- Non-centrosymmetric packing of 1-D coordination networks based on chirality
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Using CoCl2 and a chiral tecton possessing C2 chirality and based on two coordination poles composed of a pyridine unit connected at the 4-position to a pyridine bearing at the 2 and 6 positions two optically active oxazoline moieties, a polar solid is obtained. The latter results from the acentric packing of directional 1-D coordination networks.
- Jouaiti, Abdelaziz,Hosseini, Mir Wais,Kyritsakas, Nathalie
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Read Online
- Novel multi-color photoluminescence emission phosphors developed by layered gadolinium hydroxide via in situ intercalation with positively charged rare-earth complexes
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The design of multi-color phosphors has aroused great interest for practical optical applications. Herein, for the first time, the stable positively charged Eu(iii) and Tb(iii) complexes EuL and TbL (L = 2,2′-(4-(2-ethoxyethoxy)pyridine-2,6-diyl)bis(4,5-dihydrooxazole)) have been successfully intercalated in situ into the gallery of layered gadolinium hydroxide (LGdH) utilizing chelation of picolinic acid (pa) anions via ligand exchange reaction. In particular, the resulting hybrid phosphors (LGdH-pa-Eu1-xTbxL) exhibit multi-color emissions by simply fine-tuning the molar ratio of Eu(iii)/Tb(iii), which show red and green primary colors, as well as intermediate colors excited at 310 nm. The luminescence spectra, decay time, and low-temperature phosphorescence spectra analysis indicate that other than the intramolecular energy transfer (ET) process from ligand to RE(iii) and intermolecular ET process from Tb(iii) to Eu(iii), the expected and interesting interaction between host (LGdH) and guest pa anions was also observed, which dramatically enhanced the absorption cross section of pa anions. Finally, a blue emission component 4,4′-distyrylbiphenyl sodium sulfonate (Tinopal CBS) was further introduced into the hybrid material LGdH-pa-Eu0.2Tb0.8L, to provide white light emission under the 330 nm excitation. In addition, to determine the potential of these hybrid phosphors in various applications, transparent and multi-color emission composite film devices have been fabricated with poly(methyl methacrylate) (PMMA) using the solvent-casting method.
- Shen, Tingting,Zhang, Yu,Liu, Weisheng,Tang, Yu
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- G-quadruplex DNA as a molecular target for induced synthetic lethality in cancer cells
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Synthetic lethality is a genetic concept in which cell death is induced by the combination of mutations in two sensitive genes, while mutation of either gene alone is not sufficient to affect cell survival. Synthetic lethality can also be achieved "chemically" by combination of drug-like molecules targeting distinct but cooperative pathways. Previously, we reported that the small molecule pyridostatin (PDS) stabilizes G-quadruplexes (G4s) in cells and elicits a DNA damage response by causing the formation of DNA double strand breaks (DSB). Cell death mediated by ligand-induced G4 stabilization can be potentiated in cells deficient in DNA damage repair genes. Here, we demonstrate that PDS acts synergistically both with NU7441, an inhibitor of the DNA-PK kinase crucial for nonhomologous end joining repair of DNA DSBs, and BRCA2-deficient cells that are genetically impaired in homologous recombination-mediated DSB repair. G4 targeting ligands have potential as cancer therapeutic agents, acting synergistically with inhibition or mutation of the DNA damage repair machinery.
- McLuckie, Keith I. E.,Di Antonio, Marco,Zecchini, Heather,Xian, Jian,Caldas, Carlos,Krippendorff, Ben-Fillippo,Tannahill, David,Lowe, Christopher,Balasubramanian, Shankar
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Read Online
- Molecular recognition of biotin, barbital and tolbutamide with new synthetic receptors
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We have measured, by means of NMR titrations, the binding constants for the complexes between hosts N,N′-bis(6-methylpyridin-2-yl)-1,3- benzenedicarboxamide (7) and 4-chloro-N,N′-bis(6-methylpyridin-2-yl)-2,6- pyridinedicarboxamide (8, hydrated) with biot
- Claramunt, Rosa M.,Herranz, Fernando,Santa María, M. Dolores,Pinilla, Elena,Torres, M. Rosario,Elguero, José
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Read Online
- A water-soluble Pybox derivative and its highly luminescent lanthanide ion complexes
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A new water-soluble Pybox ligand, 1, has been synthesized and found to crystallize in the monoclinic P21/n space group with unit cell parameters a = 6.0936(1) A, b = 20.5265(4) A, c = 12.0548(2) A, and β = 90.614(1)°. In the crystal, a water molecule is bound through hydrogen-bonding interactions to the nitrogen atoms of the oxazoline rings. This ligand was used to complex a variety of lanthanide ions, opening up new avenues for luminescence and catalysis in aqueous environment. These complexes are highly luminescent in aqueous solutions, in acetonitrile, and in the solid state. Aqueous quantum yields are high at 30.4% for Eu(III), 26.4% for Tb(III), 0.32% for Yb(III), and 0.11% for Nd(III). Er(III) did not luminesce in water, but an emission efficiency of 0.20% could be measured in D2O. Aqueous emission lifetimes were also determined for the visible emitting lanthanide ions and are 1.61 ms for Eu(III) and 1.78 ms for Tb(III). Comparing emission lifetimes in deuterated and nondeuterated water indicates that no water molecules are coordinated to the metal ion. Speciation studies show that three species form successively in solution and the log β values are 5.3, 9.6, and 13.8 for Eu(III) and 5.3, 9.2, and 12.7 for Tb(III) for 1:1, 2:1, and 3:1 ligand to metal ratios, respectively.
