betadex and nitroaniline

Glycine derivatized beta-cyclodextrin bonded silica (GCDS) has been prepared for high performance liquid chromatography through the reactions of beta-cyclodextrin bonded silica with tosyl chloride and glycine in sequence. The separation performance of GCDS for positional isomers, dansyl amino acids and phenylpropionic acids was investigated. It was found that nitrophenols could not be eluted with methanol as mobile phase, but could be eluted with methanol-phosphate buffer solution within appropriate time, which was much different from the behavior observed on native beta-cyclodextrin bonded silica. The effect of column temperature on the enantio-separation of dansyl D,L-Phe with GCDS was examined. The results show that the enantio-separation ability of the GCDS decreases with the increase of the column temperature. Other factors such as methanol concentration and pH of the mobile phase influencing the retention behavior of solutes on the GCDS are also discussed.

Topics: Amino Acids; Aniline Compounds; beta-Cyclodextrins; Chromatography, High Pressure Liquid; Cyclodextrins; Glycine; Nitrophenols; Phenylpropionates; Silica Gel; Silicon Dioxide

beta- Cyclodextrin bonded chiral stationary phases (CD-CSP) were prepared after the method of Armstrong (CD-CSP I) and of Huang Tianbao (CD-CSP II). With the separation of o-, m- p-nitroaniline, it was found that the chromatographic properties of CD-CSP II was superior to that of CD-CSP I. Three racemes of thioglycidyl ethers and two racemes of glycidylselenides were resolved on CD-CSP II via high performance liquid chromatography. The mobile phase consisted of different volume ratios of methanol/0.3% triethylammonium acetate buffer solution(pH 5), and the eluate was detected with a UV-visible detector at a wavelength of 254 nm. With the increase of methanol volume ratio in the mobile phase, the retention time decreased rapidly, but within the range of methanol valume ratio 40/100 to 50/100, the separation factor only decreased slightly. The racemes examined contained aromatic groups and hydroxy groups which can form inclusion complexes and hydrogen bonding interactions with beta-cyclodextrin. The chiral separation of the racemes is successful with the mobile phase of V(methanol):V(buffer) = 40:60.

Topics: Aniline Compounds; beta-Cyclodextrins; Chromatography, High Pressure Liquid; Cyclodextrins; Epoxy Compounds; Stereoisomerism

The interaction between beta-cyclodextrin and five mono- and disubstituted benzenes in water was investigated by means of molecular dynamics. The trajectories were calculated for each system, imposing a 1:1 host-guest stoichiometry with 512 water molecules. Periodic boundary conditions were adopted. The results account for the formation of stable adducts and the predicted geometry agrees with experimental circular dichroism data.

Topics: Aniline Compounds; Benzene; beta-Cyclodextrins; Catechols; Computer Simulation; Cyclodextrins; Models, Molecular; Nitrophenols; Phenol