15074-61-0Relevant articles and documents
Shielded alkyl-functionalised rotaxane host cavities for improved anion recognition
Gilday, Lydia C.,White, Nicholas G.,Beer, Paul D.
, p. 62 - 83 (2016)
The synthesis and anion recognition properties of four novel [2]rotaxane host architectures containing additional alkyl functionality integrated within macrocyclic and axle components to shield the binding cavity from the solvent are described. The rotaxane species containing a tetra(methyl)-functionalised macrocycle component is found to be a weaker anion complexant than the equivalent unfunctionalised receptor, which is likely due to steric hindrance restricting the anion's access to the interlocked cavity. Rotaxane molecules containing tetra(methyl)-functionalised axle components are also investigated, and the additional alkyl functionality serves to enhance anion binding affinity and selectivity when incorporated within the axle's flexible ethylene linkages. Moreover, the equivalent unfunctionalised rotaxane displays a rare preference for oxoanions over chloride guest species.
Halogen bonding rotaxanes for nitrate recognition in aqueous media
Robinson, Sean W.,Beer, Paul D.
, p. 153 - 159 (2017)
Targeting the biologically and environmentally important nitrate anion, halogen bonding (XB) has been incorporated into three novel [2]rotaxane structural frameworks via an axle component containing covalently linked 3,5-bis-iodotriazole pyridine-pyridinium motifs. This has enabled the recognition of nitrate in aqueous media containing up to 90% water with equivalent binding affinity to chloride, illustrating the potency of XB for anion recognition in highly competitive aqueous solvent mixtures.
2,3,5,6-Tetraaminopyridine tetracarbamate from dinicotinic acid
Davis, Matthew C.,Irvin, David J.
, p. 1159 - 1167 (2008)
The tetraethylcarbamate of 2,3,5,6-tetraaminopyridine was synthesized using dinicotinic acid as starting material in 10 steps with 23% overall yield. Copyright Taylor & Francis Group, LLC.
A general method for coupling unprotected peptides to bromoacetamido porphyrin templates
Choma, Christin T.,Kaestle, Karen,Akerfeldt, Karin S.,Kim, Ronald M.,Groves, John T.,DeGrado, William F.
, p. 6191 - 6194 (1994)
An N-terminal cysteine is used to displace bromide from a bromoacetylated porphyrin to yield a thioether linkage between the peptide and the template. Unlike amide coupling reactions, this approach should be compatible with any peptide sequence provided there is only a single cysteine.
Self-assembly of a pyridyl derivative and its silver complex: Formation of a liquid crystalline phase and organogels
Yabuucki, Kazuhiro,Kato, Takashi
, p. 261 - 273 (2005)
Self-assembling behavior of N,N′-didodecyl-3,5-pyridinedicarboxamide and its silver complex has been studied. They act as gelators in solution and gelate a variety of organic solvents. Though the silver complex exhibits lower gelation abilities for halogenated and aromatic solvents, long-term stability is achieved for ethanol and acetone gels. Moreover, the silver complex exhibits a smectic A phase on cooling while a single component of N,N′-didodecyl-3-5- pyridinedicarboxamide exhibits no mesomorphic behavior. The XRD pattern for the complex shows that the layer spacing of the SA phase is 37 A.
Synthesis of chiral linear and macrocyclic candidates: VI. Synthesis and antibacterial activity of some macrocyclic tripeptides and linear dipeptide Schiff bases
Amr,Al-Omar
, p. 161 - 166 (2016)
A series of macrocyclic tripeptides and linear dipeptide Schiff base derivatives has been synthesized using pyridine-3,5-dicarboxylic acid and L-phenyalanine methyl ester as starting materials. Treatment of pyridine-3,5-dicarbonyl dichloride with L-phenylalanine methyl ester gave N,N′-(pyridine-3,5-diyldicarbonyl)bis(L-phenyalanine methyl ester) which was hydrolyzed with 1N sodium hydroxide to the corresponding bis-acid, and the latter was cyclized with diamino acids to afford macrocyclic tripeptide derivatives. The reaction of the bis ester with hydrazine hydrate gave bis-hydrazide, which was condensed with aldehydes to obtain the corresponding Schiff base derivatives. The structures of the newly synthesized compounds were confirmed by IR, 1H and 13C NMR, and MS spectral data and elemental analyses. The antimicrobial activities of some of the newly synthesized compounds were comparable with that of Streptomycin used as control.
