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May BL, Gerber J, Clements P, et al. Cyclodextrin and modified cyclodextrin complexes of E-4-tert-butylphenyl-4'-oxyazobenzene: UV-visible, 1H NMR and ab initio studies. Org Biomol Chem. 2005;3(8):1481-8doi: 10.1039/b415594g.
May, B. L., Gerber, J., Clements, P., Buntine, M. A., Brittain, D. R., Lincoln, S. F., & Easton, C. J. (2005). Cyclodextrin and modified cyclodextrin complexes of E-4-tert-butylphenyl-4'-oxyazobenzene: UV-visible, 1H NMR and ab initio studies. Organic & biomolecular chemistry, 3(8), 1481-8. https://doi.org/10.1039/b415594g
May, Bruce L, et al. "Cyclodextrin and modified cyclodextrin complexes of E-4-tert-butylphenyl-4'-oxyazobenzene: UV-visible, 1H NMR and ab initio studies." Organic & biomolecular chemistry vol. 3,8 (2005): 1481-8. doi: https://doi.org/10.1039/b415594g
May BL, Gerber J, Clements P, Buntine MA, Brittain DR, Lincoln SF, Easton CJ. Cyclodextrin and modified cyclodextrin complexes of E-4-tert-butylphenyl-4'-oxyazobenzene: UV-visible, 1H NMR and ab initio studies. Org Biomol Chem. 2005 Apr 21;3(8):1481-8. doi: 10.1039/b415594g. Epub 2005 Mar 11. PMID: 15827645.
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Org Biomol Chem. 2005 Apr 21;3(8):1481-8. doi: 10.1039/b415594g. Epub 2005 Mar 11.

Cyclodextrin and modified cyclodextrin complexes of E-4-tert-butylphenyl-4'-oxyazobenzene: UV-visible, 1H NMR and ab initio studies.

Organic & biomolecular chemistry

Bruce L May, Jacobus Gerber, Philip Clements, Mark A Buntine, David R B Brittain, Stephen F Lincoln, Christopher J Easton

Affiliations

  1. Department of Chemistry, University of Adelaide, Australia.

PMID: 15827645 DOI: 10.1039/b415594g

Abstract

alpha-Cyclodextrin, beta-cyclodextrin, N-(6(A)-deoxy-alpha-cyclodextrin-6(A)-yl)-N'6(A)-deoxy-beta-cyclodextrin-6(A)-yl)urea and N,N-bis(6(A)-deoxy-beta-cyclodextrin-6(A)-yl)urea (alphaCD, betaCD, 1 and 2) form inclusion complexes with E-4-tert-butylphenyl-4'-oxyazobenzene, E-3(-). In aqueous solution at pH 10.0, 298.2 K and I = 0.10 mol dm(-3)(NaClO(4)) spectrophotometric UV-visible studies yield the sequential formation constants: K(11) = (2.83 +/- 0.28) x 10(5) dm(3) mol(-1) for alphaCD.E-(-), K(21) = (6.93 +/- 0.06) x 10(3) dm(3) mol(-1) for (alphaCD)(2).E-3(-), K(11) = (1.24 +/- 0.12) x 10(5) dm(3) mol(-1) for betaCD.E-(-), K(21) = (1.22 +/- 0.06) x 10(4) dm(3) mol(-1) for (betaCD)(2).E-(-), K(11) = (3.08 +/- 0.03) x 10(5) dm(3) mol(-1) for .E-3(-), K(11) = (8.05 +/- 0.63) x 10(4) dm(3) mol(-1) for .E-3(-) and K(12) = (2.42 +/- 0.53) x 10(4) dm(3) mol(-1) for .(E-3(-))(2). (1)H ROESY NMR studies show that complexation of E-3(-) in the annuli of alphaCD, betaCD, 1 and 2 occurs. A variable-temperature (1)H NMR study yields k(298 K)= 6.7 +/- 0.5 and 5.7 +/- 0.5 s(-1), DeltaH = 61.7 +/- 2.7 and 88.1 +/- 4.2 kJ mol(-1) and DeltaS = -22.2 +/- 8.7 and 65 +/- 13 J K(-1) mol(-1) for the interconversion of the dominant includomers (complexes with different orientations of alphaCD) of alphaCD.E-3(-) and (alphaCD)(2).E-3(-), respectively. The existence of E-3(-) as the sole isomer was investigated through an ab initio study.

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