7 research outputs found
Kinetics of adsorption and desorption of aflatoxin B1by viable and nonviable bacteria
Journal of Food Protection663426-430JFPR
Dimerisation and complexation of 6-(4'-t-butylphenylamino)naphthalene-2-sulphonate by beta-cyclodextrin and linked beta-cyclodextrin dimers
Published online: 19 Aug 2009This study shows that stereochemical factors largely determine the extent to which 6-(4â˛-t-butylphenylamino)-naphthalene-2-sulphonate, BNSâ and its dimer, (BNSâ )2, are complexed by β-cyclodextrin, βCD, and a range of linked βCD dimers. Fluorescence and 1H NMR studies, respectively, show that BNSâ and (BNSâ )2 form hostâguest complexes with βCD of the stoichiometry βCD.BNSâ (10â 4 K 1 = 4.67 dm3 molâ 1) and βCD.BNS2 2 â (10â 2 K 2Ⲡ= 2.31 dm3 molâ 1), where the complexation constant K 1 = [βCD.BNSâ ]/([βCD][BNSâ ]) and K 2Ⲡ= [βCD. (BNSâ )2]/([βCD.BNSâ ][BNSâ ]) in aqueous phosphate buffer at pH 7.0, I = 0.10 mol dm3 at 298.2 K. (The dimerisation of BNSâ is characterised by 10â 2 K d = 2.65 dm3 molâ 1.) For N,N-bis((2AS,3AS)-3A-deoxy-3A-β-cyclodextrin)succinamide, 33βCD2su, N-((2AS,3AS)-3A-deoxy-3A-β-cyclodextrin)-Nâ˛-(6A-deoxy-6A-β-cyclodextrin)urea, 36βCD2su, N,N-bis(6A-deoxy-6A-β-cyclodextrin)succinamide, 66βCD2su, N-((2AS,3AS)-3A-deoxy-3A-β-cyclodextrin)-Nâ˛-(6A-deoxy-6A-β-cyclodextrin)urea, 36βCD2ur, and N,N-bis(6A-deoxy-6A-β-cyclodextrin)urea, 66βCD2ur, the analogous 10â 4 K 1 = 11.0, 101, 330, 29.6 and 435 dm3 molâ 1 and 10â 2 K 2Ⲡ= 2.56, 2.31, 2.59, 1.82 and 1.72 dm3 molâ 1, respectively. A similar variation occurs in K 1 derived by UVâvis methods. The factors causing the variations in K 1 and K 2 are discussed in conjunction with 1H ROESY NMR and molecular modelling studies.Duc-Truc Pham, Philip Clements, Christopher J. Easton, John Papageorgiou, Bruce L. May and Stephen F. Lincol