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One Ligand (one + ligand)
Selected AbstractsSyntheses and crystal structures of triorganotin (IV) derivatives with 2,2,-bipyridine-4,4,-dicarboxylic acidHETEROATOM CHEMISTRY, Issue 1 2009Ru-Fen Zhang Four organotin complexes with 2,2,-bipyridine-4,4,-dicarboxylic acid, H2dcbp: (Ph3n)2(dcbp) 1, [(PhCH2)3n]2(dcbp) , 2CH3OH 2, [(Me3Sn)2(dcbp)]n3, [(Bu3Sn)2(dcbp)]n4 have been synthesized. The complexes 1,4 were characterized by elemental, IR, 1H, 13C, 119n NMR, and X-ray crystallographic analyses. Crystal structures show that complex 1 is a monomer with one ligand coordinated to two triorganotin moieties, and a 1D infinite polymeric chain generates via intermolecular CH,,,N hydrogen bond; complex 2 is also a monomer and forms a 2D network by intermolecular O,H,,,O weak interaction; both of complexes 3 and 4 form 2D network structures where 2,2,-bipyridine-4,4,-dicarboxylate acts as a tetradentate ligand coordinated to trimethyltin and tri-n-butyltin ions, respectively. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:19,28, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20506 [source] Ferrocenyl-Aryl Based trans -Chelating Diphosphine Ligands: Synthesis, Molecular Structure and Application in Enantioselective HydrogenationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2010Raffael Schuecker Abstract Potentially trans -chelating diphosphine ligands based on a ferrocenyl-aryl backbone were synthesised in a four-step sequence and the molecular structures in the solid state of two representatives were determined by X-ray diffraction. High throughput screening of these ligands in rhodium-, ruthenium- and iridium-mediated hydrogenations of a variety of alkenes and ketones revealed that these ligands can deliver high enantioselectivity for alkenes (up to 98% ee) but are less selective when ketones are used as the substrates. The coordination behaviour of one ligand in its square planar palladium and platinum dichloride complexes was studied by 31P,NMR and only trans -chelated complexes, together with oligomeric by-products, were observed. Reaction with the (p -cymene)ruthenium dichloride dimer, [RuCl2(p -cymene)]2, resulted in a mixture of diastereomeric complexes. [source] Studies on 4,7-di-substitution effects of one ligand in [Ru(Phen)3]2 with DFT methodJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 4 2002Kangcheng Zheng Abstract Studies on the complex [Ru(phen)3]2+ (phen = 1,10-phenanthroline) and its derivatives with 4,7-di-substitution on one ligand(phen) were carried out using the DFT method at the B3LYP/LanL2DZ level of theory. The trends in the substituent effects caused by the electron-pushing group (OH) and the electron-withdrawing group (F), on the electronic structures and the related properties, for example, the energies and the components of some frontier molecular orbitals, the spectroscopy properties, and the net charge populations of some main atoms of the complexes, etc., have been investigated. The computational results show that the substituents have some interesting effects on the electronic structures and the related properties of the complexes. First, according to the analysis of components of LUMO of the complexes, the electron-withdrawing group (F) can activate the main ligand (the substituted ligand, i.e., 2R-phen) and passivate the coligands, on the contrary, the electron-pushing group (OH) can activate the coligands and passivate the main ligand in the first electronic excited states of complexes. Second, both the electron-pushing group (OH) and the electron-withdrawing group (F) can cause a red shift in the electronic ground bands. Third, the characteristics of the atomic net charge populations on the main ligand can also be analyzed in detail by means of a schematic map expressed by several series of arrowheads based on the law of polarity alternation and the idea of polarity interference. The most negative charges are populated on N1, the next most net negative charges are populated on C3 among the skeleton atoms for the three complexes, etc. The computational results can be better used to explain some experimental phenomena and trends. © 2002 Wiley Periodicals, Inc. J Comput Chem 4: 436,443, 2002; DOI 10.1002/jcc.10038 [source] Thermochemistry, bonding, and reactivity of Ni+ and Ni2+ in the gas phaseMASS SPECTROMETRY REVIEWS, Issue 4 2007Otilia Mó Abstract In this review, we present a general overview on the studies carried out on Ni+- - and Ni2+ -containing systems in the gas phase since 1996. We have focused