- De Bettencourt-Dias, Ana,Barber, Patrick S.,Bauer, Sebastian
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Read Online
- Azido- and amino-substituted dipicolinates for the sensitization of the luminescent lanthanides EuIII and TbIII
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Dipicolinate-based ligands substituted with azido- or amino- functional groups were synthesized and characterized. Crystal structures of EN3, CN3, CNH2, and ENH2 were obtained, and the ability of these compounds to sensitize LnIII luminescence (LnIII = EuIII and TbIII) was explored. Luminescence efficiencies of EuIII and TbIII were determined and are ?Eu = 0.11%, 0.15%, and 13.8% for [Ln(CN3)3]3+, [Ln(EN3)3]3+, [Ln(CNH2)3]3+, respectively, and ?Tb = 0.30%, 0.27%, and 28.9% for [Ln(CN3)3]3+, [Ln(EN3)3]3+, [Ln(ENH2)3]3+. The highest luminescence efficiencies are ?Eu = 14.4% for [Eu(ENH2)3]3+ and ?Tb = 29.7% for [Tb(CNH2)3]3+. Similar 1S and 3T excited state energies were observed for all ligands and did not explain the observed discrepancies in luminescence efficiency of their TbIII and EuIII complexes. Further analysis revealed that the azido-derivatives were not photostable, which likely contributed to the low luminescence efficiency.
- Johnson, Katherine R.,de Bettencourt-Dias, Ana
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- Luminescent Carbazole-Based EuIII and YbIII Complexes with a High Two-Photon Absorption Cross-Section Enable Viscosity Sensing in the Visible and near IR with One- And Two-Photon Excitation
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The newly synthesized EuIII and YbIII complexes with the new carbazole-based ligands CPAD2- and CPAP4- display the characteristic long-lived metal-centered emission upon one- and two-photon excitation. The EuIII complexes show the expected narrow emission bands in the red region, with emission lifetimes between 0.382 and 1.464 ms and quantum yields between 2.7% and 35.8%, while the YbIII complexes show the expected emission in the NIR region, with emission lifetimes between 0.52 and 37.86 μs and quantum yields between 0.028% and 1.12%. Two-photon absorption cross sections (σ2PA) as high as 857 GM were measured for the two ligands. The complexes showed a strong dependence of the one- and two-photon sensitized emission intensity on solvent viscosity in the range of 0.5-200 cP in the visible and NIR region.
- De Bettencourt-Dias, Ana,Fetto, Natalie R.,Monteiro, Jorge H. S. K.,Tucker, Matthew J.
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supporting information
p. 3193 - 3199
(2020/03/19)
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- Diastereo- And Enantioselective Synthesis of Quaternary α-Amino Acid Precursors by Copper-Catalyzed Propargylation
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A diastereo- and enantioselective propargylic substitution reaction between propargylic carbonates and α-substituted nitroacetates catalyzed by a Cu-pybox complex is described. This method allows the preparation of a series of non-proteinogenic quaternary α-amino acid precursors featuring two contiguous stereogenic centers and a terminal alkyne moiety in high yields with good to excellent diastereo- and enantioselectivities in most cases. The propargylated adducts were elaborated into a diverse set of quaternary α-amino acid derivatives.
