Jozef Hodyl PhD Thesis - Theses - Flinders University

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percent inclusion with the pK a values for each set of benzoate guest molecules it isclear that the hydroxy groups are having some effect on the binding mode in aqueousconditions. This inclusion study with methoxybenzoate guests, which was conductedunder identical conditions to the previous study with hydroxybenzoate guests,demonstrates the proposition that non-classical hydrogen bonding interactionscontribute to host-guest binding strength only in the presence of water.Another question that could be asked with regard to the studies withhydroxybenzoate and methoxybenzoate guests is why p-methoxybenzoate uptake isca. double that of p-hydroxybenzoate. Obviously, there is something other thanhydrogen bonding contributing to the increase in percent inclusion for p-methoxybenzoate as their pK a values are similar. The discrepancy observed could bethe result of a hydrophobic effect driving the p-methoxybenzoate molecule into thecavity of receptor 94, and away from the aqueous surroundings, as its methoxy groupis less hydrophilic than the hydroxy group of p-hydroxybenzoate. Conversely, thehydroxy group of p-hydroxybenzoate could be drawing it out of the cavity ofreceptor 94 by a hydrophilic effect. A lesser rendering of these hydrophobic andhydrophilic effects could describe the decrease in difference between percentinclusion values of m-methoxybenzoate and m-hydroxybenzoate since thesubstituents on these molecules are in the neighbourhood of the boundary dividingthe interior and exterior regions of the host cavity.Hydroxybenzoate guest species with various other substitution patterns were alsoused in these inclusion studies to see if any variation in the location of the hydroxysubstituent would affect binding with receptor 94. The guest molecules chosen were2,5-dihydroxybenzoate, 3,5-dihydroxybenzoate, 2,4,6-trihydroxybenzoate and 3,4,5-trihydroxybenzoate (gallate). Table 6.4 displays the percent inclusion values for103
these guest molecules with receptor 94.Table 6.4Percent guest inclusion of different hydroxybenzoate guest species with Si-GPS-[Cd(Trac)](ClO 4 ) 2 , 94, in aqueous solution with a guest concentration of 5 x 10 -3 mol dm -3at pH 7 in 0.01 mol dm -3 HEPES buffer at 298 K.Guest Species % InclusionapK a2,4,6-trihydroxybenzoate 94 1.682,5-dihydroxybenzoate 82 2.953,5-dihydroxybenzoate 50 4.043,4,5-trihydroxybenzoate 73 4.41a Values obtained in H 2 O from PHYSPROP database for their respective conjugate acids. 202High inclusion values for 2,5-dihydroxybenzoate and 2,4,6-trihydroxybenzoatefurther demonstrate that having hydroxy groups in the ortho position increasesbinding strength through hydrogen bonding interactions with the host pendant arms.The relatively high inclusion value for 3,4,5-trihydroxybenzoate is a little surprisingin that this guest molecule not only lacks a hydroxy group in the ortho position, butin that both of the meta hydroxy groups are not equally available for hydrogenbonding due to one being intramolecularly hydrogen bonded with the para hydroxygroup. This effectively leaves only one hydroxy group to form a hydrogen bond withthe host aromatic group. Some compensation by stronger bonding through thebenzoate moiety due to its higher basicity (pK a = 4.41) is suggested.6.1.4 Guest inclusion with immobilised hydroxy terminated polyether (HTPE)receptorsDue to the organic nature and hence low wettability in water of the receptorcomponent of Si-GPS-[Cd(Trac)](ClO 4 ) 2 , 94, it was thought that a receptor moietywith hydrophilic groups attached to its pendant arm framework would provide better104
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Silica Immobilised MetalIon Activat
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ABSTRACTImmobilisation of functiona
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DECLARATIONI certify that this thes
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EtOHGPDMSGPDMESGPSGPTSethanolglycid
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CHAPTER ONEINTRODUCTION
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The focus of this work was to prepa
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sequestering anions has proved to b
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ange of pH due to its high basicity
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nitrophenol or p-nitrophenolate wit
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It has been shown by NMR and crysta
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within the cavity of a p-tert-butyl
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60 in 0.5% DMSO-MeCN (v/v). 82 The
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synthesised bi- tri- and tetra - π
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adopt a trans-III conformation, whe
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amide oxygen atoms on the pendant a
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apparent there is, nonetheless, evi
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However, hetero-N-substitution on t
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Si-OH +- OH SiO - + H 2 OFor surfac
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35This material was obtained with a
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OOSiOHOROR OSiOHOOOSiOSiOSiOSiOSiOS
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Tetraaza metal complexes immobilise
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CHAPTER TWOSYNTHESIS OF MACROCYCLIC
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In addition, successful immobilisat
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3233Figure 2.3Reaction of 3-(glycid
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The methodology chosen was adapted
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agreed with literature values. 109R
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XS HO O H61, n = 262, n = 3n+ClOSO6
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anhydrous ethanol, Scheme 2.7. The
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75Figure 2.5 Structure of (S)-(-)-p
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metal ion coordination the pendant
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CHAPTER THREEGUEST MOLECULE INCLUSI
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3.1 where K A is the association, o
Page 67 and 68: 0.5cχG∆δ∆δGbaχ GFigure 3.1S
Page 69 and 70: χG∆δ∆δGFigure 3.4 Job's Plot
Page 71 and 72: The downfield movement of the guest
Page 73 and 74: arm framework. The relative magnitu
Page 75 and 76: This phenomenon correlates well wit
Page 77 and 78: non-classical hydrogen bonding is g
Page 79 and 80: The full set of logK values obtaine
Page 81 and 82: such that they would indicate precl
Page 83 and 84: CHAPTER 4MODIFICATION OF THE SILICA
Page 85 and 86: Chemical modification of the silica
Page 87 and 88: GPTSGPDMESFigure 4.4Schematic depic
Page 89 and 90: GPS, 33, linker material with an ex
Page 91 and 92: free νOHτSiOHνSi-O-SiδH 2 Oasym
Page 93 and 94: 224, 225the surface silanol groups.
