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  • Organic Chemistry  (6)
  • ionizable mobile carrier  (2)
  • Self-assembly
  • molecular devices
  • 1985-1989  (8)
  • 1975-1979
  • 1987  (3)
  • 1986  (5)
Collection
Keywords
Publisher
Years
  • 1985-1989  (8)
  • 1975-1979
Year
  • 1
    Electronic Resource
    Electronic Resource
    Transport of alkali cations through thin lipid membranes by (222)C10-Cryptand, an ionizable mobile carrier (1986)
    Springer
    The journal of membrane biology 89 (1986), S. 251-267 
    Details
    ISSN: 1432-1424
    Keywords: cryptand ; ionizable mobile carrier ; transport kinetics ; lipid membrane ; alkali cations ; valinomycin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The kinetics of K+ and Na+ transport across the membrane of large unilamellar vesicles (L.U.V.) were compared at two pH's, with two carriers: (222)C 10-cryptand (diaza-1, 10-decyl-5-hexaoxa-4,7,13,16,21,24-bicyclo[8.8.8.]hexacosane) and valinomcyin, i.e. an ionizable macrobicyclic amino polyether and a neutral macrocyclic antibiotic. The rate of cation transport by (222)C10 saturated as cation and carrier concentrations rose. The apparent affinity of (222)C10 for K+ was higher and less pH dependent than that for Na+ but resembled the affinity of valinomycin for K+. The efficiency of (222)C10 transport of K+ decreased as the pH fell and the carrier concentration rose, and was about ten times lower than that of valinomycin. Noncompetitive K+/Na+ transport selectivity of (222)C10 decreased as pH, and cation and carrier concentrations rose, and was lower than that of valinomycin. Transport of alkali cations by (222)C10 and valinomycin was noncooperative. Reaction orders in cationn(S) and carrierm(M) varied with the type of cation and carrier and were almost independent of pH;n(S) andm(M) were not respectively dependent on carrier or cation concentrations. The apparent estimated constants for cation translocation by (222)C10 were higher in the presence of Na+ than of K+ due to higher carrier saturation by K+, and decreased as pH and carrier concentration increased. Equilibrium potential was independent of the nature of carrier and transported cation. Results are discussed in terms of the structural, physicochemical and electrical characteristics of carriers and complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870668
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  • 2
    Electronic Resource
    Electronic Resource
    Efficiency, Na+/K+ selectivity and temperature dependence of ion transport through lipid membranes by (221)C10-Cryptand, an ionizable mobile carrier (1987)
    Springer
    The journal of membrane biology 97 (1987), S. 79-95 
    Details
    ISSN: 1432-1424
    Keywords: cryptand ; Na+ selectivity ; temperature ; ionizable mobile carrier ; nonactin ; cation transport kinetics ; lipid membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The kinetics of Na+ and K+ transport across the membrane of large unilamellar vesicles (LUV) were determined at two pH's when transport was induced by (221)C10-cryptand (diaza-1,10-decyl-5-pentaoxa-4,7,13,16,21-bicyclo [8.8.5.] tricosane) at various temperatures, and by nonactin at 25°C and (222)C10-cryptand at 20 and 25°C. The rate of Na+ and K+ transport by (221)C10 saturated with the cation and carrier concentrations. Transport was noncooperative and exhibited selectivity for Na+ with respect to K+. The apparent affinity of (221)C10 for Na+ was higher and less pH-dependent than that for K+, and seven times higher than that of (222)C10 for K+ ions (20.5vs. 1.7 kcal·mole−). The efficiency of (221)C10 transport of Na+ was pH-and carrier concentration-dependent, and was similar to that of nonactin; its activation energy was similar to that for (222)C10 transport of K+ (35.5 and 29.7 kcal · mole−1, respectively). The reaction orders in cationn(S) and in carrierm(M), respectively, increased and decreased as the temperature rose, and were both independent of carrier or cation concentrations; in most cases they varied slightly with the pH.n(S) varied with the cation at pH 8.7 and with the carrier for Na+ transport only, whilem(M) always depended on the type of cation and carrier. Results are discussed in terms of the structural, physico-chemical and electrical characteristics of carriers and complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869415
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  • 3
    Electronic Resource
    Electronic Resource
