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Bipyridine Ligands (bipyridine + ligand)
Selected AbstractsChemInform Abstract: Synthesis of Novel Dendritic 2,2,-Bipyridine Ligands and Their Application to Lewis Acid Catalyzed Diels,Alder and Three-Component Condensation Reactions.CHEMINFORM, Issue 8 2008Takahito Muraki Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Enantioselective Catalytic Cyclopropanation of Styrenes by Copper Complexes with Chiral Pinene-[5,6]-bipyridine Ligands.CHEMINFORM, Issue 14 2001Didier Loetscher Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Mixed iridium(III) and ruthenium(II) polypyridyl complexes containing poly(,-caprolactone)-bipyridine macroligandsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2004Veronica Marin Abstract A hydroxy-functionalized bipyridine ligand was polymerized with ,-caprolactone utilizing the controlled ring-opening polymerization of ,-caprolactone in the presence of stannous octoate. The resulting poly(,-caprolactone)-containing bipyridine was characterized by 1H NMR and IR spectroscopy, and gel permeation chromatography, as well as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, revealing the successful incorporation of the bipyridine ligand into the polymer chain. Coordination to iridium(III) and ruthenium(II) precursor complexes yielded two macroligand complexes, which were characterized by NMR, gel permeation chromatography, matrix-assisted laser desorption/ionization time-of-flight MS, cyclic voltammetry, and differential scanning calorimetry. In addition, both photophysical and electrochemical properties of the metal-containing polymers proved the formation of a trisruthenium(II) and a trisiridium(III) polypyridyl species, respectively. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4153,4160, 2004 [source] Synthesis of poly(fluorinated styrene)- block -poly(ethylene oxide) amphiphilic copolymers via atom transfer radical polymerization: potential application as paper coating materialsPOLYMER INTERNATIONAL, Issue 8 2009Khalid A Ibrahim Abstract BACKGROUND: The surface of a substrate which comprises a fibrous material is brought into contact with a type of amphiphilic block copolymer which comprises hydrophilic/hydrophobic polymeric blocks. These amphiphilic copolymers have been synthesized by atom transfer radical polymerization (ATRP) technique. The atom transfer radical polymerization of poly(2,3,4,5,6-pentafluorostyrene)- block -poly(ethylene oxide) (PFS- b -PEO) copolymers (di- and triblock structures) with various ranges of PEO molecular weights was initiated by a PEO chloro-telechelic macroinitiator. The polymerization, carried out in bulk and catalysed by copper(I) chloride in the presence of 2,2,-bipyridine ligand, led to A,B,A amphiphilic triblock and A,B amphiphilic diblock structures. RESULTS: With most of the macroinitiators, the living nature of the polymerizations led to block copolymers with narrow molecular weight distributions (1.09 < Mw/Mn < 1.33) and well-controlled molecular structures. These block copolymers turned out to be water-soluble through adjustment of the PEO block content (>90 wt%). Of all the block copolymers synthesized, PFS- b -PEO(10k)- b -PFS containing 10 wt% PFS was found to retard water absorption considerably. CONCLUSION: The printability of paper treated with the copolymers was evaluated with contact angle measurements and felt pen tests. The adsorption of such copolymers at the solid/liquid interface is relevant to the wetting and spreading of liquids on hydrophobic/hydrophilic surfaces. Copyright © 2009 Society of Chemical Industry [source] 1D Ladder-like Chain and 1D Channeled 3D Supramolecular Architectures Based on Benzophenone-2,4,-dicarboxylic AcidCHINESE JOURNAL OF CHEMISTRY, Issue 4 2008Xiao-Gang YANG Abstract The hydrothermal reactions of AgNO3, 2,2,-bipyridyl, and benzophenone-2,4,-dicarboxylic acid gave rise to two 3D supramolecular architectures, namely H2L·H2O (1), [Ag(bpy)2]·HL·H2O (2) (bpy2,2,-bipyridyl, H2Lbenzophenone-2,4,-dicarboxylic acid). The two compounds are extended by hydrogen bonds in two different approaches. In the case of 1, one-dimensional ladder-like structure is firstly formed through O,H···O hydrogen bonding between H2L ligands and water molecules, then extended to a 3D supramolecular