotti lusso di opporsi alla messa in vendita di prodotti originali da parte di un soggetto estraneo allaa rete dei distributori selezionati, con particolare riguardo alle condizioni necessarie per configurare un motivo legittimo per la mancata applicazione del principio dell'esauriment
Contraffazione online: il ruolo degli Internet Service Providers nell'uso illecito del marchio altrui
No full textIl commento esamina una recente sentenza della Corte di giustizia dell’Unione
europea in tema di contraffazione di marchio online, concentrandosi sul ruolo dei
soggetti variamente coinvolti nell’illecito ‘contraffattorio’. In particolare, tenendo conto
delle peculiarità della vicenda, si analizzano i profili di responsabilità degli Internet
Service Providers anche alla luce del panorama normativo e giurisprudenziale sull’argomento
Progress and perspectives on strategies to control photochemical properties in Metallo-Dithiolene Donor-Acceptor systems
No full textIn this mini-review recent progress in studies on heteroleptic d8-metal dithiolene complexes with a D-M-A donor–π–acceptor electronic structure showing non-linear and linear optical properties, are presented. The ligands, formally dithiolenes, consist in a variety of donors (dithiolato) and acceptors (dithioxamide and dithioxamidate), differing for electronic properties and/or structural features, varying from rigid and planar systems to conformationally-flexible ones. It is shown how the components of these D-M-A systems modulate both the energy and topology of the frontier molecular orbitals involved in the charge transport mechanism to reach a fine tuning of the optical properties and achieve high values of the quadratic hyperpolarizability. Further tailoring of the ligands by integrating specific functional groups in their periphery, such as NH and/or a quinoxaline ring, is presented as a versatile tool to achieve a reversible response to external stimuli. Accordingly, selected cases where exchange color proton and silver ions tunable properties, switching of the nonlinear optical response (with a 2.5–6.5 contrast for HCl exchange) and also uncommon emission color reversibly tunable by different stimuli, such as proton and silver ions, are presented. In the bulk, crystals gave a poor or null second harmonic generation (SHG) response, while a stable and large response has been obtained in a limited number of cases of complexes dispersed in polymethylmethacrylate films. Reported results are addressed to stimulate further work to exploit the potential of this class of complexes as molecular sensors and switches and to optimize the processing procedures to achieve good SHG responses in the bulk
Insight into the Properties of Heteroleptic Metal Dithiolenes: Multistimuli Responsive Luminescence, Chromism, and Nonlinear Optics
No full textA comprehensive investigation of the functional properties of heteroleptic donor-M-acceptor dithiolene complexes Bu4N[MII(L1)(L2)] is presented (M = Pd, Pt). The acceptor L1 consists of the chiral (R)-(+)α-methylbenzyldithiooxamidate ((R)-α-MBAdto), the donor L2 is 2-thioxo-1,3-dithiole-4,5-dithiolato (dmit) in 1 (Pd) and 2 (Pt), 1,2-dicarbomethoxyethylenedithiolate (ddmet) in 3 (Pd) and 4 (Pt), or [4′,5′:5,6][1,4]dithiino[2,3-b]quinoxaline-1′,3′-dithiolato (quinoxdt) in 5 (Pd) and 6 (Pt). L1 is capable of undergoing proton exchange and promoting crystal formation in noncentrosymmetric space groups. L2 has different molecular structures while it maintains similar electron-donating capabilities. Thanks to the synergy of the ligands, 1-6 behave as H+ and Ag+ switchable linear chromophores. Moreover, the compounds exhibit a H+-switchable second-order NLO response in solution, which is maintained in the bulk for 1, 3, and 4 when they are embedded into a PMMA poled matrix. 5 and 6 show unique anti-Kasha H+ and Ag+ tunable colored emission originating from the quinoxdt ligand. A correlation between the electronic structure and properties is shown through density functional theory (DFT) and time-dependent DFT calculations
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