    Photogeneration of Carbon Monoxide and of Hydrogen via Simultaneous Photochemical Reduction of Carbon Dioxide and Water by Visible-Light Irradiation of Organic Solutions Containing Tris(2,2′-bipyridine)ruthenium(II) and Cobalt(II) Species as Homogeneous Catalysts (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1065-1084 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: CO and H2 are photogenerated simultaneously by visible-light irradiation of systems containing a photosensitizer, the [Ru(bpy)3]2+ complex, Co(II) species as homogeneous catalysts, which mediate CO2 and H2O reduction by intermediate formation of Co(I), a tertiary amine as electron donor, which provides the electrons for the reduction, and an organic solvent which also facilitates dissolution of CO2. The efficiency of (CO + H2) gas production and the selectivity CO/H2 markedly depend upon the composition of the medium, the nature of the tertiary amine, the solvent, and the ligand of the Co ions. 2,9-Dimethyl-1,10-phenanthroline is particularly effective in promoting CO and H2 formation, giving a quantum yield of 7.7% in (CO + H2) (1.2% for CO and 6.5% for H2). The process consists of two catalytic cycles: a photocatalytic cycle for the Ru complex and a double dark reaction pathway for the Co species; oxidative and/or reductive quenching of the excited state of the photosensitizer lead to the formation of Co(I) species which reduce either CO2 or H2O to CO or H2, respectively.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690514
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  • 4
    Electronic Resource
    Electronic Resource
    Photochemical and Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide Mediated by (2,2′-Bipyridine)tricarbonylchlororhenium(I) and Related Complexes as Homogeneous CatalystsCommunicated in part at the 5ème Atelier de Photochimie et de Photophysique des Composés Organométalliques et de Coordination, Société Française de Chimie, Paris, 21-22 June, 1984; for a preliminary communication, see [38]; taken in part from J. Hawecker, Ph.D. thesis, Université Louis Pasteur, Strasbourg, 1984. (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1990-2012 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [fac-Re(bpy) (CO)3Cl] (bpy = 2,2′-bipyridine) is an efficient homogeneous catalyst for the selective and sustained photochemical or electrochemical reduction of CO2 to CO. A quantum yield of 14% and a faradic efficiency of 98% were measured in the presence of excess Cl- ions. The photochemical process took place under visible-light irradiation and consumed a tertiary amine as electron donor. A formato-rhenium complex was isolated in the absence of excess Cl- ions. Substitution by Cl- ion generated free formate, but no CO was detected. Luminescence measurements showed that the tertiary amine quenches the metal-to-ligand charge-transfer excited state of the rhenium complex via a reductive mechanism, with a rate constant of 3.4 × 107M-1S-1. The 19e-complex [Re(bpy) (CO)3X]- produced either photochemically or electrochemically appears to be the active precursor in the CO-generation process. Detailed spectroscopic studies on 13C-enriched carbonyl-rhenium and formato-rhenium complexes derived from 13C-enriched CO2 were performed in order to confirm the origin of the products and to study the exchange of the ligands. A mechanism for the present CO2 photoreduction process is presented; it involves separate pathways for CO and formate generation, in which the [Re(bpy) (CO)3X] complex plays the role of both the photoactive and the catalytic center.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690824
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  • 5
    Electronic Resource
    Electronic Resource
    Molecular Anion Binding and Substrate Photooxidation in Visible Light by 2,7-Diazapyrenium Cations (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1-12 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 2,7-diazapyrenium group (DAP2+) combines the features of pyrene, of methylviologen, and of nucleicacid intercalators and may thus present a variety of interesting properties. The cations 1 and 2 and the bis-diazapyrenium species 3 have been synthesized and shown to bind molecular anions like aromatic polycarboxylates, giving rise to pronounced shifts of 1H-NMR signals, modifications of UV/VIS absorption spectra, and quenching of fluorescence. The complexes formed probably have a face-to-face structure, and