• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 113
  • 108
  • 29
  • 13
  • 9
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 322
  • 76
  • 48
  • 45
  • 38
  • 37
  • 36
  • 30
  • 28
  • 22
  • 22
  • 21
  • 21
  • 19
  • 18
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Cholesterol metabolism in the Niemann-Pick Type C brain

Peake, Kyle 06 1900 (has links)
Niemann-Pick Type C (NPC) disease is an autosomal recessive disorder that results in accumulation of unesterified cholesterol in late endosomes/lysosomes (LE/Ls), leading to progressive neurodegeneration and premature death. Microglia are resident immune cells of the central nervous system, which upon activation can secrete potentially neurotoxic molecules such as tumor necrosis factor-alpha (TNFα). Inappropriate activation of microglia has been implicated in NPC disease. Primary microglia cultures from the cerebral cortex of Npc1-/- mice have an altered cholesterol distribution characteristic of NPC-deficient cells. Immunocytochemical analysis revealed increased TNFα staining in Npc1-/- microglia. However, Npc1-/- and Npc1+/+ microglia showed similar mRNA levels of pro-inflammatory cytokines and similar levels of TNFα secretion. To determine whether Npc1-/- microglia contribute to neuron death in NPC disease, microglia were co-cultured with cerebellar granule cells. Surprisingly, the extent of neuronal death was the same in neurons cultured with Npc1+/+ or Npc1-/- microglia. Thus, Npc1-/- microglia have an altered phenotype compared to Npc1+/+ microglia, but this does not lead to neuron death in an in vitro co-culture system. Treatment options for NPC disease remain limited. A consequence of cholesterol sequestration in the LE/Ls, is that cholesterol movement to the endoplasmic reticulum, where cholesterol metabolism is regulated, is impaired. Cyclodextrin (CD), a compound that binds cholesterol, has recently been found to delay the onset of neurological symptoms and prolong life of Npc1-/- mice. Since the brain consists of both neurons and glia, it remains unclear if CD acts directly on neurons and/or other cells in the brain. Neurons cultured from the cerebellum and astrocytes cultured from the cortex of Npc1-/- mice were treated with a low dose (0.1mM) of CD. This treatment decreased cholesterol sequestration and decreased the rate of cholesterol synthesis in Npc1-/- neurons and astrocytes. CD also decreased mRNAs encoding proteins involved in cholesterol synthesis in Npc1-/- neurons and increased genes involved in cholesterol efflux in Npc1-/- astrocytes. Moreover, CD increased cholesterol esterification in Npc1-/- astrocytes. These results suggest that cholesterol trapped in LE/Ls in Npc1-/- neurons and astrocytes was released by CD treatment and reached the ER, thereby regulating cholesterol homeostasis. / Experimental Medicine
102

Studies of cyclodextrin functionalised silica materials

Mahmud, Sarker Tarek 19 September 2007
Mesoporous silica materials containing microporous cavities provided by covalently bound ¦Â-cyclodextrin (CD ICS) were synthesized by co-condensation of a ¦Â-CD functionalized triethoxy silane (CD ICL) with tetraethyl orthosilicate (TEOS) by using neutral amine surfactants as structure directing agents (SDA). CD ICL was prepared by reacting ¦Â-CD with 3-isocyanatopropyltriethoxysilane. IR spectroscopy of CD ICL showed complete disappearance of isocyanato group at 2270 cm-1. 1H NMR results indicate an average of four isocyanate linkers covalently attached to random hydroxyl substituents of each molecule of ¦Â-CD. <p> Nine different CD ICS materials were synthesized using dodecylamine, tetradecylamine or hexadecylamine with ¦Â-CD (2, 4, and 6 mol %) with respect to TEOS. The incorporation of ¦Â-CD within the mesoporous framework was supported by IR, Raman, MALDI TOF MS, solid state 13C NMR CP-MAS and TGA results. Small angle X-ray diffraction results showed a peak at 2¦È ¡Ö 2.20, supporting the presence of an ordered silica mesostructure framework. For materials with same CD loading, the surface area and pore volume doubled as the surfactant from dodecylamine to hexadecylamine. However, as the CD loading increased from 2% to 6%, the surface area decreases by a factor of ~ 1.5. <p>MALDI TOF mass spectrometry showed two peaks at m/z 1157 a.m.u. and 1173 a.m.u. for [¦Â-CD + Na]+ and [¦Â-CD + K]+ respectively due to desorption of ¦Â-CD from the walls of the silica matrix. The 13C NMR CP MAS results showed 13C signals in the region ¦Ä=60-110 ppm due to the nuclei of ¦Â-CD. CD ICS materials were found to be effective as a sorbent in both gas and aqueous phases, respectively. The sorption capacity (mmol/g) of p-nitrophenol increased from 61% to 84% with an increase of CD loading from 2% to 6% and as the alkyl chain length of the SDA increases from dodecylamine to hexadecylamine. The adsorption isotherm of CH3Cl in the gas phase and that of p-nitrophenol in the aqueous phase at ambient temperature adopts a multilayer model of adsorption.
103

