Cypermethrin/β-CD complexes were prepared at 1:2 cypermethrin/β-CD molar ratio by different complexation methods: conventional coprecipitation, suspension and kneading methods as well as “melting in solution” technique, which was developed in our laboratory. The complexes were investigated by UV-spectrophotometry and thermal analysis. It was found that complexes made by coprecipitation, suspension and kneading methods contained cypermethrin not only in complexed but also in uncomplexed form. The guest molecule in the complex prepared by “melting in solution” technique showed to be completely complexed, so it was the most effective complexation method studied.Investigating the solubility of cypermethrin with different cyclodextrins (CDs), it was established that the increase of solubility of cypermethrin was the highest in case of methylated cyclodextrins. The equilibrium constants were calculated from solubility isotherms. On the basis of these results, the heptakis(2,6-di-O-methyl)-β-cyclodextrin (DIMEB) complex was the more stable. By UV-irradiation measurements it was found that the photodegradation of cypermethrin was inhibited by methylated β-CDs. 相似文献
The effect of cyclodextrin complexation of sulphamethizole (SM) was studied. Two systems were prepared with two cyclodextrin
derivatives, β-cyclodextrin (BCD) and hydroxypropyl-β-cyclodextrin (HPBCD): binary complexes and multicomponent systems (cyclodextrins
and a hydroxylpropylmethyl cellulose K4M). Inclusion complexes were prepared by freeze-drying and characterized by thermal
analysis (DSC) and X-ray diffractometry. The presence of the polymer in the solution increases the effect of cyclodextrins
– specially BCD – on the solubility of SM. In solid state, binary inclusion complexes enhance the dissolution behaviour of
SM but, from the multi-component complexes, the polymer controls the release of the drug.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
In order to clarify the reason why the stereospecific sulfoxides undergo racemization in solution but not in the complex crystal with -cyclodextrin (-CD) in the solid state, a crystal structure analysis of two -CD inclusion complexes with methyl-p-tolylsulfoxide (MTSO) having a chiral sulfur atom was carried out. 相似文献
A three‐step sequential self‐assembly procedure was applied in preparing gold electrodes modified in a stable and controlled way by a monolayer of thiolated β‐cyclodextrin (β‐CD), with methylene blue (MB) included in its cavity as the active component of the monolayer, and octanethiol as the nonelectroactive spacer blocking the electrode surface not occupied by β‐CD. MB acted as a mediator of electrons with respect to a solution soluble analyte, H2O2, and provided electrical contact between the electrode and solution resident enzyme, laccase, catalyzing reduction of oxygen to water. 相似文献
Racemic free mandelic acid and its methyl, ethyl, isoamyl and benzyl esters were found to form inclusion complexes with all
the three studied natural cyclodextrins proved by thermoanalytical results. Differences between the solid state stability
of guests were detected mainly by evolved gas analysis. Even signs of an eventual optical resolution by molecular inclusion
were observed in several cases, but still not sufficiently proven. Due to the rather high volatility and low melting points
of the majority of guest substances DSC technique was found to be suitable for studying the cyclodextrin complexes of mandelic
acid.
Dedicated to Prof. József Szejtli on the occasion of his 60th birthday 相似文献
A practical and convenient method for the preparation of α-, β-, and γ-cyclodextrin derivatives, in which the secondary hydroxyl faces of A- and C-glucose units are regioselectively modified, has been developed. Reactions of α-, β-, and γ-cyclodextrins with 1,4-dibenzoylbenzene-3′,3″-disulfonyl imidazole in N,N-dimethylformamide in the presence of molecular sieves regioselectively afforded the corresponding cyclic 2A,2C-(1,4-dibenzoylbenzene-3′,3″-disulfonyl)-cyclodextrins. Subsequent treatment of the sulfonylated cyclodextrins with sodium hydroxide or aqueous ammonia afforded the corresponding 2A,3A:2C,3C-di-manno-epoxy-cyclodextrins or 3A,3C-diamino-3A,3C-dideoxy-(2AS,2CS,3AS,3CS)-cyclodextrins, respectively, which can serve as important intermediates for further functionalizations of the cyclodextrins. 相似文献
Two novel monovinyl β‐cyclodextrin (β‐CD) monomers are synthesized. Their chemical compositions are characterized by means of element analysis, NMR and FT‐IR spectroscopy. The results show that the synthesis techniques used are convenient and efficient. Using N‐isopropylacrylamide as a comonomer, two novel linear copolymers can also be synthesized.