- Columnar Self-Assemblies of Triarylamines as Scaffolds for Artificial Biomimetic Channels for Ion and for Water Transport
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Triarylamine molecules appended with crown-ethers or carboxylic moieties form self-assembled supramolecular channels within lipid bilayers. Fluorescence assays and voltage clamp studies reveal that the self-assemblies incorporating the crown ethers work as single channels for the selective transport of K+ or Rb+. The X-ray crystallographic structures confirm the mutual columnar self-assembly of triarylamines and crown-ethers. The dimensional fit of K+ cations within the 18-crown-6 leads to a partial dehydration and to the formation of alternating K+ cation-water wires within the channel. This original type of organization may be regarded as a biomimetic alternative of columnar K+-water wires observed for the natural KcsA channel. Supramolecular columnar arrangement was also shown for the triarylamine-carboxylic acid conjugate. In this latter case, stopped-flow light scattering analysis reveals the transport of water across lipid bilayer membranes with a relative water permeability as high as 17 μm s-1
- Schneider, Susanne,Licsandru, Erol-Dan,Kocsis, Istvan,Gilles, Arnaud,Dumitru, Florina,Moulin, Emilie,Tan, Junjun,Lehn, Jean-Marie,Giuseppone, Nicolas,Barboiu, Mihail
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- Synthesis and properties of crown ether-modified posphines and their use as ligands in transition metal catalysts
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A novell series of crown ether-modified triarylphosphines, 1,2-diphenylphosphinino-2,3,5,6,8,9-hexahydro-1,4,7,10-benzotetraoxacyclodecin (IIIa) and its higher homolog (III) (common nomenclature is 3n-diphenylphosphinobenzo-ethers (n=4,5,6 and 7)), is reported.The thermodynamic parameters for the extraction of alkali metal picrates are evaluated.Phosphines III (n=5 and 6) from 1:1 stoichiometric crown-type complexes with Na+ and K+.The observed extractability is in good agreement with the cavity size selectivity concept.The thermodynamic parameters ΔHo and TΔSo for the extractive complexation at 25 deg C are -63 to -58 kJ/mol and -41 to -35 kJ/mol, respectively, thus ΔGo is governed by the entalphy term.These phosphines are applied to reactions in liquid-liquid or liquid-solid phases, as the auxiliary ligands of homogenous palladium and rhodium catalysts.The catalytic activities correlate well with the extractibilities of the phyosphine ligands.The compound 2, combined with IIIc and IIId, shows high activities toward catalytic hydrogenation of potassium and caesium cinnamates, respectively.Replacement of allyl bromide with powdered sodium or potassium iodide in benzene to give allyl iodide are catalyzed by (?-C3H5PdCl)2 in the presence of phosphines III.
- Okano, Tamon,Iwahara, Masahiro,Konishi, Hisatoshi,Kiji, Jitsuo
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p. 267 - 276
(2007/10/02)
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- Transition Metal Phosphine Complexes Possessing a Phase Transfer Function. Preparation and Catalytic Reactivity of Palladium Phosphine Complexes Containing Crown Ethers
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Crown-functionalized triarylphosphines and their palladium complexes were synthesized and characterized.The palladium complexes were found to fulfil the concerted function of the transition metal catalyst and the phase transfer catalyst in the two-phase reduction of 1-chloromethylnaphthalene with formate salts.
- Okano, Tamon,Iwahara, Masahiro,Suzuki, Takayoshi,Konishi, Hisatoshi,Kiji, Jitsuo
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p. 1467 - 1470
(2007/10/02)
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