Page 95 and 96: esonances, the spectrum for Si-GPS-
Page 97 and 98: increase in surface coverage from t
Page 99 and 100: and, more so due to the larger size
Page 101 and 102: CHAPTER 5METAL ION UPTAKE STUDIES W
Page 103 and 104: Scheme 5.1 Metal(II) ion coordinati
Page 105 and 106: linker material, Si-GPS, 33; endcap
Page 107 and 108: [Cd(Trac)](ClO 4 ) 2 , 94, or Si-GP
Page 109 and 110: CHAPTER 6GUEST MOLECULE INCLUSION S
Page 111 and 112: and D-histidinate. Guest inclusion
Page 113 and 114: Table 6.2Percent inclusion data for
Page 115 and 116: contains two hydroxy groups in the
Page 117: methoxy group, as portrayed by the
Page 121 and 122: only about half of that taken up by
Page 123 and 124: Percent inclusion values for these
Page 125 and 126: Table 6.7Percent guest inclusion of
Page 127 and 128: 6.1.7 Guest inclusion studies with
Page 129 and 130: A1 3542Neutral GuestBAnionic GuestH
Page 131 and 132: A1 46 7532 Anionic Guest8BCHostHost
Page 133 and 134: extent, meta-positioned hydroxy gro
Page 135 and 136: δ obs (ppm)6.2146.2136.2126.2116.2
Page 137 and 138: CHAPTER 7EXPERIMENTAL7.1 General Ex
Page 139 and 140: inding constants (logK values) and
Page 141 and 142: delay time of 4 s. 13 C CPMAS NMR s
Page 143 and 144: C, -CH 2 - CH 2 OSO 2 ); 68.11 (1 C
Page 145 and 146: A solution of 69 (2.00 g, 10.1 mmol
Page 147 and 148: Bn, meta); 127.79 (1 C, Bn, para);
Page 149 and 150: added in a single portion. The mixt
Page 151 and 152: dioxane): δ 158.67 (1 C, C=O); 135
Page 153 and 154: 1-(benzyloxycarbonyl)-4,7,10-tris-(
Page 155 and 156: 1,4,7-tris-((S)-2-hydroxy-3-phenoxy
Page 157 and 158: 1,4,7-tris(S)-2-hydroxy-3-[4-((2-(2
Page 159 and 160: 1,4,7-tris(S)-2-hydroxy-3-[4-(2-(2-
Page 161 and 162: 1-(2-hydroxypropyl)-4,7,10-tris-((S
Page 163 and 164: 7.11 Preparation of the silica mate
Page 165 and 166: To a suspension of 33 (1.48 g, 1.1
Page 167 and 168: gel-like suspension that was cooled
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Si-GPS-Tri-Trac, 4545The title comp
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APPENDIX ABINDING CONSTANT DETERMIN
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1.01000.880δ obs (ppm)0.60.4logK =
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APPENDIX BDETERMINATION OF STOICHIO
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0.5χG∆δGFigure B.2χ GSimulated
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13 C CPMAS NMR SPECTRA OF SOME HIGH
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Si-GPS-[Cd(Trac)(2,5-diydroxybenzoa
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REFERENCES
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15. D. Tzalis and Y. Tor, Tetrahedr
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42. A. P. Davis and R. S.Wareham, A
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69. R. J. Bergeron, M. A. Channing
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93. C. B. Smith, A. K. W. Stephens,
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118. D. D. Dischino, E. J. Delaney,
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144. X. Huang, X. Chang, Q. He, Y.
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169. J. M. Klunder, T. Onami and K.
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197. K. A. Connors, Binding Constan
Page 201 and 202:
221. J. Blumel, J. Am. Chem. Soc.,
Page 203:
247. W. Likussar and D. F. Botz, An
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Jozef Hodyl PhD Thesis - Theses - Flinders University

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