- Zhu, Qiongqiong,Meng, Beibei,Gu, Congzheng,Xu, Ye,Chen, Jie,Lei, Chuanhu,Wu, Xiaoyu
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supporting information
p. 9985 - 9989
(2019/12/24)
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- Heavy metal complexes of 4-chlorodipicolinic acid - structural, spectral and thermal correlations
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The ligand, 4-chloro-2,6-dipicolinic acid (H2PDA-Cl), and its two heavy metal complexes, [Ag(HDPA-Cl)(H2DPA-Cl)·2H2O] (1) and {[Cd(μ2-H2O)(H2O)(PDA-Cl)]}n (2), were prepared and then characterized by single-crystal X-ray diffraction. In addition, spectral and thermal correlations with structural results complete their solid-state description and facilitate complex 3 ([Pb(DPA-Cl)]) composition determinations. Complex 1 crystallizes in a monoclinic space group C2/c and each DPA-Cl ligand is tridentate to Ag(I) through the pyridine N and two monodentate carboxyl O atoms. The carboxy group with carbonyl C1 is semideprotonated and forms a symmetric hydrogen bond with a carboxy group of a neighboring complex. Complex 2 crystallizes in a triclinic lattice with space group P (Formula presented.) The Cd(II) ions are seven-coordinate and the coordination polyhedra can be described as a distorted pentagonal bipyramid. IR data are consistent with monodentate coordination of the carboxylate to Ag(I), Cd(II), and Pb(II) and observed wavenumber shifts confirm PDA-Cl ligand coordination to Pb(II) in 3. Thermal stability of anhydrous complexes indicates the metal–ligand interactions. The thermal stability of prepared compounds is reflected by the strength of interaction between metal–ligand and hydrogen bonds.
- Vargová,Almá?i,Gyepes,Vetráková
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p. 3013 - 3029
(2019/11/11)
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- Topology-Selective, Fluorescent “Light-Up” Probes for G-Quadruplex DNA Based on Photoinduced Electron Transfer
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Six novel probes were prepared by covalent attachment of a G4-DNA ligand (bis(quinolinium) pyridodicarboxamide; PDC) to various coumarin or pyrene fluorophores. In the absence of DNA, the fluorescence of all probes is quenched due to intramolecular photoinduced electron transfer (PET), as evidenced by photophysical and electrochemical studies, molecular modeling, and DFT calculations. All probes demonstrate similarly high thermal stabilization of various G4-DNA substrates belonging to different folding topologies, as assessed by fluorescence melting experiments; however, their fluorimetric response is strongly heterogeneous with respect to the structures of the probes and G4-DNA targets. Thus, the probes containing the 7-diethylaminocoumarin fluorophore demonstrate significant fluorescence enhancement in the presence of G4-DNA, with the strongest “light-up” response (20- to 180-fold) observed for antiparallel G4 structures as well as for hybrid G4 structures, formed by the variants of human telomeric sequence and capable of a conformation change to the antiparallel isoform. These results shed light on the influence of the linker and electronic properties of fluorophores on the efficiency of G4-DNA “light-up” probes operating via PET.
- Xie, Xiao,Reznichenko, Oksana,Chaput, Ludovic,Martin, Pascal,Teulade-Fichou, Marie-Paule,Granzhan, Anton
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supporting information
p. 12638 - 12651
(2018/08/01)
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- WATER-SOLUBLE TRIAZAPYRIDINOPHANE-BASED COMPLEXING AGENTS AND CORRESPONDING FLUORESCENT LANTHANIDE COMPLEXES
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The invention relates to complexing agents of formula (I) in which A1, A2, A3 and R1 are as defined in the description. The invention also relates to lanthanide complexes obtained from said complexing agents. The invention can be used for marking biological molecules.
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Paragraph 0081
(2019/01/04)
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- Enantioselective Photocatalytic [3 + 2] Cycloadditions of Aryl Cyclopropyl Ketones
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Control of stereochemistry in photocycloaddition reactions remains a substantial challenge; almost all successful catalytic examples to date have involved [2 + 2] photocycloadditions of enones. We report a method for the asymmetric [3 + 2] photocycloaddition of aryl cyclopropyl ketones that enables the enantiocontrolled construction of densely substituted cyclopentane structures not synthetically accessible using other catalytic methods. These results show that the dual-catalyst strategy developed in our laboratory broadens synthetic chemists' access to classes of photochemical cycloadditions that have not previously been feasible in enantioselective form.
- Amador, Adrian G.,Sherbrook, Evan M.,Yoon, Tehshik P.