our attention in the determination of binding energies in parallel with an analysis of the structure and bonding of the complexes formed by the interaction of Ni+ with one ligand, or in clusters where this metal ion binds several identical or different ligands. Solvation of Ni2+ by different ligands is also discussed, together with the theoretical information available of doubly charged Ni-containing species. The final section of this review is devoted to an analysis of the gas-phase uni- and bimolecular reactivity of Ni+ and Ni2+ complexes. © 2007 Wiley Periodicals, Inc., Mass Spectrom. Rev. [source] Ligand Reprogramming in Dinuclear Helicate Complexes: A Consequence of Allosteric or Electrostatic Effects?CHEMISTRY - A EUROPEAN JOURNAL, Issue 18 2007Abstract The ditopic ligand 6,6,-bis(4-methylthiazol-2-yl)-3,3,-([18]crown-6)-2,2,-bipyridine (L1) contains both a potentially tetradentate pyridyl-thiazole (py-tz) N - donor chain and an additional "external" crown ether binding site which spans the central 2,2,-bipyridine unit. In polar solvents (MeCN, MeNO2) this ligand forms complexes with ZnII, CdII, HgII and CuI ions via coordination of the N donors to the metal ion. Reaction with both HgII and CuI ions results in the self-assembly of dinuclear double-stranded helicate complexes. The ligands are partitioned by rotation about the central pypy bond, such that each can coordinate to both metals as a bis-bidentate donor ligand. With ZnII ions a single-stranded mononuclear species is formed in which one ligand coordinates the metal ion in a planar tetradentate fashion. Reaction with CdII ions gives rise to an equilibrium between both the dinuclear double-stranded helicate and the mononuclear species. These complexes can further coordinate s-block metal cations via the remote crown ether O - donor domains; a consequence of which are some remarkable changes in the binding modes of the N-donor domains. Reaction of the HgII - or CdII -containing helicate with either Ba2+ or Sr2+ ions effectively reprogrammes the ligand to form only the single-stranded heterobinuclear complexes [MM,(L1)]4+ (M=HgII, CdII; M,=Ba2+, Sr2+), where the transition and s-block cations reside in the N- and O-donor sites, respectively. In contrast, the same ions have only a minor structural impact on the ZnII species, which already exists as a single-stranded mononuclear complex. Similar reactions with the CdII system result in a shift in equilibrium towards the single-stranded species, the extent of which depends on the size and charge of the s-block cation in question. Reaction of the dicopper(I) double-stranded helicate with Ba2+ shows that the dinuclear structure still remains intact but the pitch length is significantly increased. [source] Transfection and ligation of CD40 in human oral keratinocytes affect proliferation, adhesion and migration but not apoptosis in vitroCLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 2 2006M. Villarroel Dorrego Summary Aims:, CD40 expression is restricted to Keratinocytes of normal epidermis or stratified squamous epithelium of oral mucosa. Ligation of CD40 inhibits keratinocyte proliferation and apoptosis. The aim of this study was to investigate the functional significance of CD40 in the proliferation, apoptosis, adhesion and migration of human oral keratinocytes in vitro. Methods., The CD40-negative oral keratinocyte line OSC19, its CD40-positive transfected derivative (OSC19T-CD40) and null transfectants (OSC19T-control), with and without stimulation by soluble protein CD40 ligand (sCD40L) or anti-CD40 antibodies were used. Results., OSC19T-CD40 showed significantly (P < 0.001) slower growth than the null transfectants and parent cells. OSC19T-CD40 proliferation was inhibited by ligation with sCD40L and blocking by two anti-CD40 antibodies, but stimulated by a third. Binding of CD40 with ligand or antibody had no effect on keratinocyte apoptosis in any cell line. The capacity of OSC19T-CD40 cells to adhere to CD40L-coated wells was significantly greater (P < 0.001) than that of parent OSC19 and OSC19T-control cells, and the migration rate of OSC19T-CD40 cells was significantly higher than parent OSC19 (P = 0.038 on fibronectin, P = 0.004 on Matrigel) or OSC19T-control (P =0.017 on fibronectin, P = 0.013 on Matrigel) cells. Conclusions., CD40 is an important molecule in keratinocyte homeostasis, and has more than one ligand. The ligand that is bound may be critical in oral epithelial homeostasis, the development of malignancy and the behaviour of the subsequent tumour. [source] | ||||||||||