Adelaide Research and Scholarship
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|Title: ||Beta-cyclodextrin modification and host-guest complexation.|
|Author: ||Pham, Duc-Truc|
|Issue Date: ||2008|
|School/Discipline: ||School of Chemistry and Physics : Chemistry|
|Abstract: ||A series of five linked β-cyclodextrin (βCD) dimers N,N-bis(6 [superscript]A-deoxy-6[superscript]A-β-cyclodextrinyl)-succinamide, 66βCD₂su, N-((2[superscript]A S,3 [superscript]A S)-3 [superscript]A-deoxy-3 [superscript]A-β-cyclodextrinyl)-N’-(6 [superscript]A-deoxy-6 [superscript]A -β-cyclodextrinyl)-urea, 36βCD₂su, N,N-bis((2 [superscript]A S,3 [superscript]A S)-3 [superscript]A -deoxy-3 [superscript]A-β-cyclodextrinyl)-succinamide, 33βCD₂su, N,N-bis(6[superscript]A-deoxy-6[superscript]A-β-cyclodextrinyl)-urea, 66βCD₂ur, and N-((2 [superscript]A S,3 [superscript]A S)-3 [superscript]A-deoxy-3 [superscript]A-β-cyclodextrinyl)-N’-(6 [superscript]A -deoxy-6 [superscript]A -β-cyclodextrinyl)urea, 36βCD₂ur, has been prepared. The complexation of 6-(4’-(toluidinyl)naphthalene-2-sulphonate, TNS⁻, by βCD and the five linked βCD dimers was
characterized by UV, fluorescence and 2D ¹H ROESY NMR spectroscopy. In aqueous phosphate buffer at pH 7.0, I = 0.10 mol dm⁻³ and 298.2 K, TNS⁻ forms host-guest complexes with βCD of stoichiometry βCD.TNS⁻ (K₁ = 3020 and 3320 dm³ mol⁻¹) and
βCD₂.TNS⁻ (K₂ = 57 and 11 dm³ mol⁻¹) where the first and second values were determined in UV and fluorescence studies, respectively. For 66βCD₂su, 36βCD₂su, 33βCD₂su, 66βCD₂ur and 36βCD₂ur, the analogous K₁ = 16100, 10900, 10700, 55100 and 18300 dm³ mol⁻¹ and K₁ = 12500, 8700, 9600, 38000 and 9800 dm³ mol⁻¹(fluorimetric studies), respectively. ¹H 2D ROESY NMR studies provided evidence for variation of the mode of complexation of the TNS⁻ guest as the βCD host is changed. The factors affecting complexation are discussed.
UV and ¹H NMR studies showed that 6-(4’-(t-butyl)-phenyl)naphthalene-2-sulphonate, BNS⁻, and its dimer, (BNS⁻)₂, form host-guest complexes with βCD of the stoichiometry βCD.BNS⁻ (K₁ = 5.54 × 10⁴ dm³ mol⁻¹ ) and βCD.BNS₂ ²⁻(K₂ = 3.07 × 10² dm³ mol⁻¹ ) where the complexation constant K₁ = [βCD.BNS⁻]/([βCD][BNS⁻] and K₂ = [βCD.(BNS⁻)₂]/([βCD.BNS⁻][BNS⁻]) in aqueous phosphate buffer at pH 7.0, I = 0.10 mol dm⁻³ and 298.2 K. For 66βCD₂su, 36βCD₂su, 33βCD₂su, 66βCD₂ur and 36βCD₂ur the analogous K₁ = 125, 74, 10.2, 364 and 16.1 (× 10⁴ dm³ mol⁻¹ ) and K₂ = 25.7, 2.30, 2.57, 17.6 and 17.2 (× 10² dm³ mol⁻¹ ), respectively. For the dimerisation of BNS⁻ K[subscript]d = 2.63 × 10² dm³ mol⁻¹ . Fluorimetric studies showed that the complexation stability for βCD.BNS⁻, forms βCD. BNS⁻, 66βCD₂su.BNS⁻, 36βCD₂su.BNS⁻, 33βCD₂su. BNS⁻, 66βCD₂ur.BNS⁻ and 36βCD₂ur. BNS⁻ characterized by K₁ = 4.67, 330, 101, 11.0, 435 and 29.6 (× 10⁴ dm³ mol⁻¹ ), respectively. The factors affecting the variations in these data are discussed.
The enantioselectivity of substituted βCDs 6 [superscript]A -[bis (carboxylatomethyl)amino]-6 [superscript]A -deoxy-β-cyclodextrin (6βCDidaH₂) and (2 [superscript]A S,3 [superscript]A S)-3 [superscript]A -[bis(carboxylatomethyl)amino]-3[superscript]A -deoxy-β-cyclodextrin (3βCDidaH₂) and 6 [superscript]A -[tris(carboxylatomethyl)(2- aminoethyl)amino]-6 [superscript]A -deoxy-β-cyclodextrin (6βCDedtaH₃) and their Eu³ ⁺ complexes in forming host-guest complexes with six enantiomeric guests in D₂O was studied by 1D and 2D ¹H NMR (600
MHz) spectroscopy. The guests are D/L-tryptophanate (Trp⁻), 4-hydroxyl-D/L-phenylglycinate (4HOPhg⁻), D/L-histidinate (His⁻), D/L-pheniramine (Phm), D/L-phenylglycinate (Phg⁻) and (D/L)-β-phenylserinate (βPhs⁻). Enantioselective host-guest complexation was observed between the [Eu(6βCDida)]⁺ , [Eu(3βCDida)]⁺ and [Eu(6βCDedta)] complexes and Trp⁻, [Eu(6βCDida)]⁺ and [Eu(3βCDida)]⁺ and 4HOPhg⁻, and βCD, 6βCDida²⁻, 3βCDida²⁻, 6βCDedta³⁻ and the Eu³⁺complexes of the three substituted βCDs and Phm. The His⁻, Phg⁻ and βPhs⁻ enantiomers showed no evidence for selective host-guest complexation. The preparation of 3βCDidaH₂ and 6βCDedtaH₃ and the determination of their pK[subscript]a s are also reported.
In collaboration with the research group of Prof. Matthew A. Tarr, (University of New Orleans, USA), the 6βCDida²⁻ and the 6βCDedta³⁻ has been utilized to improve Fenton oxidation of aromatic pollutants. To further support to this work, the binary complexation of Fe² ⁺ by 6βCDida²⁻ has been studied by potentiometric titrations.
A series of six modified poly(acrylic acid)s 3% substituted with either βCD or the adamantyl moiety with different length of substituent chain was synthesised. To advance the understanding and control of aqueous supramolecular assembly, the host-guest interactions between the βCD substituted poly(acrylic acid)s and adamantane-1-carboxylic; adamantyl substituted poly(acrylic acid)s with βCD and linked βCD dimers; and between both βCD and adamantyl substituted poly(acrylic acid)s have been studied.|
|Advisor: ||Lincoln, Stephen Frederick|
|Dissertation Note: ||Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2008|
|Keywords: ||cyclodextrin; supramolecular; host-guest complexation; NMR; fluorscence; UV; potentiometric titraties; enantioselectivity|
|Provenance: ||Copyright material removed from digital thesis. See print copy in University of Adelaide Library for full text|
|Call number: ||09PH P5341|
|Description (link): ||http://proxy.library.adelaide.edu.au/login?url=http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1311237|
|Appears in Collections:||Research Theses|
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