Search results for "Inclusion"
showing 10 items of 891 documents
Cyclodextrins in polymer synthesis: Free radical polymerization of methylated β-cyclodextrin complexes of methyl methacrylate and styrene, controlled…
2000
Methylated β-cyclodextrin (me-β-CD) was used to complex the hydrophobic monomers methyl methacrylate (1) or styrene (2) yielding the water-soluble 1 : 1-host/guest complexes methyl methacrylate/me-β-CD (1 a) and styrene/me-β-CD (2 a), respectively. In addition, the hydrophobic chain-transfer agent dodecanethiol (3) was complexed by two equivalents of me-β-CD yielding the water-soluble dodecanethiol/me-β-CD (3 a). The included monomers were polymerized in water by a free-radical mechanism in the presence of 3 a as the chain-transfer agent. The chain-transfer constants were determined. In order to evaluate these results, the chain-transfer constants of 3 were also determined in the case of th…
Supramolecular Nanocycles Comprisingβ-Cyclodextrin-click-Ferrocene Units: Rings of Rings of Rings
2010
We applied 1,3-dipolar cycloaddition to bind ethynylferrocene onto 6I-azido-6I-deoxycyclomaltoheptaose under microwave assisted conditions. The process was investigated by (1) H NMR, FT-IR spectroscopy, and MALDI-TOF mass spectrometry. The ability of the synthesized compound to self-organize to cyclic supramolecular structures was investigated by dynamic light scattering measurements and cryo-transmission electron microscopy.
Synthesis and characterisation of novel chemical conjugates based on alpha, beta-polyaspartylhydrazide and beta-cyclodextrins
2006
A new family of supramolecular systems based on a synthetic polyaminoacid and cyclic oligosaccharides such as beta-cyclodextrins (beta-CDs) was synthesised. The pharmaceutical potential of these systems arises from the proper combination between the complexing properties of cyclodextrins and the particular pharmacokinetic profile that can be obtained by using macromolecular conjugates with a biocompatible backbone. Five supramolecular conjugates were synthesised by using alpha,beta-polyaspartylhydrazide (PAHy) as a polymeric component and various amounts of two P-CD derivatives. In particular, by reaction of PAHy with beta-CD monoaldehyde, samples named as A(1), A(2) and A(3), bearing, resp…
Chemical evolution of ore-forming brines – Basement leaching, metal provenance, and the redox link between barren and ore-bearing hydrothermal veins.…
2019
Abstract Six mineralogically exemplary barren and mineralized hydrothermal veins (with Pb and Zn ores) of Jurassic-Cretaceous and Cenozoic age in the Schwarzwald mining district, SW Germany were chosen to shed light on the origin of their mineralogical diversity. The selection of the veins was guided by the fact that they represent the largest number of veins in the region, are very well known mineralogically and geochemically, and they provide nice examples of barren and mineralized veins of similar age. Fluid inclusion data from the individual veins overlap implying their diverse mineralogy is not caused by different fluid compositions participating during fluid mixing. LA-ICPMS data of s…
Modification of Chiral Properties Due to Interaction of Polymers and Small Molecules or Ions
1979
The first part of this report deals with changes in the optical rotatory dispersion and circular dichroism resulting from the chemical modification of optically active polymers. Amylose derivatives have very different chiroptical properties compared with cellulose derivatives. Variations in glucosidic bonds and differing secondary structures are described and suggested as causes for this. The N-chlorination of synthetic optically active polyamides is also described, which in all probability proceeds without changing the configuration at the asymmetric C atoms. Reactions of inactive polymers with low molecular weight chiral reagents usually give optical rotation values proportional to the de…
Heterodimeric capsules formed by tetratosyl and tetratolyl urea calix[4]arenes
2008
Predictions made by MD simulations for size, shape and guest inclusion of a heterodimer formed by a tetratosyl and a tetratolyl urea calix[4]arene and for its hydrogen bonding system have been entirely confirmed by a single crystal X-ray structure.
Wide Rim Urethanes Derived from Calix[4]arenes: Synthesis and Self-Assembly
2006
[reaction: see text] Calix[4]arenes 4, substituted at the wide rim by four N-tolyl-urethane groups, were synthesized, as well as derivatives 10a,b bearing two or three tolyl-urea groups beside of one or two urethane group(s). In contrast to tetra-tolyl urea 11, the urethane derivatives do not form hydrogen-bonded, dimeric capsules in CDCl3 or benzene-d6, but the dimerization can be induced for the triurea 10b by tetraethylammonium cations as guests. The quantitative formation of heterodimers is observed for all urethanes 4 and 10a,bin benzene-d6 in mixtures with a "tetra-loop" tetraurea 14, while "bisloop" tetraureas 13 require di- or triurea derivatives 10a,b for a clean heterodimerization.
Sulfur-incorporating cyclotriveratrylene analogues: the synthesis of cyclotrithioguaiacylene.
2011
Cyclotriguaiacylene 1 is the universal precursor of cryptophanes, and represents an important intermediate for the preparation of functionalized cavitands of the cyclotriveratrylene family. Its thio analogue (cyclotrithioguaiacylene 3) was synthesized by two different routes, involving either the Newman-Kwart or the Pummerer rearrangement. The latter, performed starting from a trisulfoxide precursor, produced a purer compound in higher overall yield.
Electrochemical determination of the stability of complexes formed by proton-ionizable ligands of 3,5-disubstituted 1H-pyrazole with phenethylamine
1999
The application of two extreme models for diffusion in two-component systems to electrochemically determine equilibrium constants is discussed. The application of cyclic voltammetric, diferential pulse and rotating-disc electrode voltammetric data to elucidate the stoichiometry and formation constant of complex species by applying a generalization of the molar-ratio method is described. Molar-ratio experiments permit the distinction between the limiting diffusive regimes. The values of the equilibrium stability constants for complexation of phenethylamine and phenethylammonium ions by a 26-membered dioxotetraester crown of 3,5-disubstituted 1H-pyrazole as free ligand 1[L] and as dipyrazolat…