their stability constants are remarkably high, in particular for the bis-diazapyrenium cation 3 which is susceptible to form intercalative chelate complexes such as 9(log Ks ≈ 3 for 1, up to ca. 7 or more for 3a). Neutral molecules like adenine are also bound, but much less strongly. Visible-light irradiation of Me2DAP2+ (1) in presence of various electron donors, such as EDTA, gives the reduced species Me2DAP+ wich has been characterized by UV/VIS and ESR spectroscopy. The results indicate that Me2DAP2+ (1) functions as a methylviologen analogue, photoactive in visible light. Thus 2,7-diazapyrenium cations are attractive subunits for incorporation into macropolycyclic structures to give photo- and electroactive receptor molecules.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700102
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  • 6
    Electronic Resource
    Electronic Resource
    Binding of AMP, ADP, and ATP Nucleotides by Polyammonium Macrocycles (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 1312-1319 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The macrocyclic polyamines 4-6, when protonated, bind strongly and selectively nucleotides (AMP, ADP, ATP) and pyrophosphate in aqueous solution. The stoichiometry of the complexes formed was determined by titration experiments followed by 31P-NMR spectroscopy. Compounds 4 and 5 form 1:1 complexes with ATP, ADP, and pyrophosphate, whereas 6 forms complexes with ATP and ADP involving 2 nucleotides and 1 receptor molecule. The stability constants of these complexes have been determined by pH-metric measurements. At pH 7, both 5 and 6 give complexes of mainly the fully protonated species 5.6H+ and 6.8H+, whereas 4 yields predominantly complexes of 4.5H+ and 4.4H+.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700512
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  • 7
    Electronic Resource
    Electronic Resource
    Ditopic Ligands. The Synthesis of a Series of Phosphine-Functionalised Macrocycles (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 580-586 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a series of phosphine-functionalised macrocycles, 1-6, is described. The combination of N-and O-sites with P- and S-sites provides ligands which may bind transition or non-transition metal ions; as a consequence, they give access to dinuclear complexes containing both a Lewis acid and a redox metallic site. Compounds 1,2 and 6 are heterodinucleating ligands capable of binding two dissimilar metals in proximity. Macrocycles 3-5 are homotopic ligands which may form homodinuclear complexes of transition metals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690307
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  • 8
    Electronic Resource
    Electronic Resource
    Anion Coreceptor Molecules. Linear Molecular Recognition in the Selective Binding of Dicarboxylate Substrates by Ditopic Polyammonium Macrocycles (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 587-603 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three macrocyclic hexaamines 1, 2, and 4, and the acyclic tetraamine 5 and hexaamine 6 have been synthesized. The hexaamines 1, 2, and 4 are ditopic coreceptor molecules containing two triamine subunits which may bind anionic substrates when protonated. The stability constants of the complexes between the protonated forms of the macrocyclic polyamines and terminal dicarboxylates -O2C-(CH2)m- CO2- as well as amino-acid and dipeptide dicarboxylates have been determined by pH-metric measurements. Around neutral pH, 1 and 2 give mainly complexes of the fully protonated species 1·6H+ and 2·6H+, whereas 4 yields predominantly complexes of 4·5H+ and 4·4H+. The stability sequences of the complexes formed indicate preferential binding of the dianionic substrates whose length is compatible with the separation of the triammonium binding subunits in the protonated receptor molecules 1, 2, and 4. This selectivity pattern corresponds to a process of linear molecular recognition based on ditopic binding between the two ammonium subunits of the coreceptor and the terminal carboxylates of the substrate of complementary length. The complexes of the acyclic ligands 5 and 6 are much weaker and much less selective, indicating a marked macrocyclic effect on both stability and selectivity of binding, i.e. on recognition.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690308
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