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p. 4722 - 4725
(2016/05/10)
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- Linking of antitumor trans NHC-Pt(II) complexes to G-quadruplex DNA ligand for telomeric targeting
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G-quadruplex structures (G4) are promising anticancerous targets. A great number of small molecules targeting these structures have already been identified through biophysical methods. In cellulo, some of them are able to target either telomeric DNA and/o
- Betzer, Jean-Fran?ois,Nuter, Frédérick,Chtchigrovsky, Mélanie,Hamon, Florian,Kellermann, Guillaume,Ali, Samar,Calméjane, Marie-Ange,Roque, Sylvain,Poupon, Jo?l,Cresteil, Thierry,Teulade-Fichou, Marie-Paule,Marinetti, Angela,Bombard, Sophie
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p. 1456 - 1470
(2016/07/06)
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- Synthesis, characterization and 1,3-butadiene polymerization studies of cobalt dichloride complexes bearing pyridine bisoxazoline ligands
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A series of ion-pair cobalt complexes bearing pyridine bisoxazoline ligands were successfully synthesized and characterized by IR spectroscopy and elemental analysis. Determined by X-ray crystallographic analysis, complexes 4a, 4b, 4e, and 4f existed as i
- Guo, Jun,Wang, Baolin,Bi, Jifu,Zhang, Chunyu,Zhang, Hexin,Bai, Chenxi,Hu, Yanming,Zhang, Xuequan
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p. 124 - 132
(2015/01/30)
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- Chiral probe development for circularly polarised luminescence: Comparative study of structural factors determining the degree of induced CPL with four heptacoordinate europium(III) complexes
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A series of bright, europium(iii) complexes has been prepared based on an achiral heptadentate triazacyclononane ligand bearing two strongly absorbing, coordinated aralkynyl pyridyl moieties. The binding of chiral carboxylates, including α-hydroxy acids such as lactate and mandelate, has been monitored by emission spectroscopy and is signalled by the switching on of strong circularly polarised emission. In each case, an R-chiral carboxylate gave rise to emission typical of a Δ complex, most clearly shown in the form of the ΔJ = 4 transition manifold around 700 nm. Variations in the sign and magnitude of the CPL allow the enantiomeric purity and absolute configuration of the acid to be assessed in a sample. Analysis of the relative energies of the parent aqua complexes and their stereoisomeric adducts has been aided by lifetime measurements and density functional theory calculations.
- Neil, Emily R.,Fox, Mark A.,Pal, Robert,P?lsson, Lars-Olof,O'Sullivan, Benjamin A.,Parker, David
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supporting information
p. 14937 - 14951
(2015/08/24)
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- Unprecedented strong lewis bases - Synthesis and methyl cation affinities of dimethylamino-substituted terpyridines
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A versatile method for the synthesis of functionalized 2,2′:6′, 2″-terpyridines by assembly of the terminal pyridine rings is presented. The cyclization precursors - bis-β-ketoenamides - are prepared from 4-substituted 2,6-pyridinedicarboxylic acids and a
- Hommes, Paul,Fischer, Christina,Lindner, Christoph,Zipse, Hendrik,Reissig, Hans-Ulrich
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supporting information
p. 7647 - 7651
(2014/08/05)
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- An efficient triazole-pyridine-bistetrazolate platform for highly luminescent lanthanide complexes
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Two new triazole-pyridine-bistetrazolate ligands were synthesized via a versatile procedure that allows for further derivatization; their corresponding homoleptic tris-ligand nona-coordinated lanthanide complexes are highly luminescent in the solid state and in a PVA polymeric matrix with measured values for the luminescence quantum yield of 70(7) and 98(9)% for Eu III and TbIII, respectively. This journal is the Partner Organisations 2014.
- Di Pietro,Imbert,Mazzanti
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supporting information
p. 10323 - 10326
(2014/08/18)
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- Pt-free tandem molecular photoelectrochemical cells for water splitting driven by visible light
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Photoelectrochemical (PEC) cells using molecular catalysts to split water into hydrogen and oxygen have been investigated intensively during the past years. However, the high-cost of Pt counter electrodes and instability of molecular PEC cells hinder the practical applications. We describe in this article a Pt-free tandem molecular PEC cell, for the first time, employing molecular ruthenium- and cobalt-catalysts with strong dipicolinic acid anchoring groups on the respective photoanode and photocathode for total water splitting. The Pt-free tandem molecular PEC cell showed an effective and steady photocurrent density of ca. 25 μA cm-2 for water splitting driven by visible light without external bias. This study indicates that tandem molecular PEC cells can provide great potential to the Pt-free devices for light driven total water splitting. This journal is
- Fan, Ke,Li, Fusheng,Wang, Lei,Daniel, Quentin,Gabrielsson, Erik,Sun, Licheng
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p. 25234 - 25240
(2015/02/18)
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- Scale-up of flow-assisted synthesis of C2-symmetric chiral PyBox ligands
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A series of PyBox ligands were prepared from commercially available chelidonic acid by a multistep flow sequence using mesoreactor technology. A chloro group introduced onto the ligand scaffold was subsequently exploited to give amine derivatives ready for immobilization through microencapsulation technologies. Georg Thieme Verlag Stuttgart · New York.
- Battilocchio, Claudio,Baumann, Marcus,Baxendale, Ian R.,Biava, Mariangela,Kitching, Matthew O.,Ley, Steven V.,Martin, Rainer E.,Ohnmacht, Stephan A.,Tappin, Nicholas D. C.
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p. 635 - 647
(2012/04/17)
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- Toward reactant encapsulation for substrate-selectivity
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A synthetic tris-(bis-(aminomethyl)pyridine) receptor was prepared in excellent yields via reversible imine condensation strategy. Catalytic activity in Henry reactions of the corresponding copper(II) complex was studied. Capitalizing on previous works by
- De Rycke, Nicolas,Couty, Fran?ois,David, Olivier R.P.