architecture. Compound 2 possesses 3D supramolecular architecture containing 1D open channels, which are driven due to the strong H-bonding interactions occurring between the HL anions and water molecules; interestingly, [Ag(bpy)2]+ cations are linked together through ,-, interactions between bpy ligands and weak Ag···Ag interactions, and then reside in these channels by C,H···O hydrogen-bond. The photoluminescence properties of these compounds were also investigated, the emission maxima for 2 exhibits red-shift compared with that of free ligand and 1 due to chelating effect of the 2,2,-bipyridine ligand to the silver ion and the presence of aromatic ,-packing. [source] Hybrid 2D and 3D Frameworks Based on ,-Keggin Polyoxometallates: Experiment and SimulationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2005Anne Dolbecq Abstract The ,-Keggin polyoxomolybdate {,-PMoV8MoVI4O40,x(OH)xM4} is a versatile building unit, with M being either a ZnII or a LaIII capping ion located at the vertices of a slightly distorted tetrahedron. The charge of the Keggin unit depends on the number of protonated oxo bridging ligands, which has been shown to vary from 0 to 5. The Keggin entity can thus be either an anion (M = Zn, x = 0) or a cation (M = La, x = 3,5). The Zn derivative has been generated in situ by hydrothermal synthesis and forms a 2D material built from the connection of the cations by 4,4'-bipyridine ligands linked to the capping ZnII ions. The reaction of the chloride salt of the La derivative with di-, tri- and tetrasubstituted benzenecarboxylate ligands has allowed us to isolate 2D and 3D materials. The 3D materials seem to be the first examples of hybrid open frameworks based on Keggin building blocks. The 3D framework built from the connection of ,-Keggin units by trimesate ions exhibits tunnels filled only by water molecules, which can be partly removed and reintroduced at room temperature. Besides these experimental results, simulation has allowed us to generate two virtual hybrid structures derived from those of known silicates by replacing the Si ions by hypothetical ,-Keggin cations and the O -bridging ligands by terephthalate ions, thus showing that 3D frameworks with large pores can be envisioned in the chemistry of hybrid organic,inorganic materials based on ,-Keggin units and motivating further experimental investigations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Structural Studies on Hydrogen-Bonding Receptors for Barbiturate Guests That Use Metal Ions as Allosteric InhibitorsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2004Mohammad H. Al-Sayah Abstract Receptor 1 was designed to bind barbiturate substrates through a six-point hydrogen-bonding motif only in the absence of metal allosteric cofactors. It was predicted that the binding of metal ions by bipyridine ligands in 1 would result in a geometric change in the receptor to inhibit substrate recognition. However, receptor 1 showed minimal affinity for the barbiturate guests even in the absence of the metal. Binding studies on model compounds 2, 3, 5, and 6 revealed that the inactivity of 1 is due to an intramolecular hydrogen bond between the N,H donor groups and the nitrogen atoms on the first heterocycle of the bipyridine ligands. This intramolecular hydrogen-bonding was eliminated by altering the position of the tether between the bipyridine ligands and the active site to produce receptor 7. Consequently, the high affinity exhibited by 7 for the barbiturate substrate (Ka = 2.8±0.7 × 103M,1 in 9:1 CD2Cl2/CD3CN) was significantly reduced by the addition of ZnII ions as a negative allosteric co-factor. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] A three-dimensional homochiral metal,organic framework constructed from manganese(II) with S -carboxymethyl- N -(p -tosyl)- l -cysteine and 4,4,-bipyridineACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009Wei Xiong In the chiral polymeric title compound, poly[aqua(4,4,-bipyridine)[,3 - S -carboxylatomethyl- N -(p -tosyl)- l -cysteinato]manganese(II)], [Mn(C12H13NO6S2)(C10H8N2)(H2O)]n, the MnII ion is coordinated in a distorted octahedral geometry by one water molecule, three carboxylate O atoms from three S -carboxyatomethyl- N -(p -tosyl)- l -cysteinate (Ts-cmc) ligands and two N atoms from two 