Studies of cyclodextrin functionalised silica materials

Mahmud, Sarker Tarek 19 September 2007 (has links)
Mesoporous silica materials containing microporous cavities provided by covalently bound ¦Â-cyclodextrin (CD ICS) were synthesized by co-condensation of a ¦Â-CD functionalized triethoxy silane (CD ICL) with tetraethyl orthosilicate (TEOS) by using neutral amine surfactants as structure directing agents (SDA). CD ICL was prepared by reacting ¦Â-CD with 3-isocyanatopropyltriethoxysilane. IR spectroscopy of CD ICL showed complete disappearance of isocyanato group at 2270 cm-1. 1H NMR results indicate an average of four isocyanate linkers covalently attached to random hydroxyl substituents of each molecule of ¦Â-CD. <p> Nine different CD ICS materials were synthesized using dodecylamine, tetradecylamine or hexadecylamine with ¦Â-CD (2, 4, and 6 mol %) with respect to TEOS. The incorporation of ¦Â-CD within the mesoporous framework was supported by IR, Raman, MALDI TOF MS, solid state 13C NMR CP-MAS and TGA results. Small angle X-ray diffraction results showed a peak at 2¦È ¡Ö 2.20, supporting the presence of an ordered silica mesostructure framework. For materials with same CD loading, the surface area and pore volume doubled as the surfactant from dodecylamine to hexadecylamine. However, as the CD loading increased from 2% to 6%, the surface area decreases by a factor of ~ 1.5. <p>MALDI TOF mass spectrometry showed two peaks at m/z 1157 a.m.u. and 1173 a.m.u. for [¦Â-CD + Na]+ and [¦Â-CD + K]+ respectively due to desorption of ¦Â-CD from the walls of the silica matrix. The 13C NMR CP MAS results showed 13C signals in the region ¦Ä=60-110 ppm due to the nuclei of ¦Â-CD. CD ICS materials were found to be effective as a sorbent in both gas and aqueous phases, respectively. The sorption capacity (mmol/g) of p-nitrophenol increased from 61% to 84% with an increase of CD loading from 2% to 6% and as the alkyl chain length of the SDA increases from dodecylamine to hexadecylamine. The adsorption isotherm of CH3Cl in the gas phase and that of p-nitrophenol in the aqueous phase at ambient temperature adopts a multilayer model of adsorption.
104

Studies on Inclusion Complexes of Cyclodextrin and Dyes; I.Synthesis and Properties of Dye Rotaxanes, II. Formation of Anisotropic Supremolecules