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supporting information; experimental part
p. 462 - 466
(2012/02/01)
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- Electronic effects in 4-substituted bis(imino)pyridines and the corresponding reduced iron compounds
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A family of 4-substituted bis(imino)pyridines, 4-X-iPrPDI (4-X-iPrPDI = 2,6-(2,6-iPr2-C6H 3N=CMe)2-4-X-C5H2N; X = CF 3, tBu, Bn, NMe2), has been synthesized and the iron coordination chemistry studied. Sodium amalgam reduction of the iron dihalides (4-X-iPrPDI)FeX2 (X = Cl, Br) in the presence of excess carbon monoxide furnished the corresponding iron dicarbonyl compounds (4-X-iPrPDI)Fe(CO)2. Equilibrium mixtures of the four- and five-coordinate iron dinitrogen compounds (4-X-iPrPDI)FeN 2 and (4-X-iPrPDI)Fe(N2)2 were prepared by performing the sodium amalgam reduction of the iron dihalides under a dinitrogen atmosphere. Electrochemical and spectroscopic measurements were conducted on the free ligands and the iron derivatives to systematically evaluate the influence of each para pyridine substituent on the electronic structure of the compound.
- Darmon, Jonathan M.,Turner, Zoe R.,Lobkovsky, Emil,Chirik, Paul J.
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scheme or table
p. 2275 - 2285
(2012/06/04)
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- Rotaxane-based mechanically linked block copolymers
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We just clicked: A convergent approach consisting of two successive copper(I)-catalyzed azide-alkyne cycloaddition "click" reactions leads to a diblock copolymer in which the two blocks are linked by a rotaxane-type mechanical bond (see scheme). Rotaxane formation is templated by a square-planar PdII complex. Copyright
- De Bo, Guillaume,De Winter, Julien,Gerbaux, Pascal,Fustin, Charles-Andre
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supporting information; experimental part
p. 9093 - 9096
(2011/10/13)
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- Neutral push-pull chromophores for nonlinear optical imaging of cell membranest
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A new class of push-pull molecules was recently identified, based on pyridine dicarboxamide as an electron acceptor group and bearing a fluorenethynyl π-conjugated bridge. The molecules present good second and third order nonlinear properties, with a stat
- Barsu, Cyril,Cheaib, Rouba,Chambert, Stephane,Queneau, Yves,Maury, Olivier,Cottet, Davy,Wege, Hartmut,Douady, Julien,Bretonniere, Yann,Andraud, Chantal
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scheme or table
p. 142 - 150
(2010/04/06)
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- Convenient multigram synthesis of 4-chloropyridine-2,6-dicarbonyl dichloride
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A method amenable to the multigram-scale preparation of 4-chloropyridine-2,6-dicarbonyl dichloride is described. The key transformation is the deoxygenative chlorination of the pyridine N- oxide with oxalyl choride. Georg Thieme Verlag Stuttgart.
- Mitsui, Kazuhiko,Parquette, Jon R.
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experimental part
p. 713 - 714
(2009/08/07)
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- Significance of interactions of BACE1-Arg235 with its ligands and design of BACE1 inhibitors with P2 pyridine scaffold
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Recently, we reported potent substrate-based pentapeptidic BACE1 inhibitors possessing a hydroxymethylcarbonyl isostere as a substrate transition-state mimic. Because these inhibitors contained some natural amino acids, we would need to improve their enzymatic stability in vivo and permeability across the blood-brain barrier, so that they become practically useful. Subsequently, non-peptidic and small-sized BACE1 inhibitors possessing a heterocyclic scaffold, 2,6-pyridenedicarboxylic, chelidamic or chelidonic moiety, at the P2 position were reported. These inhibitors were designed based on the conformer of docked inhibitor in BACE1. In this study, we discuss the role and significance of interactions between Arg235 of BACE1 and its inhibitor in BACE1 inhibitory mechanism. Moreover, we designed more potent small-sized BACE1 inhibitors with a 2,6-pyridinedicarboxylic scaffold at the P2 position, that were optimized for the interactions with Arg235 of BACE1.
