Cyclodextrin modified with

Cyclodextrines, modified with 2-cyanoethyl and with bis(2-cyanoethyl)amino groups were used as ligands in the [PdCy + [CuCU]-catalyzed Wacker-oxidation of 1-octene. Without the modified cyclodextrins the yield of 2-octanone was less than 1 %, which could be raised to 73 % by the addition of nitrile-modified P-cyclodextrin ligands (60 °C, 2 h). 

Complexes of cyclodextrin modified with catechol groups 75 proved to be less active in phenol hydroxylation the main product was catechol and the selectivity with respect to this product exceeded 90%. For copper complexes... 

A palladium complex with cyclodextrin modified with propionitrile and benzoylnitrile groups 73-74 was active in Wacker oxidation of higher 1-alkenes (Experiment 11-4, Section 11.7), and its activity was much higher than the activity of a catalj ic system prepared as a mixture of cyclodextrin and the palladium complex owing to the cooperative substrate binding and to the increase in the stability constant of the catalyst-substrate complex. As in hydroformylation, the catalyst was more active in the reaction with an aromatic substrate, styrene, than with linear alkenes [59,210-211], The catalyst activity depended on the 1-alkene chain length and was maximum for 1-heptene. 

Cyclodextrins modified with dansyl (5-dimethylamino-l-naphthalenesulfonyl) fluorophore were used by us for generating enantioselective fluorescence response... 

The data were collected using fluorescence measurements, which allow both identification and quantitation of the fluorophore in solvent extraction. Important experimental considerations such as solvent choice, temperature, and concentrations of the modifier and the analytes are discussed. The utility of this method as a means of simplifying complex PAH mixtures is also evaluated. In addition, the coupling of cyclodextrin-modified solvent extraction with luminescence measurements for qualitative evaluation of components in mixtures will be discussed briefly. 

Cyclodextrin-modified solvent extraction has been used to extract several PAHs from ether to an aqueous phase. Data evaluation shows that the degree of extraction is related to the size of the potential guest molecule and that the method successfully separates simple binary mixtures in which one component does not complex strongly with CDx. The most useful application of cyclodextrin-modified solvent extraction is for the simplification of complex mixtures. The combined use of CDx modifier and data-analysis techniques may simplify the qualitative analysis of PAH mixtures. 

Reaction conditions 0.1 g of the zeolite Y modified catalyst, tested in a conventional glass microreactor with racemic butan-2-ol (7.35 x 10" mol h-1), prevaporized in a nitrogen diluent (6.2 -6.7 x 10" mol h-1). Products were analyzed using on-line GC with a 40m capillary y- cyclodextrin colimm with trifluoroacetyl stationary phase, temperature programmed from 25-70 "C with a split ratio of 120 1. 

Miniaturized columns have provided a decisive advantage in speed. Uracil, phenol, and benzyl alcohol were separated in 20 seconds by CEC in an 18 mm column with a propyl reversed phase.29 A19 cm electrophoretic channel was etched into a glass wafer, filled with a y-cyclodextrin buffer, and used to resolve chiral amino acids from a meteorite in 4 minutes.30 A 6 cm channel equipped with a syringe pump to automate sample derivatization was used to separate amino acids modified with fluorescein isothiocyanate.31 Nanovials have been used to perform tryptic digests on the 15 nL scale for subsequent separation on capillary Electrophoresis.32 A microcolumn has also been used to generate fractions representing time-points of digestion from a 40 pL sample.33 A disposable nanoelectrospray emitter has been... 

The mobile phases used with cyclodextrin CSPs are similar to those used in reverse phase chromatography, ie water or buffer solutions modified with methanol or acetonitrile. 

Lin et al. [95] used capillary electrophoresis with dual cyclodextrin systems for the enantiomer separation of miconazole. A cyclodextrin-modified micellar capillary electrophoretic method was developed using mixture of /i-cyclodextrins and mono-3-0-phenylcarbamoyl-/j-cyclodextrin as chiral additives for the chiral separation of miconazole with the dual cyclodextrins systems. The enantiomers were resolved using a running buffer of 50 mmol/L borate pH 9.5 containing 15 mmol/L jS-cyclodextrin and 15 mmol/L mono-3-<9-phcnylcarbamoyl-/j-cyclodextrin containing 50 mmol/L sodium dodecyl sulfate and 1 mol/L urea. A study of the respective influence of the /i-cyclodcxtrin and the mono-3-(9-phenylcarbamoyl-/i-cyclodextrin concentration was performed to determine the optical conditions with respect to the resolution. Good repeatability of the method was obtained. 

A. Kitajima, T. Teranishi, and M. Miyake, Detection of nitric oxide on carbon electrode modified with ionic polymers and alpha-cyclodextrin. Electrochemistry 69, 16-20 (2001). 

Figure 15.14 illustrates a typical voltammetric result for the determination of dopamine in the presence of ascorbic acid with a CNT-modified electrode. The selective voltammetric detection of uric acid [82] or norepinephrine [83] in the presence of ascorbic acid has been demonstrated with a (3-cyclodextrin-modified electrodes incorporating CNTs. Ye et al. [84] have studied the electrocatalytic oxidation of uric acid and ascorbic acid at a well-aligned CNT electrode, which can be used for the selective determination of uric acid in the presence of ascorbic acid. The simultaneous determination of dopamine and serotonin on a CNT-modified GC electrode has also been described [85],... 