Park, Jong Seung 26 August 2005 (has links)
Supramolecular chemistry covers intermolecular interactions where non-covalent bonds are involved, and many of them are based on host-guest interactions. Cyclodextrins (CDs) are cyclic oligosaccharides consisting of 6-, 7- or 8-glucose units, which are called alpha-, beta- or gamma-CDs, respectively. They have hydrophobic interior and hydrophilic exterior, and are widely being used as hosts for various organic molecules. The formation of CD inclusion complexes with a variety of dyes has continuously drawn our interests, since CDs are readily available and have ability to include dye molecules altering their properties. The present thesis covers the study of inclusion complexes of CDs and chromophore dyes, largely in two ways; rotaxane and pseudorotaxane. The stable rotaxane structure is achieved with the synthesis of dye rotaxane. The introduction of CD ring around azo chromophore provides a simple way to improve the solubility and stability of azo dye. We have shown that by incorporating proper compounds as a coupler, azo dye rotaxanes can be used as pH indicators and metal ion sensors. We have described the synthesis of novel acetylene dye rotaxane using the Pd-catalyzed reaction of Heck-Cassar-Sonogashira-Hagihara type. Its fluorescence properties in the solid state as well as in solutions are examined and compared with those of free dye. Free dye, which has tetra-carboxylic groups, is found to be highly sensitive to various metal ions, exhibiting high Stern-Volmer constants, K(SV). On the contrary, acetylene dye rotaxane exhibits much less quenching against various quenchers. The appearance of fluorescent anisotropic structure has been observed by the formation of inclusion complex between acetylene dye and gamma-CD. Its structural nature is studied by various techniques, including fluorescence, fluorescence anisotropy, wide angle X-ray scattering (WAXD) and differential scanning calorimetry (DSC) measurements. Methyl orange, an acid azo dye, forms a dimeric inclusion complex with gamma-CD, resulting in the formation stable anisotropic aggregates. Several other azo dyes are found to form anisotropic supramolecule in the presence of gamma-CD, and their structural characteristic has been discussed in terms of the number and position of solubilizing groups.
105

Synthesis of Heptakis-2-O-Sulfo-Cyclomaltoheptaose, a Single-Isomer Chiral Resolving Agent for Enantiomer Separations in Capillary Electrophoresis

Tutu, Edward 2010 December 1900 (has links)
Single-isomer sulfated cyclodextrins (SISCDs) have proven to be reliable, effective, robust means for separation of enantiomers by capillary electrophoresis (CE). SISCD derivatives used as chiral resolving agents in CE can carry the sulfo groups either at the C2, C3 or C6 positions of the glucopyranose subunits which provides varied intermolecular interactions to bring about favorable enantioselectivities. The first single-isomer, sulfated β-CD that carries the sulfo group at the C2 position, the sodium salt of heptakis(2-O-sulfo-3-O-methyl-6-Oacetyl) cyclomaltoheptaose (HAMS) has been synthesized. The purity of each synthetic intermediate and of the final product was determined by HILIC and reversed phase HPLC. The structural identity of each intermediate and the final product was verified by 1D, and 2D NMR, and MALDI-TOF mass spectrometry. HAMS has been used as chiral resolving agent for the CE separation of a set of nonionic, weak base and strong acid enantiomers in pH 2.5 background electrolytes. Rapid separations with satisfactory peak resolution values were obtained for the enantiomers of most of the nonionic and weak base analytes. Typically, low concentrations of HAMS were required to effect good enantiomer resolution. The trends in the effective mobilities and separation selectivities as a function of HAMS concentrations followed the predictions of the ionic strength-corrected charged resolving agent migration model (CHARM model). HAMS showed poor complexation with the anionic strong electrolyte enantiomers for which no peak resolution was observed. The separation patterns observed with HAMS as chiral resolving agent were compared with those of other β-cyclodextrin analogues, including heptakis(2-O-methyl- 3-O-acetyl-6-O-sulfo)-b-cyclodextrin (HMAS), heptakis(2-O-methyl-3,6-di-O-sulfo)-b- cyclodextrin (HMdiSu), heptakis(2,3-di-O-acetyl-6-O-sulfo)-b-cyclodextrin (HDAS) and heptakis(2,3-di-O-methyl-6-O-sulfo)-b-cyclodextrin (HDMS).
106