- Hamada, Yoshio,Ohta, Hiroko,Miyamoto, Naoko,Sarma, Diganta,Hamada, Takashi,Nakanishi, Tomoya,Yamasaki, Moe,Yamani, Abdellah,Ishiura, Shoichi,Kiso, Yoshiaki
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scheme or table
p. 2435 - 2439
(2009/12/25)
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- Ionic probe attachment ionization mass spectrometry
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A new ionization method that uses metal-complex-based ionization probes containing the 2,6-bis(oxazolinyl)pyridine (pybox) ligand is presented. This method was proven to effectively ionize large complex molecules, including biomolecules. The preparation o
- Ito, Fumihiro,Nakamura, Tomoko,Yorita, Satoko,Danjo, Hiroshi,Yamaguchi, Kentaro
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supporting information; experimental part
p. 6252 - 6255
(2010/01/11)
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- Design and synthesis of new differentiated concurrent mono- and tridentate ligands (tectons) based on pyridine, terpyridine, and dihydrooxazole units
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The design, synthesis, and characterization of the 10 linear and bent acentric ligands 1 - 10 (tectons) based on the differentiation of two divergently disposed coordinating poles is reported. The nature of the two poles and their distance are varied by t
- Jouaiti, Abdelaziz,Hosseini, Mir Wais
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experimental part
p. 2497 - 2506
(2010/03/25)
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- Synthesis, structures, optical properties, and TD-DFT studies of donor-π-conjugated dipicolinic acid/ester/amide ligands
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A series of 2,6- and 4-functionalized dipicolinic acid, ester, or amide featuring π-conjugated substituents such as donor-(phenyl or fluorenyl)-acetylene groups have been synthesized. Four crystallographic structures are reported. The influence of the sub
- Picot, Alexandre,Feuvrie, Christophe,Barsu, Cyril,Malvolti, Floriane,Le Guennic, Boris,Le Bozec, Hubert,Andraud, Chantal,Toupet, Lo?c,Maury, Olivier
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p. 399 - 411
(2008/09/16)
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- Highly selective recognition of adenine nucleobases by synthetic hosts with a linked five-six-five-membered triheteroaromatic structure and the application to potentiometric sensing of the adenine nucleotide
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A new structure for an adenine-selective host molecule, featuring the pertinent link of five-six-five-membered heteroaromatic rings and two carbamoyl NH sites, was developed. This structure provides a correctly oriented array of complementary hydrogen bonding sites for the adenine nucleobase, which exploits both Watson-Crick and Hoogsteen-type interactions. The complexation with adenine nucleobases by multiple hydrogen bonding was supported by 1H NMR spectroscopy. This type of host displayed high selectivity in complexation, with an accompanying fluorescent response to lipophilized adenosine in CHCl 3. Furthermore, a remarkably selective po tentiometric response was attained for adenosine 5′-monophosphate over 5′-GMP, 5′-CMP, and 5′-UMP by using an ion-selective electrode with a PVC-supported solvent polymeric membrane. This indicates recognition of water-soluble nucleotide guests through the membrane-water interface. These findings are expected to form a reliable basis for the development of artificial sensing systems for mononucleotides in biological systems.
- Hisamatsu, Yosuke,Hasada, Keiko,Amano, Fumi,Tsubota, Yasuhiro,Wasada-Tsutsui, Yuko,Shirai, Naohiro,Ikeda, Shin-Ichi,Odashima, Kazunori
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p. 7733 - 7741
(2007/10/03)
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- Ruthenium-catalyzed asymmetric epoxidation of olefins using H 2O2, part I: Synthesis of new chiral N,N,N,-tridentate pybox and pyboxazine ligands and their ruthenium complexes
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The synthesis of chiral tridentate N,N,N-pyridine-2.6-bisoxazolines 3 (pyhox ligands) and N,N,N-pyridine-2.6-bisoxazines 4 (pyboxazine ligands) is described in detail. These novel ligands constitute a useful tool-box for the application in asymmetric catalysis. Compounds 3 and 4 are conveniently prepared by cyclization of enantiomerically pure α- or β-amino al cohols with dimethyl pyridine-2,6-dicarboximidate. The corresponding ruthenium complexes are efficient asymmetric epoxidation catalysts and have been prepared in good yield and fully char acterized by spectroscopic means. Four of these ruthenium complexes have been characterized by X-ray crystallography. For the first time the molecular structure of a pyboxazine complex (2,6-bis-[(4S)-4-phenyl-5,6- dihydro-4H-[1,3]oxazinyl]pyridine)(pyridine-2,6-dicarboxylate)ruthenium (S)-2aa, is presented.
- Tse, Man Kin,Bhor, Santosh,Klawonn, Markus,Anilkumar, Gopinathan,Jiao, Haijun,Doebler, Christian,Spannenberg, Anke,Magerlein, Wolfgang,Hugl, Herbert,Beller, Matthias
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p. 1855 - 1874
(2008/02/02)
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- A flexible and versatile strategy for the covalent immobilization of chiral catalysts based on pyridinebis(oxazoline) ligands
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Flexible and versatile methods have been developed for the immobilization of chiral pyridinebis(oxazoline) ligands by covalent bonding to a solid support, either by grafting or by polymerization. Different spacers can easily be introduced to modulate the
- Cornejo, Alfonso,Fraile, Jose M.,Garcia, Jose I.,Gil, Maria J.,Luis, Santiago V.,Martinez-Merino, Victor,Mayoral, Jose A.