Perfluorinated Pyridinium and Imidazolium ionic liquids
Alpers, Torben,Schmidtmann, Marc,Muesmann, Thomas W. T.,Temme, Oliver,Christoffers, Jens
, p. 4283 - 4290 (2017)
Ionic liquids with perfluorinated side chains were prepared as hybrid materials for surface impregnation. For the cationic part, methyl and ethyl pyridinium as well as imidazolium scaffolds were used. The anions investigated were hydroxide, acetate, trifluoroacetate, triflate, triflimide, chloride, bromide, iodide, hydrogensulfate, and perfluorododecanoate. A key feature of this investigation is the finding that the use of relatively short perfluorohexyl residues as the fluorinated part of the salts is beneficial for the target compounds compared with established products, because of their lower bioaccumulativity. One compound yielded single crystals that were suitable for X-ray structure analysis, revealing a layered structure with relatively well-resolved, hard ionic domains alternating with disordered, soft perfluorinated layers. The wettability of all 30 materials was investigated by water contact angle measurements of a thin film on a glass surface. In two cases, promising contact angles (130° and 140°) were observed, indicating that the products might be suitable candidates for the impregnation of surfaces.
Do high-spin topology rules apply to charged polyradicals? Theoretical and experimental evaluation of pyridiniums as magnetic coupling units
West Jr.,Silverman,Dougherty
, p. 1452 - 1463 (1996)
Ab initio calculations on pyridine and pyridinium analogues of m-xylylene indicate that the neutral heterocycle is essentially equivalent to benzene as a ferromagnetic coupling unit, while the cationic pyridiniums behave much differently. Depending on the substitution pattern, a protonated pyridine can serve as a ferromagnetic coupling unit or an antiferromagnetic coupling unit. Both valence bond and molecular orbital arguments provide qualitative rationalizations of these results. In an effort to test the theoretical predictions, bis(trimethylenemethane) analogues of the pyridine and pyridinium biradicals were synthesized and analyzed by electron paramagnetic resonance spectroscopy. General support for the theoretical predictions is obtained.
Recognition by a solubilized receptor: Hydrogen bonding, solvophobic interactions, and solvent engineering inside micelles
Bonar-Law, Richard P.
, p. 12397 - 12407 (1995)
This paper shows how a hydrophobic porphyrin-based receptor capable of multipoint recognition in organic solvents can be solubilized directly in water by incorporation inside micelles. Binding of ligands from the aqueous phase is analyzed in sodium dodecylsulphate (SDS) micelles using a simple model in which ligands first partition into the micelle and are then complexed by the receptor. Subtraction of ligand-micelle partitioning terms from observed binding energies gives energies for bimolecular association inside SDS micelles, which range from +1 to -22 kJ/mol (equilibrium constants from 0.7 to 7900 M-1). Comparison of two receptors binding the same set of ligands in SDS and organic solvents then provides insight into the roles of ligand and receptor solvation in micellar recognition. Binding inside SDS micelles is found to be energetically similar to binding in methanol, in that hydrogen bonding in the SDS pseudophase is reduced relative to CH2Cl2, and association of ligands capable of nonpolar contacts with the receptor is enhanced. Micellar recognition is most effective when both hydrogen bonding and solvophobic forces act together, leading to increased chiral discrimination of hydrophobic amino acid derivatives. It is finally shown how receptor solvation inside micelles can be tuned by the addition of organic cosolvents, reducing solvophobic association and restoring some of the hydrogen bonding energy.
Pseudorotaxane composed of heteroditopic macrobicycle and pyridine N -oxide based axle: Recognition site dependent axle orientation
Saha, Subrata,Santra, Saikat,Ghosh, Pradyut
, p. 1854 - 1857 (2015)
A strategy for threading an axle having a hydrogen bond acceptor unit in the cavity of a C3v symmetric amido-amine macrobicycle is investigated. The macrobicycle acts as a wheel in its neutral as well as triprotonated states to form threaded architectures with a pyridine N-oxide derivative. The negative oxygen dipole of the axle is capable of [2]pseudorotaxane formation in two different orientations with the wheel in its neutral and triprotonated states.