4,4,-bipyridine molecules. Each Ts-cmc ligand behaves as a chiral ,3 -linker connecting three MnII ions. The two-dimensional frameworks thus formed are further connected by 4,4,-bipyridine ligands into a three-dimensional homochiral metal,organic framework. This is a rare case of a homochiral metal,organic framework with a flexible chiral ligand as linker, and this result demonstrates the important role of noncovalent interactions in stabilizing such assemblies. [source] Fe2 and Fe4 Clusters Encapsulated in Vacant Polyoxotungstates: Hydrothermal Synthesis, Magnetic and Electrochemical Properties, and DFT CalculationsCHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2008Céline Pichon Abstract While the reaction of [PW11O39]7, with first row transition-metal ions Mn+ under usual bench conditions only leads to monosubstituted {PW11O39M(H2O)} anions, we have shown that the use of this precursor under hydrothermal conditions allows the isolation of a family of novel polynuclear discrete magnetic polyoxometalates (POMs). The hybrid asymmetric [FeII(bpy)3][PW11O39Fe2III(OH)(bpy)2],12,H2O (bpy=bipyridine) complex (1) contains the dinuclear {Fe(,-O(W))(,-OH)Fe} core in which one iron atom is coordinated to a monovacant POM, while the other is coordinated to two bipyridine ligands. Magnetic measurements indicate that the FeIII centers in complex 1 are weakly antiferromagnetically coupled (J=,11.2,cm,1, H=,JS1S2) compared to other {Fe(,-O)(,-OH)Fe} systems. This is due to the long distances between the iron center embedded in the POM and the oxygen atom of the POM bridging the two magnetic centers, but also, as shown by DFT calculations, to the important mixing of bridging oxygen orbitals with orbitals of the POM tungsten atoms. The complexes [Hdmbpy]2[FeII(dmbpy)3]2[(PW11O39)2Fe4IIIO2(dmbpy)4],14,H2O (2) (dmbpy=5,5,-dimethyl-2,2,-bipyridine) and H2[FeII(dmbpy)3]2[(PW11O39)2Fe4IIIO2(dmbpy)4],10,H2O (3) represent the first butterfly-like POM complexes. In these species, a tetranuclear FeIII complex is sandwiched between two lacunary polyoxotungstates that are pentacoordinated to two FeIII cations, the remaining paramagnetic centers each being coordinated to two dmbpy ligands. The best fit of the ,MT=f(T) curve leads to Jwb=,59.6,cm,1 and Jbb=,10.2,cm,1 (H=,Jwb(S1S2+S1S2*+S1*S2+S1*S2*),Jbb(S2S2*)). While the Jbb value is within the range of related exchange parameters previously reported for non-POM butterfly systems, the Jwb constant is significantly lower. As for complex 1, this can be justified considering FewO distances. Finally, in the absence of a coordinating ligand, the dimeric complex [N(CH3)4]10[(PW11O39FeIII)2O],12,H2O (4) has been isolated. In this complex, the two single oxo-bridged FeIII centers are very strongly antiferromagnetically coupled (J=,211.7,cm,1, H=,JS1S2). The electrochemical behavior of compound 1 both in dimethyl sulfoxide (DMSO) and in the solid state is also presented, while the electrochemical properties of complex 2, which is insoluble in common solvents, have been studied in the solid state. [source] Impact of the Aliphatic Dicarboxylate Chain of Novel Dinuclear Palladium(II) Complexes: Synthesis and Biological EvaluationCHINESE JOURNAL OF CHEMISTRY, Issue 2 2010Enjun Gao Abstract Five dinuclear palladium(II) complexes with HOOC(CH2)nCOOH (n=2,6) and 2,2,-bipyridine ligands were synthesigned by a reaction with K2PdCl4. To prepare such complexes with different aliphatic dicarboxylate chain lengths was in an attempt to correlate this length factor, which influences the biological activity of the complexes, with fluorescence spectra, DNA cleavage and cytotoxic activity. The results indicate that the complexes bind to fish sperm DNA (FS-DNA) in an intercalative mode via fluorescence spectra, and the five complexes show different cleavage of supercoiled DNA, and then a cytotoxicity assay of these dinuclear palladium(II) complexes on human tumor cell lines was performed. In most of the cell lines, complex 5 (n=6) and 4 (n=5) showed much higher cytotoxicity than cis -platin. On the other hand, complex 3 (n=4) was found to be moderately active, and complex 1 (n=2), complex 2 (n=3) were found only marginally cytotoxic. Implications of these findings were discussed from a structure-activity relationship. [source] | ||||||||||||||||||||||