70735-00-1Relevant academic research and scientific papers
Complexation of Methyl Orange and Tropaeolin 000 No. 2 by β-cyclodextrin dimers
Haskard, Carolyn A.,May, Bruce L.,Kurucsev, Tomas,Lincoln, Stephen F.,Easton, Christopher J.
, p. 279 - 282 (2007/10/03)
Spectrophotometric studies of the complexation of Methyl Orange (MO-) and Tropaeolin 000 No. 2 (TR-) anions by dimeric N,N′-bis(6A-deoxy-6A-β-cyclodextrin)urea (βCD)2ur and its oxalamide and succinamide analogues, (βCD)2ox and (βCD)2su, respectively, are consistent with the predominant formation of complexes of the general formulae (βCD)2x·MO- characterized by stability constants K1 = (1.05 ± 0.04) × 105, (1.92 ± 0.04) × 105 and (2.50 ± 0.02) × 104 dm3 mol-1 and (βCD)2x·TR- characterized by K1 = (1.39 ± 0.03) × 104, (7.4 ± 0.1) × 103 and (4.60 ± 0.05) × 103 dm3 mol-1, in aqueous phosphate buffer at pH 9.0 and 5.5 and 298.2 K. These values are significantly greater than K1 = 2160 and 710 dm3 mol-1 for the β-cyclodextrin complexes, βCD·MO- and βCD·TR- and are indicative of cooperative binding in (βCD)2x·MO- and (βCD)2x·TR-. The factors affecting complex stability are discussed and comparisons are made with related systems.
Effect of β-cyclodextrin on the thermal Cis-trans isomerization of azobenzenes
Sanchez, Ana M.,De Rossi, Rita H.
, p. 3446 - 3451 (2007/10/03)
The cis-trans thermal isomerization of p-methyl red (1), o-methyl red (2), and methyl orange (3) was inhibited by β-cyclodextrin (β-CD) at constant pH. Their isomerization rate decreased 4, 8, and 1.67 times, respectively, in a solution containing 0.01 M β-CD. This effect can be attributed to the formation of an inclusion complex between the substrate and β-CD which hinders the rotation of the N=N bond. The isomerization rate of methyl yellow (4), 4-(dimethylamino)-4′-methoxy-azobenzene (5), and naphthalene-1-azo[4′-(dimethylamino)benzene] (6) was not affected by β-CD due to the presence of an organic cosolvent in the solution which displaces the azobenzene from the cavity, and the complex formed is probably equatorial. In addition, the transition state for the isomerization of compounds 1-3 involves rotation and that of 4-6, which have only electron-donating groups, inversion. This latter process brings about less volume change than rotation so it is less hindered by the complexation with β-CD.