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p. 5536 - 5544
(2007/10/03)
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- Synthesis of poly(pyridylthioether) dendrimers incorporating a Fe 2(CO)6 cluster core
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New pyridylthioether-based dendrons bearing a thiol moiety at their focal point have been prepared by a convergent synthetic approach. These dendrons were readily attached to a Fe2(CO)6 core to generate two-directional dendritic molecules incorporating an iron-carbonyl cluster.
- Chessa, Gavino,Canovese, Luciano,Visentin, Fabiano,Santo, Claudio,Seraglia, Roberta
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p. 1755 - 1763
(2007/10/03)
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- Diamino-C,N-diarylpyridine positional isomers as inhibitors of lysophosphatidic acid acyltransferase-β
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2,6-Diamino-4,N-diarylpyridines were identified as potent, isoform selective inhibitors of the enzymatic activity of lysophosphatidic acid acyltransferase-β (LPAAT-β).
- Hong, Feng,Hollenback, David,Singer, Jack W.,Klein, Peter
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p. 4703 - 4707
(2007/10/03)
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- Pyridines and uses thereof
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The invention relates to pyridines and uses thereof, including to inhibit lysophosphatidic acid acyltransferase β (LPAAT-β) activity and/or proliferation of cells such as tumor cells.
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Page/Page column 8
(2008/06/13)
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- The Effect of Global Compaction on the Local Secondary Structure of Folded Dendrimers
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The effect of nonlocal interactions on the local structural propensities of folded dendrimers was evaluated in this work by comparing, under identical conditions, the conformational properties of isomeric dendrimers differing in their global packing effic
- Huang, Baohua,Prantil, Matthew A.,Gustafson, Terry L.,Parquette, Jon R.
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p. 14518 - 14530
(2007/10/03)
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- New synthons for the synthesis of lanthanide containing macrocyclic schiff bases featuring substituents available for tethering
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2,6-Diacetylpyridine substituted with amine or alcohol groups in the 4- position have been prepared from chelidamic acid. The key 4-chloro derivative was synthesized in high yield via a diazo intermediate and was protected as a bis-1,3-dioxane before substitution with various amino alcohol groups. Lanthanide macrocyclic tetra-imine complexes were obtained by a template procedure that leads to stable paramagnetic and/or fluorescent derivatives with anchor groups available for linkage to macromolecules. (C) 2000 Elsevier Science Ltd.
- Dumont, Arnaud,Jacques, Vincent,Desreux, Jean F.
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p. 2043 - 2052
(2007/10/03)
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- Folding Dendrons: The Development of Solvent-, Temperature-, and Generation-Dependent Chiral Conformational Order in Intramolecularly Hydrogen-Bonded Dendrons
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The synthesis of intramolecularly hydrogen-bonded dendrons with stereogenic terminal groups derived from (1S,2S)-(+)-thiomicamine up to the third generation is described. Circular dichroism (CD) studies reveal that the equilibria interconverting two diast
- Recker, Janosch,Tomcik, Dennis J.,Parquette, Jon R.
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p. 10298 - 10298
(2007/10/03)
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- Synthesis and structure of intramolecularly hydrogen bonded dendrons
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(matrix presented)A convenient synthesis of monodendrons whose conformation is restricted through the intervention of intramolecular hydrogen bonding and repulsive electrostatic interactions is described. X-ray crystal structure analysis of the second gen
- Huang, Baohua,Parquette, Jon R.
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p. 239 - 242
(2007/10/03)
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- Effect of a halogenide substituent on the stability and photophysical properties of lanthanide triple-stranded helicates with ditopic ligands derived from bis(benzimidazolyl)pyridine
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Bis {1-ethyl-2-[6-(N,N-diethylcarbamoyl)-4-halogenopyridin-2-yl]benzimidazol-5-yl} methane (halogeno = chloro, LE; bromo, LF) have been synthesized as ditopic receptors for the development of lanthanide-containing helicates able to couple with biological material and to test the influence of the halogeno substituent on the wrapping process, the structure of the resulting dimetallic edifices, and the photophysical properties of the encapsulated ions. The stability of the [Eu2(L)3]6+ helicates, as determined by NMR competitive titrations, decreases by respectively one (LF) and three (LE) orders of magnitude compared to the value found for the unsubstituted ligand (LB) although it remains large, log β23 = 23.8 (LF) and 21.8 (LE) in acetonitrile. The [Ln2(LE)3]6+ helicates are shown to be isostructural in acetonitrile over the lanthanide series (Pr to Yb) and the crystal structure of [Tb2(LB)3]6+ appears to be a good model for their solution structure, as demonstrated by paramagnetic NMR measurements (lanthanide induced shift method) and relaxation time determination. Ligand LE appears to be a fair sensitiser of EuIII, the quantum yield of [Eu2(LE)3]6+ being 25% larger than that found for [Eu2(LB)3]6+, but the ligand 3ππ* state and Tb(5D4) excited level are in resonance, which limits the sensitisation of TbIII. High resolution luminescence spectra of [Eu2(LE)3]6+, both in solution and in the solid state, are presented and discussed in terms of site symmetry and vibronic coupling mechanisms. The Royal Society of Chemistry 2000.