Cholesterol metabolism in the Niemann-Pick Type C brain

Peake, Kyle Unknown Date
No description available.
107

Host-guest dynamics for three different host systems: cucurbit[7]uril, β-cyclodextrin and octa acid capsule

Tang, Hao 07 September 2011 (has links)
Supramolecular systems, which are formed by the noncovalent intermolecular interactions between molecules, are highly dynamic. The high reversibility of supramolecular systems leads to some functional features that cannot be achieved by the single chemical component. The kinetic information for the supramolecular systems can not be inferred from thermodynamic studies or structural studies. Furthermore, the information provided by the dynamic study can be employed to infer or explain the results from the thermodynamic study and the structural study. The first objective of this work was to study the dynamics and the binding mechanism of cucurbit[7]uril with a charged guest molecule (2-naphthyl-1-ethylammonium cation, NpAmH+). In general, the binding affinity of cucurbit[7]uril to the positively charged guests are very high compared with other host systems such as cyclodextrins and bile salt aggregates. In this work, the complexation of cucurbit[7]uril and NpAmH+ was studied from a kinetic point of view. Results showed that the high binding affinity of cucurbit[7]uril to NpAmH+ was due to the high association rate constant and the low dissociation rate constant for the complexation of cucurbit[7]uril and NpAmH+. Moreover, the competition between co-cations and NpAmH+ for the binding sites of cucurbituril molecules retarded the complexation process for cucurbit[7]uril binding to NpAmH+ and decreased the overall equilibrium constant for the formation of cucurbit[7]uril-NpAmH+ complex. The second objective of this work was to study the chiral recognition observed for the formation of 2:2 complexes between β-cyclodextrin and 2-naphthyl-1-ethanol (NpOH). The binding of β-cyclodextrin and NpOH leads to the formation of two 1:1 complexes and three 2:2 complexes. The binding dynamics of NpOH with β-cyclodextrin in the 1:1 complex is fast and occurs within microseconds. A much slower dynamics was observed for the formation of the 2:2 complex. Results showed that more 2:2 complex were formed for (R)-NpOH than for (S)-NpOH, which is due to the difference of the dissociation rate constant of the 2:2 complex for both NpOH enantiomers. The dissociation rate constant of the 2:2 complex for (R)-NpOH is 46.8% lower than that for (S)-NpOH while the association rate constant of the 2:2 complex are similar for both NpOH enantiomers. The third objective of this work was to study the dynamics and the binding mechanism of octa acid with pyrene. As known from the work of other researchers, the accessibility of small molecules (e.g. I- or O2) to pyrene bound to octa acid is largely limited by the octa acid capsule. In this study, a two-step successive process was observed for the complexation of octa acid and pyrene. The first step, which was related to the formation of octa acid-pyrene 1:1 complex, was sufficiently fast to be viewed as a pre-equilibrium process. The second step, which was related to the formation of octa acid-pyrene 2:1 complex, was slow on the millisecond – second time scale. The high binding affinity of octa acid to pyrene was observed, which is due to the low dissociation rate constant for the octa acid-pyrene 2:1 complex. / Graduate
108

Skystų oftalmologinių sistemų modeliavimas / Ophthalmic liquid systems design

Jarošaitė, Roberta 18 June 2014 (has links)
Darbo tikslas – sumodeliuoti skystą oftalmologinę hidrofilinę sistemą su numatytais fizikocheminiais rodikliais ir įvertinti modelinės medžiagos – natrio diklofenako atpalaidavimą biofarmaciniu metodu in vitro. / Objective of work: to design liquid hydrophilic ophthalmic system with provided physicochemical characteristics and determine the release of the model material - sodium diclofenac in vitro.
109

Beta-cyclodextrin modification and host-guest complexation.

Pham, Duc-Truc January 2008 (has links)
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. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1311237 / Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2008
110

Beta-cyclodextrin modification and host-guest complexation.

Pham, Duc-Truc January 2008 (has links)
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. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1311237 / Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2008

Page generated in 0.0298 seconds