Organolead and organoselenium compounds were separated satisfactorily by high-performance capillary electrophoresis, using /1-cyclodextrin-modified micellar electroki-netic chromatography with on-column UVV detector set at 210 nm130. 

CL Copper, MJ Sepaniak. Cyclodextrin-modified micellar electrokinetic capillary chromatography separations of benzopyrene isomers. Correlation with computationally derived host-guest energies. Anal Chem 66 147—154, 1994. 

An example of the above mentioned cascade complexation of carboxylates by macrocyclic receptors containing metal ionic centers is the inclusion of oxalate by the dien dicobalt complex 9 (Martell, Mitsokaitis) [12]. Similarly, the -cyclodextrin (jS-CD) 10, modified with a zinc cation bound by a triamine side chain, encapsulates anions like 1-adamantylcarboxylate in its cavity, fixing them by combined electrostatic and hydrophobic interactions [13], Zinc s group achieved the enantioselective transport of the potassium salts of N-protected amino acids and dipeptides by making use of the cation affinity of... 

The use of graphite anodes modified with cyclodextrins allows to increase the pjo ratio to above 4 and at the same time to use aqueous electrolytes (NaCl, HC1—H20) 95-96) Electrochemical halogenation has been used in particular by Japanese companies for the synthesis of intermediates on the laboratory scale. A few examples are given below ... 

Fig. 3 Photoresponsive polymer surface sensitive to pH and light. Adsorption and release of cytochrome c triggered by pH (b, c, and d) release of the polymer layer and cytochrome c by breaking the host-guest interactions between surface-tethered azo dye and cyclodextrin via light irradiation (a and d). The molecular structure on the right represents the host-guest complexa-tion of the azo dye with the cyclodextrin-modified poly(acrylic acid). Reprinted, with permission, from [68]. Copyright (2009) Wiley Interscience...

Huq and Mercier191 synthesized cyclodextrin modified silicas by first coupling the cyclodextrin units to 3-aminopropyltriethoxysilane (APTES) and then subjecting it to a co-condensation reaction with TEOS (Fig. 3.15c). Interestingly, all attempts to anchor cyclodextrins by grafting onto previously thiol-functionalized silicas have been unsuccessful. It has also been demonstrated that the cyclodextrin units on the... 

The complex multicomponent system, called CALAA-01, has been developed by Davis for Calando Pharmaceuticals and is the first of many possible RONDEL therapeutics based on a biomimetic approach to drug delivery [24], The approach combines a linear cationic polymer that incorporates cyclodextrins, a therapeutic payload (siRNA strands that target a specific process), and adamantane molecules modified with biocompatible polyethylene glycol chains (PEGs) or complementary proteins that bind to the target cell types. 

Anodic chlorination of toluene and anisole using graphite electrodes, chemically modified with a-cyclodextrin, results in higher para selectivity in comparison to chlorination with NaOCl in presence of a-cyclodextrin in solution384. Similar results are observed with a Pt electrode38. ... 

Microsolvent effects in the cyclodextrin cavity have also been observed in hypochlorite chlorination of acetophenone1029. Higher para selectivity has been observed in the bromination of acetanilide and benzanilide in presence of cyclodextrins or amylose1030 and in the anodic chlorination of anisole with cyclodextrin-modified electrode1031. 

The FITC labeling method was also applied to chiral separations of amino acids on a microchip to determine the enantiomeric ratios of amino acids found on a meteorite [27], Since biotic amino acids are normally single enantiomers, chiral separations of amino acids are not truly clinical in nature, but illustrate the potential for chiral separations of small molecules of clinical interest. Ma-thies and co-workers used this technique to search for evidence of life in extraterrestrial environments. Enantiomeric forms of Val, Ala, Glu, and Asp could be discriminated by addition of a-, (3-, or y-cyclodextrin (CD) to the run buffer. Improved resolution with faster separations was found with respect to conventional CE. This method has been modified, by addition of SDS to the buffer, to perform cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) [28]. Increasing the SDS concentration decreased the magnitude of elec-troosmotic flow (EOF), increasing the effective migration distance, and therefore the resolution on the microchips. 

Cyclodextrins form inclusion compounds in aqueous solution with various molecules which may then exhibit modified reactivity (see reference 185 above). It was reported in 1975 that the presence of p-cyclodextrin modified the ortho para ratio of hydroxyacetophenones formed photochemically from phenyl acetate,and the photoinduced rearrangements of acetanilide, ben-zanilide, and ethyl phenyl carbonate under similar conditions are now reported. In each case the para rearrangement isomer is favoured, and this is rationalized in terms of the aromatic nucleus being bonded into the cyclodextrin cavity such that the ortho and weta positions are shielded whDe the para position is accessible. This proposal is supported by observations that para but not ortho disubstituted arenes are well bonded into p-cyclodextrin cavities. The by-product formation of aniline from the amides and of phenol from the carbonate is also markedly reduced for reactions in the presence of the cyclodextrin. 

The pH, temperature, and ionic strength of the mobile phase also affect the cyclodextrin-solute complexation and retention properties. Many enantioseparations using cyclodextrin-modified systems involve solutes with an aromatic ring substituent or similar cyclic structure at the chiral center. A variety of chiral barbiturates, hydantoins, and related compounds have been resolved by using (3-cyclodextrin and alkylated B-cyclodextrin-modified systems. 

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