- Iglesias, Carlos Platas,Elhabiri, Mourad,Hollenstein, Marcel,Buenzli, Jean-Claude G.,Piguet, Claude
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p. 2031 - 2043
(2007/10/03)
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- Synthesis and structure-activity relationships of phenylenebis(methylene)-linked bis-azamacrocycles that inhibit HIV-1 and HIV- 2 replication by antagonism of the chemokine receptor CXCR4
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Bis-tetraazamacrocycles such as the bicyclam AMD3100 are a class of potent and selective anti-HIV-1 and HIV-2 agents that inhibit virus replication by binding to the chemokine receptor CXCR4, the co-receptor for entry of X4 viruses. With the aim of optimi
- Bridger, Gary J.,Skerlj, Renato T.,Padmanabhan, Sreenivasan,Martellucci, Stephen A.,Henson, Geoffrey W.,Struyf, Sofie,Witvrouw, Myriam,Schols, Dominique,De Clercq, Erik
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p. 3971 - 3981
(2007/10/03)
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- Novel synthesis of substituted 4′-hydroxy-2,2′:6′,2″-terpyridines
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4-Substituted-2,6-diacetylpyridines 2-4 have been synthesised; by using the Kroehnke-methodology, chalcone and methylacylpyridinium salts have been reacted to yield 4′-ethoxy-2,2′:6′,2″-terpyridines 5-7. These novel 2,2′:6′,2″-terpyridines are functionali
- Fallahpour, Reza-Ali,Constable, Edwin C.
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p. 2263 - 2264
(2007/10/03)
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- Design and synthesis of complementary components for the formation of self-assembled supramolecular rigid rods
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The complementary components AP2 and AU2, resulting respectively from the linking of diacylaminopyridine and uracil derivatives to an anthracenic core, have been designed in order to self-assemble, through hydrogen bonding, into polymeric supramolecular rigid rods (AP2, AU2)(n). The synthesis of these compounds is reported.
- Kotera, Mitsu,Lehn, Jean-Marie,Vigneron, Jean-Pierre
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p. 1953 - 1972
(2007/10/02)
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- Studies on Cation Selectivities of Some Pyridine-Based Ionophores for Use in Polymer Membrane Chemical Sensors
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The synthesis of some macrocyclic compounds based on 4-octyloxypyridine-2,6-dicarboxylic acid, containing sulfur and/or oxygen atoms in the 2 to 6-bridging unit, along with some non-cyclic analogues is reported.These were tested for cation selectivity in poly(vinyl chloride)-based membrane electrodes.Little selectivity was found for any ion with the oxygen-containing compounds, and none approached the selectivity for potassium reported previously for a related compound.High bonding affinities for class b acceptors, particularly Ag+ and Hg2+, were found for sulfur- containing compounds.The complexation with Hg2+ was so strong that the electrodes showed behaviour characteristic of an anion response.
- Bates, Marie-Rose M.,Cardwell, Terence J.,Cattrall, Robert W.,Deady, Leslie W.,Murphy, Kathryn
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p. 1603 - 1613
(2007/10/02)
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- THE DESIGN OF MAGNETIC RESONANCE CONTRAST AGENTS: NEW IRON (III) DIHYDROXAMATE COMPLEXES
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We have prepared a series of dihydroxamates and their iron(III) complexes in view of obtaining new NMR imaging agents.Four new dihydroxamic acid ligands have been synthesized by condensation of 4-substituted-2,6-pyridine dicarboxylic acids with N-aminopro
- Chaubet, Frederic,Nguyen Van Duong, Marguerite,Gref, Aurore,Courtieu, Jacques,Crumbliss, Alvin L.,Gaudemer, Alain
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p. 5729 - 5732
(2007/10/02)
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- Cation Complexing Properties of Synthetic Macrocyclic Polyether-Diester Ligands Containing the Pyridine Subcyclic Unit
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Ten new macrocyclic polyether-diester compounds containing a pyridine subcyclic unit substituted in the 4 position with chloro or methoxy groups have been prepared.These compounds along with their unsubstituted pyridine analogues form strong complexes wit
- Bradshaw, J. S.,Maas, G. E.,Lamb, J. D.,Izatt, R. M.,Christensen J. J.
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p. 467 - 474
(2007/10/02)
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