Depriving microorganisms of bioavailable iron is a promising strategy for new anti-infective agents. The new, highly water-soluble, low molecular weight co-polymer DIBI was developed to selectively bind iron(iii) ions as a tris chelate and acts as a standalone anti-infective. Minimum inhibitory concentration (MIC) studies show DIBI is effective against representative reference strains for Gram-positive and Gram-negative bacteria and, and the fungus . Compared to the small molecule iron chelators, deferiprone and deferoxamine, DIBI outclassed these by factors of 100 to 1000 for inhibition of initial growth. DIBI and a series of related co-polymers ( of 2-9 kDa) were synthesized reversible addition-fragmentation chain transfer (RAFT) polymerization of a chelating 3-hydroxypyridin-4-one (HPO) methacrylamide monomer and-vinylpyrrolidone (NVP). Full incorporation of the HPO monomer into the co-polymers from the reaction solution was determined by H NMR spectroscopy and ranged from 4.6 to 25.6 mol%. UV-vis spectroscopy showed that all the HPO in DIBI binds readily to iron(iii) in a tris chelate mode to the maximum theoretical iron(iii) binding capacity of the co-polymer. Chemical characterization including single crystal X-ray diffraction analyses of the-benzyl protected and the functional HPO monomer are discussed. By design, DIBI is highly water soluble; the highest mass fraction in water tested was 70% w/w, without the need of organic co-solvents.
Amine-functionalized mono- and diphosphines have been used to prepare a series of ruthenium complexes which exhibit a variety of coordination modes depending on the number of donors possessed by the ligands, the degree of amine methylation, the solvent system used, and the oxidation state of the metal. Reactions of the monophosphinoanilines, Ph(2)PAr or Ph(2)PAr' (Ar = o-C(6)H(4)NHMe, Ar' = o-C(6)H(4)NMe(2)), with 0.5 equiv of [RuCl(mu-Cl)(eta(6)-p-cymene)](2) in dichloromethane result in the formation of [RuCl(2)(eta(6)-p-cymene)(P-Ph(2)PAr)] or [RuCl(eta(6)-p-cymene)(P,N-Ph(2)PAr')]Cl, respectively. In refluxing methanol, [RuCl(2)(eta(6)-p-cymene)(P-Ph(2)PAr)] gradually undergoes chloride ion dissociation to afford the P,N-chelate, [RuCl(eta(6)-p-cymene)(P,N-Ph(2)PAr)]Cl. This chelate can then be deprotonated to afford the amido complex, [RuCl(eta(6)-p-cymene)(P,N-Ph(2)PAr(-))] (Ar(-) = o-C(6)H(4)NMe(-)), which is an active ketone transfer hydrogenation catalyst. Reactions of the diphosphines, Ar(2)PCH(2)PAr(2) (mapm) or Ar'(2)PCH(2)PAr'(2) (dmapm) with 0.5 equiv of [RuCl(mu-Cl)(eta(6)-p-cymene)](2) result in the formation of [RuCl(2)(P,P',N,N'-mapm)] or [RuCl(eta(6)-p-cymene)(P,P'-dmapm)]Cl, respectively, in which increased methyl substitution in the latter actually inhibits amine coordination with retention of the p-cymene fragment. Reaction of mapm with 1 equiv of [Ru(CO)(4)(eta(2)-C(2)H(4))] in dichloromethane initially produces [Ru(CO)(4)(P-mapm)] which, over a 24 h period with exposure to ambient light, is completely converted to the P,P'-chelate, [Ru(CO)(3)(P,P'-mapm)], by photodissociation of carbon monoxide. The same reaction with 2 equiv of [Ru(CO)(4)(eta(2)-C(2)H(4))] generates a mixture of [Ru(3)(CO)(10)(mu-P,P'-mapm)] and the mononuclear P,P'-chelate. The trinuclear complex can also be synthesized by direct reaction of mapm with 1 equiv of [Ru(3)(CO)(12)].
Monophosphines of the type Ph(x)PAr(3-x) (x = 0, 1 or 2, Ar = o-N-methylanilinyl) and the diphosphine, Ar(2)PCH(2)PAr(2) (mapm) have been synthesized for use as chelating and/or bridging P,N-ligands within mono- and binuclear rhodium(i) complexes, respectively. The previously prepared phosphines, Ph(x)PAr'(3-x) (x = 0, 1 or 2, Ar' = o-N,N-dimethylanilinyl) and Ar'(2)PCH(2)PAr'(2) (dmapm), have also been used to prepare analogous mono- and binuclear complexes. Variable temperature (1)H NMR spectroscopy of the mononuclear complexes, [RhCl(CO)(L)] (L = PhPAr(2), PhPAr'(2), PAr(3) and PAr'(3)), and line-shape analyses of the resultant spectra indicate the substantially increased lability of the N,N-dimethylanilinyl donors relative to the related monomethylanilinyl groups. X-Ray structural analyses of the mononuclear complexes suggest that the enhanced Type II hemilability in the dimethylanilinyl complexes compared to their monomethyl analogues results from increased steric interactions involving the coordinated dimethylanilinyl substituents. In the case of the binuclear, dmapm-bridged compound [Rh(2)Cl(2)(CO)(2)(micro-dmapm)], there are additional transannular repulsions between the chloro ligand on one metal and the coordinated dimethylanilinyl group on the other, which result in a Rh-Rh separation of over 4.1 A. For the analogous mapm-bridged species, the transannular interactions between the chloro ligands and the amine hydrogens are in fact attractive, resulting in a much closer Rh-Rh separation (3.450 A). The chloride substituents of [Rh(2)Cl(2)(CO)(2)(micro-mapm)] can be replaced to generate the complexes, [Rh(2)(X)(2)(CO)(2)(micro-mapm)] (X = I, CF(3)SO(3), CH(3)CO(2)), the last of which also exhibits pronounced transannular hydrogen-bonding interactions in the solid state.
δ‐D‐Gluconolactone, δ‐D‐mannonolactone, and — for the first time — the thermodynamically unstable δ‐D‐galactonolactone have been prepared and isolated from DMF solution by oxidizing the corresponding sugars with Shvo’s catalyst [(C4Ph4CO)(CO)2Ru]2 and a hydrogen acceptor. The preferred conformation of δ‐D‐galactonolactone in [D6]DMSO solution has been determined by 1H NMR spectroscopy experiments and DFT calculations to be 4H3 and is compared to those of the previously established conformations of δ‐D‐gluconolactone (4H3) and δ‐D‐mannonolactone (B2,5). The conformations of the lactones suggest an explanation for their relative rates of isomerization to their respective γ‐D‐lactones by an intramolecular mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
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